Drop-in Replacement For R134a Research Articles

Energy and exergy analysis of LPG (liquefied petroleum gas) as a drop in replacement for R134a in domestic refrigerators

This study presents a comparison of energetic and exergetic performance of a vapour compression refrigeration system using pure HC (hydrocarbon) refrigerants. In this study, three different pure HCs propane (R290), butane (R600) and commercial LPG (liquefied petroleum gas) are used in the theoretical analysis. R134a is also used in the analysis as a reference refrigerant. The evaporator temperature ranges from −30 to 0 °C while the condenser ranges from 30 to 50 °C. MATLAB software is used for solving the thermodynamic equations, while the thermo-physical properties are calculated using REFPROP software. The results show that R600 has the highest COPc and exergetic efficiency, while LPG has the lowest. When compared to R134a, the COPc for R134a is higher than that for LPG by 10%. Also, the exergetic efficiency is higher by 5%. However, LPG has the advantage of being not expensive, available in large amounts and zero ozone depletion potential and low global warming potential.

Experimental analysis of the internal heat exchanger influence on a vapour compression system performance working with R1234yf as a drop-in replacement for R134a

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.

Exergy analysis of hydrocarbons mixture refrigerants R436A and R436B as a drop in replacement for R134a with TiO<SUB align="right">2 nanoparticles

The refrigerator exergy efficiency (EE) with nanoparticles in the working fluid was investigated experimentally. Mineral oil (MO) with TiO2 nanoparticles mixtures were used as the lubricant instead of Polyol ester (POE) oil in the R134a, R436A (R290/R600a–56/44–weight %) and R436B (R290/R600a–52/48–weight %) refrigerator. The results indicate that R134a, R436A and R436B and MO with TiO2 nanoparticles work normally and safely in the refrigerator. The refrigerator EE (34.1, 40.1 and 41.6%) was better than the R134a, R436A and R436B and POE oil system (23.4, 35.3 and 37.7%). The same tests with Al2O3 nanoparticles showed that the different nanoparticles properties have little effect on the refrigerator EE. Thus, TiO2 nanoparticles can be used in refrigerator to considerably increase the EE.

Experimental analysis of R1234yf as a drop-in replacement for R134a in a vapor compression system

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.

Experimental analysis of the low-GWP refrigerant R1234yf as a drop-in replacement for R134a in a typical mobile air conditioning system

This study investigated the performance of a typical mobile air conditioning system using R134a and R1234yf as the working fluids under different working conditions. The system is composed of a microchannel parallel flow condenser, a laminated plate evaporator, a variable displacement compressor, and a thermal expansion valve. The different working cycles of each refrigerant were comprehensively compared. The optimum refrigerant charge amount of the R1234yf system was approximately 95% of the R134a system during drop-in tests. The performance of the R134a system was a little higher than that of the R1234yf system. The cooling capacity and system coefficient of performance of the R134a system were 12.4% and 9% larger, respectively. This result is mainly because of the thermophysical property differences between the two refrigerants and the improper expansion valve opening of R1234yf. Analysis on the whole cycle revealed that the R1234yf system could obtain a higher evaporating pressure and a larger superheat and subcooling. Redesigning the expansion valve for R1234yf could improve performance of the system.

ASSESSMENT OF PROPANE/COMMERCIAL BUTANE MIXTURES AS POSSIBLE ALTERNATIVES TO R134a IN DOMESTIC REFRIGERATORS

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

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.