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1
Zhu, Qidi, Zhiqiang Sun, and Jiemin Zhou. "Performance analysis of organic Rankine cycles using different working fluids." Thermal Science 19, no. 1 (2015): 179–91. http://dx.doi.org/10.2298/tsci120318014z.
Повний текст джерелаАнотація:
Low-grade heat from renewable or waste energy sources can be effectively recovered to generate power by an organic Rankine cycle (ORC) in which the working fluid has an important impact on its performance. The thermodynamic processes of ORCs using different types of organic fluids were analyzed in this paper. The relationships between the ORC?s performance parameters (including evaporation pressure, condensing pressure, outlet temperature of hot fluid, net power, thermal efficiency, exergy efficiency, total cycle irreversible loss, and total heat-recovery efficiency) and the critical temperatures of organic fluids were established based on the property of the hot fluid through the evaporator in a specific working condition, and then were verified at varied evaporation temperatures and inlet temperatures of the hot fluid. Here we find that the performance parameters vary monotonically with the critical temperatures of organic fluids. The values of the performance parameters of the ORC using wet fluids are distributed more dispersedly with the critical temperatures, compared with those of using dry/isentropic fluids. The inlet temperature of the hot fluid affects the relative distribution of the exergy efficiency, whereas the evaporation temperature only has an impact on the performance parameters using wet fluid.
2
Liu, Guanglin, Qingyang Wang, Jinliang Xu, and Zheng Miao. "Exergy Analysis of Two-Stage Organic Rankine Cycle Power Generation System." Entropy 23, no. 1 (December 30, 2020): 43. http://dx.doi.org/10.3390/e23010043.
Повний текст джерелаАнотація:
Organic Rankine cycle (ORC) power generation is an effective way to convert medium and low temperature heat into high-grade electricity. In this paper, the subcritical saturated organic Rankine cycle system with a heat source temperature of 100~150 °C is studied with four different organic working fluids. The variations of the exergy efficiencies for the single-stage/two-stage systems, heaters, and condensers with the heat source temperature are analyzed. Based on the condition when the exergy efficiency is maximized for the two-stage system, the effects of the mass split ratio of the geothermal fluid flowing into the preheaters and the exergy efficiency of the heater are studied. The main conclusions include: The exergy efficiency of the two-stage system is affected by the evaporation temperatures of the organic working fluid in both the high temperature and low temperature cycles and has a maximum value. Under the same heat sink and heat source parameters, the exergy efficiency of the two-stage system is larger than that of the single-stage system. For example, when the heat source temperature is 130 °C, the exergy efficiency of the two-stage system is increased by 9.4% compared with the single-stage system. For the two-stage system, analysis of the four organic working fluids shows that R600a has the highest exergy efficiency, although R600a is only suitable for heat source temperature below 140 °C, while other working fluids can be used in systems with higher heat source temperatures. The mass split ratio of the fluid in the preheaters of the two-stage system depends on the working fluid and the heat source temperature. As the heat source temperature increases, the range of the split ratio becomes narrower, and the curves are in the shape of an isosceles triangle. Therefore, different working fluids are suitable for different heat source temperatures, and appropriate working fluid and split ratio should be determined based on the heat source parameters.
3
Imre, Attila R., Réka Kustán, and Axel Groniewsky. "Thermodynamic Selection of the Optimal Working Fluid for Organic Rankine Cycles." Energies 12, no. 10 (May 27, 2019): 2028. http://dx.doi.org/10.3390/en12102028.
Повний текст джерелаАнотація:
A novel method proposed to choose the optimal working fluid—solely from the point of view of expansion route—for a given heat source and heat sink (characterized by a maximum and minimum temperature). The basis of this method is the novel classification of working fluids using the sequences of their characteristic points on temperature-entropy space. The most suitable existing working fluid can be selected, where an ideal adiabatic (isentropic) expansion step between a given upper and lower temperature is possible in a way, that the initial and final states are both saturated vapour states and the ideal (isentropic) expansion line runs in the superheated (dry) vapour region all along the expansion. Problems related to the presence of droplets or superheated dry steam in the final expansion state can be avoided or minimized by using the working fluid chosen with this method. Results obtained with real materials are compared with those gained with model (van der Waals) fluids; based on the results obtained with model fluids, erroneous experimental data-sets can be pinpointed. Since most of the known working fluids have optimal expansion routes at low temperatures, presently the method is most suitable to choose working fluids for cryogenic cycles, applied for example for heat recovery during LNG-regasification. Some of the materials, however, can be applied in ranges located at relatively higher temperatures, therefore the method can also be applied in some limited manner for the utilization of other low temperature heat sources (like geothermal or waste heat) as well.
4
Shuja, Shahzada Zaman, Bekir Sami Yilbas, and Hussain Al-Qahtani. "Thermal Assessment of Selective Solar Troughs." Energies 12, no. 16 (August 15, 2019): 3130. http://dx.doi.org/10.3390/en12163130.
Повний текст джерелаАнотація:
A comparative study was carried out incorporating a novel approach for thermal performance evaluations of commonly used parabolic trough collectors, namely the Euro, Sky, and Helio troughs. In the analysis, pressurized water and therminol-VP1 (eutectic mixture of diphenyl oxide (DPO) and biphenyl) fluid were introduced as working fluids, and the governing equation of energy was simulated for various working fluid mass flow rates and inlet temperatures. The thermal performance of the troughs was assessed by incorporating the first- and second-law efficiencies and by using temperature increases and pressure drops of the working fluid. It was found that the first-law efficiency of the troughs increased with the working fluid mass flow rate, while it decreased with an increasing working fluid inlet temperature. The first-law efficiency remained the highest for the Euro trough, followed by the Sky and Helio troughs. The second-law efficiency reduced with an increasing working fluid mass flow rate, while it increased with an increasing working fluid inlet temperature. The second-law efficiency became the highest for the Helio Trough, followed by the Sky and Euro troughs. The temperature increase remained the highest along the length of the receiver for the Helio Trough compared to that corresponding to the Euro and Sky troughs for the same mass flow rate of the working fluid. The pressure drops in the working fluid became high for the Euro Trough, followed by the Sky and Helio troughs. The pressurized water resulted in higher second-law efficiency than the therminol-VP1 fluid did for all of the troughs considered.
5
Kolasiński, Piotr. "The Method of the Working Fluid Selection for Organic Rankine Cycle (ORC) Systems Employing Volumetric Expanders." Energies 13, no. 3 (January 24, 2020): 573. http://dx.doi.org/10.3390/en13030573.
Повний текст джерелаАнотація:
The working fluid selection is one of the most important issues faced when designing Organic Rankine Cycle (ORC) systems. The choice of working fluid is dictated by different criteria. The most important of them are safety of use, impact on the environment, and physical and chemical parameters. The type of ORC system in which the working fluid is to be used and the type of expander applied in this system is also affecting the working fluid selection. Nowadays, volumetric expanders are increasingly used in ORC systems. In the case of volumetric expanders, in addition to the aforementioned working fluid selection criteria, additional parameters are considered during the selecting of the working fluid, such as the range of operating pressures and geometric dimensions (determining the volume of working chambers) affecting the achieved power and efficiency of the expander. This article presents a method of selecting a working medium for ORC systems using volumetric expanders. This method is based on the dimensionless rating parameters applied for the comparative analysis of different working fluids. Dimensionless parameters were defined for selected thermal properties of the working fluids, namely thermal capacity, mean temperature of evaporation, mean temperature of condensation, pressure and volumetric expansion ratio, volumetric expandability, as well as the heat of preheating, vaporization, superheating, cooling, and liquefaction. Moreover, isentropic expansion work was considered as the rating parameter. In this article, in addition to the working fluid selection method, computational examples related to the selection of the working fluid for the ORC system fed by a heat source featuring specified temperatures are presented. The results of calculations of rating parameters and their comparison gave an outlook on the selection of appropriate working fluids.
6
Vijayaraghavan, Sanjay, and D. Y. Goswami. "Organic Working Fluids for a Combined Power and Cooling Cycle." Journal of Energy Resources Technology 127, no. 2 (February 6, 2005): 125–30. http://dx.doi.org/10.1115/1.1885039.
Повний текст джерелаАнотація:
A new thermodynamic cycle has been developed for the simultaneous production of power and cooling from low-temperature heat sources. The proposed cycle combines the Rankine and absorption refrigeration cycles, providing power and cooling as useful outputs. Initial studies were performed with an ammonia-water mixture as the working fluid in the cycle. This work extends the application of the cycle to working fluids consisting of organic fluid mixtures. Organic working fluids have been used successfully in geothermal power plants, as working fluids in Rankine cycles. An advantage of using organic working fluids is that the industry has experience with building turbines for these fluids. A commercially available optimization program has been used to maximize the thermodynamic performance of the cycle. The advantages and disadvantages of using organic fluid mixtures as opposed to an ammonia-water mixture are discussed. It is found that thermodynamic efficiencies achievable with organic fluid mixtures, under optimum conditions, are lower than those obtained with ammonia-water mixtures. Further, the refrigeration temperatures achievable using organic fluid mixtures are higher than those using ammonia-water mixtures.
7
Zhang, Bing, Shuang Yang, Jin Liang Xu, and Guang Lin Liu. "Working Fluid Selection for Organic Rankine Cycles from a Molecular Structural Point of View." Advanced Materials Research 805-806 (September 2013): 649–53. http://dx.doi.org/10.4028/www.scientific.net/amr.805-806.649.
Повний текст джерелаАнотація:
The optimum working conditions of 11 working fluids under different heat source temperatures for an organic Rankine cycle (ORC) were located in our previous work. In the current work, the system irreversibility of each candidate were calculated and compared at their optimal operating conditions. Obvious variation trends of both the cycle efficiency and irreversibility were found for different types of organic fluids. It is suggested, when selecting working fluid for our ORC system, the critical temperature should be as close as possible to the heat source temperature to achieve high cycle efficiency but avoid large irreversibility. The relationships between the structure of the molecules and the critical temperature of the working fluids are investigated qualitatively and potentially meaningful for the rational selection of proper organic fluids for certain ORCs.
8
Mikielewicz, Dariusz, and Jarosław Mikielewicz. "Criteria for selection of working fluid in low-temperature ORC." Chemical and Process Engineering 37, no. 3 (September 1, 2016): 429–40. http://dx.doi.org/10.1515/cpe-2016-0035.
Повний текст джерелаАнотація:
Abstract The economics of an ORC system is strictly linked to thermodynamic properties of the working fluid. A bad choice of working fluid could lead to a less efficient and expensive plant/generation unit. Some selection criteria have been put forward by various authors, incorporating thermodynamic properties, provided in literature but these do not have a general character. In the paper a simple analysis has been carried out which resulted in development of thermodynamic criteria for selection of an appropriate working fluid for subcritical and supercritical cycles. The postulated criteria are expressed in terms of non-dimensional numbers, which are characteristic for different fluids. The efficiency of the cycle is in a close relation to these numbers. The criteria are suitable for initial fluid selection. Such criteria should be used with other ones related to environmental impact, economy, system size, etc. Examples of such criteria have been also presented which may be helpful in rating of heat exchangers, which takes into account both heat transfer and flow resistance of the working fluid.
9
Li, Jinwang, Ningxiang Lu, and Tianshu Cong. "Experimental study on evaporation-capillary pumping flow in capillary wick and working fluid system." Thermal Science, no. 00 (2019): 413. http://dx.doi.org/10.2298/tsci180918413l.
Повний текст джерелаАнотація:
The evaporation-capillary pumping flow of the capillary wick and the working fluid system was experimentally studied in this paper. The capillary wick used in the experiment was fiber, and the working fluid contained water, ethanol and ethanol aqueous solution with water content of 25wt.%, 50wt.% and 75wt.%. The results show that the capillary pumping rate with ethanol as working fluid is between 210.0kg/m2sand 1812.5kg/m2swhen there is no heat load added. When the heating flux is 10616W/m2, 15924W/m2, 21231W/m2, 26539W/m2, the evaporation-capillary pumping rate is102.5kg/m2s, 247.5kg/m2s, 390.0kg/m2s and 530.0kg/m2s, respectively. The higher the heat load power, the greater the evaporation-capillary pumping rate and the higher the final stable temperature. With the increase of heat load power, the time required to reach temperature balance becomes shorter and the temperature fluctuations after reaching temperature equilibrium become larger. The obvious temperature fluctuation has occurred when the heat flux is 26539W/m2. The evaporation capillary pumping rate corresponding to the four different concentrations of ethanol solution in the experiment gradually decreases with the increase of water content. The temperature change processes and the final equilibrium temperatures of the four working fluids are nearly the same. The differences in boiling point of the working fluids do not have much influence here.
10
Mustapic, Nenad, Vladislav Brkic, and Matija Kerin. "Subcritical organic ranking cycle based geothermal power plant thermodynamic and economic analysis." Thermal Science 22, no. 5 (2018): 2137–50. http://dx.doi.org/10.2298/tsci180104275m.
Повний текст джерелаАнотація:
This paper is focused both on the thermodynamic and economic analysis of an organic Rankine cycle (ORC) based geothermal power plant. The analysis is applied to a case study of the geothermal field Recica near the city of Karlovac. Simple cycle configuration of the ORC was applied. Thermodynamic and economic performance of an ORC geothermal system using 8 working fluids: R134a, isobutane, R245fa, R601, R601a, R290, R1234yf, and R1234ze(E)], with different critical temperatures are analyzed. The thermodynamic analysis is performed on the basis of the analysis of influence of the operation conditions, such as evaporation and condensation temperatures and pressures, and evaporator and con-denser pinch point temperature difference, on the cycle characteristics such as net power output, and plant irreversibility. The economic analysis is performed on the basis of relationship between the net power output and the total cost of equipment used in the ORC. Mathematical models are defined for proposed organic Rankine geothermal power plant, and the analysis is performed by using the software package engineering equation solver. The analysis reveals that the working fluids, n-pentane and isopentane, show the best economic performances, regardless the evaporation temperatures, while the working fluid R1234yf and R290 have the best thermodynamic performances. In addition, each analyzed working fluid has its corresponding economically optimal condensation temperature (and condensation pressure). Economically optimal pinch point temperature difference of evaporator has different values, depending on the working fluid, while pinch point temperature difference of condenser has similar values for all analyzed working fluids. Analysis results demonstrate that the subcritical ORC geothermal power plant represents a promising option for electricity production application.
11
Wang, Zhijian, Hua Tian, Lingfeng Shi, Gequn Shu, Xianghua Kong, and Ligeng Li. "Fluid Selection of Transcritical Rankine Cycle for Engine Waste Heat Recovery Based on Temperature Match Method." Energies 13, no. 7 (April 10, 2020): 1830. http://dx.doi.org/10.3390/en13071830.
Повний текст джерелаАнотація:
Engines waste a major part of their fuel energy in the jacket water and exhaust gas. Transcritical Rankine cycles are a promising technology to recover the waste heat efficiently. The working fluid selection seems to be a key factor that determines the system performances. However, most of the studies are mainly devoted to compare their thermodynamic performances of various fluids and to decide what kind of properties the best-working fluid shows. In this work, an active working fluid selection instruction is proposed to deal with the temperature match between the bottoming system and cold source. The characters of ideal working fluids are summarized firstly when the temperature match method of a pinch analysis is combined. Various selected fluids are compared in thermodynamic and economic performances to verify the fluid selection instruction. It is found that when the ratio of the average specific heat in the heat transfer zone of exhaust gas to the average specific heat in the heat transfer zone of jacket water becomes higher, the irreversibility loss between the working fluid and cold source is improved. The ethanol shows the highest net power output of 25.52 kW and lowest electricity production cost of $1.97/(kWh) among candidate working fluids.
12
Yang, Shuang, Bing Zhang, Jin Liang Xu, Wei Zhang, and Chao Xian Wang. "Working Fluid Selection for an Organic Rankine Cycle for Waste Heat Recovery under Different Heat Source Temperatures." Advanced Materials Research 732-733 (August 2013): 213–17. http://dx.doi.org/10.4028/www.scientific.net/amr.732-733.213.
Повний текст джерелаАнотація:
Optimum working conditions of 11 working fluids under different heat source temperatures in an organic Rankine cycle were systematically investigated. Cycle efficiency of each fluid was compared at their optimal operating conditions were then analyzed. R141b appears to be the best choice when the heat source temperature is around 200oC. Heptane is suggested the suitable working fluids for the ORC system when the heat source is 300oC.
13
Mikielewicz, Dariusz, and Jarosław Mikielewicz. "Utilisation of bleed steam heat to increase the upper heat source temperature in low-temperature ORC." Archives of Thermodynamics 32, no. 3 (December 1, 2011): 57–70. http://dx.doi.org/10.2478/v10173-011-0013-5.
Повний текст джерелаАнотація:
Utilisation of bleed steam heat to increase the upper heat source temperature in low-temperature ORC In the paper presented is a novel concept to utilize the heat from the turbine bleed to improve the quality of working fluid vapour in the bottoming organic Rankine cycle (ORC). That is a completely novel solution in the literature, which contributes to the increase of ORC efficiency and the overall efficiency of the combined system of the power plant and ORC plant. Calculations have been accomplished for the case when available is a flow rate of low enthalpy hot water at a temperature of 90 °C, which is used for preliminary heating of the working fluid. That hot water is obtained as a result of conversion of exhaust gases in the power plant to the energy of hot water. Then the working fluid is further heated by the bleed steam to reach 120 °C. Such vapour is subsequently directed to the turbine. In the paper 5 possible working fluids were examined, namely R134a, MM, MDM, toluene and ethanol. Only under conditions of 120 °C/40 °C the silicone oil MM showed the best performance, in all other cases the ethanol proved to be best performing fluid of all. Results are compared with the "stand alone" ORC module showing its superiority.
14
Zhao, Guo Chang, Li Ping Song, Xiao Chen Hou, and Yong Wang. "Thermodynamic Optimization of the Organic Rankine Cycle in a Concentrating Photovoltaic/Thermal Power Generation System." Applied Mechanics and Materials 448-453 (October 2013): 1514–18. http://dx.doi.org/10.4028/www.scientific.net/amm.448-453.1514.
Повний текст джерелаАнотація:
The selection criteria of working fluids for solar thermal organic Rankine cycle and the features of R245fa as a working fluid are analyzed. A thermodynamic analysis of photovoltaic / thermal organic Rankine cycle system and the influence of evaporation temperature of working fluid in the evaporator coupled with solar panels are conducted. The results show that the performance of the solar photovoltaic/thermal organic Rankine cycle can be improved by optimizing the evaporation temperature, and 130°C is an appropriate evaporation temperature.
15
Ruonan, Wang, Liu Bin, and Liu Haodong. "Experimental results and analysis of throttling refrigeration with ternary mixed refrigerant." E3S Web of Conferences 236 (2021): 01008. http://dx.doi.org/10.1051/e3sconf/202123601008.
Повний текст джерелаАнотація:
In-depth analysis of the influence of mixed working fluids on the thermodynamic performance of a throttling refrigeration cycle through experimental research. After optimizing the calculation of two ternary mixed working fluids with different compositions, the charging test is carried out, and the throttle characteristic curve of the mixed working fluid the law of temperature and pressure changes in the experiment was analyzed. The results show that: a mixed working fluid with a mixing ratio of 30.39mol% R14, 10.73mol% R170 and 58.87mol% R600A, at a pressure ratio of 2.5/0.1, a low temperature of -67.7°C is obtained, and the cooling time is 113.42min. The refrigeration system COP is 0.076; the mixing ratio is 30.39mol%R14, 15.73mol%R23 and 53.87mol%R600A mixed working fluid, in the case of a pressure ratio of 2.14/0.1, a low temperature of -76.4°C is obtained, and the cooling time is 160min, the refrigeration system COP is 0.106.
16
Dutkowski, Krzysztof, Marcin Kruzel, and Tadeusz Bohdal. "Experimental Studies of the Influence of Microencapsulated Phase Change Material on Thermal Parameters of a Flat Liquid Solar Collector." Energies 14, no. 16 (August 19, 2021): 5135. http://dx.doi.org/10.3390/en14165135.
Повний текст джерелаАнотація:
The article presents the results of preliminary research aimed at determining the possibility of using microencapsulated phase change material (mPCM) slurries as a working fluid in installations with a flat liquid solar collector. In the tests, the following were used as the working fluid: water (reference liquid) and 10% wt. and 20% wt. of an aqueous solution of the product under the trade name MICRONAL® 5428 X. As the product contained 43% mPCM, the mass fraction of mPCM in the working liquid was 4.3% and 8.6%, respectively. The research was carried out in laboratory conditions in the range of irradiance I = 250–950 W/m2. Each of the three working fluids flowed through the collector in the amount of 20 kg/h, 40 kg/h, and 80 kg/h. The working fluid was supplied to the collector with a constant temperature Tin = 20 ± 0.5 °C. It was found that the temperature of the working fluid at the collector outlet increases with the increase in the radiation intensity, but the temperature achieved depended on the type of working fluid. The greater the share of mPCM in the working liquid, the lower the temperature of the liquid leaving the solar collector. It was found that the type of working fluid does not influence the achieved thermal power of the collector. The negative influence of mPCM on the operation of the solar collector was not noticed; the positive aspect of using mPCM in the solar installation should be emphasized—the reduced temperature of the medium allows the reduction in heat losses to the environment from the installation, especially in a low-temperature environment.
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Radermacher, R., and L. A. Howe. "Temperature Transformation for High-Temperature Heat Pumps." Journal of Engineering for Gas Turbines and Power 110, no. 4 (October 1, 1988): 652–57. http://dx.doi.org/10.1115/1.3240186.
Повний текст джерелаАнотація:
A heat pump cycle is introduced that allows heat pumping between two very high temperature levels, while the suction temperature of the working fluid vapor passing through the compressor is considerably lower. This effect of “Temperature Transformation” is achieved by using a working fluid mixture instead of a single pure component and by employing an unconventional cycle design. The proposed cycle allows the extension of heat pump applications to high temperature levels without encountering operating problems for conventional compressors. This cycle and its features are explained. Its performance has been calculated and the results are presented and discussed.
18
Sucahyo, Lilis. "PERFORMANCE ANALYSIS OF WORKING FLUIDS ON ORGANIC RANKIE CYCLE (ORC) MODEL WITH BIOMASS ENERGY AS A HEAT SOURCES." Jurnal Teknik Pertanian Lampung (Journal of Agricultural Engineering) 8, no. 3 (September 30, 2019): 175. http://dx.doi.org/10.23960/jtep-l.v8i3.175-186.
Повний текст джерелаАнотація:
Organic Rankine Cycle (ORC) is an electricity power technology particularly suitable for medium-low temperature heat sources and/or for small available termal power. This paper presents the simulation and performance analysis of working fluids R-134a, R-414B, R-404A and R-407C on ORC with biomass energy as a heat source. Simulation of the ORC system using Cycle Tempo software. The property of working fluids is obtained by using Reference Fluid Properties (Refprop). The best result performance of ORC was shown by working fluid R-404A with thermal efficiency 7.54 % and electric power output ranges between 0.075 kW. This condition operated on turbine inlet temperature at 60 oC, difference turbine working temperature of 15 oC, condensing temperature 25 oC and water boiler mass flow rate 3 lpm.
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Han, Zhong He, and Yi Da Yu. "Selection of Working Fluids for Low-Temperature Power Generation Organic Rankine Cycles System." Advanced Materials Research 557-559 (July 2012): 1509–13. http://dx.doi.org/10.4028/www.scientific.net/amr.557-559.1509.
Повний текст джерелаАнотація:
A Rankine cycle using organic fluids as working fluids, called organic Rankine cycle (ORC), is potentially feasible in recovering low enthalpy containing heat sources. The choices of fluids should meet the requirement of environment, safety, critical pressure and critical temperature etc. Under the proposed working conditions, R600a, R245fa, R236fa, R236ea, R227ea are chosen as the working fluids of the low-temperature Rankine cycle system, then those fluids are investigated and compared from cycle efficiency, work ratio, exergy efficiency, irreversible loss. The results show that R245fa is an available and effective working fluid for low-temperature Rankine cycle.
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Matuszewska, Dominika, Marta Kuta, and Jan Górski. "A thermodynamic assessment of working fluids in ORC systems." EPJ Web of Conferences 213 (2019): 02057. http://dx.doi.org/10.1051/epjconf/201921302057.
Повний текст джерелаАнотація:
ORC (Organic Rankine Cycle) is widely used to convert low temperature heat into electricity using organic working fluid. The performance of an ORC installation is influenced deeply by selected working fluid and operation conditions. Recently has been presented a new generation of working fluids dedicated to ORC systems. They are characterized by near zero ODP (Ozone Depletion Potential) coefficient and significantly smaller GWP (Global Warming Potential) in comparison with currently used refrigerants. This paper presents preliminary research on selected dry and isentropic ORC fluids and some peculiarities in their behaviour.
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Oko, C. O. C., and S. N. Nnamchi. "Heat transfer in a low latitude flat-plate solar collector." Thermal Science 16, no. 2 (2012): 583–91. http://dx.doi.org/10.2298/tsci100419075o.
Повний текст джерелаАнотація:
Study of rate of heat transfer in a flat-plate solar collector is the main subject of this paper. Measurements of collector and working fluid temperatures were carried out for one year covering the harmattan and rainy seasons in Port Harcourt, Nigeria, which is situated at the latitude of 4.858oN and longitude of 8.372oE. Energy balance equations for heat exchanger were employed to develop a mathematical model which relates the working fluid temperature with the vital collector geometric and physical design parameters. The exit fluid temperature was used to compute the rate of heat transfer to the working fluid and the efficiency of the transfer. The optimum fluid temperatures obtained for the harmattan, rainy and yearly (or combined) seasons were: 317.4, 314.9 and 316.2 [K], respectively. The corresponding insolation utilized were: 83.23, 76.61 and 79.92 [W/m2], respectively, with the corresponding mean collector efficiency of 0.190, 0.205 and 0.197 [-], respectively. The working fluid flowrate, the collector length and the range of time that gave rise to maximum results were: 0.0093 [kg/s], 2.0 [m] and 12PM - 13.00PM, respectively. There was good agreement between the computed and the measured working fluid temperatures. The results obtained are useful for the optimal design of the solar collector and its operations.
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Geng, Changyou, Xinli Lu, Hao Yu, Wei Zhang, Jiaqi Zhang, and Jiansheng Wang. "Theoretical Study of a Novel Power Cycle for Enhanced Geothermal Systems." Processes 10, no. 3 (March 4, 2022): 516. http://dx.doi.org/10.3390/pr10030516.
Повний текст джерелаАнотація:
As obtained geofluids from enhanced geothermal systems usually have lower temperatures and contain chemicals and impurities, a novel power cycle (NPC) with a unit capacity of several hundred kilowatts has been configured and developed in this study, with particular reference to the geofluid temperature (heat source) ranging from 110 °C to 170 °C. Using a suitable CO2-based mixture working fluid, a transcritical power cycle was developed. The novelty of the developed power cycle lies in the fact that an increasing-pressure endothermic process was realized in a few-hundred-meters-long downhole heat exchanger (DHE) by making use of gravitational potential energy, which increases the working fluid’s pressure and temperature at the turbine inlet and, hence, increases the cycle’s power output. The increasing-pressure endothermic process in the DHE has a better match with the temperature change of the heat source (geofluid), as does the exothermic process in the condenser with the temperature change of the sink (cooling water), which reduces the heat transfer irreversibility and improves the cycle efficiency. Power cycle performance has been analyzed in terms of the effects of mass fraction of the mixture working fluids, the working fluid’s flowrate and its DHE inlet pressure, geofluid flowrate, and the length of the DHE. Results show that, for a given geofluid’s temperature and mass flowrate, the cycle’s net power output is a strong function of the working-fluid’s flowrate, as well as of its DHE inlet pressure. Too high or too low of a DHE inlet pressure results in a lower power output. When geofluid temperature is 130 °C, the optimum DHE inlet pressure is found to be 11 MPa, corresponding to an optimum working-fluid flowrate of 6.5 kg/s. The longer the DHE, the greater the corresponding working-fluid flowrate and the higher the net power output. For geofluid temperature ranging from 110 °C to 170 °C, the developed NPC has a better thermodynamic performance than the conventional ORC. The advantage of using the developed NPC becomes obvious when geofluid temperature is low. The maximum net power output difference between the NPC and the ORC happens when the geofluid temperature is 130 °C and NPC’s working fluid mass fraction (R32/CO2) is 0.5/0.5.
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Ovsyannik, A. V., and V. P. Kliuchinski. "Thermodynamic Analysis and Optimization of Secondary Overheating Parameters in Turbo-Expander Plants on Low Boiling Working Fluids." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 64, no. 2 (April 9, 2021): 164–77. http://dx.doi.org/10.21122/1029-7448-2021-64-2-164-177.
Повний текст джерелаАнотація:
The paper presents a thermodynamic analysis of secondary overheating in turbo-expander plants on low-boiling working fluids. The possibility of optimizing the parameters of the working fluid in a secondary stem superheater has been studied. The research was carried out for two typical turbo-expander cycles: with a heat exchanger at the outlet of the turbo-expander, intended for cooling an overheated low-boiling working fluid, and without a heat exchanger. Cycles in T–s coordinates were constructed for the studied schemes. The influence of pressure and temperature in the intermediate superheater on the exergetic efficiency of the turbo-expander unit was studied. Thus, the dependences of the exergetic efficiency and losses on the elements of the turbo-expander cycle are obtained when the temperature of the working fluid changes and pressure of the working fluid not changes in the intermediate superheater, and when the pressure changes and the temperature does not change. As a low-boiling working fluid, the ozone-safe freon R236EA is considered, which has a “dry” saturation line characteristic, zero ozone layer destruction potential, and a global warming potential equal to 1370. It has been determined that increasing the parameters of the low-boiling working fluid in front of the low-pressure turbo expander (regardless of the scheme of the turbo expander cycle) does not always cause an increase in the exergetic efficiency. Thus, overheating of the working fluid at a pressure exceeding the critical pressure causes a positive exergetic effect, but for each temperature there is an optimal pressure at which the efficiency will be maximum. At a pressure below the critical pressure, overheating leads to a decrease in the exergetic efficiency, and the maximum exergetic effect is achieved in the absence of a secondary steam superheater. All other things being equal, a turbo-expander cycle with a heat exchanger is more efficient than without it over the entire temperature range and pressure of the low-boiling working fluid under study.
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Wei, Danchen, Cheng Liu, and Zhongfeng Geng. "Conversion of Low-Grade Heat from Multiple Streams in Methanol to Olefin (MTO) Process Based on Organic Rankine Cycle (ORC)." Applied Sciences 10, no. 10 (May 23, 2020): 3617. http://dx.doi.org/10.3390/app10103617.
Повний текст джерелаАнотація:
The organic rankine cycle (ORC) has been widely used to convert low-grade thermal energy to electricity. The selection of the cycle configuration, working fluid, and operating parameters is crucial for the economic profitability of the ORC system. In the methanol to olefin (MTO) process, multi-stream low-temperature waste heat has not been effectively utilized. The previous study mostly focused on the optimization of a single stream system and rarely considered the comprehensive optimization of multi-stream ORC systems which have multi-temperature heat sources. This paper proposes five kinds of system design schemes, and determines the optimal output work and the highest exergy efficiency through the selection of working fluid and optimization of system parameters. In addition, the influence of mixed working fluid on the thermodynamic performance of the system was also investigated. It is found that there is an optimal evaporation temperature due to the restriction of pinch temperature. At the optimal temperature the ORC system obtains the maximum net output power of 4.95 MW. The optimization results show that the working fluid R227EA selected from seven candidate working fluids shows the optimal thermodynamic performance in all the five design schemes, and obtains the maximum output work and exergy efficiency.
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Roupec, Jakub, Filip Jeniš, Zbyněk Strecker, Michal Kubík, and Ondřej Macháček. "Stribeck Curve of Magnetorheological Fluid within Pin-on-Disc Configuration: An Experimental Investigation." Materials 13, no. 20 (October 20, 2020): 4670. http://dx.doi.org/10.3390/ma13204670.
Повний текст джерелаАнотація:
The paper focuses on the coefficient of friction (COF) of a magnetorheological fluid (MRF) in the wide range of working conditions across all the lubrication regimes—boundary, mixed, elastohydrodynamic (EHD), and hydrodynamic (HD) lubrication, specifically focused on the common working area of MR damper. The coefficient of friction was measured for MR fluids from Lord company with concentrations of 22, 32, and 40 vol. % of iron particles at temperatures 40 and 80 °C. The results were compared with a reference fluid, a synthetic liquid hydrocarbon PAO4 used as a carrier fluid of MRF. The results show that at boundary regime and temperature 40 °C all the fluids exhibit similar COF of 0.11–0.13. Differences can be found in the EHD regime, where the MR fluid COF is significantly higher (0.08) in comparison with PAO4 (0.04). The COF of MR fluid in the HD regime rose very steeply in comparison with PAO4. The effect of particle concentration is significant in the HD regime.
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Gakal, P., D. Mishkinis, A. Leilands, I. Usakovs, R. Orlov, and Y. Rogoviy. "Analysis of working fluids applicable for high-temperature loop heat pipe applications." IOP Conference Series: Materials Science and Engineering 1226, no. 1 (February 1, 2022): 012036. http://dx.doi.org/10.1088/1757-899x/1226/1/012036.
Повний текст джерелаАнотація:
Abstract An objective of this study was to perform an analysis of available working fluids and select those one(s) that will be able to comply with the specific requirements of the ultra-high bypass ratio (UHBR) engine air bleed system and ensure efficient LHP operation. A multi-step approach was applied to analyse more than 700 working fluids and select four potential candidates, taking into account (1) working fluids compliance with EU regulations; (2) working fluids freezing, boiling, and critical points for the operating temperature range; (3) working fluids specific properties that influence the LHP performances. Selected fluids (toluene, acetone, methanol, 1,2-dichlorobenzene) were subjected to accelerated life tests to check their chemical compatibility with AISI 316 stainless steel to be used as the LHP material. Based on the results obtained, the toluene was selected as the working fluid for application in the innovative LHP-based thermal management solution for the UHBR engine air bleed system.
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Khatoon, Saboora, Nasser Mohammed A. Almefreji, and Man-Hoe Kim. "Thermodynamic Study of a Combined Power and Refrigeration System for Low-Grade Heat Energy Source." Energies 14, no. 2 (January 13, 2021): 410. http://dx.doi.org/10.3390/en14020410.
Повний текст джерелаАнотація:
This study focuses on the thermal performance analysis of an organic Rankine cycle powered vapor compression refrigeration cycle for a set of working fluids for each cycle, also known as a dual fluid system. Both cycles are coupled using a common shaft to maintain a constant transmission ratio of one. Eight working fluids have been studied for the vapor compression refrigeration cycle, and a total of sixty-four combinations of working fluids have been analyzed for the dual fluid combined cycle system. The analysis has been performed to achieve a temperature of −16 °C for a set of condenser temperatures 34 °C, 36 °C, 38 °C, and 40 °C. For the desired temperature in the refrigeration cycle, the required work input, mass flow rate, and heat input for the organic Rankine cycle were determined systematically. Based on the manifestation of performance criteria, three working fluids (R123, R134a, and R245fa) were chosen for the refrigeration cycle and two (Propane and R245fa) were picked for the organic Rankine cycle. Further, a combination of R123 in the refrigeration cycle with propane in the Rankine cycle was scrutinized for their highest efficiency value of 16.48% with the corresponding highest coefficient of performance value of 2.85 at 40 °C.
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Lebedev, A. V., and S. N. Lysenko. "Extension of the Working Temperature Range of Magnetic Fluid Susceptibility Measurements." Solid State Phenomena 190 (June 2012): 649–52. http://dx.doi.org/10.4028/www.scientific.net/ssp.190.649.
Повний текст джерелаАнотація:
Tests have been carried out to measure the temperature dependence of static susceptibility of a magnetic fluid stabilized with polypropylene glycol (PPG) in propanol, ethyl ether and propylene oxide. The use of propylene oxide provides the widest temperature range for measurements of fluid susceptibility. The coagulation stability of the PPG-stabilized magnetic fluid against ethylene glycol and 1,4-butylene glycol is investigated. It has been shown that ethylene glycol can be used to separate PPG magnetic fluid into fractions. The fluid separation begins as soon as the volumetric fraction of ethylene glycol exceeds 30%. Butylene glycol is unsuitable for fractionation but can be used to remove excess surfactant - PPG.
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Nowak, Władysław, Aleksandra Borsukiewicz-Gozdur, and Sławomir Wiśniewski. "Influence of working fluid evaporation temperature in the near-critical point region on the effectiveness of ORC power plant operation." Archives of Thermodynamics 33, no. 3 (September 1, 2012): 73–83. http://dx.doi.org/10.2478/v10173-012-0019-7.
Повний текст джерелаАнотація:
Abstract In the paper presented are definitions of specific indicators of power which characterize the operation of the organic Rankine cycle (ORC) plant. These quantities have been presented as function of evaporation temperature for selected working fluids of ORC installation. In the paper presented also is the procedure for selection of working fluid with the view of obtaining maximum power. In the procedure of selection of working fluid the mentioned above indicators are of primary importance. In order to obtain maximum power there ought to be selected such working fluids which evaporate close to critical conditions. The value of this indicator increases when evaporation enthalpy decreases and it is known that the latent heat of evaporation decreases with temperature and reaches a value of zero at the critical point.
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Lim, Elaine, and Yew Mun Hung. "Suppression of Thermocapillary Effect in Evaporating Thin Film of Micro Heat Pipes." Advanced Materials Research 1101 (April 2015): 467–70. http://dx.doi.org/10.4028/www.scientific.net/amr.1101.467.
Повний текст джерелаАнотація:
This paper presents a theoretical study on the flow mechanism of different types of working fluids incorporated with Marangoni effect in a microelectronics cooling device. It is known that surface tension gradient effect or thermocapillary effect can be induced by temperature gradient which leads to the thermocapillary flow. By adding a small quantity of alcohol into the pure working fluid, the characteristics of surface tension can be altered without changing other thermo physical properties of the working fluid. A theoretical model is employed to focus on the suppression of thermocapillary effect in evaporating thin liquid film. The study reveals the fluid flow mechanism of a working fluid can be altered with thermocapillary effect. Thermal performance of microelectronics cooling devices can also be enhanced by utilizing aqueous solution as the working fluid.
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Imre, Attila, Réka Kustán, and Axel Groniewsky. "Mapping of the Temperature–Entropy Diagrams of van der Waals Fluids." Energies 13, no. 6 (March 23, 2020): 1519. http://dx.doi.org/10.3390/en13061519.
Повний текст джерелаАнотація:
The shape of the temperature vs. specific entropy diagram of a working fluid is very important to understanding the behavior of fluid during the expansion phase of the organic Rankine cycle or similar processes. Traditional wet-dry-isentropic classifications of these materials are not sufficient; several materials remain unclassified or misclassified, while materials listed in the same class might show crucial differences. A novel classification, based on the characteristic points of the T–s diagrams was introduced recently, listing eight different classes. In this paper, we present a map of these classes for a model material, namely, the van der Waals fluid in reduced temperature (i.e., reduced molecular degree of freedom) space; the latter quantity is related to the molar isochoric specific heat. Although van der Waals fluid cannot be used to predict material properties quantitatively, the model gives a very good and proper qualitative description. Using this map, some peculiarities related to T–s diagrams of working fluids can be understood.
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Yu, Lei, and Wei Qiang Liu. "Analysis of the Evaporating Characteristics of the Grooved Micro Heat Pipe with Alkali Metals as Working Fluid." Advanced Materials Research 516-517 (May 2012): 84–87. http://dx.doi.org/10.4028/www.scientific.net/amr.516-517.84.
Повний текст джерелаАнотація:
This paper has built a mathematical model for the evaporating characteristics of the grooved micro heat pipe’s thin film region and computed them in a specific working condition. The evaporating model of Wayner was employed in this mathematical model. The results from computation showed, for the H2O and NH3 as working fluid, at the beginning of the thin film region, the heat flux raised rapidly to a peak value and then declined to almost 0 also rapidly in a very short distance. Differently, for the Na and K as working fluid, the heat flux raised quickly but declined slower. Therefore, the alkali metals working fluids had larger area of high heat flux covered. The results indicated that the alkali metals working fluid has better evaporating characteristics for the high-temperature heat pipe than normal working fluids.
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Lei, Huan, Jin Fu Yang, and Dong Jiang Han. "The Performance of a Novel Solar Cooling and Power System with Different Working Fluids." Applied Mechanics and Materials 672-674 (October 2014): 86–93. http://dx.doi.org/10.4028/www.scientific.net/amm.672-674.86.
Повний текст джерелаАнотація:
Due to serious environmental problems and energy supply and demand issues, solar energy as a clean and abundant energy gets more and more attention. This paper presented a novel cooling and power system combined with PTCs. The system performance analysis was conducted with four different organic working fluids. The impacts of organic Rankine cycle (ORC) evaporation temperature, ORC condensing temperature and heat transfer fluid (HTF) mass flow rate in evaporator on system thermal performance were analyzed. The results show that system with toluene as working fluid has the highest thermal and exergy efficiency, and D4 and MDM have the lowest. Different working fluids have different cooling power to electricity ratios. The HTF mass flow rate in evaporator has a significant effect on system thermal performance.
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Nemec, Patrik, Zuzana Kolková, and Milan Malcho. "Operating Activity Visualization and Thermal Performance Measurement of Pulsating Heat Pipe." Defect and Diffusion Forum 369 (July 2016): 42–47. http://dx.doi.org/10.4028/www.scientific.net/ddf.369.42.
Повний текст джерелаАнотація:
Heat pipe is well known device which is used to heat transfer phase-change of working fluid. Pulsating heat pipe (PHP) is special type of heat pipe which heat transfer by pulsating movement of working fluid. Article deals about operating activity and thermal performance measurement of this special heat pipe. Operating activity visualization of PHP was performed with PHP made from glass. The two types of PHPs were made. The first PHP has internal diameter of tube 1 mm, second PHP has internal diameter of tube 1.5 mm and both PHPs have eleven meanders. The working fluids used in PHP were water and Fluorinert FC-72. These fluids were chose for their different thermo-physical properties and the visualization observe formation of liquid and vapour phase working fluid during filling process and working operation.Next, the article describes thermal performance measurement of PHP depending on working fluid amount and heat source temperature. Measurement was performed with PHP made from copper tube with inner diameter 1.5 mm curved to the twenty one meanders and filled with water. The results give us image about formation and distribution of working fluid in pulsating heat pipe and about influence of working fluid amount on the heat transfer ability of pulsating heat pipe.
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Negovora, A. V., R. G. Magafurov, and A. I. Nizamutdinov. "SUBSTATIATION OF THE WORKING FLUID TEMPERATURE WHEN TESTING DIESEL INJECTORS." VESTNIK OF THE BASHKIR STATE AGRARIAN UNIVERSITY 51, no. 3 (September 20, 2019): 99–106. http://dx.doi.org/10.31563/1684-7628-2019-51-3-99-106.
Повний текст джерелаАнотація:
This paper substantiates the permissible temperature limits of the working fluid when testing diesel fuel equipment. The normative and technical documentation does not indicate the optimum temperature of the working fluid during the test. The results are confirmed by experimental data obtained on a device developed by the authors for evaluating the injection characteristics. The developed device was based on the method of fuel injection into a long pipeline. The tests revealed the effect of fuel temperature on the performance of diesel fuel equipment. Also, the tests proved that in order to obtain reliable indicators when diagnosing diesel fuel equipment it is necessary to stably maintain the operating temperature of the device in the range of 60 ± 5 °С.
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Chernysheva, M. A., S. V. Vershinin, and Yu F. Maydanik. "Operating temperature and distribution of a working fluid in LHP." International Journal of Heat and Mass Transfer 50, no. 13-14 (July 2007): 2704–13. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2006.11.020.
Повний текст джерела
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Ye, Shuang, Yan Xu, Yu Chen, and Wei Huang. "Analysis of heat transfer and irreversibility of organic rankine cycle evaporator for selecting working fluid and operating conditions." Thermal Science 24, no. 3 Part B (2020): 2013–22. http://dx.doi.org/10.2298/tsci180716305y.
Повний текст джерелаАнотація:
Organic Rankine cycle (ORC) is suitable to converting the normally hard to utilize low temperature thermal energies, such as geothermal energy, solar energy, and industrial waste heat, to electricity through utilizing low boiling organic working fluids. The performance of ORC system is dramatically affected by the selections of working fluid and working conditions. As a key component of waste heat recovery, the irreversible loss of evaporator also has great influence on the performance of ORC system. In this paper, we study the heat transfer performance in evaporator under the condition that the heat source parameters and pinch point temperature difference are identified. It is found that the heat transfer performance is affected by Cr, the ratio of heat capacity flow rates between the working fluid and the heat source fluid. The equivalent thermal resistance, deducing from the concept of entransy, to measure the irreversability during the heat transfer process is used. Then, the parameter ?r, the ratio between latent heat and sensible heat of working fluid is defined. With the parameters Cr and ?r, we investigate the relationship between the heat transfer and irreversible loss, and deduce the condition that maximum heat transfer and minimum equivalent thermal resistance occurs. Finally, a calculation method is established to choose the optimum working fluid and the evaporation condition.
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Russo, G. M., L. Krambeck, F. B. Nishida, P. H. D. Santos, and T. Antonini Alves. "THERMAL PERFORMANCE OF THERMOSYPHON FOR DIFFERENT WORKING FLUIDS." Revista de Engenharia Térmica 15, no. 1 (June 30, 2016): 03. http://dx.doi.org/10.5380/reterm.v15i1.62150.
Повний текст джерелаАнотація:
In this paper, an experimental investigation was performed of the thermal performance of different working fluids in thermosyphons that can be used in thermal control of electronic equipment. The working fluids were considered acetone, water, ethanol, and methanol. The thermosyphon are manufactured of copper with an outer diameter of 9.45 mm, an inner diameter of 7.75 mm, a total length of 200 mm, whereas an evaporator of 80 mm length, an adiabatic region of 20 mm in length and a condenser of 100 mm in length. They were loaded with 1.39 ml of the working fluid, corresponding to a filling ratio of 40% of the evaporator volume. Experimental tests were performed in a vertical position considering thermal loads between 5W and 25W. The thermosyphons operated satisfactorily in all the tests. The operating temperature distribution as a function of time and the heat resistance behavior as a function of power dissipation have been presented for each analyzed working fluid. These results indicated that acetone is the working fluid that has the best thermal performance.
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Wang, Ruijie, Jingquan Zhao, Lei Zhu, and Guohua Kuang. "Multi-Objective Optimization of Organic Rankine Cycle for Low-Grade Waste Heat Recovery." E3S Web of Conferences 118 (2019): 03053. http://dx.doi.org/10.1051/e3sconf/201911803053.
Повний текст джерелаАнотація:
The organic Rankine cycle (ORC) is considered as one of the most viable technology to recover low-grade waste heat. A multi-objective optimization model is established to simultaneously derive the maximum exergy efficiency and the minimum electricity production cost (EPC) of a specific ORC system by employing the genetic algorithm (GA). Evaporation temperature and condensation temperature are selected as decision variables. At first, variations of exergy efficiency and EPC with evaporation temperature and condensation temperature are investigated respectively using R245fa, R245ca, R600, R600a, R601 and R601a as working fluids. Subsequently, a multi-objective optimization is performed and the Pareto frontiers for various working fluids are obtained. Results indicate that performance of the specific ORC system with R245fa as working fluid is better that with other working fluids.
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Pimonov, Igor, Igor Pohorilyi, and Maksim Fedyuchkov. "Establishment of rational parameters of temperature of working liquid in the hydraulic drive of the excavator of the fourth dimensional group at different equipment." Bulletin of Kharkov National Automobile and Highway University, no. 95 (December 16, 2021): 98. http://dx.doi.org/10.30977/bul.2219-5548.2021.95.0.98.
Повний текст джерелаАнотація:
The article considers the hydraulic drive of a modern excavator on which the influence of the working fluid temperature on the power is established, depending on the technical condition of the hydraulic elements. Studies have shown that new pumps and which have operating wear, have different rational temperature of the working fluid. It is impossible to imagine modern construction machines without equipping them with a hydraulic drive. The operation of the hydraulic drive largely determines the efficiency of operation of both a single machine and the entire fleet, which consists of new and old machines . The efficiency of hydrated machines is ensured in their design, manufacture, and operation, where an important role is played by the parameters of the working fluid: the degree of its contamination and temperature (viscosity). The influence of the temperature of the working fluid on the efficiency of the hydraulic drive and the ability to control the efficiency of the hydraulic drive with the help of temperature have not been studied enough. One of the promising areas in determining the rational temperature of the working fluid is the development of new designs of heat exchangers, heaters, diagnostic devices, which will be able to assess the technical condition of individual elements and the hydraulic drive as a whole. Establishing a rational temperature of the working fluid as a necessary parameter of the hydraulic system is mandatory when using modern methods to increase the efficiency of operation, maintenance and repair of hydraulic drives. With increasing temperature of the working fluid, its viscosity decreases and the loss of pressure and power in the mains of the hydraulic drive. However, this increases the internal flow of hydraulic units, which leads to an increase in power loss. Studies have shown that new pumps and which have operational wear, have different rational temperature of the working fluid. At rational values of temperature to the hydraulic motor the worn out pumps can give almost twice more power, than at 50 ° C, recommended for new pumps. The driving power of the pump, thus, practically does not change.
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Kareem, Aya H. A. Kareem, and Ali A. F. Al-Hamadan. "Experimental study of Organic Rankine cycle system by using R141b as working fluid." Wasit Journal of Engineering Sciences 8, no. 1 (July 5, 2020): 21–30. http://dx.doi.org/10.31185/ejuow.vol8.iss1.152.
Повний текст джерелаАнотація:
Organic Rankine cycle (ORC) is one of the renewable energy to generate power at low temperatures; however, the thermal and physical properties data of the working fluid in this system are limited. In this regards, the experimental study by using R-141b as the working fluid and hot water (i.e. 50°C and 90°C) on the ORC system was conducted in order to evaluate the ORC performance via changing temperatures. Further, the air compressor was modified to act as a multi-vane expander in the ORC system. Energy and exergy analysis of ORC system was done by using Engineering Equation Solver (EES) program.
It was found that the performance of the expander is acceptable and suitable for operating conditions. In addition, the heat source temperature has a direct effect on expander performance. The higher temperatures of the heat source led to an increase the expander inlet temperature. This system satisfied maximum thermal and exergy efficiency and they found equal to 1.8 % and 21%, respectively. Moreover, the rotation speed and power of expander are equal to 1200 RPM and 2.331 kW respectively. It was concluded that the working fluid R-141b is suitable for ORC system due to consider the working fluid that do not need high temperatures to evaporate.
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Wang, Shuang, Wei Zhang, Yong-Qiang Feng, Xin Wang, Qian Wang, Yu-Zhuang Liu, Yu Wang, and Lin Yao. "Entropy, Entransy and Exergy Analysis of a Dual-Loop Organic Rankine Cycle (DORC) Using Mixture Working Fluids for Engine Waste Heat Recovery." Energies 13, no. 6 (March 11, 2020): 1301. http://dx.doi.org/10.3390/en13061301.
Повний текст джерелаАнотація:
The exergy, entropy, and entransy analysis for a dual-loop organic Rankine cycle (DORC) using a mixture of working fluids have been investigated in this study. A high-temperature (HT) loop was used to recover waste heat from internal combustion engine in 350 °C, and a low-temperature loop (LT) was used to absorb residual heat of engine exhaust gas and HT loop working fluids. Hexane/toluene, cyclopentane/toluene, and R123/toluene were selected as working fluid mixtures for HT loop, while R245fa/pentane was chosen for LT loop. Results indicated that the variation of entropy generation rate, entransy loss, entransy efficiency, and exergy loss are insensitive to the working fluids. The entransy loss rate and system net power output present the same variation trends, whereas a reverse trend for entropy generation rate and entransy efficiency, while the exergy analysis proved to be only utilized under fixed stream conditions. The results also showed that hexane/toluene is the preferred mixture fluid for DORC.
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Ge, Zhong, Jian Li, Yuanyuan Duan, Zhen Yang, and Zhiyong Xie. "Thermodynamic Performance Analyses and Optimization of Dual-Loop Organic Rankine Cycles for Internal Combustion Engine Waste Heat Recovery." Applied Sciences 9, no. 4 (February 16, 2019): 680. http://dx.doi.org/10.3390/app9040680.
Повний текст джерелаАнотація:
Waste heats of an internal combustion engine (ICE) are recovered by a dual-loop organic Rankine cycle (DORC). Thermodynamic performance analyses and optimizations are conducted with 523.15–623.15 K exhaust gas temperature (Tg1). Cyclopentane, cyclohexane, benzene, and toluene are selected as working fluids for high-temperature loop (HTL), whereas R1234ze(E), R600a, R245fa, and R601a are selected as working fluids for low-temperature loop (LTL). The HTL evaporation temperature, condensation temperature, and superheat degree are optimized through a genetic algorithm, and net power output is selected as the objective function. Influences of Tg1 on system net power output, thermal efficiency, exergy efficiency, HTL evaporation temperature, HTL condensation temperature, HTL superheat degree, exhaust gas temperature at the exit of the HTL evaporator, heat utilization ratio, and exergy destruction rate of the components are analyzed. Results are presented as follows: the net power output is mainly influenced by HTL working fluid. The optimal LTL working fluid is R1234ze(E). The optimal HTL evaporator temperature increases with Tg1 until it reaches the upper limit. The optimal HTL condensation temperature increases initially and later remains unchanged for a cyclopentane system, thus keeping constant for other systems. Saturated cycle is suitable for cyclohexane, benzene, and toluene systems. Superheat cycle improves the net power output for a cyclopentane system when Tg1 is 568.15–623.15 K.
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Li, Peng, Zhonghe Han, Xiaoqiang Jia, Zhongkai Mei, and Xu Han. "Analysis of the Effects of Blade Installation Angle and Blade Number on Radial-Inflow Turbine Stator Flow Performance." Energies 11, no. 9 (August 28, 2018): 2258. http://dx.doi.org/10.3390/en11092258.
Повний текст джерелаАнотація:
Organic Rankine cycle (ORC) is a reliable technology to recover low-grade heat sources. The radial-inflow turbine is a critical component, which has a significant influence on the overall efficiency of ORC system. This study investigates the effects of the blade installation angle and blade number on the flow performance of radial-inflow turbine stator. R245fa and toluene were selected as the working fluids in the low and high temperature range, respectively. Two-dimensional stator blades model for the two working fluids were established, and numerical simulation was conducted through Computational Fluid Dynamics (CFD) software. The results show that for low temperature working fluid R245fa, when the installation angle is 32° and blade number is 22, the distribution of static pressure along the stator blade has no obvious pressure fluctuation, and the flow loss is least. Meanwhile, the stator blade obtained the optimal performance. For high temperature working fluid toluene, when the installation angle is 28° and blade number is 32, the average outlet temperature is the lowest, while the average outlet velocity is the largest. The flow state is well and smooth, and the remarkable flow separation and shock wave are not present. Moreover, the stator blade for R245fa has a larger chord length, cascade inlet diameter, and cascade outside diameter but a lower blade number compared to toluene.
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Bellos, Evangelos, and Christos Tzivanidis. "Parametric Analysis of a Polygeneration System with CO2 Working Fluid." Applied Sciences 11, no. 7 (April 3, 2021): 3215. http://dx.doi.org/10.3390/app11073215.
Повний текст джерелаАнотація:
The objective of the present work is the investigation of a novel polygeneration system for power, refrigeration and heating production at two temperature levels. The present system uses CO2 as the working fluid, which is an environmentally friendly fluid. The total configuration is a combination of a transcritical refrigeration cycle coupled to a Brayton cycle with recompression, which is fed by a biomass boiler. The examined system, at nominal operating conditions, produces refrigeration at 5 °C, and heating at 45 °C and 80 °C. Additionally, the system can be converted into a trigeneration system where the two heating outputs are produced at the same temperature level. The system was studied parametrically by changing the following seven critical parameters: turbine inlet temperature, high pressure, medium pressure, heat exchanger effectiveness, refrigeration temperature, heat rejection temperature and high heating temperature. In nominal operating conditions, the system energy and exergy efficiencies were 78.07% and 26.29%, respectively. For a heat input of 100 kW, the net power production was 24.50 kW, the refrigeration production was 30.73 kW, while the low and high heating production was 9.24 kW and 13.60 kW, respectively. The analysis was conducted with a developed model in Engineering Equation Solver.
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Cihan, Ertugrul, and Barıs Kavasogullari. "Energy and exergy analysis of a combined refrigeration and waste heat driven organic Rankine cycle system." Thermal Science 21, no. 6 Part A (2017): 2621–31. http://dx.doi.org/10.2298/tsci150324002c.
Повний текст джерелаАнотація:
Energy and exergy analysis of a combined refrigeration and waste heat driven organic Rankine cycle system were studied theoretically in this paper. In order to complete refrigeration process, the obtained kinetic energy was supplied to the compressor of the refrigeration cycle. Turbine, in power cycle, was driven by organic working fluid that exits boiler with high temperature and pressure. Theoretical performances of proposed system were evaluated employing five different organic fluids which are R123, R600, R245fa, R141b, and R600a. Moreover, the change of thermal and exergy efficiencies were examined by changing the boiling, condensing, and evaporating temperatures. As a result of energy and exergy analysis of the proposed system, most appropriate organic working fluid was determined as R141b.
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Liu, Shi Jie, Wen Sheng Yu, and Wu Chen. "Development and Experimental Study of New Working Fluids for Moderate-High-Temperature Heat Pumps." Advanced Materials Research 468-471 (February 2012): 1313–21. http://dx.doi.org/10.4028/www.scientific.net/amr.468-471.1313.
Повний текст джерелаАнотація:
Some suggestions for developing new working fluids for moderate-high-temperature heat pump with excellent thermal and environmental performance were given firstly in this paper. The theoretical and experimental performance analysis of new-developed working fluids M1-M6 was carried out. The theoretical performance results showed that M1-M6 had high heating efficiency and GWP (Global Warming Potential) of M2 was less than 150. The experimental results showed that M5 had higher thermal efficiency than other two working fluids under same working condition. At the ambient temperature respectively of 30 Centigrade Degree and 40 Centigrade Degree, it took 70 and 65 minutes by the heat pump charged with M5 as working fluid to heat 100 liters of water respectively from 30 Centigrade Degree to 80 Centigrade Degree. Meanwhile the system’s COP (Coefficient of Performance) was respectively 2.9 and 3.0.
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Stefanovic, Velimir, Sasa Pavlovic, Marko Ilic, Nenad Apostolovic, and Dragan Kustrimovic. "Numerical simulation of concentrating solar collector P2CC with a small concentrating ratio." Thermal Science 16, suppl. 2 (2012): 471–82. http://dx.doi.org/10.2298/tsci120430184s.
Повний текст джерелаАнотація:
Solar energy may be practically utilized directly through transformation into heat, electrical or chemical energy. A physical and mathematical model is presented, as well as a numerical procedure for predicting thermal performances of the P2CC solar concentrator. The demonstrated prototype has the reception angle of 110? at concentration ratio CR = 1.38, with the significant reception of diffuse radiation. The solar collector P2CC is designed for the area of middle temperature conversion of solar radiation into heat. The working fluid is water with laminar flow through a copper pipe surrounded by an evacuated glass layer. Based on the physical model, a mathematical model is introduced, which consists of energy balance equations for four collector components. In this paper, water temperatures in flow directions are numerically predicted, as well as temperatures of relevant P2CC collector components for various values of input temperatures and mass flow rates of the working fluid, and also for various values of direct sunlight radiation and for different collector lengths. The device which is used to transform solar energy to heat is referred to as solar collector. This paper gives numerical estimated changes of temperature in the direction of fluid flow for different flow rates, different solar radiation intensity and different inlet fluid temperatures. The increase in fluid flow reduces output temperature, while the increase in solar radiation intensity and inlet water temperature increases output temperature of water. Furthermore, the dependence on fluid output temperature is determined, along with the current efficiency by the number of nodes in the numerical calculation.
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Khan, Muhammad Sajid, Muhammad Abid, Khuram Pervez Amber, Hafiz Muhammad Ali, Mi Yan, and Samina Javed. "Numerical Performance Investigation of Parabolic Dish Solar-Assisted Cogeneration Plant Using Different Heat Transfer Fluids." International Journal of Photoenergy 2021 (April 28, 2021): 1–15. http://dx.doi.org/10.1155/2021/5512679.
Повний текст джерелаАнотація:
Parabolic dish solar collectors gain higher solar to thermal conversion efficiency due to their maximum concentration ratio. The present research focuses by integrating the parabolic dish solar collector to the steam cycle producing power and rate of process heating. Pressurized water, therminol VP1, and supercritical carbon dioxide are the examined working fluids in the parabolic dish solar collector. The aim of the current research is to observe the optimal operating conditions for each heat transfer fluid by varying inlet temperature and flow rate of the working fluid in the parabolic dish solar collector, and combination of these parameters is predicted to lead to the maximum energy and exergy efficiencies of the collector. The operating parameters are varied to investigate the overall system efficiencies, work output, and process heating rate. Findings of the study declare that water is an efficient heat transfer fluid at low temperature levels, whereas therminol VP1 is effective for a higher temperature range. The integrated system efficiencies are higher at maximum flow rates and low inlet temperatures. The efficiency map of solar collector is located at the end of study, and it shows that maximum exergy efficiency gains at inlet temperature of 750 K and it is observed to be 37.75%.
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Liang, Feng, Ghaithan Al-Muntasheri, Hooisweng Ow, and Jason Cox. "Reduced-Polymer-Loading, High-Temperature Fracturing Fluids by Use of Nanocrosslinkers." SPE Journal 22, no. 02 (October 5, 2016): 622–31. http://dx.doi.org/10.2118/177469-pa.
Повний текст джерелаАнотація:
Summary In the quest to discover more natural-gas resources, considerable attention has been devoted to finding and extracting gas locked within tight formations with permeability in the nano- to microdarcy range. The main challenges associated with working in such formations are the intrinsically high-temperature and high-pressure bottom conditions. For formations with bottomhole temperatures at approximately 350–400°F, traditional hydraulic-fracturing fluids that use crosslinked polysaccharide gels, such as guar and its derivatives, are not suitable because of significant polymer breakdown in this temperature range. Fracturing fluids that can work at these temperatures require thermally stable synthetic polymers such as acrylamide-based polymers. However, such polymers have to be used at very-high concentrations to suspend proppants. The high-polymer concentrations make it very difficult to completely degrade at the end of a fracturing operation. As a consequence, formation damage by polymer residue can reduce formation conductivity to gas flow. This paper addresses the shortcomings of the current state-of-the-art high-temperature fracturing fluids and focuses on developing a less-damaging, high-temperature-stable fluid that can be used at temperatures up to 400°F. A laboratory study was conducted with this novel system, which comprises a synthetic acrylamide-based copolymer gelling agent and is capable of being crosslinked with an amine-containing polymer-coated nanosized particulate crosslinker (nanocrosslinker). The laboratory data have demonstrated that the temperature stability of the crosslinked fluid is much better than that of a similar fluid lacking the nanocrosslinker. The nanocrosslinker allows the novel fluid system to operate at significantly lower polymer concentrations (25–45 lbm/1,000 gal) compared with current commercial fluid systems (50–87 lbm/1,000 gal) designed for temperatures from 350 to 400°F. This paper presents results from rheological studies that demonstrate superior crosslinking performance and thermal stability in this temperature range. This fracturing-fluid system has sufficient proppant-carrying viscosity, and allows for efficient cleanup by use of an oxidizer-type breaker. Low polymer loading and little or no polymer residue are anticipated to facilitate efficient cleanup, reduced formation damage, better fluid conductivity, and enhanced production rates. Laboratory results from proppant-pack regained-conductivity tests are also presented.