The Experts below are selected from a list of 86706 Experts worldwide ranked by ideXlab platform
Jean Lebrun - One of the best experts on this subject based on the ideXlab platform.
-
testing and modeling a scroll expander integrated into an organic rankine cycle
Applied Thermal Engineering, 2009Co-Authors: Vincent Lemort, Sylvain Quoilin, Cristian Cuevas, Jean LebrunAbstract:Abstract Organic Rankine Cycles (ORC’s) are particularly suitable for recovering energy from low-grade heat sources. This paper first presents the results of an experimental study carried out on a prototype of an open-drive oil-free scroll expander integrated into an ORC working with refrigerant HCFC-123. By exploiting the overall expander performance measurements, the eight parameters of a scroll expander semi-empirical model are then identified. The model is able to compute variables of first importance such as the mass flow rate, the delivered shaft power and the Discharge Temperature, and secondary variables such as the supply heating-up, the exhaust cooling-down, the ambient losses, the internal leakage and the mechanical losses. The maximum deviation between the predictions by the model and the measurements is 2% for the mass flow rate, 5% for the shaft power and 3 K for the Discharge Temperature. The validated model of the expander is finally used to quantify the different losses and to indicate how the design of the expander might be altered to achieve better performances. This analysis pointed out that the internal leakages and, to a lesser extent, the supply pressure drop and the mechanical losses are the main losses affecting the performance of the expander.
-
experimental analysis and simplified modelling of a hermetic scroll refrigeration compressor
Applied Thermal Engineering, 2002Co-Authors: Eric Winandy, Claudio Saavedra O, Jean LebrunAbstract:Abstract The first part of this paper presents a detailed analysis of the results obtained in a previous experimental study. In the frame of that study, a hermetic scroll compressor has been equipped with internal sensors by the manufacturer. The analysis reveals the main processes affecting the refrigerant mass flow rate as well as the compressor power and the Discharge Temperature. Based on these experimental results, a simplified model of the scroll compressor is proposed. It assumes that the refrigerant mass flow rate is affected by a suction Temperature increase due to heat gained from a uniform wall Temperature. This fictitious wall is supposed to gain heat from the electromechanical losses and from the Discharged gas and to loose heat to the suction gas and to the ambient. The compression process is considered to be isentropic up to the “adapted” pressure and then isochoric until the Discharge pressure. The model is able to compute variables of primary importance, like the mass flow rate, the electric power and the Discharge Temperature, as well as secondary variables such as suction heating-up, Discharge cooling-down, and ambient losses.
Cao Feng - One of the best experts on this subject based on the ideXlab platform.
-
Performance Investigation of Two-stage Heat Pump with Vapor Injection Using R410A as Working Fluid
Purdue University, 2018Co-Authors: Wang Yikai, Ye Zuliang, Cao FengAbstract:The heating capacity and coefficient of performance (COP) will significantly decrease when the conventional air source heat pump (ASHP) system is operated under low ambient Temperature conditions, with the high Discharge Temperature. The vapor injection technique with an internal heat exchanger (IHX) has been proposed as an effective way to acquire better performance. In this paper, the performance of a R410A two-stage air source heat pump system with the scroll compressor was studied experimentally. According to the experimental results, the heating capacity increased with the vapor injection at the fixed ambient Temperature and water Temperature, however the Discharge Temperature decreased. One interesting founding was that the Discharge Temperature at the ambient Temperature of -6°C and -12°C increased slightly when a little refrigerant was injected into the compressor. The optimal point always occurred when the system COP was maximized with the other constant parameters. Furthermore, the peak points of each COP curve were shifted to the right if the ambient Temperature was elevated. With variation of the ambient Temperature, the peak points of the heat pump with vapor injection technique were compared with those of the conventional system. The results showed that the vapor injection technique could improve the heating performance and enhance the stability and reliability of the compressor. At the ambient Temperature of -20°C, the system could have up to 17.01% improved COP and 13.73% decreased Discharge Temperature, respectively. In addition, the variation of injection ratio with intermediate pressure and expansion valve operating reliability were also investigated
-
Experimental Research On Gas Injection High Temperature Heat Pump With An Economizer
'Purdue University (bepress)', 2014Co-Authors: He Yongning, Cao Feng, Jin Lei, Chen ShengkunAbstract:Gas injection technology is often used in cold regions to solve heat pump’s low heating capacity and high Discharge Temperature at low ambient Temperature. Injecting gas into port opened at specific position of compressor could increase mass flow rate of compressor and total heating capacity of heat pump. Gas injection also changes compression ratio of compressor and decreases Discharge Temperature. An optimal gas injection pressure is got when the coefficient of performance reached to peak value at a certain working condition. It’s a feasible way to increase performance of heat pump at cold regions. High Temperature heat pump could provide higher Temperature water for industrial usage regions but there still existed some problems on its usage. Total heating capacity decreased and Discharge Temperature increased with the raise of condensation Temperature. Refrigerant Temperature before throttling valve was high and may exceed working Temperature range of electrical expansion valve. Gas injection technology with an economizer was adopted to solve these problems. A new high Temperature heat pump cycle was designed based on gas injection and outlets water Temperature of the prototype manufactured was reached to 90?. Temperature before throttling valve was well controlled by the usage of economizer. Heating capacity, Discharge Temperature, compressor power consumption of the heat pump system at different amount of injected gas was conducted by theoretical and experimental research in this paper. This study showed the function of gas injection technology which used in high Temperature heat pump
-
investigation of the heat pump water heater using economizer vapor injection system and mixture of r22 r600a
International Journal of Refrigeration-revue Internationale Du Froid, 2009Co-Authors: Cao Feng, Wang Shouguo, Xing Ziwen, Shu PengchengAbstract:This paper presents the experimental study of a heat pump water heater (HPWH) using economizer vapor injection system and mixture of R22/R600a. Performances of HPWH using economizer vapor injection system are compared with that at different mixed mass ratios of R22/R600a. Study demonstrates that the heating capacity and energy efficiency ratio (EER) of the unit increased, and the Discharge Temperature of compressor decreased when using vapor injection and mixing refrigerant of R22/R600a. It is also found that the HPWH unit with economizer vapor injection system has a better performance for the high outlet water Temperature under lower Temperature conditions at 15% mass ratio of R600a for the mixing refrigerant. In addition, fundamental and practical influence of vapor injection pressure on the HPWH performance has been investigated experimentally. The simplified model is proposed for predicting the optimal vapor injection pressure of compressor using the mixing refrigerant R22/R600a.
Jose Gonzalvezmacia - One of the best experts on this subject based on the ideXlab platform.
-
semi empirical model of scroll compressors and its extension to describe vapor injection compressors model description and experimental validation
International Journal of Refrigeration-revue Internationale Du Froid, 2019Co-Authors: Fernando M Tellooquendo, Emilio Navarroperis, Francisco Barceloruescas, Jose GonzalvezmaciaAbstract:Abstract This paper presents a semi-empirical model of scroll compressors and proposes a methodology in order to extend this model to vapor-injection scroll compressors. The model takes into account the ideal evolution of the refrigerant throughout the compressor and considers the main sources of losses in the compression process. The model is able to predict the compressor and volumetric efficiencies in terms of ten empirical parameters, which have a direct physical interpretation. For the model validation, a series of four non-injected scroll compressors of different capacities were tested using R-290 and a scroll compressor with vapor-injection (SCVI) was characterized using R-407C. Results show a correct agreement between the experimental and calculated compressor efficiencies, with a maximum deviation of ±5%. Furthermore, the model estimates accurately the Discharge Temperature of the refrigerant, compressor power input, and refrigerant mass flow rate in the suction and injection port. Finally, the SCVI model response was evaluated by varying the intermediate pressure and the injection superheat.
El M Kafafy - One of the best experts on this subject based on the ideXlab platform.
-
assessment of propane commercial butane mixtures as possible alternatives to r134a in domestic refrigerators
International Conference on Aerospace Sciences and Aviation Technology, 2011Co-Authors: M Fatouh, El M KafafyAbstract:The possibility of using hydrocarbon mixtures as working fluids to replace R134a in domestic refrigerators has been evaluated through a simulation analysis in the present work. Performance characteristics of domestic refrigerators were predicted over a wide range of evaporation Temperatures (-35 to -10°C) and condensation Temperatures (40 to 60°C) for various working fluids such as R134a, propane, commercial butane and propane/iso-butane/n-butane mixture with various propane mass fractions. Performance characteristics of the considered domestic refrigerator was identified by the coefficient of performance (COP), volumetric cooling capacity, cooling capacity, condenser capacity, input power to the compressor, Discharge Temperature, pressure ratio and the refrigerant mass flow rate. Results showed that pure propane could not be used as a drop-in replacement for R134a in domestic refrigerators because of its high operating pressures and low COP. Commercial butane yields many desrirable characteristics, but requires compressor change. Coefficient of performance of the domestic refrigerator using a ternary hydrocarbon mixture with propane mass fraction from 0.5 to 0.7 is higher than that of R134a. Comparison among the considered working fluids confirmed that average refrigerant mass flow rate of propoane/commercial butane mixture is 50% lqwer than that of R134a. Also, results indicated that R134a and propoane/commercial butane mixture of 60% propane mass concentration have approximately the same values of saturation pressure, compressor Discharge Temperature, condenser heat load, input power, cooling capacity and volumetric cooling capacity. However, the pressure ratio of the hydrocarbon mixture with 60% propane is lower than that of R134a by about 11.1%. Finally, the reported results confirmed that the propane/iso-butane/n-butane mixture with 60% propane is the best drop-in replacement for R134a in domestic refrigerators under normal, subtropical and tropical operating conditions.
-
assessment of propane commercial butane mixtures as possible alternatives to r134a in domestic refrigerators
Energy Conversion and Management, 2006Co-Authors: M Fatouh, El M KafafyAbstract:Abstract The possibility of using hydrocarbon mixtures as working fluids to replace R134a in domestic refrigerators has been evaluated through a simulation analysis in the present work. The performance characteristics of domestic refrigerators were predicted over a wide range of evaporation Temperatures (−35 to −10 °C) and condensation Temperatures (40–60 °C) for various working fluids such as R134a, propane, commercial butane and propane/iso-butane/ n -butane mixtures with various propane mass fractions. The performance characteristics of the considered domestic refrigerator were identified by the coefficient of performance (COP), volumetric cooling capacity, cooling capacity, condenser capacity, input power to compressor, Discharge Temperature, pressure ratio and refrigerant mass flow rate. The results showed that pure propane could not be used as a drop in replacement for R134a in domestic refrigerators because of its high operating pressures and low COP. Commercial butane yields many desirable characteristics but requires a compressor change. The coefficient of performance of the domestic refrigerator using a ternary hydrocarbon mixture with propane mass fractions from 0.5 to 0.7 is higher than that of R134a. Comparison among the considered working fluids confirmed that the average refrigerant mass flow rate of the propoane/commercial butane mixture is 50% lower than that of R134a. Also, the results indicated that R134a and the propoane/commercial butane mixture with 60% propane mass concentration have approximately the same values of saturation pressure, compressor Discharge Temperature, condenser heat load, input power, cooling capacity and volumetric cooling capacity. However, the pressure ratio of the hydrocarbon mixture with 60% propane is lower than that of R134a by about 11.1%. Finally, the reported results confirmed that the propane/iso-butane/ n -butane mixture with 60% propane is the best drop in replacement for R134a in domestic refrigerators under normal, subtropical and tropical operating conditions.
Minsoo Kim - One of the best experts on this subject based on the ideXlab platform.
-
comparison of the heating performance of an inverter driven heat pump system using r410a vapor injection into accumulator and compressor
International Journal of Refrigeration-revue Internationale Du Froid, 2012Co-Authors: Chul Woo Roh, Minsoo KimAbstract:In cold regions, a refrigerant injection technique has been used for enhancing heating capacity and avoiding the excessively high Discharge Temperature which is detrimental to reliability of a heat pump system. The heat pump system in this study having an additional refrigerant injection line into the accumulator was tested to compare with the heating performances of classic vapor-injection cycle. The heat pump system was designed to inject vapor refrigerant into the compressor and accumulator, selectively. Although the refrigerant injection into the compressor (classic vapor-injection cycle) was more effective to enhance heating capacity, the refrigerant injection into the accumulator could decrease Discharge Temperature and increase both heating capacity and COP slightly at the condition of high compressor frequency. In terms of mass balance, the injection stream into the accumulator substituted the evaporator's suction stream flowing to the compressor, so the mass flow rate of condenser was not increased as much as the amount of injected refrigerant.