The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Jianlin Yu - One of the best experts on this subject based on the ideXlab platform.
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theoretical investigation on the performance of a modified refrigeration cycle using binary zeotropic hydrocarbon mixture r170 r290
International Journal of Refrigeration-revue Internationale Du Froid, 2018Co-Authors: Changxiang He, Jianlin YuAbstract:Abstract In this study, a modified refrigeration cycle (MRC) using refrigerant mixture R170/R290 was proposed for applications in low-Temperature freezers. Different from traditional auto-cascade cycle (ARC), additional recuperator and expansion valve are set between condenser and separator to realize phase separation at an intermediate pressure. The MRC can significantly improve volumetric refrigeration capacity ( q ev ) and the coefficient of performance (COP) especially in low Evaporating Temperature condition. As Evaporating Temperature is set at −60°C, using MRC system can acquire 18% and 35% COP and q ev improvements, and the compression ratio in MRC reduced 23% in comparison to ARC. In general, decreasing both separating Temperature and quality of condenser outlet will benefit the performance of MRC. Besides, there exist an appropriate mixture quality at evaporator outlet to obtain the best COP and q ev under the given condition.
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energy and exergy analysis of a new ejector enhanced auto cascade refrigeration cycle
Energy Conversion and Management, 2015Co-Authors: Jiaheng Chen, Jianlin YuAbstract:Abstract A new ejector enhanced auto-cascade refrigeration cycle using R134a/R23 refrigerant mixture is proposed in this paper. In the new cycle, an ejector is used to recover part of the work that would otherwise be lost in the throttling processes. The performance comparison between the new cycle and a basic auto-cascade refrigeration cycle is carried out based on the first and second laws of thermodynamics. The simulation results show that both the coefficient of performance and exergy efficiency of the new cycle can be improved by 8.42–18.02% compared with those of the basic cycle at the same operation conditions as the ejector has achieved pressure lift ratios of 1.12–1.23. It is found that in the new cycle, the highest exergy destruction occurs in the compressor followed by the condenser, cascade condenser, expansion valve, ejector and evaporator. The effect of some main parameters on the cycle performance is further investigated. The results show that for the new cycle, the achieved performance improvement over the basic cycle is also dependent on the mixture composition and the vapor quality at the condenser outlet. The coefficient of performance improvement of the new cycle over the basic cycle degrades with increasing vapor quality. In addition, there exists an optimum mixture composition to obtain the maximum coefficient of performance for the new cycle when other operation conditions are given. The optimum mixture composition of both cycles may be fixed at about 0.5 under the given Evaporating Temperature.
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thermodynamic analysis on a two stage transcritical co2 heat pump cycle with double ejectors
Energy Conversion and Management, 2014Co-Authors: Meibo Xing, Jianlin YuAbstract:Abstract In this study, two ejectors are proposed as expansion devices for a two-stage transcritical CO 2 heat pump cycle to enhance the cycle performance. The two ejectors are arranged at the low- and high-pressure stages, respectively, to recover more available expansion work, and significantly reduce the throttling loss at each stage. The performance of the improved two-stage cycle is evaluated by using the developed mathematical model, and then compared with those of the basic two-stage cycle with a flash tank. The simulation results show that the improved two-stage cycle exhibits higher heating COP and volumetric heating capacity compared to the basic two-stage cycle. By further incorporating an internal heat exchanger, the heating COP can be increased by 10.5–30.6% above that of the baseline cycle when the subcooling degree varied from 0 to 15 °C under given operation conditions of −15 °C Evaporating Temperature, 10 MPa gas cooler pressure and 35 °C outlet Temperature. Additionally, the effects of the gas cooler pressure and intermediate pressure on the maximal heating COP are also discussed.
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a theoretical study of an innovative ejector enhanced vapor compression heat pump cycle for water heating application
Energy and Buildings, 2011Co-Authors: Xiaojuan Chen, Yuanyuan Zhou, Jianlin YuAbstract:Abstract This study presents a novel vapor compression heat pump cycle in which an ejector associated with a subcooler is applied to enhance the heating performance for air-source heat pump water heater application. The heating coefficient of performance (COP h ) and heating capacity of the novel cycle using the non-azeotropic mixture refrigerant R417A are theoretically investigated, for the ranges of Evaporating Temperature (−15 to 10 °C) and condensing Temperature (55–60 °C). The theoretical results show that the COP h and volumetric heating capacity of the novel cycle are better than that of the conventional heat pump cycle. It is found that for the operating conditions considered, the maximum COP h and volumetric heating capacity can be improved by up to 1.62–6.92% and 15.20–37.32% over the conventional heat pump cycle, respectively. The performance characteristics of the novel cycle show its promise in air-source heat pump water heater applications.
Angel Barragancervera - One of the best experts on this subject based on the ideXlab platform.
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drop in analysis of an internal heat exchanger in a vapour compression system using r1234ze e and r450a as alternatives for r134a
Energy, 2015Co-Authors: Adrian Motababiloni, Angel Barragancervera, Francisco Moles, Joaquin Navarroesbri, Bernardo PerisAbstract:The IHX (internal heat exchanger) is introduced in some refrigeration systems in order to achieve higher energy performances. Results obtained vary greatly depending on the refrigerant used and working conditions. This paper describes a drop-in analysis of IHX effects on the performance of a vapour compression system using R1234ze(E) and R450A (R134a/R1234ze(E) commercial mixture) as R134a low-GWP replacements. The tests were carried out in a completely monitored vapour compression system varying the condensing and Evaporating Temperature, with and without a counter-current flow tube-in-tube IHX. Because the cooling capacity rises and the power consumption remains similar, the conclusion is that the IHX has a positive influence on the energy efficiency for all refrigerants tested. The COP (coefficient of performance) gain using R1234ze(E) is the highest observed (overcomes the R134a COP for the same conditions). The R1234ze(E) and R450A discharge Temperature increments are lower than those of R134a so does not reach dangerous values and the IHX pressure drops are also below than that of R134a.
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experimental analysis of the internal heat exchanger influence on a vapour compression system performance working with r1234yf as a drop in replacement for r134a
Applied Thermal Engineering, 2013Co-Authors: Joaquin Navarroesbri, Francisco Moles, Angel BarragancerveraAbstract:This paper presents an experimental analysis of the influence of an internal heat exchanger on the performance of a vapour compression system using R1234yf as a drop-in replacement for R134a. In this work, we compare the energy performance of a monitored vapour compression system using both refrigerants, R134a and R1234yf, with and without the presence of an internal heat exchanger under a wide range of working conditions. A set of experimental tests are carried out varying the condensing Temperature, the Evaporating Temperature and the internal heat exchanger use. From the experimental results, reductions in cooling capacity and COP between 6 and 13% have been observed when R134a is replaced by the drop-in fluid R1234yf, although the presence of an IHX can help to lessen these reductions between 2 and 6%. Finally, the experimental results obtained agree with the theoretical evaluations developed neglecting the pressure drops.
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experimental analysis of r1234yf as a drop in replacement for r134a in a vapor compression system
International Journal of Refrigeration-revue Internationale Du Froid, 2013Co-Authors: Joaquin Navarroesbri, Adrian Motababiloni, J M Mendozamiranda, Angel Barragancervera, J M BelmanfloresAbstract:This paper presents an experimental analysis of a vapor compression system using R1234yf as a drop-in replacement for R134a. In this work, we compare the energy performance of both refrigerants, R134a and R1234yf, in a monitored vapor compression system under a wide range of working conditions. So, the experimental tests are carried out varying the condensing Temperature, the Evaporating Temperature, the superheating degree, the compressor speed, and the internal heat exchanger use. Comparisons are made taking refrigerant R134a as baseline, and the results show that the cooling capacity obtained with R1234yf in a R134a vapor compression system is about 9% lower than that obtained with R134a in the studied range. Also, when using R1234yf, the system shows values of COP about 19% lower than those obtained using R134a, being the minor difference for higher condensing Temperatures. Finally, using an internal heat exchanger these differences in the energy performance are significantly reduced.
Wonjae Yoon - One of the best experts on this subject based on the ideXlab platform.
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performance characteristics of a household refrigerator with dual evaporators using two stage compression cycle
International Journal of Air-conditioning and Refrigeration, 2009Co-Authors: Wonjae YoonAbstract:The objective of this study is to investigate performance characteristics of a household refrigerator using a two-stage compression cycle. The performance of the two-stage compression cycle was measured by varying the compressor speed, condensing Temperature, and Evaporating Temperature. The COP of the two-stage compression cycle was analyzed and then compared with that of the single-stage compression cycle. The optimum combination of compressor speeds for a low- and a high-stage was determined. The COP of the two-stage compression cycle using a PTC (parallel two-stage compression) method was 5.85% higher than that of a STC (serial two-stage compression) method at optimum operating conditions.
Joaquin Navarroesbri - One of the best experts on this subject based on the ideXlab platform.
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drop in analysis of an internal heat exchanger in a vapour compression system using r1234ze e and r450a as alternatives for r134a
Energy, 2015Co-Authors: Adrian Motababiloni, Angel Barragancervera, Francisco Moles, Joaquin Navarroesbri, Bernardo PerisAbstract:The IHX (internal heat exchanger) is introduced in some refrigeration systems in order to achieve higher energy performances. Results obtained vary greatly depending on the refrigerant used and working conditions. This paper describes a drop-in analysis of IHX effects on the performance of a vapour compression system using R1234ze(E) and R450A (R134a/R1234ze(E) commercial mixture) as R134a low-GWP replacements. The tests were carried out in a completely monitored vapour compression system varying the condensing and Evaporating Temperature, with and without a counter-current flow tube-in-tube IHX. Because the cooling capacity rises and the power consumption remains similar, the conclusion is that the IHX has a positive influence on the energy efficiency for all refrigerants tested. The COP (coefficient of performance) gain using R1234ze(E) is the highest observed (overcomes the R134a COP for the same conditions). The R1234ze(E) and R450A discharge Temperature increments are lower than those of R134a so does not reach dangerous values and the IHX pressure drops are also below than that of R134a.
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experimental analysis of the internal heat exchanger influence on a vapour compression system performance working with r1234yf as a drop in replacement for r134a
Applied Thermal Engineering, 2013Co-Authors: Joaquin Navarroesbri, Francisco Moles, Angel BarragancerveraAbstract:This paper presents an experimental analysis of the influence of an internal heat exchanger on the performance of a vapour compression system using R1234yf as a drop-in replacement for R134a. In this work, we compare the energy performance of a monitored vapour compression system using both refrigerants, R134a and R1234yf, with and without the presence of an internal heat exchanger under a wide range of working conditions. A set of experimental tests are carried out varying the condensing Temperature, the Evaporating Temperature and the internal heat exchanger use. From the experimental results, reductions in cooling capacity and COP between 6 and 13% have been observed when R134a is replaced by the drop-in fluid R1234yf, although the presence of an IHX can help to lessen these reductions between 2 and 6%. Finally, the experimental results obtained agree with the theoretical evaluations developed neglecting the pressure drops.
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experimental analysis of r1234yf as a drop in replacement for r134a in a vapor compression system
International Journal of Refrigeration-revue Internationale Du Froid, 2013Co-Authors: Joaquin Navarroesbri, Adrian Motababiloni, J M Mendozamiranda, Angel Barragancervera, J M BelmanfloresAbstract:This paper presents an experimental analysis of a vapor compression system using R1234yf as a drop-in replacement for R134a. In this work, we compare the energy performance of both refrigerants, R134a and R1234yf, in a monitored vapor compression system under a wide range of working conditions. So, the experimental tests are carried out varying the condensing Temperature, the Evaporating Temperature, the superheating degree, the compressor speed, and the internal heat exchanger use. Comparisons are made taking refrigerant R134a as baseline, and the results show that the cooling capacity obtained with R1234yf in a R134a vapor compression system is about 9% lower than that obtained with R134a in the studied range. Also, when using R1234yf, the system shows values of COP about 19% lower than those obtained using R134a, being the minor difference for higher condensing Temperatures. Finally, using an internal heat exchanger these differences in the energy performance are significantly reduced.
Hong-li Wang - One of the best experts on this subject based on the ideXlab platform.
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theoretical analysis and experimental research on transcritical co2 two stage compression cycle with two gas coolers tscc tg and the cycle with intercooler tscc ic
Energy Conversion and Management, 2011Co-Authors: Jing Rui Tian, Hong-li Wang, Minxia LiAbstract:Abstract As one of the natural refrigerants, CO 2 is a potential substitute for synthesized refrigerants with favorable environmental properties. In order to improve the performance of the CO 2 transcritical compression cycle, the performance of the two stage compression cycle with two gas coolers (TSCC + TG) and the two stage compression cycle with intercooler (TSCC + IC) were analyzed, respectively. Under the given calculation condition, the optimum intermediate pressure of the cycle TSCC + TG and the TSCC + IC are 7.09 MPa and 5.89 MPa, and the maximal COP are 2.77 and 3.08, respectively. Range of the given Evaporating Temperature and outlet Temperature of gas cooler, the experimental testing shows that the performance of cycle TSCC + IC are 11.88% and 10.87% better than that of the cycle TSCC + TG, respectively. Range of the given inlet Temperature and cooling water volume flow of gas cooler, the refrigeration COP (COP c ) and heat COP (COP h ) of the cycle TSCC + IC are average 10.97% and 4.39% higher than that of the cycle TSCC + TG. Range of the given inlet Temperature and chilled water volume flow of evaporator, the refrigeration COP (COP c ) and heat COP (COP h ) of the cycle TSCC + IC are average 10.71% and 3.67% higher than that of the cycle TSCC + TG, respectively. The error between theoretical calculation and experimental testing is not exceeds 20%.