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1
Трушляков, Євген Іванович, Андрій Миколайович Радченко, Микола Іванович Радченко, Сергій Анатолійович Кантор та Веніамін Сергійович Ткаченко. "ПІДВИЩЕННЯ ЕФЕКТИВНОСТІ КОНДИЦІЮВАННЯ ЗОВНІШНЬОГО ПОВІТРЯ СИСТЕМИ КОМБІНОВАНОГО ТИПУ". Aerospace technic and technology, № 4 (31 серпня 2019): 9–14. http://dx.doi.org/10.32620/aktt.2019.4.02.
Повний текст джерелаАнотація:
One of the most attractive reserves of enhancing the energetic efficiency of air conditioning systems is to provide the operation of refrigeration compressors in nominal or close to nominal modes by choosing rational design cooling loads (cooling capacities) and their distribution according to a cooling load behaviour within the overall design (installed) cooling load band to match current changeable climatic conditions and provide close to maximum annual cooling capacity generation according to cooling duties. The direction of increasing the efficiency of outdoor air conditioning in combined central-local type systems by rationally distributing the heat load - cooling capacity of the central air conditioner into zones of variable heat load in accordance with current climatic conditions and its relatively stable value, i.e. cooling capacity required for further air cooling at the entrance to the indoor recirculation air conditioning system is justified. By comparing the values of the excessive production of cold and its deficit within every 3 days for a rational design heat load of the air conditioning system (cooling capacity of the installed refrigeration machine), which provides close to maximum annual production of cold, and the corresponding values of the excess and deficit of cooling capacity in accordance with current climatic conditions during July substantiated the feasibility of accumulating the excess of cooling capacity of a central air conditioner at low current loads and its use for covering cooling deficit at elevated heat loads through pre-cooling the outdoor air. It is developed a scheme of a combined central-local air conditioning system, which includes the subsystems for the outdoor air conditioning in a central air conditioner and the local indoor recirculated air conditioning.
2
Трушляков, Євген Іванович, Микола Іванович Радченко, Андрій Миколайович Радченко, Сергій Георгійович Фордуй, Сергій Анатолійович Кантор, Веніамін Сергійович Ткаченко та Богдан Сергійович Портной. "ПІДВИЩЕННЯ ЕФЕКТИВНОСТІ СИСТЕМ КОНДИЦІЮВАННЯ ПОВІТРЯ ШЛЯХОМ РОЗПОДІЛУ ТЕПЛОВОГО НАВАНТАЖЕННЯ ЗА СТУПЕНЕВИМ ПРИНЦИПОМ". Aerospace technic and technology, № 8 (31 серпня 2019): 49–53. http://dx.doi.org/10.32620/aktt.2019.8.07.
Повний текст джерелаАнотація:
Maintaining the operation of refrigeration compressors in nominal or close modes by selecting a rational design thermal load and distributing it in response to the behavior of the current thermal load according to the current climatic conditions is one of the promising reserves for improving the energy efficiency of air conditioning systems, which implementation ensures maximum or close to it in the annual cooling production according to air conditioning duties. In general case, the total range of current thermal loads of any air-conditioning system includes a range of unstable loads caused by precooling of ambient air with significant fluctuations in the cooling capacity according to current climatic conditions, and a range of relatively stable cooling capacity expended for further lowering the air temperature from a certain threshold temperature to the final outlet temperature. If a range of stable thermal load can be provided within operating a conventional compressor in a mode close to nominal, then precooling the ambient air with significant fluctuations in thermal load requires adjusting the cooling capacity by using a variable speed compressor or using the excess of heat accumulated at reduced load. Such a stage principle of cooling ensures the operation of refrigerating machines matching the behavior of current thermal loads of any air-conditioning system, whether the central air conditioning system with ambient air procession in the central air conditioner or its combination with the local indoors recirculation air conditioning systems in the air-conditioning system. in essence, as combinations of subsystems – precooling of ambient air with the regulation of cooling capacity and subsequent cooling air to the mouth of the set point temperature under relatively stable thermal load.
3
Трушляков, Євген Іванович, Андрій Миколайович Радченко, Микола Іванович Радченко, Сергій Георгійович Фордуй, Сергій Анатолійович Кантор та Богдан Сергійович Портной. "МЕТОДОЛОГІЧНІ ПІДХОДИ ДО ВИЗНАЧЕННЯ ХОЛОДОПРОДУКТИВНОСТІ СИСТЕМ КОНДИЦІЮВАННЯ ПОВІТРЯ ЗА ЗМІННИХ КЛІМАТИЧНИХ УМОВ". Aerospace technic and technology, № 7 (31 серпня 2019): 71–75. http://dx.doi.org/10.32620/aktt.2019.7.09.
Повний текст джерелаАнотація:
One of the most attractive reserves for improving the energy efficiency of air conditioning systems is to ensure the operation of refrigeration compressors in nominal or close to nominal modes by selecting a rational design heat load and distributing it within its design value according to the behavior of the current heat load under variable current climatic conditions to provide the maximum or close to maximum annual cooling capacity generation according to cooling duties of air conditioning. In the general case, the overall range of current thermal loads of any air conditioning system includes a range of unstable loads associated with the precooling of ambient air with significant fluctuations in cooling capacity according with current climatic conditions, and a relatively stable range of cooling capacity consumed to further reduce air temperature from a certain threshold temperature to the final outlet temperature. It is quite obvious that a stable range of heat load can be ensured within operating a conventional compressor in a mode close to the nominal mode while precooling the ambient air with significant fluctuations in heat load requires regulation of the cooling capacity through the use of a variable speed compressor. Thus, in response of the behavior of the change in current heat loads, any air conditioning system, whether the central air-conditioning system with its heat procession in a central air conditioner, or a combination thereof with a local recirculation system of indoor air, essentially consists of two subsystems: pre-cooling the ambient air and then cooling it to the set point temperature. The proposed method of distribution of design heat load depending on the behavior of the current heat load is useful for the rational design of central air conditioning systems and their combined versions with the local air conditioning system.
4
Радченко, Андрій Миколайович, Євген Іванович Трушляков, Сергій Анатолійович Кантор та Богдан Сергійович Портной. "ВИЗНАЧЕННЯ РАЦІОНАЛЬНОГО ТЕПЛОВОГО НАВАНТАЖЕННЯ ГРАДИРЕНЬ ВІДВЕДЕННЯ ТЕПЛОТИ У ПРОЦЕСАХ КОНДИЦІЮВАННЯ ПОВІТРЯ НА ВХОДІ ЕНЕРГОУСТАНОВОК". Aerospace technic and technology, № 5 (8 листопада 2018): 19–22. http://dx.doi.org/10.32620/aktt.2018.5.03.
Повний текст джерелаАнотація:
The air conditioning processes (heat-humidity treatment) at the inlet of energy units by heat-energized refrigeration mechanisms with heat removal cooling towers of the cooling system are studied on the example of a gas turbine unit. Two-stage air cooling is considered applying a two-stage combined type heat-energized refrigeration mechanism, which applies the exhaust gas heat of a gas turbine unit and which includes absorption lithium-bromide and refrigerant ejector refrigeration mechanism as steps to convert waste heat into cold. Based on the results of modeling the operation of the cooling complex of a gas turbine unit, data was obtained on current heat loads on heat-energized refrigeration mechanisms and cooling towers in accordance with the climatic conditions of operation with different distribution of project heat loads on the air cooling stages and, accordingly, on the transformation of waste heat into cold. Due to the fact that the heat load on the cooling towers depends on the efficiency of transformation of waste heat into cold (heat coefficients) by absorption lithium-bromide and refrigerant ejector refrigeration mechanisms, a rational distribution of the project heat loads to the absorption and ejector stages of a combined type heat-energized refrigeration mechanisms that provides reduce heat load on cooling towers. It is demonstrated that due to this approach to determining the rational heat load on the cooling towers of the cooling system, which consists of calculation the redistribution of heat load between the absorption lithium-bromide and refrigerant ejector cooling stages with different efficiency and transformation of waste heat (different heat coefficients) in accordance with current climate conditions, is possible to minimize the number of cooling with a corresponding reduction in capital expenditures on the air conditioning system at the inlet of gas turbine unit
5
Портной, Богдан Сергійович, Андрій Миколайович Радченко, Роман Миколайович Радченко та Сергій Анатолійович Кантор. "ВИКОРИСТАННЯ РЕЗЕРВУ ХОЛОДОПРОДУКТИВНОСТІ АБСОРБЦІЙНОЇ ХОЛОДИЛЬНОЇ МАШИНИ ПРИ ОХОЛОДЖЕННІ ПОВІТРЯ НА ВХОДІ ГТУ". Aerospace technic and technology, № 3 (27 червня 2018): 39–44. http://dx.doi.org/10.32620/aktt.2018.3.05.
Повний текст джерелаАнотація:
The processes of air cooling at the gas turbine unit inlet by absorption lithium-bromide chiller have been analyzed. The computer programs of firms-producers of heat exchangers were used for the gas turbine unit inlet air cooling processes simulation. The absorption lithium-bromide chiller refrigeration capacity reserve (the design heat load excess over the current heat loads) generated at the reduced current heat loads on the air coolers at the gas turbine unit inlet in accordance with the lowered ambient air parameters has been considered. The absorption lithium-bromide chiller refrigeration capacity reserve is expedient to use at increased heat load on the air cooler. To solve this problem the refrigeration capacity required for cooling air at the gas turbine unit inlet has been compared with the excessive absorption lithium-bromide chiller refrigeration capacity exceeding current heat loads during July 2017.The scheme of gas turbine unit inlet air cooling system with using the absorption lithium-bromide chiller refrigeration capacity reserve has been proposed. The proposed air cooling system provides gas turbine unit inlet air precooling in the air cooler booster stage by using the absorption lithium-bromide chiller excessive refrigeration capacity. The absorption chiller excessive refrigeration capacity generated during decreased heat loads on the gas turbine unit inlet air cooler is accumulated in the thermal storage. The results of simulation show the expediency of the gas turbine unit inlet air cooling by using the absorption lithium-bromide chiller refrigeration capacity reserve, which is generated at reduced thermal loads, for the air precooling in the air cooler booster stage. This solution provides the absorption lithium-bromide chiller installed (designed) refrigeration capacity and cost reduction by almost 30%. The solution to increase the efficiency of gas turbine unit inlet air cooling through using the absorption chiller excessive refrigeration potential accumulated in the thermal storage has been proposed.
6
Mahmoud, Rana M., Mohsen Sharifi, Eline Himpe, Marc Delghust, and Jelle Laverge. "Estimation of load duration curves from general building data in the building stock using dynamic BES-models." E3S Web of Conferences 111 (2019): 01078. http://dx.doi.org/10.1051/e3sconf/201911101078.
Повний текст джерелаАнотація:
Modelling and simulation of building stock is a valuable source of information for investigating the feasibility of implementing new heating and cooling system technologies. Some of these technologies have oversizing problem as the designers rely on their experience and previous knowledge. Building stock modelling can provide a solution for more accurate designing process. However, some of the current building stock modelling methods uses a representative building which can exclude whole ranges of the different combinations of building geometry and physical properties that can be crucial for heating and cooling load estimation. Therefore, we developed a methodology that allows faster and accurate building energy simulation (BES) multizone models from general building information of the whole building stock that is able to estimate load duration. This will help engineers and designers to decide on the system sizing at the early design stages. This paper presents first, the process of generating dynamically heating and cooling load duration curves by using BES-models from general geometrical data of the building stock. Second, we examine the process on a sample of the building stock where geometrical and physical parameters were varied. The workflow of the process has worked successfully, generating heating and cooling duration curves for 14 case studies. We observed that heating and cooling loads are highly influenced by different combinations of parameters. High glazing percentage affects highly the heat losses, thus more heating loads. Besides, for a west oriented building, the high glazing percentage combined with high internal gains can be the reason for significant cooling loads. In next steps, we are going to extend the current methodology to cover different building typologies within different climates across Europe.
7
Радченко, Андрій Миколайович, Ян Зонмін, Микола Іванович Радченко, Сергій Анатолійович Кантор, Богдан Сергійович Портной та Юрій Георгійович Щербак. "ВИЗНАЧЕННЯ ВСТАНОВЛЕНОЇ ХОЛОДОПРОДУКТИВНІСТІ СИСТЕМИ ОХОЛОДЖЕННЯ ПОВІТРЯ НА ВХОДІ ГАЗОТУРБІННОЇ УСТАНОВКИ ЗА ПОТОЧНИМ ТЕПЛОВИМ НАВАНТАЖЕННЯМ". Aerospace technic and technology, № 2 (22 квітня 2019): 56–60. http://dx.doi.org/10.32620/aktt.2019.2.07.
Повний текст джерелаАнотація:
Significant fluctuations of the current temperature and relative humidity of the ambient air lead to significant changes in the thermal load on the cooling system at the inlet of gas turbine units (GTU), which acutely raises the problem of choosing their installed (design) thermal load. Calculations of ambient air cooling processes were carried out for different climatic conditions, for example, southern Ukraine (Mykolaiv) and Central China (Beijing). It is analyzed two methods of determination of the installed (design) cooling capacity of the ambient air cooling system at the GTU inlet according to the maximum current reduction of fuel consumption and according to the maximum rate (increase) of annual reduction of fuel consumption following to increasing of the installed cooling capacity, calculated by summarizing the current values of fuel consumption reduction. It is shown that the values of the installed cooling capacity of the air cooling system at the GTU inlet, determined by both methods, are close enough but differ significantly for different climatic conditions. The advantage of the method of calculating the installed cooling capacity of the air cooling system at the GTU inlet according to the maximum rate of annual reduction in fuel consumption is the possibility of a more precise definition of it due to the absence of significant fluctuations in the annual reduction in fuel consumption, calculated by summarizing the current values of fuel consumption reduction. Since the maximum reduction in fuel consumption per year is achieved with some decrease in the rate of its increment at high values of the design cooling capacity, required in the hottest hours in the summer and excessive in somewhat cool periods (at night and in the morning even in the summer), the installed cooling capacity, determined according to the maximum rate of the reduction of fuel consumption, will be insufficient in times of increased thermal loads above their design value. In such cases, the elimination of the deficit in cooling capacity is possible by using an excess of cold accumulated during reduced thermal loads
8
Радченко, Роман Николаевич. "ПОЛУЧЕНИЕ КОНДЕНСАТА КАК СОПУТСТВУЮЩЕГО ПРОДУКТА ОХЛАЖДЕНИЯ ВОЗДУХА НА ВХОДЕ ГАЗОТУРБИННОЙ УСТАНОВКИ". Aerospace technic and technology, № 1 (25 лютого 2018): 59–63. http://dx.doi.org/10.32620/aktt.2018.1.06.
Повний текст джерелаАнотація:
The processes of gas turbine unit inlet air cooling with generation of condensate as a subproduct were investigated. The heat-humidity processes in the two-stage air cooler of combined type with the first low temperature cooling stage were water with temperature of about 7 °C as a coolant for precooling air from the changeable ambient temperature to the temperature not lower than 15 °C is used and low temperature cooling stage with a refrigerant boiling at the temperature of 2-4 °C as a coolant for further deep cooling air to the temperature of about 10 °C by utilizing the exhaust gas waste heat in the absorption lithium-bromide chiller as the high temperature cooling stage and refrigerant ejector chiller as the low temperature cooling stage of the combined thermotransformer has been analyzed for daily changing ambient air temperatures and heat loads on the stages as consequence. The processes of generating the condensate as a subproduct of gas turbine unit intake air two-stage cooling were simulated by using the computer simulation programs of the firms-producers of heat equipment for more than twice decreased heat load upon the high temperature cooling stage as compared with a heat load upon the low temperature cooling stage. The data about amount of condensate extracted in each air cooler stage was summed up over a day, three days and July and its temperature was calculated. The results of calculation have shown that the temperature of condensate received in the refrigerant low temperature cooling stage are lower by about 4 °C as compared with its value for high temperature cooling stage with a chilled water temperature of 7 °C from absorption lithium-bromide chiller. It was also shown that inspite of intensive changeable current temperatures of condensate from each and both stages mean weighted values of temperature of condensate from both stages of a combined two-stage air cooler remained nearly unchangeable during days. A conclusion about using the condensate from low temperature cooling stage as a coolant has been made
9
Трушляков, Євген Іванович, Андрій Миколайович Радченко, Микола Іванович Радченко, Ян Зонмін, Анатолій Анатолійович Зубарєв та Веніамін Сергійович Ткаченко. "ХОЛОДОПРОДУКТИВНІСТЬ СИСТЕМИ КОНДИЦІЮВАННЯ ЗОВНІШНЬОГО ПОВІТРЯ ЗА ПОТОЧНИМ ТЕПЛОВИМ НАВАНТАЖЕННЯМ". Aerospace technic and technology, № 2 (22 квітня 2019): 51–55. http://dx.doi.org/10.32620/aktt.2019.2.06.
Повний текст джерелаАнотація:
The efficiency of the outdoor air conditioning systems application depends on how full the installed cooling capacity is applied, that is, with a more complete load and for as long as the possible yearly duration in actual climatic conditions. The production of cold is taken as a criteria of a quantitative evaluation of the efficiency of applying the cooling capacity of air conditioning systems – the amount of cold produced in accordance with its current demand for air conditioning, which in turn depends on the current consumption of cooling capacity and its duration and equals to their multiplication. It is obvious that the maximum value of the current amount of cold produced/consumed indicates an effective application of the installed cooling capacity. However, since the current demands of cooling capacity and their duration, that is, the amount of cold produced/consumed, depending on the changing current climatic conditions, they are characterized by significant fluctuations, which makes it difficult to choose the installed cooling capacity of the air conditioning system. Obviously, if we determine the amount of cold produced/consumed by its current values and summarized during the year, it is possible to significantly simplify the choice of the installed cooling capacity. At the same time, the current amount of cold produced/consumed causes a change in the rate of increment of the annual cold production with a change in the installed cooling capacity, and the maximum rate corresponds to the installed cooling capacity, which provides its efficient use. Proceeding from a different rate of increment of annual cold production with an increase in the installed cooling capacity of the air conditioning system due to a change in heat load in accordance with current climatic conditions during the year, the value of design heat load on the air conditioning system (installed cooling capacity) that provides maximum or close to it the rate of increment of the annual production of cold, and hence the maximum efficient use of installed cooling capacity is chosen
10
Ruiz-Ortega, Pablo, and Miguel Olivares-Robles. "Peltier Supercooling in Transient Thermoelectrics: Spatial Temperature Profile and Characteristic Cooling Length." Entropy 21, no. 3 (February 27, 2019): 226. http://dx.doi.org/10.3390/e21030226.
Повний текст джерелаАнотація:
Thermoelectric coolers (TECs) can reach temperatures below that obtained with a steady-state current by applying an electrical current pulse which enables a transitory state in a Peltier device. This effect is known as supercooling. In this paper, we study characteristics parameters, such as the minimum cooling temperature and spatial temperature profile, in a TEC operated under current pulses and a cooling load ( Q c ) . Numerical analysis for a one-dimensional thermoelectric model of the cooling system is developed, and a novel MATLAB programming code is proposed for the transient state based on finite element analysis. We also investigate the influence of the thermoelement’s length upon the cooling mechanism. A new parameter called the “characteristic cooling length” is proposed to describe the length in which the minimum cooling temperature occurs along the elements of a TEM. Results show the transient temperature profiles along the elements of the semiconductor P-type element, and a “characteristic cooling length” is characterized. We also propose a general principle, and the lowest cooling temperature values are obtained for a semiconductor’s small length and variable pulse cooling load under current pulse operation. The present study will serve as guidance for the geometric design of TECs under current pulse operations.
11
Радченко, Андрій Миколайович. "МЕТОД ВИЗНАЧЕННЯ ХОЛОДОПРОДУКТИВНОСТІ ТЕРМОТРАНСФОРМАТОРА ЗА МАКСИМАЛЬНИМ ТЕМПОМ ПРИРОЩЕННЯ ТЕРМОЧАСОВОГО ПОТЕНЦІАЛУ ОХОЛОДЖЕННЯ ПОВІТРЯ". Aerospace technic and technology, № 4 (14 жовтня 2018): 53–57. http://dx.doi.org/10.32620/aktt.2018.4.07.
Повний текст джерелаАнотація:
It is proved a possibility of using the thermohour cooling potential method, developed by the author, for defining the installed (design) refrigeration capacity of term transformer (refrigeration machine), providing a maximum rate of thermo-hour cooling potential increasing according to the current climatic conditions for a definite period of operation.It is proposed to define the effect, gained due to cooling air, in particular at the inlet of GTU, depends on duration and depth of cooling, by thermohour potential ÕS,°С·h, as air temperature decrease Δta multiplied by duration τ of GTU operation at decreased temperature: ÕS = ∑(Δta ∙°τ), which to some extent characterizes heat load on the cooling system.It is shown that taking into consideration a different rate of annual thermohour cooling potential arising with increasing the installed refrigeration capacity of term transformer, caused by changing the heat load according to current climatic conditions during a year, it is necessary to choose such design heat load on the air cooling system (refrigeration capacity of term transformer) that provides a maximum value of annual thermohour cooling potential or close it with relatively high rates of its increasing. To define the installed refrigeration capacity, providing a maximum rate of annual thermohour cooling potential increasing, it is analyzed the dependence of annual thermohour cooling potential related to the installed refrigeration capacity of term transformer, from the installed refrigeration capacity of term transformer. As a result of the investigation, it is proposed the method of defining the design heat load (installed refrigeration capacity) of term transformer with maximum rates of increasing thermohour cooling potential, as a further development of methodology of rational designing of them transformers for combustion engine inlet air cooling on the base of thermohour potential, developed by author
12
Afiq, Aiman Dahlan, Amirah Haziqah Zulkifli, Nasution Henry, Abdul Aziz Azhar, Mohd Rozi Mohd Perang, and Hishammudin Mohd Jamil. "Performance Study of Electric Compressor in Non-Electric Vehicle." Applied Mechanics and Materials 554 (June 2014): 464–68. http://dx.doi.org/10.4028/www.scientific.net/amm.554.464.
Повний текст джерелаАнотація:
The usage of electric compressor inside conventional non-electric vehicle is a new shifts in current vehicle air conditioning system which currently using belt-driven compressor to operate. The usage of belt-driven compressor causes the compressor speed to vary with engine speed rotation, which we cannot control. The usage of electric compressor to replace the belt-driven compressor makes the speed to be according to the cooling load and thus reducing engine load. The current research activity focuses on the development of electric compressor using direct current (DC) from vehicles battery to replace current belt-driven in vehicle air conditioning system. Performance study is focusing on temperature inside cabin, cooling capacity, compressor power consumption and coefficient of performance (COP). The DC compressor speed is varying at 1800, 2000, 2200, 2400, 2500 and 3000 rpm at internal heat load of 1000W with temperature set-point of 20°C. The system uses On/Off controller and compared to belt-driven compressor. The overall experimental results in better energy efficiency at the expense of lower cooling capacity.
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Alam, M. Kevin Rambang, Helmi Fitriawan, F. X. Arinto Setyawan, and Umi Murdika. "Design of Cooling and Heating Tool Using Thermoelectric Peltier Based On Arduino Uno." ELKHA 13, no. 1 (April 20, 2021): 41. http://dx.doi.org/10.26418/elkha.v13i1.44421.
Повний текст джерелаАнотація:
Cooler is an electronic device used to cool food and drinks. The current cooling system still uses refrigerants that can damage the ozone layer. The thermoelectric based cooling system can be used as an alternative since it produces sufficient temperature difference on both sides by considering its advantages that is more environmentally friendly. This research is aimed to design and built a cooling and heating system using a thermoelectric Peltier TEC 12715 based on microcontroller Arduino uno. This system uses the Peltier thermoelectric effects as coolant and warmer because it produces temperature difference on both sides. Based on this research, in the no load condition the system can produce a cold temperature of 21,3 ℃ and a hot temperature of 80,2 ℃ in the 40th minute of use. When given a load of 300 ml and 220 ml drink bottles, the system can produce a cold temperature of 22,2 ℃ and a hot temperature of 70,7 ℃ in the 40th minute of use. The TEC 12715 Peltier component used in this research produces the optimal temperature if a voltage of 12 volts and a current of 15 amperes are applied to each Peltier component. The designed system is able to operate repeatedly, properly, and continuously since it is directly connected to alternative current power which is common in households.
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Трушляков, Євген Іванович. "МЕТОДОЛОГИЧЕСКИЙ ПОДХОД К ЭНЕРГОСБЕРЕГАЮЩЕМУ ХЛАДОСНАБЖЕНИЮ СИСТЕМ КОНДИЦИОНИРОВАНИЯ ВОЗДУХА АДАПТАЦИЕЙ К ТЕКУЩИМ КЛИМАТИЧЕСКИМ УСЛОВИЯМ". Aerospace technic and technology, № 4 (14 жовтня 2018): 58–62. http://dx.doi.org/10.32620/aktt.2018.4.08.
Повний текст джерелаАнотація:
The methodological approach was suggested to define a rational heat load of the air conditioning system (ACS) with taking into consideration the current climatic conditions of operation. The proposed approach is based on the hypothesis of sharing the current changeable heat load on the relatively stable share as the basic one for choosing installed (designed) refrigeration capacity of the refrigeration machine, operating with high energy efficiency in nominal or similar modes, and unstable heat load, corresponding to ambient air precooling at changeable current temperatures. To prove the methodological approach to defining a rational heat load of the ACS was carried out the analysis of current values of heat loads of the refrigeration machine ACS during cooling ambient air from its changeable current temperature to the temperature of 10, 15 and 20 ºС . It is shown that due to the different rates of annular refrigeration capacity production increment to cover the current heat loads with increasing the installed refrigeration capacity of the refrigeration machine, caused by the changes in heat load according to current climatic conditions during all the year round, it is necessary to choose a such heat load on the refrigeration machine of ACS (its installed refrigeration capacity), that provides a maximum or similar annular refrigeration capacity production at relatively high rates of its increment. Therein, the value of heat load for ambient air precooling is calculated according to remained principle as the difference between the rational total heat load and its basic relatively stable share. The proposed method is useful for defining a basic installed refrigeration capacity of the refrigeration machine of ACS with the accumulation of excessive (unapplied) refrigeration capacity at lowered current heat loads on ACS and its application for ambient air precooling, that is for covering unstable heat load share on ACS
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Nurhalim, Riski, Gunarto Gunarto, Eko Sarwono, and Fuazen Fuazen. "Analisis Tingkat Efisiensi pada Sistem Pengkondisian Udara Gedung Auditorium di Universitas Muhammadiyah Pontianak." Creative Research in Engineering 1, no. 1 (January 17, 2021): 19. http://dx.doi.org/10.30595/cerie.v1i1.9215.
Повний текст джерелаАнотація:
Observing various events such as the angle of sunlight, measuring the temperature of the outer wall, various accessories available and the types of activities carried out. Then do the calculations with CLTD (Cooling Load Temperature Difference) method based on ASHRAE 1997. The results obtained are cooling loads from such as brick walls with plaster layers, glass, aluminum alloy roofs, concrete and ceramic floors, lamps, occupants, electronic equipment. and 1,500 maximum number of people in the Pontianak Muhammadiyah Auditorium Building was 349.772,358 Watt or 132,60 PK. The current installed air conditioner has a capacity of 40 PK, so it needs 92,6 PK PK more or 19 units of cooling equipment, each of which has a capacity of 5 PK so that cooling in the room is more efficient.
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Трушляков, Євген Іванович, Андрій Миколайович Радченко, Ян Зонмін, Анатолій Анатолійович Зубарєв та Веніамін Сергійович Ткаченко. "МЕТОД ВИЗНАЧЕННЯ ХОЛОДОПРОДУКТИВНОСТІ УСТАНОВОК КОНДИЦІЮВАННЯ ПОВІТРЯ КОМФОРТНОГО Й ЕНЕРГЕТИЧНОГО ПРИЗНАЧЕННЯ". Aerospace technic and technology, № 1 (7 березня 2019): 53–58. http://dx.doi.org/10.32620/aktt.2019.1.06.
Повний текст джерелаАнотація:
The efficiency of applying air conditioning units for comfort and energetics for a certain period, as well as any power plant, is determined by the effect obtained, primarily in the form of reducing fuel consumption over the year or increasing the production of electrical (mechanical) energy in the case of air conditioning at the heat engine inlet and by annual cold production as an indicator of the efficiency of using the cooling capacity of comfort air-conditioning plants. Since in both cases the effect depends on the duration and depth of cooling, it is quite justified to estimate it in the first approximation by the thermal hourly potential, which is the result of summation hour by hour of air temperature drops multiplied by duration of operation at a lowered temperature and, thus, takes into account current climatic conditions. Obviously, the realization of the cooling potential (air conditioning) of the ambient air depends on the installed (design) cooling capacity of the air conditioning units, which, in turn, must take into account the fluctuations in thermal loads in accordance with the current variable thermal and humidity parameters of the ambient air. Based on the different rates of the increment of the annual thermal hourly cooling potential with an increase in the installed cooling capacity of the air conditioning unit due to a change in the heat load in accordance with current climatic conditions during the year, it is necessary to choose such a design thermal load on the air conditioning unit (its installed cooling capacity) that ensures maximum or close to it the annual thermo-hour cooling potential at a relatively high rate of its increment, respectively, and the effect of cooling in the form of a decrease in fuel consumption per year in the case of air conditioning at the inlet of heat engine and annual cold production of comfort air conditioning units. It is shown that under the same climatic conditions during the year and the depth of ambient air cooling, the rational values of the design cooling capacity of air conditioning units for comfort and energy purposes are the same.
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Kumar, Micha, N. Alagumurthi, and K. Palaniradja. "Conjugated heat transfer analysis of gas turbine vanes using MacCormack's technique." Thermal Science 12, no. 3 (2008): 65–73. http://dx.doi.org/10.2298/tsci0803065k.
Повний текст джерелаАнотація:
It is well known that turbine engine efficiency can be improved by increasing the turbine inlet gas temperature. This causes an increase of heat load to the turbine components. Current inlet temperature level in advanced gas turbine is far above the melting point of the vane material. Therefore, along with high temperature material development, sophisticated cooling scheme must be developed for continuous safe operation of gas turbine with high performance. Gas turbine blades are cooled internally and externally. Internal cooling is achieved by passing the coolant through passages inside the blade and extracting the heat from outside of the blade. This paper focuses on turbine vanes internal cooling. The effect of arrangement of rib and parabolic fin turbulator in the internal cooling channel and numerical investigation of temperature distribution along the vane material has been presented. The formulations for the internal cooling for the turbine vane have been done and these formulated equations are solved by MacCormack's technique.
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Soeb, Md Janibul Alam, Md Shahid Iqbal, Md Abu Naser Mojumder, Muhammad Rashed Al Mamun, A. S. M. Shahjalal Atik, and Md Fahad Jubayer. "Electrical Power Generation System: Optimal Design for Medium-Load Industries with High-Rated Generators." European Journal of Engineering and Technology Research 6, no. 7 (December 23, 2021): 133–39. http://dx.doi.org/10.24018/ej-eng.2021.6.7.2686.
Повний текст джерелаАнотація:
The demand for electrical power is rapidly increasing due to the rise of industries in developing countries. Power generation stations are having troubles to strike a balance between demand and generation. In this situation, it is urged that appropriate remedial action be taken. Rising power demand can be met by designing an efficient electric power generation system which will also help lowering the generation cost. It is shown that while high rated electric power generators are connected in parallel the value of neutral current is rising and the cooling temperature is also increased. Here, the goal of this experimental work is to present a new model for designing an efficient power production system for average-load (ranging up to 8000 Amp, 440 V) industries to minimize the demand on centralized interconnected grid. A scheme is proposed with four generators (2500 kVA, 2000 kVA, 2000 kVA and 1250 KVA) in parallel and enough cooling arrangement is provided with minimal cost. The coolant temperature is maintained 61 °C to 61.5 °C and at that time diesel temperature is not more than 38.5 °C. The amount of neutral-current is also optimized (up to 8.5 Amp.) which was more than 12 Amp. At the morning and afternoon, the neutral current is almost constant, but it is bit fluctuating between 7.5 Amp to 8.2 Amp at mid-day. The final outcome shows, the suggested system is efficiently stable with the change of load and generates optimal electricity.
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Soeb, Md Janibul Alam, Md Shahid Iqbal, Md Abu Naser Mojumder, Muhammad Rashed Al Mamun, A. S. M. Shahjalal Atik, and Md Fahad Jubayer. "Electrical Power Generation System: Optimal Design for Medium-Load Industries with High-Rated Generators." European Journal of Engineering and Technology Research 6, no. 7 (December 23, 2021): 133–39. http://dx.doi.org/10.24018/ejeng.2021.6.7.2686.
Повний текст джерелаАнотація:
The demand for electrical power is rapidly increasing due to the rise of industries in developing countries. Power generation stations are having troubles to strike a balance between demand and generation. In this situation, it is urged that appropriate remedial action be taken. Rising power demand can be met by designing an efficient electric power generation system which will also help lowering the generation cost. It is shown that while high rated electric power generators are connected in parallel the value of neutral current is rising and the cooling temperature is also increased. Here, the goal of this experimental work is to present a new model for designing an efficient power production system for average-load (ranging up to 8000 Amp, 440 V) industries to minimize the demand on centralized interconnected grid. A scheme is proposed with four generators (2500 kVA, 2000 kVA, 2000 kVA and 1250 KVA) in parallel and enough cooling arrangement is provided with minimal cost. The coolant temperature is maintained 61 °C to 61.5 °C and at that time diesel temperature is not more than 38.5 °C. The amount of neutral-current is also optimized (up to 8.5 Amp.) which was more than 12 Amp. At the morning and afternoon, the neutral current is almost constant, but it is bit fluctuating between 7.5 Amp to 8.2 Amp at mid-day. The final outcome shows, the suggested system is efficiently stable with the change of load and generates optimal electricity.
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Irshad, Kashif. "Performance Improvement of Thermoelectric Air Cooler System by Using Variable-Pulse Current for Building Applications." Sustainability 13, no. 17 (August 28, 2021): 9682. http://dx.doi.org/10.3390/su13179682.
Повний текст джерелаАнотація:
The thermoelectric air conditioning system (TE-AC) is a small, noiseless alternative to standard vapor compression refrigeration (VCR) systems. The cooling characteristics of a TE-AC system operating under two conditions, i.e., steady current and current pulses, are investigated in this study. This system consists of three thermoelectric modules, a heat sink, and an air circulation fan. The result shows that maximum temperature reduction in cooling side of TE-AC system was achieved at 6 A input current under steady state operation. The optimum performance of the TE-AC system under steady state operation depends upon the combined effect of the cooling load, Joule, Fourier, and Peltier heat. In TE-AC pulse operation, both current width and cooling load applied on the cold side of the thermoelectric module (TEMs) play an important role in achieving optimum cooling performance of the system. When normal input current operation (i.e., no current pulse) was compared to pulse-operated TE-AC system operation, it was found that pulse operation provides an additional average temperature reduction of 3–4 °C on the cold side of TEMs. Although on the hot side, it maintains a temperature in the range of 18 °C to 24 °C to reduce overshoot heat flux. The duration of operation is also important in determining pulse width and pulse amplitude. Minimum and overshoot peak temperature rises during each cycle for longer run operation. In the TE-AC system, the accumulated Joule heat during a current pulse frequently causes a temperature overshoot, which lasts much longer. As a result, the next current pulse was not released until the temperature of TE was restored to its initial value.
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Waqas, Adeel, Jie Ji, Majid Ali, and Jahan Zeb Alvi. "Effectiveness of the phase change material-based thermal energy storage integrated with the conventional cooling systems of the buildings – A review." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 232, no. 6 (January 24, 2018): 735–66. http://dx.doi.org/10.1177/0957650917754033.
Повний текст джерелаАнотація:
A significant portion of energy is consumed by the buildings to provide thermal comfort for its occupants. Energy consumed by the conventional cooling machines is expected to increase substantially around the globe. Cooling systems coupled with phase change materials offer a high potential to minimize the cooling energy demand and shifting peak time cooling load to off-peak time period without compromising the indoor comfort conditions. The interest in phase change material utilization for cooling applications has been increasing significantly over the last decade because of their energy saving benefits in building sector. Therefore, in this work, effectiveness of the phase change material storage coupled with free cooling, evaporative cooling, and compressor-based cooling techniques in reducing the energy consumption or shifting the peak cooling load have been discussed and analyzed in detail. Different types of phase change materials used for active cooling systems along with their selection criteria for a particular application have been elaborated and discussed. Techniques to estimate the thermophysical properties of phase change material have also been explained. Phase change material capsulation techniques along with their merits and demerits are also described. Challenges and issues that may arise during integrating of phase change material storage with the active cooling system have also been explained. Finally, this review also presents some current problems that needed further research in this area. Current review will be a useful guide for the research community working or intending to work in the field of phase change material-based cooling system.
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Al-Amiri, Abdalla M., and Montaser M. Zamzam. "Systematic Assessment of Combustion Turbine Inlet Air-Cooling Techniques." Journal of Engineering for Gas Turbines and Power 127, no. 1 (January 1, 2005): 159–69. http://dx.doi.org/10.1115/1.1805008.
Повний текст джерелаАнотація:
The current study is centered on assessing the benefits of incorporating combustion turbine inlet air-cooling systems into a reference combustion turbine plant, which is based on a simple cycle under base load mode. Actual climatic conditions of a selected site were examined thoroughly to identify the different governing weather patterns. The main performance characteristics of both refrigerative and evaporative cooling systems were explored by examining the effect of several parameters including inlet air temperature, airflow-to-turbine output ratio, coefficient of performance (for refrigerative cooling systems), and evaporative degree hours (for evaporative cooling systems). The impact of these parameters was presented against the annual gross energy increase, average heat rate reduction, cooling load requirements and net power increase. Finally, a feasibility design chart was constructed to outline the economic returns of employing a refrigerative cooling unit against different prescribed inlet air temperature values using a wide range of combustion turbine mass flow rates.
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Радченко, Андрій Миколайович, Микола Іванович Радченко, Богдан Сергійович Портной, Сергій Анатолійович Кантор та Олександр Ігорович Прядко. "ВИКОРИСТАННЯ НАДЛИШКУ ХОЛОДОПРОДУКТИВНОСТІ ХОЛОДИЛЬНИХ МАШИН ПРИ ОХОЛОДЖЕННІ ПОВІТРЯ НА ВХОДІ ГТУ". Aerospace technic and technology, № 5 (29 серпня 2020): 47–52. http://dx.doi.org/10.32620/aktt.2020.5.06.
Повний текст джерелаАнотація:
The processes of the gas turbine inlet air cooling by exhaust heat conversion chillers, which utilizing the gas turbine exhaust gas heat, converting it into cold were analyzed. The use of two-stage air cooling has been investigated: to a temperature of 15°C – in an absorption lithium-bromide chiller and below to a temperature of 10°C – in an ejector chiller as stages of a two-stage absorption-ejector chiller. To simulate air cooling processes, the program "Guentner Product Calculator", one of the leading manufacturers of heat exchangers "Guentner", was used. The possibility of using the accumulated excess refrigeration capacity of a combined absorption-ejector chiller, which is formed at reduced current heat loads on air coolers at the gas turbine inlet, to cover the refrigeration capacity deficit arising at increased heat loads due to high ambient air temperatures has been investigated. The refrigeration capacity required to the gas turbine inlet air cooling was compared to an excess refrigeration capacity which excess of the current heat load. The considered air cooling system provides pre-cooling of air at the gas turbine inlet by using the excess refrigeration capacity of the absorption-ejector chiller, accumulated in the cold accumulator, to provide the required refrigeration capacity of the air pre-cooling booster stage. The simulation results proved the expediency of the gas turbine inlet air cooling using the accumulated excess refrigeration capacity of the combined absorption-ejector chiller. The proposed solution reduces by about 50% the design refrigeration capacity and, accordingly, the cost of the installed absorption lithium-bromide chiller, which acts as a high-temperature stage for cooling the ambient air at the gas turbine inlet.
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Kim, Hyemi, Kyung-soon Park, Hwan-yong Kim, and Young-hak Song. "A Study on the Changes in the Heat Source Capacity and Air-Conditioning Load due to Retrofit; Focusing on a Large Office Building in Korea." Energies 12, no. 5 (March 3, 2019): 835. http://dx.doi.org/10.3390/en12050835.
Повний текст джерелаАнотація:
In an office building, the internal heat and the skin load are both expected to change. Thus, this study is an initial step that searches for optimum replacement measures when a heat source system is replaced on an office building in Korea. The operation status of office buildings in Korea was investigated, and the heat source capacities at the retrofit and the design times were quantitatively studied to determine the optimum capacity during of a heat source during retrofit. For the four retrofit scenarios, the maximum cooling and heating loads were calculated to show that, when retrofit is performed, the maximum cooling and heating loads are decreased by 40%, while the heat source capacity is reduced by around 43%. This is believed to be because of the replacement of the window chassis, which are better sealed with higher heat insulation performance, due to the enhanced design criteria for exterior load designing, and an improved installation process. Concerning the air-conditioning load, the influence of the internal heat load turned out to be significant, indicating that such a factor should be considered when retrofit. Thus, if the heat source capacity at the initial design time is applied equivalently during the office building retrofit, it would lead to degradation in energy efficiency due to the excessive design. Thus, it is necessary to calculate a heat source capacity by reflecting the operational and current status of the load in an actual building at the time of a retrofit.
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Rasheed, Kashif, Shimza Jamil, Muhammad Ramzan, and Muhammad Zulqarnain. "Thermal Analysis of an Educational Building with Different Construction Materials." Journal of Art, Architecture and Built Environment 01, no. 02 (December 2018): 75–86. http://dx.doi.org/10.32350/jaabe.12.05.
Повний текст джерелаАнотація:
The energy consumption has been increased to an alarming rate in the current world. This scenario has raised many problems like depletion of energy resources, energy supply difficulties and increased carbon footprint (global warming, climate change). The objective of this research is to minimize the energy consumption in educational institutions. This study will help us in reducing the heating and cooling loads of building and resulting to saving cost. A prototype building was modelled in Autodesk Software, Ecotect 2011 for the climatic zone of Multan to examine the thermal performance with different construction materials. The building studied with different aspects including passive and active techniques, planning and design. These aspects were analyzed and results were evaluated. Various construction materials were listed and examined for the development of energy efficient envelope. The results showed 11.86 % decrease in energy usage including 11.76% decrease in cooling load and 46.59% in heating load with locally available building materials.
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Gao, Li Ying, and Rui Li. "The Research on Relationship of Load Rate and Outdoor Temperature for Air-Cooled Unit." Advanced Materials Research 347-353 (October 2011): 1210–13. http://dx.doi.org/10.4028/www.scientific.net/amr.347-353.1210.
Повний текст джерелаАнотація:
In the paper, based on the current understanding of the IPLV principle and method of calculation, select occurrence temperature during the cooling season in five typical cities for further calculating the equation of IPLV, which exist quite differences with the current national standard IPLV formula. Moreover, the study of load rate for chillers will definitely closely relate to the climatic conditions in China.
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Zeferina, Vasco, Christina Birch, Rodger Edwards, and Ruth Wood. "Sensitivity analysis of peak and annual space cooling load at simplified office dynamic building model." E3S Web of Conferences 111 (2019): 04038. http://dx.doi.org/10.1051/e3sconf/201911104038.
Повний текст джерелаАнотація:
The focused investigation of building design is necessary to understand and quantify the implication of different design parameters on their energy performance. The design of future buildings is a major challenge, as current designs may be inappropriate in a future with global warming due to climate change impacts. In addition this understanding is necessary to be able to predict timing and profile of future energy demand, which is crucial for the long-term planning of energy infrastructures – particularly electricity. In this paper, the Morris Elementary Effects method is used as a screening method, to identify the key parameters of the design and operation of office buildings that affect the estimation of space cooling peak load and annual energy demand. Internal heat gains, cooling set-point and ventilation rates are identified as the parameters with larger implications for both annual and peak space cooling demand. In future climate scenarios, the magnitude of change of annual space cooling demand is significantly (around five times) larger than the change in the peak demand. Asides from the potential increase of space cooling demand in future scenarios, the sensitivity of the space cooling demand relative to the change in design parameters is potentially much larger.
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Athavale, Jayati, Minami Yoda, and Yogendra Joshi. "Genetic algorithm based cooling energy optimization of data centers." International Journal of Numerical Methods for Heat & Fluid Flow 31, no. 10 (January 18, 2021): 3148–68. http://dx.doi.org/10.1108/hff-01-2020-0036.
Повний текст джерелаАнотація:
Purpose This study aims to present development of genetic algorithm (GA)-based framework aimed at minimizing data center cooling energy consumption by optimizing the cooling set-points while ensuring that thermal management criteria are satisfied. Design/methodology/approach Three key components of the developed framework include an artificial neural network-based model for rapid temperature prediction (Athavale et al., 2018a, 2019), a thermodynamic model for cooling energy estimation and GA-based optimization process. The static optimization framework informs the IT load distribution and cooling set-points in the data center room to simultaneously minimize cooling power consumption while maximizing IT load. The dynamic framework aims to minimize cooling power consumption in the data center during operation by determining most energy-efficient set-points for the cooling infrastructure while preventing temperature overshoots. Findings Results from static optimization framework indicate that among the three levels (room, rack and row) of IT load distribution granularity, Rack-level distribution consumes the least cooling power. A test case of 7.5 h implementing dynamic optimization demonstrated a reduction in cooling energy consumption between 21%–50% depending on current operation of data center. Research limitations/implications The temperature prediction model used being data-driven, is specific to the lab configuration considered in this study and cannot be directly applied to other scenarios. However, the overall framework can be generalized. Practical implications The developed framework can be implemented in data centers to optimize operation of cooling infrastructure and reduce energy consumption. Originality/value This paper presents a holistic framework for improving energy efficiency of data centers which is of critical value given the high (and increasing) energy consumption by these facilities.
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Turski, Michał, and Robert Sekret. "Conceptual adsorption system of cooling and heating supplied by solar energy." Chemical and Process Engineering 37, no. 2 (June 1, 2016): 293–304. http://dx.doi.org/10.1515/cpe-2016-0024.
Повний текст джерелаАнотація:
Abstract This paper presents the possibility of reducing the demand for nonrenewable primary energy for buildings using a new conceptual adsorption system of cooling and heating supplied by solar energy. Moreover, the aim of this study is to shorten the payback time of investment in the standard adsorption cooling system through its integration with the heating system. Research has been carried out for an energy-efficient medium-sized single-family building with a floor area of 140 m2 and a heat load of 4.2 kW and cold load of 4.41 kW. It has been shown that the use of an adsorption system of cooling and heating supplied by solar energy decreased the demand for nonrenewable primary energy by about 66% compared to the standard building that meets the current requirements.
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Bieniek, Artur, Jan Kuchmacz, Karol Sztekler, Lukasz Mika, and Ewelina Radomska. "A New Method of Regulating the Cooling Capacity of a Cooling System with CO2." Energies 14, no. 7 (March 31, 2021): 1922. http://dx.doi.org/10.3390/en14071922.
Повний текст джерелаАнотація:
New guidelines set by international organizations for refrigeration companies cause that natural working fluids such as carbon dioxide are increasingly used in new refrigeration systems. Carbon dioxide (R-744) is used in freezing, cooling, or air conditioning installations, in which the cooling load fluctuates hourly. To adapt the cooling capacity of the evaporator to the current cooling load of the cooled space, a number of control elements are used. The paper proposes a new method of regulating the cooling capacity for a one-stage refrigeration cycle with the R-744 refrigerant and an internal heat exchanger (IHX). The proposed method involves using an additional evaporator and combines the possibility of regulating the cooling capacity with the possibility of energy efficiency ratio (EER) improvement. The energy analysis of the proposed method of regulating the cooling capacity was performed and the results were compared with the control method. The control method was using the compressor hot gas bypass valve which allows the flow of hot vapor refrigerant to the suction side. The energy analysis was carried out for both subcritical and supercritical cycles using the energy equations. For each of the considered methods, the characteristics of the change in the EER as a function of the reduction of the cooling capacity in both supercritical and subcritical cycles were determined. It was found that when the cooling capacity decreased by 50%, the hot gas bypass regulating method was around 30% less efficient compared to the proposed additional evaporator regulating method.
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Трушляков, Евгений Иванович, Николай Иванович Радченко та Вениамин Сергеевич Ткаченко. "ПОДХОД К АНАЛИЗУ ЭФФЕКТИВНОСТИ РЕГУЛИРОВАНИЯ ХОЛОДОПРОИЗВОДИТЕЛЬНОСТИ СИСТЕМ КОНДИЦИОНИРОВАНИЯ ПРИТОЧНОГО ВОЗДУХА". Aerospace technic and technology, № 6 (20 грудня 2018): 29–33. http://dx.doi.org/10.32620/aktt.2018.6.04.
Повний текст джерелаАнотація:
It is determined that the operation of ambient air conditioning systems (AACS) has significant fluctuations in the heat load in accordance with current climatic conditions. This makes very problematic the application of refrigeration compressors with frequency converters, which are very effective for controlling the refrigeration capacity in closed air conditioning systems, in which the temperature control range and, accordingly, fluctuations in thermal load are insignificant in comparison with the ambient air cooling. For the purpose of analyzing the efficiency of controlling the refrigeration capacity of the AACS by changing the electric motor speed of the piston compressor in current climatic conditions, the entire range of changing current thermal loads is divided into two parts according to controlling the refrigeration capacity by appling a frequency converter: the part of effective cooling capacity adjustment without energy losses (without reducing the coefficient of performance) from nominal to its threshold value and the part of reduced refrigeration capacity without its controlling by a frequency converter. It is revealed that for the warmest summer month, the proportion of refrigeration capacity spent for cooling ambient air to the temperature of 10 °C with 50 % frequency controlling the refrigeration capacity is about 10 % of the total amount of that could be produced at nominal refrigeration capacity. At higher temperatures of cooled air is even less. This shows the low efficiency of controlling the refrigeration capacity of the AACS by changing the speed of rotation of the piston compressor electric motor and the need to use other methods of controlling the refrigeration capacity. The proposed approach to analyzing the efficiency of controlling the refrigeration capacity of AACS in current climatic conditions allows not only to estimate the efficiency of refrigeration capacity controlling method but also to reveal the reserves for increasing the efficiency of applying the available refrigeration capacity
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Радченко, Микола Іванович, Євген Іванович Трушляков, Сергій Анатолійович Кантор, Богдан Сергійович Портной та Анатолій Анатолійович Зубарєв. "МЕТОД ВИЗНАЧЕННЯ ТЕПЛОВОГО НАВАНТАЖЕННЯ СИСТЕМИ КОНДИЦІЮВАННЯ ПОВІТРЯ ЗА МАКСИМАЛЬНИМ ТЕМПОМ ПРИРОЩЕННЯ ХОЛОДОПРОДУКТИВНОСТІ (на прикладі кондиціювання повітря енергетичного призначення)". Aerospace technic and technology, № 4 (14 жовтня 2018): 44–48. http://dx.doi.org/10.32620/aktt.2018.4.05.
Повний текст джерелаАнотація:
It is justified the necessity of taking into consideration changes in thermal loads on the air conditioning system (heat and moisture treatment of air by cooling it with decreasing temperature and moisture content) in accordance with the current climatic conditions of operation. Since the effect of air cooling depends on the duration of its use and the amount of cold consumption, it is suggested that it be determined by the amount of cold spent per year for air conditioning at the GTU inlet, that is, for annual refrigerating capacity. The example of heat-using air conditioning at the inlet of a gas turbine unite (energy–efficient air conditioning systems) analyzes the annual costs of cooling for cooling ambient air to the temperature of 15 °C by an absorption lithium-bromide chiller and two-stage air cooling: to a temperature of 15 °C in an absorption lithium-bromide chiller and down to temperature 10 °С – in a refrigerant ejector chiller as the stages of a two-stage absorption-ejector chiller, depending on the installed (project) refrigerating capacity of waste heat recovery chiller.It is shown that, based on the varying rate of increment in the annual production of cold (annual refrigeration capacity) due to the change in the thermal load in accordance with current climatic conditions, it is necessary to select such a design thermal load for the air conditioning system (installed refrigeration capacity of chillers), which ensures the achievement of maximum or close to it annual production of cold at a relatively high rate of its increment. It is analyzed the dependence of the increment on the annual refrigerated capacity, relative to the installed refrigeration capacity, on the installed refrigeration capacity, in order to determine the installed refrigeration capacity, which provides the maximum rate of increase in the annual refrigerating capacity (annual production of cold). Based on the results of the research, it is proposed the method for determining the rational thermal load of the air conditioning system (installed – the design refrigeration capacity of the chiller) in accordance with the changing climatic conditions of operation during the year, which provides nearby the maximum annual production of cold at relatively high rates of its growth
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Kunt, M. Akif. "An experimental investigation of exhaust waste heat recycling by thermoelectric generators under different thermal conditions for internal combustion engines." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 232, no. 12 (November 14, 2017): 1648–53. http://dx.doi.org/10.1177/0954407017733253.
Повний текст джерелаАнотація:
Almost 70% of heat power produced by pistons in internal combustion engines is lost due to exhaust and cooling. In the course of the heating process, 25% of useful energy transfers to the exit shaft. There have been a lot of studies on recycling waste heat of internal combustion engines, especially on cooling and exhaust systems. A thermoelectric generator is an important way to recycle waste energy in exhaust systems of internal combustion engines. In this study, an air-cooled thermoelectric generator was designed to recycle waste heat energy in exhaust systems of internal combustion engines and its performance was tested. Waste heat recycling tests were conducted by measuring voltage, current, and power values under different thermal conditions depending on the change in load resistance. The results obtained were compared with the results of analyses and experiments. Maximum voltage value at RI = 45Ω load resistance was obtained as 11.03 V (experiment) and 11.22 V (analysis), and maximum current value at RI = 5Ω load resistance as 0.42 A (experiment) at Th = 250°C, Δ T = 40°C.
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Lim, Hong Soo, and Gon Kim. "Analysis of Energy Performance on Envelope Ratio Exposed to the Outdoor." Advances in Civil Engineering 2018 (2018): 1–10. http://dx.doi.org/10.1155/2018/7483619.
Повний текст джерелаАнотація:
The shape of a building largely contributes to its energy consumption. The current study utilized metrics of surface-to-volume ratio, surface-to-floor ratio, area-to-perimeter ratio, and volume ratio to evaluate building energy performance. Also, the paper focused on the relation between the air-conditioned room and non-air-conditioned room. This approach affects both the design stages of the floor plan and the main designing factors that decide which spaces would become air-conditioned spaces such as those mostly occupied by residents or non-air-conditioned space such as staircases and elevators. The heating load and cooling load were calculated using the new equation based on the location of non-air-conditioned spaces and envelope ratio facing the outdoor. Both the width-depth ratio and envelope ratio were analyzed using the IES_V.E (Integrated Environmental Solutions Virtue Environment) program. It turns out that, as the non-air-conditioned spaces increase, both heating load and cooling load were reduced.
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Tsitsikyan, G., and S. Kunaev. "Appraisal of linear load effect on non-linear distortion coefficient from rectifier." Transactions of the Krylov State Research Centre 3, no. 397 (August 6, 2021): 92–96. http://dx.doi.org/10.24937/2542-2324-2021-3-397-92-96.
Повний текст джерелаАнотація:
Object and purpose of research. The object of research is the rectifier (transducer) OPED-12,5-115 (О – single phase; P – direct current; Е – natural air cooling; D – on diodes with an example of document record; 12.5 – current rating; 115 – voltage rating). Materials and methods. Methods of power electronics and harmonic analysis are applied. Main results. Ways of appraisal and restriction for the harmonic coefficient (non-linear distortion coefficient from transducer) are worked out taking account of an active load of higher frequencies generator (400 Hz). Conclusion. Numerical estimations for the attenuation coefficient of harmonics 3, 5 and 7 are obtained using basic values Xd and Xq of generator АТО-20.
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Chen, Shu, Zhengen Ren, Zhi Tang, and Xianrong Zhuo. "Long-Term Prediction of Weather for Analysis of Residential Building Energy Consumption in Australia." Energies 14, no. 16 (August 6, 2021): 4805. http://dx.doi.org/10.3390/en14164805.
Повний текст джерелаАнотація:
Globally, buildings account for nearly 40% of the total primary energy consumption and are responsible for 20% of the total greenhouse gas emissions. Energy consumption in buildings is increasing with the increasing world population and improving standards of living. Current global warming conditions will inevitably impact building energy consumption. To address this issue, this report conducted a comprehensive study of the impact of climate change on residential building energy consumption. Using the methodology of morphing, the weather files were constructed based on the typical meteorological year (TMY) data and predicted data generated from eight typical global climate models (GCMs) for three representative concentration pathways (RCP2.6, RCP4.5, and RCP8.5) from 2020 to 2100. It was found that the most severe situation would occur in scenario RCP8.5, where the increase in temperature will reach 4.5 °C in eastern Australia from 2080–2099, which is 1 °C higher than that in other climate zones. With the construction of predicted weather files in 83 climate zones all across Australia, ten climate zones (cities)—ranging from heating-dominated to cooling-dominated regions—were selected as representative climate zones to illustrate the impact of climate change on heating and cooling energy consumption. The quantitative change in the energy requirements for space heating and cooling, along with the star rating, was simulated for two representative detached houses using the AccuRate software. It could be concluded that the RCP scenarios significantly affect the energy loads, which is consistent with changes in the ambient temperature. The heating load decreases for all climate zones, while the cooling load increases. Most regions in Australia will increase their energy consumption due to rising temperatures; however, the energy requirements of Adelaide and Perth would not change significantly, where the space heating and cooling loads are balanced due to decreasing heating and increasing cooling costs in most scenarios. The energy load in bigger houses will change more than that in smaller houses. Furthermore, Brisbane is the most sensitive region in terms of relative space energy changes, and Townsville appears to be the most sensitive area in terms of star rating change in this study. The impact of climate change on space building energy consumption in different climate zones should be considered in future design strategies due to the decades-long lifespans of Australian residential houses.
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Wu, Yanwen, Wenna Jian, Liu Yang, Tengyue Zhang, and Yan Liu. "Effects of Different Surface Heat Transfer Coefficients on Predicted Heating and Cooling Loads towards Sustainable Building Design." Buildings 11, no. 12 (December 3, 2021): 609. http://dx.doi.org/10.3390/buildings11120609.
Повний текст джерелаАнотація:
The transfer of surface heat between a building and the outdoor environment is the energy transfer channel and it is important for the energy efficiency of buildings. Early stage building design is a critical stage and it can directly determine the energy consumption by a building. Therefore, selecting appropriate surface heat transfer coefficients (SHTCs) is a key issue in building energy consumption prediction. In this study, EnergyPlus was employed to investigate the building load in Chinese cities with different SHTCs: (1) constant SHTCs based on national standards; and (2) dynamically changing SHTCs based on the Thermal Analysis Research Program (TARP). Based on investigations of the hourly load, daily cumulative load in a typical day, and annual cumulative load with different SHTCs, corrections for the annual cumulative load were obtained according to the relative deviations between the results produced with the TARP model and traditional SHTCs. The greatest relative deviations were 67.5% and 25.3% for the building shape factor φ = 0.49 and 0.29 in Lhasa. The relative deviations were 13.3% and 12.0% for φ = 0.49 in Xi’an and Beijing, respectively. Corrections were not essential for other conditions because the relative deviations were lower than 5.0%. Considering the current characteristics of engineering calculations and the need to obtain more accurate design results, dynamically changing SHTCs should be applied. These correction factors can obtain more accurate results for the current building energy efficiency system with traditional SHTCs.
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Badran, Younis, and Ishaq Sider. "Solar Cooling Technologies in Jordan: A Technical Study." WSEAS TRANSACTIONS ON POWER SYSTEMS 16 (October 8, 2021): 220–30. http://dx.doi.org/10.37394/232016.2021.16.23.
Повний текст джерелаАнотація:
In the recent years, solar cooling technologies for buildings have garnered increased attention. This study aimed to evaluate the performance of current solar thermal and solar photovoltaic (PV) air-conditioning technologies. Hence, the annual heating/cooling load profile and energy consumption of a reference building in the climate of Aqaba, Jordan were simulated using the TRNSYS software. The solar thermal and solar PV air-conditioning systems were designed and simulated to compensate the cooling demands. It was found that the annual cooling energy accounted for 96.3 % of the total annual energy demand (heating plus cooling) of the reference building. The solar PV and solar thermal air-conditioning systems compensated for direct cooling by 35.8 % and 30.9 %, respectively, and the corresponding compensations of cooling energy by the storage system were 7.3 % and 11.9 %, respectively. Thus, through this comparative study, we found that the storage system significantly contributed in compensating the cooling demands of the solar thermal system; however, the compensation to direct cooling was lower relative to the solar PV system
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Li, Wei Bo, Wang Xin, Quan Feng, Wei Chao Li, and Zhao Long Sun. "Some Considerations of the Pulse Power Switch Centered on Thyristor Device." Applied Mechanics and Materials 336-338 (July 2013): 60–64. http://dx.doi.org/10.4028/www.scientific.net/amm.336-338.60.
Повний текст джерелаАнотація:
For high energy short pulse discharge applications, like electromagnetic launchers or magnetic forming, mostly the thyristor technology is used. The presented thyristor switch assemblies using 125 mm wafer size are made to switch 62.4MJ stored energy into a load in very short time. The maximum transient peak current of 26 kilo-amperes peak for 20 ms with convection water and air cooling. For this presentation we concentrate on the Thyristor technology as this offer the highest current capability but are not in the position to switch-off any current. Some measures must be used to the pulse switch centered on Thyristor device, i.e., proper selection of the static and dynamic parameters of the thyristor, enough power for triggering the device, and efficient cooling of the device, which can make it possible to produce devices with high blocking voltage combined with very high current handling.
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Thango, Bonginkosi A., and Pitshou N. Bokoro. "Stray Load Loss Valuation in Electrical Transformers: A Review." Energies 15, no. 7 (March 23, 2022): 2333. http://dx.doi.org/10.3390/en15072333.
Повний текст джерелаАнотація:
The electricity production opus in South Africa has transformed over the last few years from predominantly coal power generation to a blend of renewable energy generation. The necessity emerges to ascertain whether electrical transformer design philosophies in local manufacturers are contemporary in reference to customer specifications, under increasing penetration of harmonics and distortion as a result of increasing deployment of decentralized power systems. Accurate computation of transformer stray load loss is imperative in localizing the hotspot regions and design of adequate insulation system and consequently cooling system. This loss must also be met by manufacturers based on the customer specifications to avoid penalties. The review of current scientific works affirms the ongoing interest in utilizing the advancement of computational power for painstaking evaluation and management of stray load loss in electric transformers. This article confers overview research, evolution and application of diverse computer-based tools for analyzing the stray load loss based on over 60 published scientific works. Mathematical formulations that can be practically employed by transformer designers during the design phase under normal and harmonic load current conditions are discussed.
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Gao, Yi, Ping Cai, Feng Chen, and Ru Qin. "Study on Temperature Rise Modeling of Main Motor of Hot Rolling Mill Based on Support Vector Machines." Applied Mechanics and Materials 870 (September 2017): 427–31. http://dx.doi.org/10.4028/www.scientific.net/amm.870.427.
Повний текст джерелаАнотація:
Along with the ongoing process of the adjustment of industrial structure in China, overcapacity of the traditional heavy industry has become an issue of deep concern, and the direct consequence of overcapacity is energy waste. Tandem rolling mill is the typical equipment whose designed capacity is greater that the current real need. In many steel mills the practical work load of tandem rolling mill is far below the rated, while its forced-air cooling motor still runs at full capacity regardless of any change of heat load or season, leading to energy waste. Adjusting drive frequency of the air cooling motor according to its heat load is a practical and feasible measure for energy saving. As one of the important aspects of variable speed control of the air-cooling motor, to establish a precise temperature rise model for the object is critical. This research focuses on the temperature rise modeling of the main motor of hot rolling mill. The temperature rise mechanism of the main motor is first analyzed, and then the support vector machines regression algorithm is used for parameter identification of the model. To ensure the security and reliability of the production line, different penalty coefficients are adopted for positive error and negative error. Long term workshop data are collected and used for comparison with the predicted data. Comparison results demonstrate the feasibility of the established model.
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Hendrarsakti, Jooned, RB Dinda Permatasari, Erstrela Belia Muaja, Iqbal Muwahid, Leonard Alvin, Muhammad Romadhona, and Naufal Riyandi. "Identification of Potential Geothermal Energy Used for Vaccine COVID-19 Cold Storage Box Using Absorptive Refrigeration." IOP Conference Series: Earth and Environmental Science 1014, no. 1 (April 1, 2022): 012012. http://dx.doi.org/10.1088/1755-1315/1014/1/012012.
Повний текст джерелаАнотація:
Abstract A variety of vaccines of Covid 19 have been developed by different drug makers. Each vaccine brand requires different storage temperature ranged from 2-8°C, which then requires a cold storage box. In Indonesia, vaccine transportation and storage become big challenges to ensure the vaccines in good condition before use. This research focused to find out the possibility of using geothermal energy from Lahendong geothermal power plant unit 5 in Tompaso, North Sulawesi, for 5 liters-cold storage for Covid-19 vaccine using ammonia-water absorptive refrigeration and to identify the possible temperatures for storage of vaccine. Based on the absorption refrigeration system calculation, the current study found that the average evaporator temperature is 3°C, with cooling load of 1.03 kW and COP of 0.43. This cooling load requires a brine of 59.98 kg/s from the Lahendong geothermal power plant.
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Радченко, Андрій Миколайович, Богдан Сергійович Портной, Сергій Анатолійович Кантор та Ігор Петрович Єсін. "ОЦІНКА ЕФЕКТИВНОСТІ ГЛИБОКОГО ОХОЛОДЖЕННЯ ПОВІТРЯ НА ВХОДІ ГТУ ТЕПЛОВИКОРИСТОВУЮЧИМИ ХОЛОДИЛЬНИМИ МАШИНАМИ". Aerospace technic and technology, № 6 (24 грудня 2019): 10–14. http://dx.doi.org/10.32620/aktt.2019.6.02.
Повний текст джерелаАнотація:
Significant fluctuations in the current temperature and relative humidity of the ambient air lead to significant changes in the heat load on the air cooling system at the inlet of the gas turbine unit, which urgently poses the problem of choosing their design heat load, as well as evaluating the efficiency of the air cooling system for a certain period of time. The efficiency of deep air cooling at the inlet of gas turbine units was studied with a change during July 2015–2018 for climatic conditions of operation at the compressor station Krasnopolie, Dnepropetrovsk region (Ukraine). For air cooling, the use of a waste heat recovery chiller, which transforms the heat of exhaust gases of gas turbine units into the cold, has been proposed. The efficiency of air cooling at the inlet of gas turbine units for different temperatures has been analyzed: down to 15 °C – an absorption lithium-bromide chiller, which is used as the first high-temperature stage for pre-cooling of ambient air, and down to 10 °C – a combined absorption-ejector chiller (with using a refrigerant low-temperature air cooler as the second stage of air cooling). The effect of air-cooling was assessed by comparing the increase in the production of mechanical energy as a result of an increase in the power of a gas turbine unit and fuel saved during the month of July for 2015-2018 in accumulating. Deeper air cooling at the inlet of the gas turbine unit to a temperature of 10 °C in a combined absorption-ejector chiller compared to its traditional cooling to 15 °C in an absorption bromine-lithium chiller provides a greater increase in net power and fuel saved. It is shown that due to a slight discrepancy between the results obtained for 2015-2018, a preliminary assessment of the efficiency of air cooling at the inlet of gas turbine plants can be carried out for one year.
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Mescheryakov, Vladimir Ivanovich, Vladimir Petrovich Zaykov, and Yurii Ivanovich Zhuravlov. "THERMAL CONTROL OF THERMOELECTRIC COOLING DEVICES OF TRANSMISSION AND RECEIVING ELEMENTS OF ON-BOARD INFORMATION SYSTEMS." Herald of Advanced Information Technology 3, no. 4 (November 20, 2020): 263–78. http://dx.doi.org/10.15276/hait.04.2020.5.
Повний текст джерелаАнотація:
The work is a continuation of studies of the dynamic characteristics of thermoelectric coolers aimed at analyzing the influence of temperature differences, current operating modes, design parameters of the device and physical parameters of the material of thermoelements for a time constant. The article analyzes the effect of the heat sink capacity of the radiator on the dynamic characteristics, energy and reliability indicators of a single-stage thermoelectric cooler. A dynamic model of a thermoelectric cooler has been developed taking into account the weight and size parameters of the radiator, which relate the main energy indicators of the cooler with the heat removal capacity of the radiator, operating currents, the value of the heat load and the relative temperature difference. The analysis of the dynamic model shows that with an increase in the heat-removing capacity of the radiator at a given thermal load and various current modes, the main parameters of the cooler change. The required number of thermoelements, power consumption, time to reach a stationary mode, and relative failure rate are reduced. With an increase in the relative operating current, the time to reach the stationary mode of operation decreases for different values of the heat sink capacity of the radiator. It is shown that the minimum time to reach the stationary operating mode is provided in the maximum refrigerating capacity mode. The studies were carried out at different values of the heat sink capacity of the radiator in the operating range of temperature drops and the geometry of thermoelements. The possibility of minimizing the heat-dissipating surface of the radiator at various current operating modes and the relationship with the main parameters, reliability indicators and the time to reach the stationary operating mode are shown. Comparative analysis of weight and size characteristics, main parameters, reliability indicators and dynamics of functioning with rational design makes it possible to choose compromise solutions, taking into account the weight of each of the limiting factors.
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Sajjad, Muhammad, Samee Ullah Khan, Noman Khan, Ijaz Ul Haq, Amin Ullah, Mi Young Lee, and Sung Wook Baik. "Towards Efficient Building Designing: Heating and Cooling Load Prediction via Multi-Output Model." Sensors 20, no. 22 (November 10, 2020): 6419. http://dx.doi.org/10.3390/s20226419.
Повний текст джерелаАнотація:
In the current technological era, energy-efficient buildings have a significant research body due to increasing concerns about energy consumption and its environmental impact. Designing an appropriate energy-efficient building depends on its layout, such as relative compactness, overall area, height, orientation, and distribution of the glazing area. These factors directly influence the cooling load (CL) and heating load (HL) of residential buildings. An accurate prediction of these load facilitates a better management of energy consumption and enhances the living standards of inhabitants. Most of the traditional machine learning (ML)-based approaches are designed for single-output (SO) prediction, which is a tedious task due to separate training processes for each output with low performance. In addition, these approaches have a high level of nonlinearity between input and output, which need more enhancement in terms of robustness, predictability, and generalization. To tackle these issues, we propose a novel framework based on gated recurrent unit (GRU) that reliably predicts the CL and HL concurrently. To the best of our knowledge, we are the first to propose a multi-output (MO) sequential learning model followed by utility preprocessing under the umbrella of a unified framework. A comprehensive set of ablation studies on ML and deep learning (DL) techniques is done over an energy efficiency dataset, where the proposed model reveals an incredible performance as compared to other existing models.
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Zhang, Zhe, Yuqi Zhang, Xiaomei Sui, Wenbin Li, and Daochun Xu. "Performance of Thermoelectric Power-Generation System for Sufficient Recovery and Reuse of Heat Accumulated at Cold Side of TEG with Water-Cooling Energy Exchange Circuit." Energies 13, no. 21 (October 22, 2020): 5542. http://dx.doi.org/10.3390/en13215542.
Повний текст джерелаАнотація:
Aiming to reduce thermal energy loss at the cold side of a thermoelectric generator (TEG) module during thermoelectric conversion, a thermoelectric energy conversion system for heat recovery with a water-cooling energy exchange circuit was devised. The water-cooling energy exchange circuit realized sufficient recovery and reuse of heat accumulated at the cold side of the TEG, reduced the danger of heat accumulation, improved the stability and output capacity of thermoelectric conversion, and provided a low-cost and high-yield energy conversion strategy in energy conversion and utilization. Through the control variable method to adjust the heat generation of the heat source in the thermoelectric conversion, critical parameters (e.g., inner resistance of the TEG, temperatures of thermoelectric modules, temperature differences, output current, voltage, power, and efficiency of thermoelectric conversion) were analyzed and discussed. After using the control variable method to change the ratio of load resistance and internal resistance, the impacts of the ratio of load resistance to inner resistance of the TEG on the entire energy conversion process were elaborated. The results showed that the maximum value of output reached 397.47 mV with a current of 105.56 mA, power of 41.96 mW, and energy conversion efficiency of 1.16%. The power density of the TEG module is 26.225 W/m2. The stability and practicality of the system with a water-cooling energy exchange circuit were demonstrated, providing an effective strategy for the recovery and utilization of heat energy loss in the thermoelectric conversion process.
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Портной, Богдан Сергійович. "ВИБІР ТЕПЛОВОГО НАВАНТАЖЕННЯ АПАРАТІВ ОХОЛОДЖЕННЯ ПОВІТРЯ НА ВХОДІ ГТУ В РІЗНИХ КЛІМАТИЧНИХ УМОВАХ". Aerospace technic and technology, № 4 (14 жовтня 2018): 49–52. http://dx.doi.org/10.32620/aktt.2018.4.06.
Повний текст джерелаАнотація:
It is proposed the definition of the installed (rational) refrigeration capacity of a waste heat-recovery absorption-ejector chiller that utilizes the heat of the exhaust gases of a gas turbine unite to cool the air at the inlet. Since the effect of air cooling, in particular in the form of a reduction in the specific fuel consumption, depends on its depth (the magnitude of the decrease in air temperature) and duration, it is proposed to determine it by the annual fuel economy. As an example of air cooling at the inlet of a gas turbine unit, the value of reducing specific fuel consumption due to cooling the air at the inlet to the temperature of 15 °C by an absorption lithium-bromide chiller and two-stage air cooling: to a temperature of 15 °C in an absorption lithium-bromide chiller and down to 10 °C – in a refrigerant ejector chiller as the stages of a two-stage absorption-ejector chiller, depending on the installed (design) refrigeration capacity is analyzed.It is shown that proceeding from the different rate of increment of the annual reduction in the specific fuel consumption due to the change in the thermal load in accordance with the current climatic conditions, it is necessary to choose such design heat load for the air cooling system (installed refrigeration capacity of the chillers), which ensures the achievement of the maximum or close to annual reduction in the specific fuel consumption at relatively high rates of its increment. In order to determine the installed refrigeration capacity, which ensures the maximum annual refrigeration capacity (annual production of cold), the dependence of the increment of annual fuel economy from the installed refrigeration capacity is analyzed. Based on the results of the investigation, it was proposed to determine the rational thermal load of the air cooling system (installed - the design refrigeration capacity of the chiller) in accordance with the changing climatic conditions of operation during the year, which provides a maximum annual reduction in the specific fuel consumption at relatively high rates of its increment
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Sheikh, U. A., D. Shiraki, R. Sweeney, P. Carvalho, S. Jachmich, E. Joffrin, M. Lehnen, et al. "Disruption thermal load mitigation with shattered pellet injection on the Joint European Torus (JET)." Nuclear Fusion 61, no. 12 (November 12, 2021): 126043. http://dx.doi.org/10.1088/1741-4326/ac3191.
Повний текст джерелаАнотація:
Abstract Disruption mitigation remains a critical, unresolved challenge for ITER. To aid in addressing this challenge, a shattered pellet injection (SPI) system was installed on JET and experiments conducted at a range of thermal energy fractions and stored energies in excess of 7 MJ. The primary goals of these experiments were to investigate the efficacy of the SPI on JET and the ability of the plasma to assimilate multiple pellets. Single pellet injections produced a saturation in total radiated energy (W rad) with increasing injected neon content, suggesting total radiation of stored thermal energy. Further increases in injected neon quantities resulted in reduced cooling times and current quench (CQ) durations, indicating higher impurity assimilation. No significant variation in CQ duration or W rad was observed when varying the deuterium content at fixed neon quantities. Higher assimilation, inferred by shorter CQ durations, was measured when a mechanical punch was used to launch the pellets and this was attributed to a lower pellet velocity leading to higher solid content in the pellet plume and larger fragments penetrating deeper into the plasma. Radiation asymmetries averaged over the cooling time were inferred from Emis3D and ranged from 1.6 to 1.9. Asymmetries averaged over the entire disruption sequence were found to increase at higher thermal energy fractions. The radiated energy fractions decreased with increasing thermal energy fractions but this trend was eliminated when toroidal asymmetries were accounted for with Emis3D. Pure deuterium pellets were able to produce cooling times of up to 75 ms with a gradual loss in thermal stored energy of up to 80%. Experiments with multiple pellet injection indicated W rad can be increased through pellet superposition and density can be increased with an additional D2 injection without a reduction in W rad. KPRAD modelling accurately reproduced the cooling times and the CQ duration at high thermal energies. Assimilation estimates from KPRAD indicated CQ rates scale strongly whilst W rad scales weakly and saturates with assimilated neon content. Comparable W rad can be achieved with lower assimilated neon quantities as longer cooling times are attained. Thus reduced neon content can be preferential in a thermal load mitigation scheme as it may reduce radiation asymmetries and prevent flash melting.
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Радченко, Роман Миколайович, Богдан Сергійович Портной, Сергій Анатолійович Кантор, Веніамін Сергійович Ткаченко та Анатолій Анатолійович Зубарєв. "ОТРИМАННЯ І ВИКОРИСТАННЯ КОНДЕНСАТУ ПРИ ОХОЛОДЖЕННІ ПОВІТРЯ НА ВХОДІ ЕНЕРГОУСТАНОВКИ ТА ПРОБЛЕМА СЕПАРАЦІЇ КРАПЕЛЬНОЇ ВОЛОГИ З АЕРОЗОЛЬНОЇ СУМІШІ В ГРАДИРНЯХ". Aerospace technic and technology, № 5 (8 листопада 2018): 23–27. http://dx.doi.org/10.32620/aktt.2018.5.04.
Повний текст джерелаАнотація:
The processes of heat-humidity treatment (cooling with dehumidification) of air in a two-stage air cooling system at the inlet of a gas turbine unit applying a combined type heat-energized refrigeration mechanism, which consists of an absorption lithium-bromide high-temperature refrigeration mechanism to approximately 15 °C and a refrigerant ejector low-temperature refrigeration mechanism to 10 °С and below, which transform the heat of exhaust gases from gas turbine unit to the cold with the production of condensate in air cooling system as a by-product of air cooling has been analyzed. The analysis was carried out for the climatic conditions of the south of Ukraine. The heat removal from the condensers and the absorber of the heat-energized refrigeration mechanism are carried out with open wet cooling towers. Based on the distribution of the heat load on the steps of the two-stage air cooling system and the heat coefficients of the heat-energized refrigeration mechanisms, the project load on the cooling towers was determined and their number was selected. Based on the results of modeling of the operation of the air cooling system at the inlet of the gas turbine unit, were obtained data from the current and total amount of condensate that falls in the air cooling system during the condensation of water vapor, which is always contained in moist air, as well as the amount of water needed to feed an open cooling tower. In this case, only water losses due to mechanical removal (without taking into account its evaporation in cooling towers) were considered, which poses the problem of separation of droplet moisture from the aerosol mixture. As a result of comparing the amount of water needed to feed the cooling towers, on the one hand, and the amount of condensate obtained in the process of air cooling at the inlet of the gas turbine unit, on the other hand, was demonstrated that it is possible to partially satisfy the necessary water needs for cooling towers. A scheme of two-stage air cooling system at the inlet of a gas turbine unit with absorption lithium-bromide and refrigerant ejector refrigeration mechanism and wet cooling towers is proposed, to discharge heat from heat-energized refrigeration mechanisms, to produce condensate as a by-product of air cooling, and apply it to feed cooling towers
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Jarfors, Anders E. W., Ruslan Sevastopol, Karamchedu Seshendra, Qing Zhang, Jacob Steggo, and Roland Stolt. "On the Use of Conformal Cooling in High-Pressure Die-Casting and Semisolid Casting." Technologies 9, no. 2 (May 21, 2021): 39. http://dx.doi.org/10.3390/technologies9020039.
Повний текст джерелаАнотація:
Today, tool life in high pressure die casting (HPDC) is of growing interest. A common agreement is that die life is primarily decided by the thermal load and temperature gradients in the die materials. Conformal cooling with the growth of additive manufacturing has raised interest as a means of extending die life. In the current paper, conformal cooling channels’ performance and effect on the thermal cycle in high-pressure die casting and rheocasting are investigated for conventional HPDC and semisolid processing. It was found that conformal cooling aids die temperature reduction, and the use of die spray may be reduced and support the die-life extension. For the die filling, the increased temperature was possibly counterproductive. Instead, it was found that the main focus for conformal cooling should be focused to manage temperature around the in-let bushing and possibly the runner system. Due to the possible higher inlet pressures for semisolid casting, particular benefits could be seen.