Journal articles on the topic 'Design refrigeration capacity'
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1
Dubey, Gautam A., Vinay R. Chaurasia, Amit Kumar, S. Chaurasiya, Vidyesh T. Churi, and M. A. Gulbarga. "Design and Fabrication of Solar Powered Portable Medical Refrigerator for Remote and Rural areas based on Peltier Effect." International Journal for Research in Applied Science and Engineering Technology 10, no. 4 (April 30, 2022): 903–9. http://dx.doi.org/10.22214/ijraset.2022.41380.
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Abstract: The medicine and vaccine require to store in the refrigerator the continuous provision of electrical energy is required so that their efficacy is not affected. This represents an important problem for rural areas where there is no continuous electrical energy. In this work, we design a solar energy system for refrigeration of cold storage medicines to be used in rural towns without giving continuous electrical. The system uses a thermoelectric refrigerator based on the Peltier effect, which produces a temperature difference when electrical power is provided to it. It will be shown that for a typical application for vaccine refrigeration, the required solar panel is about 100W peak connected to batteries with a storage capacity of 20Ah. The designed refrigeration system has a 14-liter volume capacity of vaccines at temperatures in the range of 14° to 15°C using a Peltier cell (TEC) that consumes 28 W at 12V. Keywords: Refrigeration, Thermoelectric, Solar energy, Peltier.
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Yadav, Varun, Supradeepa Panual G, Neeraj Yadav, Ratnam Bordia, Rohini Soni, and Rinkesh Khandey. "Design and Fabrication of Solar Powered Vapour Absorption Refrigeration System." E3S Web of Conferences 170 (2020): 02011. http://dx.doi.org/10.1051/e3sconf/202017002011.
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Engineering is all about the application of knowledge and ideas for continuous development in society. In today’s world, there is a strong need for an environment-friendly refrigerating system, therefore, our focus is on a solar powered vapour absorption refrigeration system. This project focuses on a cooling system that minimizes the dependency over electricity and to show our ability to save our resources for future generations. The objective of this work was to design and fabricate a vapour absorption refrigeration system, using LiBr-H20, as the refrigerants and powered by solar energy. Performance Evaluation of the system has been done on the basis of different operating conditions and parameters like, solar irradiance, collector, generator, condenser and evaporator temperature. The COP of the system was obtained as 0.1 and the capacity was 0.01 TR. Since it’s an ab-initio development it will be a unique one in terms of understanding and underlying engineering. The system is an eccentric one that can be operated by multiple heat sources like solar energy, biomass etc. without much change in the design. This system can be used to develop an Air Conditioner, Refrigerator or a Chiller.
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Радченко, Микола Іванович, Євген Іванович Трушляков, Сергій Анатолійович Кантор, Богдан Сергійович Портной, and 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, no. 4 (October 14, 2018): 44–48. http://dx.doi.org/10.32620/aktt.2018.4.05.
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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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Радченко, Андрій Миколайович, Богдан Сергійович Портной, Сергій Анатолійович Кантор, Олександр Ігорович Прядко, and Іван Володимирович Калініченко. "ПІДВИЩЕННЯ ЕФЕКТИВНОСТІ ОХОЛОДЖЕННЯ ПОВІТРЯ НА ВХОДІ ГТД ХОЛОДИЛЬНИМИ МАШИНАМИ ШЛЯХОМ АКУМУЛЯЦІЇ ХОЛОДУ." Aerospace technic and technology, no. 4 (August 28, 2020): 22–27. http://dx.doi.org/10.32620/aktt.2020.4.03.
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The efficiency of air cooling at the inlet of gas turbine engines by exhaust heat conversion chiller, which transforms the GTE exhaust gases heat into cold, under variable climatic operating conditions, has been investigated. Considered is the use of a combined absorption-ejector exhaust heat conversion chiller with a step-by-step principle of air cooling at the gas turbine engines inlet: preliminary down to 15°C – by an absorption lithium-bromide chiller (ACh), which is used as a high-temperature air cooling stage, and further cooling down to 10°C – by a refrigerant ejector chiller (ECh) as a low-temperature cooling stage. Reserves have been identified for reducing the design (installed) refrigeration capacity of chillers by accumulating excess cold at reduced current heat loads with its use at increased heat loads. In this case, the design (installed) refrigeration capacity of chillers was determined by two methods: the first – based on the close to the maximum reduction in annual fuel consumption, the second – according to the maximum rate of increase in the reduction in annual fuel consumption. A scheme of the air cooling system at the gas turbine engines inlet using the refrigeration capacity reserve of the ACh, which provides preliminary cooling of the ambient air at the gas turbine engines inlet, in the booster stage, using the ACh accumulated excess refrigeration capacity has been proposed. The ACh excess refrigerating capacity, which is formed at decreased heat loads on the air coolers at the gas turbine engines inlet, is accumulated in the cold accumulator and is used at increased heat loads. The simulation results show the advisability of using the air cooling system at the gas turbine engine inlet with using the ACh accumulated excess refrigeration capacity, which allows reducing the ACh design (installed) refrigeration capacity by approximately 40%.
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Ganesh, Mandave. "Design of Evaporator Coil and Performance Evaluation of Vapour Compression Refrigeration System with Three Layer Evaporator." International Journal for Research in Applied Science and Engineering Technology 9, no. VI (June 30, 2021): 5130–33. http://dx.doi.org/10.22214/ijraset.2021.36096.
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The performance of a vapour compression refrigeration system with a three-layer zigzag evaporator is evaluated in this research. The primary goal of this study is to compare the performance of a household refrigerator with a capacity of 165 litres, R-12as refrigerant, and a three layer zigzag shaped evaporator to that of an existing system. The refrigerant capacity of this evaporator assembly is maximised.
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Keawkamrop, Thawatchai, and Somchai Wongwises. "Effect of Cycle Frequency of a Reciprocating Magnetic Refrigerator Prototype on the Temperature Span and Cooling Capacity." International Journal of Air-Conditioning and Refrigeration 27, no. 01 (March 2019): 1950002. http://dx.doi.org/10.1142/s2010132519500020.
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Magnetic refrigeration is an environment-friendly cooling technology and an interesting potential replacement for the vapor compression refrigeration system. This paper presents a linear reciprocating magnetic refrigerator prototype that operates at room temperature by using gadolinium parallel plates under a maximum magnetic field intensity of 0.94[Formula: see text]T. The design, installation and preliminary results are reported. The temperature span and cooling capacity are studied in a function of cycle frequency, and the results show the cycle frequency effects on temperature span and cooling capacity. The maximum temperature span and cooling capacity for cycle frequency of 0.16[Formula: see text]Hz are 1.3[Formula: see text]K and 4.68[Formula: see text]W, respectively. The results from the experiment will be a guideline to determine the maximum performance of the magnetic refrigerator prototype.
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KHOROLSKY, Valentyn, Yurii KORENETS, Yulіya PETRUSHYNA, and Ivan RASCHEKHMAROV. "IMPROVEMENT OF SYSTEMS FOR MONITORING AND CONTROLLING THE PROCESS OF FREEZING PRODUCTS IN REFRIGERATING CHAMBERS OF INDUSTRIAL REFRIGERATORS." Herald of Khmelnytskyi National University 305, no. 1 (February 23, 2022): 247–55. http://dx.doi.org/10.31891/2307-5732-2022-305-1-247-255.
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The article proposes a set of theoretical and practical attributes associated with design decisions regarding the processes of freezing meat products in refrigerators with a large load capacity of industrial refrigerators. A system of intelligent sensors has been developed to control the parameters of the geometry of the carcass of cattle meat and signs of the state of the evaporators of the refrigeration chamber and the refrigeration supply system of an industrial refrigerator. An automatic recognition system has been developed that works in real time and determines: geometric parameters of local and integral sections of the carcass in the form of a plane, radii, length, width, number of contour inflection points, geometric center of image elements; humidity settings. This system constantly analyzes the space of sections of the refrigerating chamber. An intelligent system for neurocontrol of the refrigeration supply of a refrigerating chamber is proposed, in which two video cameras and matrix sensors with piezoelectric elements for assessing the shape of a cattle carcass are mounted; it has been proved that the expert ink image bank allows using reference methods of comparative analysis. Thanks to the interface with information support subsystems, the system provides the operator-technologist with video information and automatically affects the intelligent actuators of compressors, fans, condensers. A system for neuro-fuzzy control of the evaporator freezing process has been developed, which provides for an expert system, a recognition algorithm, an expert image bank of an evaporator with a snow coat and an intelligent mechanism for the impact of ultrasonic vibrations on the surface of a cooling device. A generalized algorithm for the operation of refrigeration control systems for the refrigerating chamber of an industrial refrigerator and a method for its use are presented.
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Li, Jie, Xin Ping Ou Yang, and Lian Jie Zhang. "Structure Design of a New Kind of Rotary Refrigeration Compressor." Advanced Materials Research 201-203 (February 2011): 2544–49. http://dx.doi.org/10.4028/www.scientific.net/amr.201-203.2544.
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This paper introduces the working principle and components structure of a new kind rotary refrigeration compressor which receives the merits of some existing rotary refrigeration compressors and discards some application limitation. The new type refrigeration compressor has the characteristics of fewer parts as well as simple structure, easy manufacturing, smooth operation and wide application capacity. In this paper the author puts emphasis on the discharge structure, capacity regulation mechanism, piston flexibleness and seal body.
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Mani, Kolandavel, Vellappan Selladurai, and Natarajan Murugan. "Experimental investigations with eco-friendly refrigerants using design of experiments technique-mathematical modeling and experimental validation." Thermal Science 18, suppl.2 (2014): 363–74. http://dx.doi.org/10.2298/tsci110805114m.
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In this paper mathematical models were developed using design of experiments technique for the performance prediction of refrigeration system parameters such as refrigerating capacity, power consumption and coefficient of performance. The models developed were checked for their adequacy using F-test. The performances of vapour compression refrigeration system with different refrigerants R12, R134a and R290/R600a were compared. The R290/R600a mixture showed 10.7-23.6% higher coefficient of performance than that with R12 and R134a and it was found that the hydrocarbon mixture with 68% propane and 32% iso-butane could be used as a substitute for R12 and R134a.
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Alahmer, Ali, Malik Al-Amayreh, Ahmad O. Mostafa, Mohammad Al-Dabbas, and Hegazy Rezk. "Magnetic Refrigeration Design Technologies: State of the Art and General Perspectives." Energies 14, no. 15 (July 31, 2021): 4662. http://dx.doi.org/10.3390/en14154662.
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Magnetic refrigeration is a fascinating superior choice technology as compared with traditional refrigeration that relies on a unique property of particular materials, known as the magnetocaloric effect (MCE). This paper provides a thorough understanding of different magnetic refrigeration technologies using a variety of models to evaluate the coefficient of performance (COP) and specific cooling capacity outputs. Accordingly, magnetic refrigeration models are divided into four categories: rotating, reciprocating, C-shaped magnetic refrigeration, and active magnetic regenerator. The working principles of these models were described, and their outputs were extracted and compared. Furthermore, the influence of the magnetocaloric effect, the magnetization area, and the thermodynamic processes and cycles on the efficiency of magnetic refrigeration was investigated and discussed to achieve a maximum cooling capacity. The classes of magnetocaloric magnetic materials were summarized from previous studies and their potential magnetic characteristics are emphasized. The essential characteristics of magnetic refrigeration systems are highlighted to determine the significant advantages, difficulties, drawbacks, and feasibility analyses of these systems. Moreover, a cost analysis was provided in order to judge the feasibility of these systems for commercial use.
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Радченко, Андрій Миколайович. "МЕТОД ВИЗНАЧЕННЯ ХОЛОДОПРОДУКТИВНОСТІ ТЕРМОТРАНСФОРМАТОРА ЗА МАКСИМАЛЬНИМ ТЕМПОМ ПРИРОЩЕННЯ ТЕРМОЧАСОВОГО ПОТЕНЦІАЛУ ОХОЛОДЖЕННЯ ПОВІТРЯ." Aerospace technic and technology, no. 4 (October 14, 2018): 53–57. http://dx.doi.org/10.32620/aktt.2018.4.07.
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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
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GANJEHSARABI, HADI, IBRAHIM DINCER, and ALI GUNGOR. "THERMODYNAMIC ANALYSIS AND PERFORMANCE ASSESSMENT OF A CASCADE ACTIVE MAGNETIC REGENERATIVE REFRIGERATION SYSTEM." International Journal of Air-Conditioning and Refrigeration 21, no. 03 (September 2013): 1350016. http://dx.doi.org/10.1142/s2010132513500168.
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In the present study, a thermodynamic model is proposed to analyze and assess the performance, through energy and exergy, of a cascade active magnetic regenerative (AMR) refrigerator operation a regenerative Brayton cycle. This cascade refrigeration system works with Gd x Tb 1–x alloys as magnetic materials where the composition of the alloy varies for different stages. In this model, the heat transfer fluid considered is a water– glycol mixture (50% by weight). The refrigeration capacity, total power consumption, coefficients of performance (COP), exergy efficiency and exergy destruction rate of a cascade AMR refrigeration (AMRR) system are determined. To understand the system performance more comprehensively, a parametric study is performed to investigate the effects of several important design parameters on COP and exergy efficiency of the system.
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Monsef, Hamed, Naghash Zadegan, and Koroush Javaherdeh. "Design and construction of a low capacity pump-less absorption system." Thermal Science 18, no. 2 (2014): 577–90. http://dx.doi.org/10.2298/tsci120119016m.
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In this investigation, a low capacity absorption system has been designed and constructed where the mechanical pump has been replaced with a bubble pump, reducing the cost and eliminating the electrical power. Initially, a test rig bubble pump has been built with a single Pyrex tube to test the effect of different parameters on pumping flow rate. An absorption refrigeration system with a capacity of 2.5 kW has been designed and constructed. Results have shown that a bubble pump with five horizontal tubes with 2.5 mm diameter and submergence ratio of 0.4 has the best performance for this low capacity absorption refrigeration system. The COP of this structure was about 0.51 and mathematical modeling shows that increasing the solution concentration at generator outlet decreases the COP of the system.
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Портной, Богдан Сергійович, Андрій Миколайович Радченко, Роман Миколайович Радченко, and Сергій Анатолійович Кантор. "ВИКОРИСТАННЯ РЕЗЕРВУ ХОЛОДОПРОДУКТИВНОСТІ АБСОРБЦІЙНОЇ ХОЛОДИЛЬНОЇ МАШИНИ ПРИ ОХОЛОДЖЕННІ ПОВІТРЯ НА ВХОДІ ГТУ." Aerospace technic and technology, no. 3 (June 27, 2018): 39–44. http://dx.doi.org/10.32620/aktt.2018.3.05.
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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.
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Портной, Богдан Сергійович. "ВИБІР ТЕПЛОВОГО НАВАНТАЖЕННЯ АПАРАТІВ ОХОЛОДЖЕННЯ ПОВІТРЯ НА ВХОДІ ГТУ В РІЗНИХ КЛІМАТИЧНИХ УМОВАХ." Aerospace technic and technology, no. 4 (October 14, 2018): 49–52. http://dx.doi.org/10.32620/aktt.2018.4.06.
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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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Farfán, Ricardo Fabricio Muñoz, Telly Yarita Macías Zambrano, Víctor Manuel Delgado Sosa, and Vicente Zambrano. "Design of eco-friendly refrigeration system." International journal of physical sciences and engineering 3, no. 2 (May 14, 2019): 1–11. http://dx.doi.org/10.29332/ijpse.v3n2.285.
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The present study of a freezing system has developed based on an air conditioning system, whose purpose is to take advantage of the technological transfer of cold producing equipment for food storage and conservation uses. The installed capacity of 9000 BTU/Hr was considered for the choice of equipment. We studied the freezing process of fish, water, and the preservation of legumes with a volume of 1 kg per product individually. The freezing temperature has evaluated with a mechanical compression refrigeration system of Gas R22 with temperature interactions of 29.6 ° C to -12 ° C. and monitored with a Proportional Integrative Derivative (PID) controller. For production cost, the equipment was mostly made of its parts and pieces with recycling material. A descriptive experimental design has carried out, for the verification of results. The equipment managed to reach chamber temperatures of -13 ° C from 20 minutes once the equipment (compressor) has turned on under specific product descriptions.
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Effatpisheh, Aref, Amir Vadiee, and Behzad A. Monfared. "Mathematical Modelling of Active Magnetic Regenerator Refrigeration System for Design Considerations." Energies 13, no. 23 (November 29, 2020): 6301. http://dx.doi.org/10.3390/en13236301.
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A magnetic refrigeration system has the potential to alternate the compression system with respect to environmental compatibility. Refrigeration systems currently operate on the basis of the expansion and compression processes, while active magnetic refrigeration systems operate based on the magnetocaloric effect. In this study, a single layer of Gd was used as the magnetocaloric material for six-packed-sphere regenerators. A one-dimensional numerical model was utilized to simulate the magnetic refrigeration system and determine the optimum parameters. The optimum mass flow rate and maximum cooling capacity at frequency of 4 Hz are 3 L·min−1 and 580 W, respectively. The results show that the maximum pressure drop increased by 1400 W at a frequency of 4 Hz and mass flow rate of 5 L·min−1. In this study, we consider the refrigeration system in terms of the design considerations, conduct a parametric study, and determine the effect of various parameters on the performance of the system.
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Радченко, Андрій Миколайович, Микола Іванович Радченко, Богдан Сергійович Портной, Сергій Анатолійович Кантор, and Олександр Ігорович Прядко. "ВИКОРИСТАННЯ НАДЛИШКУ ХОЛОДОПРОДУКТИВНОСТІ ХОЛОДИЛЬНИХ МАШИН ПРИ ОХОЛОДЖЕННІ ПОВІТРЯ НА ВХОДІ ГТУ." Aerospace technic and technology, no. 5 (August 29, 2020): 47–52. http://dx.doi.org/10.32620/aktt.2020.5.06.
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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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Saravanan, N., R. Rathnasamy, and V. Ananchasivan. "Design and Analysis of Cooling Cabinet for Vaccine Storage." Advanced Materials Research 984-985 (July 2014): 1180–83. http://dx.doi.org/10.4028/www.scientific.net/amr.984-985.1180.
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Solar powered adsorption refrigeration system is renewable source in the future energy demands and more useful for off-grid area. In this paper a mathematical model was developed to investigate the performance of a cooling cabinet of a activated carbon-ammonia adsorption refrigeration system, and a new effective method about the refrigeration studies. A brief thermodynamic study of the cooling cabinet is carried out and the effect of operating parameters such as temperature, pressure, cooling effect of the system is numerically analyzed. The impact of solar intensity on performance of the system is significant. The cooling cabinet model is completely analysied for varies capacity and it is able to calculate the cooling cabinet coil length .The designed mathematical model is analyzed by the use of coolpack software and the results are compared with ansys software. It is observed that the system operate more efficient while maximum solar intensity and the cooling effect. Key words: Solar, Adsorption Refrigeration, Mathematical model, Analysis, Solar intensity.
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Liu, Qing Jiang, and Fang Han. "Study on the Effect of the Evaporator Area on the Heat Transfer Performance in the Gravity Feed Liquid Refrigeration System." Applied Mechanics and Materials 441 (December 2013): 112–15. http://dx.doi.org/10.4028/www.scientific.net/amm.441.112.
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In order to study the effect on heat transfer performance of evaporator in the gravity feed liquid refrigeration system the different evaporator area, the simulation procedure is worked out. The procedure uses the visual basic language. The procedure can figure out the heat transfer coefficient and the temperature difference in different evaporator area and evaporating temperature with the required refrigerating capacity. Through simulation calculation, when the area is 80% of the original design area of evaporator, the evaporator of the heat transfer coefficient and heat transfer temperature difference is the most reasonable and the evaporator of the refrigerating capacity can meet the requirements of cold storage. The program provides the reliable data for the gravity feed liquid cooling system optimization.
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Vicatos, George, and E. Krafft. "Comparison between two different solution-pumping methods in absorption refrigeration machines." Journal of Energy in Southern Africa 21, no. 3 (August 1, 2010): 16–22. http://dx.doi.org/10.17159/2413-3051/2010/v21i3a3257.
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This paper presents a pumping method in absorp-tion refrigeration where a vapour-driven pump is to replace the electricity-driven pump. The vapour pump is driven by a fraction of the generator’s hot, high-pressure, vapour mixture. The refrigerator is thus exclusively heat-powered and rendered inde-pendent of the availability of electricity as the main energy source. The design and operation of the vapour pump is presented. The results obtained by a computer simulation program show a decrease in performance (COP), which is confirmed by the data obtained from a 1 kW cooling capacity refrigerator. Peak performances occur at higher generator tem-peratures when compared to a cycle using an elec-tricity-driven pump
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Goenaga, Ane, Koldobika Martin-Escudero, Iván Flores-Abascal, Zaloa Azkorra-Larrinaga, César Escudero, and Josu Soriano. "Design of a Microscale Refrigeration System for Optimizing the Usable Space in Compact Refrigerators." Energies 15, no. 3 (January 24, 2022): 819. http://dx.doi.org/10.3390/en15030819.
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This research aims to enter the miniature refrigeration machine sector with the objective of designing a small scale unit while maintaining a competitive coefficient of performance (COP), comparing with a Peltier plates system. To this end, a research of the current technology was carried out in order to obtain indicative values on the scales that were being worked on and their application. After the previous research, a refrigeration cycle was designed in EES (engineering equation solver). From this design, different conclusions were obtained: (1) The correct sizing of the compressor revolutions together with its displacement is crucial for the equipment to be able to provide the desired cooling capacity. (2) In order to obtain the desired cooling capacity in the microscale refrigeration system, the heat exchangers must have fins. (3) Of the analysed refrigerants, R600a is the best choice, as it shows favourable characteristics (high COP and low compression ratio) when working in this type of cycle.
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Et.al, Anoop Kumar M. "Modelling and thermodynamic analysis of ejector flow for application at design and off design operating conditions in an ejector air conditioner." Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, no. 3 (April 11, 2021): 3455–67. http://dx.doi.org/10.17762/turcomat.v12i3.1617.
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Ejector flow in an ejector air conditioning system using R245fa is analysed for entrainment ratio and potential refrigeration effect, at varying temperature and heat input conditions in the generator ranging from 60C to 100C and 2kW to 5kW respectively. The effect of varying generator temperature in cooling capacity of the system when the vapour ejectoris operating at design evaporator and condenser temperatures of 10C and 35C respectively is investigated. The mathematical model of the vapour ejector with optimum area ratio is developed and validated. A critical entrainment ratio of 0.385 is obtained corresponding to generator temperature of 100C. When the generator temperature is varied from 60C to 100C, the cooling capacity range from 0.3kW at generator heat input of 2 kW to 1.78 kW at 5 kW heat input. Further, the operation of the system is analysed for off design operating condition corresponding to reduced heat input rate in the generator. In that case the state of primary refrigerant flow in ejector inlet will be two phase and a mathematical model for two-phase ejector flow is developed and validated. Ejector flow analysis revealed the minimum quality of flow at ejector inlet to maintain adequate backpressure for condensation to occur range from 0.72 at 60C to 0.22 at 100C. The corresponding refrigeration refrigeration effect produced is less than the respective designed operation value byits 12.2% to 8%. Further, analysis of the system shows that at least 7 kW heat input at 100C is required to produce 1 ton of cooling effect.
Ejector flow in an ejector air conditioning system using R245fa is analysed for entrainment ratio and potential refrigeration effect, at varying temperature and heat input conditions in the generator ranging from 60C to 100C and 2kW to 5kW respectively. The effect of varying generator temperature in cooling capacity of the system when the vapour ejectoris operating at design evaporator and condenser temperatures of 10C and 35C respectively is investigated. The mathematical model of the vapour ejector with optimum area ratio is developed and validated. A critical entrainment ratio of 0.385 is obtained corresponding to generator temperature of 100C. When the generator temperature is varied from 60C to 100C, the cooling capacity range from 0.3kW at generator heat input of 2 kW to 1.78 kW at 5 kW heat input. Further, the operation of the system is analysed for off design operating condition corresponding to reduced heat input rate in the generator. In that case the state of primary refrigerant flow in ejector inlet will be two phase and a mathematical model for two-phase ejector flow is developed and validated. Ejector flow analysis revealed the minimum quality of flow at ejector inlet to maintain adequate backpressure for condensation to occur range from 0.72 at 60C to 0.22 at 100C. The corresponding refrigeration refrigeration effect produced is less than the respective designed operation value byits 12.2% to 8%. Further, analysis of the system shows that at least 7 kW heat input at 100C is required to produce 1 ton of cooling effect.
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Liu, Li Li, Jin Sheng Sun, Lan Mei, and Yan Hong Wang. "Design and Optimization FCCU Absorption-Stabilization System through Process Simulation." Advanced Materials Research 391-392 (December 2011): 1400–1405. http://dx.doi.org/10.4028/www.scientific.net/amr.391-392.1400.
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In this preparation, FCCU main fractionator and corresponding absorption-stabilization system are systemically simulated on the basis of industrial data. Through analysis, a heat exchanging column is added to improve the flowsheet before rich gas cooler to make good use of heat of the compressed rich gas. To decrease LPG lost along with dry gas, a dry gas compression-expansion refrigeration circle is proposed to offer refrigeration capacity in place of the cooling water for the absorber pumparounds. Compared with the regular scheme, energy consumption and C3+ components in dry gas is reduced respectively by 17.18% and 7.16% and LPG yield is increased by 0.41% simultaneously.
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Lee, Keuntae, Deuk-Yong Koh, Junseok Ko, Hankil Yeom, Chang-Hyo Son, and Jung-In Yoon. "Design and Performance Test of 2 kW Class Reverse Brayton Cryogenic System." Energies 13, no. 19 (September 29, 2020): 5089. http://dx.doi.org/10.3390/en13195089.
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With the increased commercialization of high-temperature superconducting (HTS) power cables cooled using liquid nitrogen and the use of liquefied natural gas as fuel, the need for large-capacity reverse Brayton cryogenic systems is gradually increasing. In this paper, the thermodynamic design of a reverse Brayton cryogenic system with a cooling capacity of the 2 kW class at 77 K using neon as a refrigerant is described. Unlike conventional reverse Brayton systems, the proposed system uses a cryogenic turbo-expander, scroll compressor, and plate-type heat exchanger. The performance test conducted on the fabricated system is also described. The isentropic efficiency of the cryogenic turbo-expander was measured to be 86%, which is higher than the design specification. The effectiveness of the heat exchanger and the flow rate and operating pressure of the refrigerant were found to be lower than the design specifications. Consequently, the refrigeration capacity of the fabricated reverse Brayton cryogenic system was measured to be 1.23 kW at 77 K. In the future, we expect to achieve the targeted refrigeration capacity through further improvements. In addition, the faster commercialization of HTS power cables and more efficient storage of liquefied natural gas will be realized.
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Song, Peng, Jinju Sun, and Changjiang Huo. "Enhancing refrigeration capacity of turbo expander by means of multipoint design optimization." International Journal of Refrigeration 108 (December 2019): 60–78. http://dx.doi.org/10.1016/j.ijrefrig.2019.08.035.
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Liu, Yan Ling, Ling Qun Wang, and Zai Zhong Xia. "Design and Performance Study of a Novel Refrigeration System." Advanced Materials Research 354-355 (October 2011): 819–27. http://dx.doi.org/10.4028/www.scientific.net/amr.354-355.819.
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In order to solve the problems of pressure drop and leakage in the refrigerant circuit, a novel continuous adsorption system suited to use low heat source (75-85 oC) was designed and set up. To analyze and compare with the conventional system to reveal the similarity and difference, this paper sets up the mathematical models for these two systems. The adsorbers, condensers and evaporators in these two systems are exactly the same and the two systems are compared by working at the identical conditions, which is not feasible in real experimental lab. All the parameters and models used in this calculation are based on experimental results. Analysis demonstrates that the two kinds of system have very close performances, that is, the novel system has a relatively higher cooling capacity while the conventional system has a relatively higher COP.
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Vicatos, G., and A. Bennett. "Multiple lift tube pumps boost refrigeration capacity in absorption plants." Journal of Energy in Southern Africa 18, no. 4 (August 1, 2007): 49–57. http://dx.doi.org/10.17159/2413-3051/2007/v18i4a3396.
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The technology of the diffusion absorption refriger-ator is receiving renewed attention due to its ability to use exclusively, low-grade heat to produce cool-ing or heating. Its capacity, however, has been large-ly restricted to small domestic-type units because of the flow rate limitations imposed by its single lift-tube pump. To increase its refrigeration capacity, a multiple lift-tube bubble pump can be used, in order to increase the volume flow rates of the fluids, which are directly related to the amount of refriger-ant produced. Testing on a diffusion absorption plant using a multiple lift tube bubble pump, and the effects of additional tubes on the system’s per-formance have been recorded. Although a full range of heat inputs could not be implemented, because of the limitations of the components of the unit itself, it was observed that the refrigeration cooling capacity was increased without a significant drop in Coefficient of Performance (COP). It was concluded that the multiple lift tube bubble pump has no limitation to the fluid flow rate and depends solely on the amount of heat input. This gives the freedom to design the lift tube pump according to the refrigeration demand of the unit, and not the other way round which is the current approach by the manufacturers world wide.
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Fielding, J. P., and M. A. F. Vaziry-Z. "Avionics cooling-rate trade-off modelling for ultra-high capacity aircraft." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 211, no. 6 (June 1, 1997): 403–12. http://dx.doi.org/10.1243/0954410971532767.
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A computer aided conceptual aircraft design methodology (CACAD) has been developed to size ultra-high capacity jet transport aircraft. Modules were also developed for predicting maintenance costs of each airframe and avionics system and these were incorporated into CACAD. A methodology was developed to enhance the reliability of avionics systems, based on experimentally-proven engineering design solutions. A number of avionics cooling techniques were investigated, and reliability and maintainability models of thermal management were developed and linked to an avionics maintenance cost module. Further models were produced to investigate the impact of proposed changes on the environmental control systems, engine-provided bleeds and power off-takes. It was found that increased flowrates above the normally recommended values for the avionics bay, and to the flight deck instruments, may increase the reliability of the avionics systems, and also increase aircraft dispatch reliability. They may not, however, greatly improve direct operating costs (DOC), due to significant fuel penalties. A separate refrigeration unit was investigated and found to be a feasible cost-effective measure, even allowing for increased engine fuel consumption caused by the effect of the engine power off-take required to drive the refrigeration unit.
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Primal, F., and P. Lundqvist. "Refrigeration systems with minimized refrigerant charge: System design and performance." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 219, no. 2 (May 1, 2005): 127–37. http://dx.doi.org/10.1243/095440805x7062.
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Independently of the choice of refrigerant, environmental and/or safety issues can be minimized by reducing leakage and the amount of refrigerant charge in heat pump or refrigeration systems, preferably both. In the investigation reported here, a laboratory test rig was built, simulating a water-to-water heat pump with a heating capacity of 5 kW. The system was designed to minimize the charge of refrigerant mainly by use of minichannel aluminium heat exchangers and a compact system design. It was shown that the system could be run with 200 g of propane at typical domestic heat pump operating conditions without reduction in the heating coefficient of performance (COP1) compared with a traditional design. Additional charge reduction is possible by selecting proper compressor lubrication oils or by employing a compressor simply using less lubrication oil.
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Klein, S. A., and D. T. Reindl. "The Relationship of Optimum Heat Exchanger Allocation and Minimum Entropy Generation Rate for Refrigeration Cycles." Journal of Energy Resources Technology 120, no. 2 (June 1, 1998): 172–78. http://dx.doi.org/10.1115/1.2795030.
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This paper investigates the effect of heat exchanger allocation on overall system performance using both reverse Carnot and vapor compression refrigeration cycle models to calculate system performance and entropy generation rate. The algebraically simple constraints applied in previous studies are shown to be justifiable. The vapor compression model considers nonideal compressor performance, compressor volumetric efficiency, refrigerant properties, and throttling, in addition to mechanistic heat exchanger models. The results support the conclusions of previous studies in that maximum performance is observed when the condenser and evaporator thermal sizes are approximately equal. For air-to-air systems, this result indicates that the areas of the heat exchangers should be approximately equal. However, it is found that minimizing the entropy generation rate does not always result in the same design as maximizing the system performance unless the refrigeration capacity is fixed. Minimizing the entropy generation rate per unit capacity is found to always correspond to maximizing the coefficient of performance of refrigeration systems.
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Ezgi, Cüneyt, and Sinem Bayrak. "Experimental Analysis of a Laboratory-Scale Diesel Engine Exhaust Heat-Driven Absorption Refrigeration System as a Model for Naval Surface Ship Applications." Journal of Ship Production and Design 36, no. 02 (May 1, 2020): 152–59. http://dx.doi.org/10.5957/jspd.2020.36.2.152.
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Decreasing industrial energy sources and major environmental problems caused by uncontrolled energy consumption have led to studies on alternative energy sources. This study presents a design and experimental analysis of an exhaust gas-driven absorption refrigeration system for the purpose of air conditioning by using the exhaust heat of a diesel engine, which is installed in the Naval Academy Mechanics Laboratory. The diesel engine is loaded with a dynamometer, and water and ammonia are used as an absorbent and refrigerant, respectively. At various diesel engine loads, cooling capacity and coefficient of performance (COP) of the absorption refrigeration system are calculated. Experimental results have indicated the cooling capacity as 1.098 kW at a maximum engine power of 4.9 HP. The highest COP value in the designed system has been calculated to be .3022 for the generator temperature of 160 C. Although the COP of refrigeration is low, the absorption refrigeration system can be provided a great cooling load from the exhaust heat of diesel engines and can be used in naval surface ships. In addition to energy efficiency of naval surface ships, infrared and acoustic signature can be minimized and a ships susceptibility can be dramatically reduced.
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Mahmood, R. A., O. M. Ali, A. Al-Janabi, G. Al-Doori, and M. M. Noor. "Review of Mechanical Vapour Compression Refrigeration System Part 2: Performance Challenge." International Journal of Applied Mechanics and Engineering 26, no. 3 (August 26, 2021): 119–30. http://dx.doi.org/10.2478/ijame-2021-0039.
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Abstract Reducing energy consumption and providing high performance for a vapour compression refrigeration system are big challenges that need more attention and investigation. This paper provides an extensive review of experimental and theoretical studies to present the vapour compression refrigeration system and its modifications that can be used to improve system’s performance and reduce its energy consumption. This paper also presents the challenges that can be considered as a gab of research for the future works and investigations. Cooling capacity, refrigerant effect, energy consumption can be improved by using vapour injection technique, natural working fluid, and heat exchanger. Based on the outcome of this paper, vapour injection technique using natural refrigerant such as water can provide ultimate friendly refrigeration system. Future vision for the vapour compression refrigeration system and its new design technique using Computational Fluid Dynamic (CFD) is also considered and presented.
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Amber, I., C. O. Folayan, R. B. O. Suleiman, and A. Y. Atta. "Design, Construction and Testing of a Solar Adsorption Refrigerator Using Synthesised Zeolite A and Water as Adsorbent/Adsorbate Pair." Advanced Materials Research 367 (October 2011): 495–500. http://dx.doi.org/10.4028/www.scientific.net/amr.367.495.
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This paper presents the design and construction of a simple Zeolite-water solar adsorption refrigeration system which has been fabricated and tested in the Department of Mechanical Engineering, Ahmadu Bello University, Zaria, Nigeria at a geographical location of latitude 11o11’’NE. The theory on which this design is based is on the use of Zeolite-water adsorbent/ adsorbate pair to produce refrigeration. The energy source is a parabolic trough solar concentrator that collects and radiates solar thermal energy onto an air tight black coated absorber (generator) charged with Zeolite and water placed at the trough’s focal point. The absorber adsorbs and desorbs the adsorbate and produces refrigeration as vapor is released through a condenser and an evaporator. Constructional details of the system show the systems height at 1.2 m, parabolic trough dimensions of 0.6m by 0.45m, the cold chamber, has a capacity of 36 liters. The system was evaluated by leaving it outside under solar radiation and monitoring temperatures at various points inside the collector, the generator, and the evaporator through the use of thermocouple sensors. The highest and lowest temperatures of the absorber were 60.1°C and 25°C respectively. The lowest refrigeration temperature of 9.8°C was attained with 179J of cooling.
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Hermes, Christian J. L., Joel Boeng, Diogo L. da Silva, Fernando T. Knabben, and Andrew D. Sommers. "Evaporator Frosting in Refrigerating Appliances: Fundamentals and Applications." Energies 14, no. 18 (September 21, 2021): 5991. http://dx.doi.org/10.3390/en14185991.
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Modern refrigerators are equipped with fan-supplied evaporators often tailor-made to mitigate the impacts of frost accretion, not only in terms of frost blocking, which depletes the cooling capacity and therefore the refrigerator coefficient of performance (COP), but also to allow optimal defrosting, thereby avoiding the undesired consequences of condensate retention and additional thermal loads. Evaporator design for frosting conditions can be done either empirically through trial-and-error approaches or using simulation models suitable to predict the distribution of the frost mass along the finned coil. Albeit the former is mandatory for robustness verification prior to product approval, it has been advocated that the latter speeds up the design process and reduces the costs of the engineering undertaking. Therefore, this article is aimed at summarizing the required foundations for the design of efficient evaporators and defrosting systems with minimized performance impacts due to frosting. The thermodynamics, and the heat and mass transfer principles involved in the frost nucleation, growth, and densification phenomena are presented. The thermophysical properties of frost, such as density and thermal conductivity, are discussed, and their relationship with refrigeration operating conditions are established. A first-principles model is presented to predict the growth of the frost layer on the evaporator surface as a function of geometric and operating conditions. The relation between the microscopic properties of frost and their macroscopic effects on the evaporator thermo-hydraulic performance is established and confirmed with experimental evidence. Furthermore, different defrost strategies are compared, and the concept of optimal defrost is formulated. Finally, the results are used to analyze the efficiency of the defrost operation based on the net cooling capacity of the refrigeration system for different duty cycles and evaporator geometries.
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Bykanov, Serhii, Babak Tetiana Babak, and Roman Stotskyi. "THERMAL INTEGRATION OF COMPRESSION REFRIGERATION UNITS IN DAIRY FACILITIES." Bulletin of the National Technical University "KhPI". Series: Chemistry, Chemical Technology and Ecology, no. 1(5) (May 15, 2021): 92–98. http://dx.doi.org/10.20998/2079-0821.2021.01.14.
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The heat integration of an ammonia compression refrigeration unit, that is used in different dairy facilities, was carried out by the pinch analysis methods. The schematic diagram of such unit with a cooling capacity of 1000 kW was taken as a basis. The main cycle temperatures, refrigerant consumption and its specific heat capacity were calculated for a given refrigerating capacity. Based on these data, a stream table was formed, that included a hot stream of a refrigerant – ammonia – and also two cold streams: water for chemical water treatment and water for technology. The hot stream of ammonia was divided into three streams: cooling of ammonia vapors, condensation and subcooling. Heat capacities flowrates and heat loads (stream enthalpy change) of the streams were determined. The minimum temperature difference in heat exchangers DTmin = 8°С was determined on the basis of technical and economic calculations for this process. The composite curves were plotted for the minimum temperature difference. The pinch temperatures were determined by the problem table algorithm for the hot and cold streams. The minimum values of hot and cold utilities load (QHmin and QСmin) were determined. The heat recovery capacity was determined, which was 701.8 kW. A grid diagram was built and heat exchangers are arranged in accordance with CP and N rules. The retrofit of process flowsheet is proposed on the basis of the grid diagram that includes the installation of three heat exchangers, one cooler and two heaters to achieve the target temperatures and flow rates. The use of Alfa Laval plate heat exchangers is proposed as heat exchange equipment. The payback period of the design is about two years.
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Su, Shan He, Zhi Chao Xu, Guo Xing Lin, Gildas Diguet, and Jin Can Chen. "Thermodynamic Performance Characteristics of a Regenerative Brayton Refrigeration Cycle Using Gd0.45Tb0.55 and Gd as the Working Substance." Advanced Materials Research 750-752 (August 2013): 1016–19. http://dx.doi.org/10.4028/www.scientific.net/amr.750-752.1016.
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Based on experimental characteristics of the iso-field heat capacity of the working substances Gd0.45Tb0.55and Gd, the magnetic entropy change with temperature is calculated. The regenerative Brayton refrigeration cycles employing these materials as the working substances are established. By means of thermodynamic analysis and numerical calculation, the effects of the non-perfect regeneration on the performance characteristics of the refrigeration cycles are revealed. Furthermore, the cyclic performances employing Gd0.45Tb0.55and Gd as the working substances are evaluated and compared. The results obtained may provide some useful information for the optimal design of the room temperature magnetic refrigerators.
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Yang, Jun Hong, Qiang Zhu, and Shen Liu. "CO2 Heat Pump Intelligent Defrosting Design Based on PLC." Advanced Materials Research 1079-1080 (December 2014): 476–79. http://dx.doi.org/10.4028/www.scientific.net/amr.1079-1080.476.
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CO2 heat pump is a new type refrigeration equipment of energy saving, environmental protection and high efficiency, it is the basic direction of future sustainable development in HVAC. But it runs in winter, because of the influence of the external environment will be the formation of frost on the evaporator surface, thereby reducing the heat capacity of heat pump units, even in normal operation. Combined with the practical application of CO2 heat pump, the design of a PLC based intelligent defrosting system; this system is a good solution to the CO2 heat pump, low temperature and high humidity environment of the defrosting problem.
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Ochoa, Guillermo Valencia. "Design of a mechanical subcooling system device for increasing a low temperature refrigeration system’s capacity." Prospectiva 11, no. 2 (July 22, 2014): 13. http://dx.doi.org/10.15665/rp.v11i2.33.
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Malchevsky, V., and R. Varbanets. "RESEARCH OF THE EFFICIENCY OF MARINE DIESEL FUEL COOLING SYSTEM ON THE BASIS OF NEW REFRIGERANTS." Internal Combustion Engines, no. 1 (July 26, 2021): 3–9. http://dx.doi.org/10.20998/0419-8719.2021.1.01.
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The requirements of the International Maritime Organization, government environmental agencies and other non-governmental groups are aimed at reducing emissions of harmful substances into the environment during the operation of diesel engines. Among these substances, the most dangerous are sulfur oxide (SOx), nitrogen oxide (NOx) and particulate matter (PM). In accordance with the specified requirements, there is an active transition to fuels with ultra-low sulfur content. The use of these fuels in marine diesel engines is associated with a number of difficulties, because these engines are usually designed for operation on fuels with high viscosity and lubricity. The viscosity values for ultra-low sulfur fuels are close to the permitted minimums for diesel engines at normal engine room temperature. The greatest difficulties occur when the viscosity values fall below the specific range when the fuel temperature before the engine increases. For reliable operation of the engine, the fuel temperature must be constantly maintained at a range in which the fuel viscosity will have the required values. For this purpose the engine design provides presence of fuel cooling system with a water cooler and a chiller for heat removal from water. In this paper the efficiency of chiller refrigeration plant was investigated using new perspective refrigerant mixtures R125/R290 and R134a/R290 as working fluids in comparison with basic R134a and R22. The values of composition for both mixtures are chosen such that they are closest to the azeotrope. It is possible for azeotrope mixtures to minimize the temperature difference between heat exchanging medias in condenser and evaporator of refrigeration plant. During the investigation it was revealed that the values of refrigeration coefficient of refrigerating plant when using mixtures as working fluids were somewhat lower when operating on R134a and R22. But the values of volumetric refrigeration capacity with mixtures as working fluids are significantly higher.
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Трушляков, Євген Іванович, Андрій Миколайович Радченко, Микола Іванович Радченко, Сергій Анатолійович Кантор, and Веніамін Сергійович Ткаченко. "ПІДВИЩЕННЯ ЕФЕКТИВНОСТІ КОНДИЦІЮВАННЯ ЗОВНІШНЬОГО ПОВІТРЯ СИСТЕМИ КОМБІНОВАНОГО ТИПУ." Aerospace technic and technology, no. 4 (August 31, 2019): 9–14. http://dx.doi.org/10.32620/aktt.2019.4.02.
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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.
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Yang, Zongming, Mykola Radchenko, Andrii Radchenko, Dariusz Mikielewicz, and Roman Radchenko. "Gas Turbine Intake Air Hybrid Cooling Systems and a New Approach to Their Rational Designing." Energies 15, no. 4 (February 17, 2022): 1474. http://dx.doi.org/10.3390/en15041474.
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Gas turbine intake air cooling (TIAC) by exhaust gas heat recovery chillers is a general trend to improve turbine fuel efficiency at increased ambient temperatures. The high efficiency absorption lithium–bromide chillers of a simple cycle are the most widely used, but they are unable to cool inlet air lower than 15 °C. A two-stage hybrid absorption–ejector chillers were developed with absorption chiller as a high temperature stage and ejector chiller as a low temperature stage to subcool air from 15 °C to 10 °C and lower. A novel trend in TIAC by two-stage air cooling in hybrid chillers has been substantiated to provide about 50% higher annual fuel saving in temperate climate as compared with absorption cooling. A new approach to reduce practically twice design cooling capacity of absorption chiller due to its rational distribution with accumulating excessive refrigeration energy at decreased thermal loads to cover the picked demands and advanced design methodology based on it was proposed. The method behind this is issued from comparing a behavior of the characteristic curves of refrigeration energy required for TIAC with its available values according to various design cooling capacities to cover daily fluctuation of thermal loads at reduced by 15 to 20% design cooling capacity and practically maximum annual fuel reduction.
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Elbarghthi, Anas F. A., Mohammad Yousef Hdaib, and Václav Dvořák. "A Novel Generator Design Utilised for Conventional Ejector Refrigeration Systems." Energies 14, no. 22 (November 17, 2021): 7705. http://dx.doi.org/10.3390/en14227705.
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Ejector refrigeration systems are rapidly evolving and are poised to become one of the most preferred cooling systems in the near future. CO2 transcritical refrigeration systems have inherently high working pressures and discharge temperatures, providing a large volumetric heating capacity. In the current research, the heat ejected from the CO2 gas cooler was proposed as a driving heating source for the compression ejector system, representing the energy supply for the generator in a combined cycle. The local design approach was investigated for the combined plate-type heat exchanger (PHE) via Matlab code integrated with the NIST real gas database. HFO refrigerants (1234ze(E) and 1234yf) were selected to serve as the cold fluid on the generator flowing through three different phases: subcooled liquid, a two-phase mixture, and superheated vapour. The study examines the following: the effectiveness, the heat transfer coefficients, and the pressure drop of the PHE working fluids under variable hot stream pressures, cold stream flow fluxes, and superheated temperatures. The integration revealed that the cold fluid mixture phase dominates the heat transfer coefficients and the pressure drop of the heat exchanger. By increasing the hot stream inlet pressure from 9 MPa to 12 MPa, the cold stream two-phase convection coefficient can be enhanced by 50% and 200% for R1234yf and R1234ze(E), respectively. Conversely, the cold stream two-phase convection coefficient dropped by 17% and 37% for R1234yf and R1234ze(E), respectively. The overall result supports utilising the ejected heat from the CO2 transcritical system, especially at high CO2 inlet pressures and low cold channel flow fluxes. Moreover, R1234ze(E) could be a more suitable working fluid because it possesses a lower pressure drop and bond number.
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Hwang, YoonJei, HanYoung Park, SaiKee Oh, HoRim Lee, YoungSu Park, and KamGyu Lee. "The evaluation of energy saving performance for the modular design centrifugal chiller." E3S Web of Conferences 111 (2019): 01018. http://dx.doi.org/10.1051/e3sconf/201911101018.
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The modular concept design and operation of a centrifugal chiller offers the potential of increased cycle efficiency both at full load and off load conditions compared to the single compressor chiller. Modular chiller design is that a smaller, individual chiller can be connected with another, to make a larger capacity system. In the case of a tandem chiller, there would be faced to the higher initial cost or bigger foot print than a single compressor chiller at the same capacity because manufacturing cost, weight and size will be decreased according to increase of the refrigeration capacity. Therefore, it is obvious that a modular chiller have to be improved its efficiency first by both the operation algorithm and major cycle components. Eventually, the efficiency of the modular chiller achieves up to 6% at the full load condition after added series counter flow effect as much as 3% and more 3% added by improved aerodynamic design for impeller. Moreover, maximize off design potential through the capacity combination algorithm as the way of uneven loading makes 24% improved based on AHRI 550/590.
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Atmaca, Ayşe Uğurcan, Aytunç Erek, and Orhan Ekren. "Preliminary Design of the Two-Phase Ejector under Constant Area Mixing Assumption for 5 kW Experimental System." E3S Web of Conferences 103 (2019): 01002. http://dx.doi.org/10.1051/e3sconf/201910301002.
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Ejector expansion refrigeration cycle is the modification of the vapour compression refrigeration cycle with the implementation of a two-phase ejector and a vapour-liquid separator to improve the cycle performance. In this study, main geometrical parameters of an ejector, i.e. diameters of the motive nozzle throat, motive nozzle outlet, suction nozzle outlet, and constant area mixing section are calculated in order to provide the preliminary design aspects at various operation conditions. The thermodynamic model of the ejector is established with reference to constant-area mixing assumption. The equations are solved in Matlab®. The environmentally-friendly refrigerants, R1234yf and R1234ze(E) from the hydrofluoroolefins (HFOs) and R134a which is about to be phased out by the F-gas Regulation are used in the analyses. When compared to the previous literature findings, the current research aims to compare the dimensions of a two-phase ejector to be used in an experimental system having 5 kW cooling capacity for these three refrigerants.
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Xu, Aixiang, Mengjin Xu, Nan Xie, Yawen Xiong, Junze Huang, Yingjie Cai, Zhiqiang Liu, and Sheng Yang. "Thermodynamic Analysis of a Hybrid System Coupled Cooling, Heating and Liquid Dehumidification Powered by Geothermal Energy." Energies 14, no. 19 (September 24, 2021): 6084. http://dx.doi.org/10.3390/en14196084.
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The utilization of geothermal energy is favorable for the improvement of energy efficiency. A hybrid system consisting of a seasonal heating and cooling cycle, an absorption refrigeration cycle and a liquid dehumidification cycle is proposed to meet dehumidification, space cooling and space heating demands. Geothermal energy is utilized effectively in a cascade approach. Six performance indicators, including humidity efficiency, enthalpy efficiency, moisture removal rate, coefficient of performance, cooling capacity, and heating capacity, are developed to analyze the proposed system. The effect of key design parameters in terms of desiccant concentration, air humidity, air temperature, refrigeration temperature and segment temperature on the performance indicators are investigated. The simulation results indicated that the increase of the desiccant concentration makes the enthalpy efficiency, the coefficient of performance, the moisture removal rate and the cooling capacity increase and makes the humidity efficiency decrease. With the increase of air humidity, the humidity efficiency and moisture removal rate for the segment temperatures from 100 to 130 °C are approximately invariant. The decreasing rates of the humidity efficiency and the moisture removal rate with the segment temperature of 140 °C increases respectively. Six indicators, except the cooling capacity and heating capacity, decrease with an increase of air temperature. The heating capacity decreases by 49.88% with the reinjection temperature increasing from 70 to 80 °C. This work proposed a potential system to utilize geothermal for the dehumidification, space cooling and space heating effectively.
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Masiá, Carmen, Poul Erik Jensen, Iben Lykke Petersen, and Patrizia Buldo. "Design of a Functional Pea Protein Matrix for Fermented Plant-Based Cheese." Foods 11, no. 2 (January 11, 2022): 178. http://dx.doi.org/10.3390/foods11020178.
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The production of a fermented plant-based cheese requires understanding the behavior of the selected raw material prior to fermentation. Raw material processing affects physicochemical properties of plant protein ingredients, and it determines their ability to form fermentation-induced protein gels. Moreover, the addition of oil also influences structure formation and therefore affects gel firmness. This study focuses on identifying and characterizing an optimal pea protein matrix suitable for fermentation-induced plant-based cheese. Stability and gel formation were investigated in pea protein matrices. Pea protein isolate (PPI) emulsions with 10% protein and 0, 5, 10, 15, and 20% olive oil levels were produced and further fermented with a starter culture suitable for plant matrices. Emulsion stability was evaluated through particle size, ζ-potential, and back-scattered light changes over 7 h. Gel hardness and oscillation measurements of the fermented gels were taken after 1 and 7 days of storage under refrigeration. The water-holding capacity of the gels was measured after 7 days of storage and their microstructure was visualized with confocal microscopy. Results indicate that all PPI emulsions were physically stable after 7 h. Indeed, ζ-potential did not change significantly over time in PPI emulsions, a bimodal particle size distribution was observed in all samples, and no significant variation was observed after 7 h in any of the samples. Fermentation time oscillated between 5.5 and 7 h in all samples. Higher oil content led to weaker gels and lower elastic modulus and no significant changes in gel hardness were observed over 7 days of storage under refrigeration in closed containers. Water-holding capacity increased in samples with higher olive oil content. Based on our results, an optimal pea protein matrix for fermentation-induced pea protein gels can be produced with 10% protein content and 10% olive oil levels without compromising gel hardness.
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Kula, Sinan. "Design Studies of Two Stage Cooling Loop for New Generation Vehicles." Academic Perspective Procedia 3, no. 1 (October 25, 2020): 550–59. http://dx.doi.org/10.33793/acperpro.03.01.104.
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In this article, the design and integration of an intelligent refrigeration system that increases air conditioning and engine efficiency, reduces fuel consumption and emission levels in vehicles manufactured today will be examined. This design will include a two-stage cooling system. Two-stage cooling unit consist; high temperature radiator and low temperature radiator. The engine coolant will be cooled in the high temperature radiator. In the low temperature radiator, coolant of water cooled air charger and air conditioning condenser will be cooled. It is aimed to increase the engine efficiency by cooling more efficiently, thanks to the heat carrying capacity of the water which is high compared to air. With this project, it is aimed to cool the heated air after the turbocharging and air conditioning gas in the vehicle with water instead of air.
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Raja, V. Boopathi, and V. Shanmugam. "Experimental Analysis of Newly Designed Solar Assisted Single Effect Absorption Cooling System of 5.25 kW Cooling Capacity for Domestic Use." Applied Mechanics and Materials 787 (August 2015): 32–36. http://dx.doi.org/10.4028/www.scientific.net/amm.787.32.
Full textAbstract:
Many research studies have been carried out to develop small capacity absorption cooling systems as an alternative to conventional vapour compression refrigeration (VCR) systems with respect to performance and economic aspects. The aim of this work is to design a solar assisted single effect absorption cooling system of 5.25 kW cooling capacity to cool a room having floor area of 15 m2. Based on the design, an experimental setup is constructed and operated by supplying heat to the generator using solar energy. The performance analysis of the cooling system is carried out by measuring the various operational parameters. The minimum cooling temperature of 16°C is observed in the evaporator and maximum COP of 0.9 is obtained when the hot water storage tank reaches 90°C. As per this new design, the operational cost is minimized and the COP obtained is slightly higher when compared to that of earlier similar works.
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Mussati, Sergio F., Tatiana Morosuk, and Miguel C. Mussati. "Superstructure-Based Optimization of Vapor Compression-Absorption Cascade Refrigeration Systems." Entropy 22, no. 4 (April 10, 2020): 428. http://dx.doi.org/10.3390/e22040428.
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A system that combines a vapor compression refrigeration system (VCRS) with a vapor absorption refrigeration system (VARS) merges the advantages of both processes, resulting in a more cost-effective system. In such a cascade system, the electrical power for VCRS and the heat energy for VARS can be significantly reduced, resulting in a coefficient of performance (COP) value higher than the value of each system operating in standalone mode. A previously developed optimization model of a series flow double-effect H2O-LiBr VARS is extended to a superstructure-based optimization model to embed several possible configurations. This model is coupled to an R134a VCRS model. The problem consists in finding the optimal configuration of the cascade system and the sizes and operating conditions of all system components that minimize the total heat transfer area of the system, while satisfying given design specifications (evaporator temperature and refrigeration capacity of −17.0 °C and 50.0 kW, respectively), and using steam at 130 °C, by applying mathematical programming methods. The obtained configuration is different from those reported for combinations of double-effect H2O-LiBr VAR and VCR systems. The obtained optimal configuration is compared to the available data. The obtained total heat transfer area is around 7.3% smaller than that of the reference case.