Theoretical assessment of new low global warming potential refrigerant mixtures as eco-friendly alternatives in domestic refrigeration systems

Performance assessment of a refrigeration system with an integrated condenser under different environmental conditions

This paper presents a workable vapour compression system (VCS) for evaluating the performance of a refrigeration system with an integrated condenser that uses a long-term alternative refrigerant to halocarbon as a heat transfer medium (R600a). India's refrigeration system uses halocarbon refrigerants due to their excellent thermophysical and thermodynamic properties. Greenhouse gas emissions from halocarbon refrigerants and fossil fuel combustion contribute to global warming that engenders climate change and the deterioration of the ecosystem. The halocarbon refrigerant was discontinued based on high global warming potential. The system was investigated under various ambient temperatures of 16, 20, 24, and 28 °C (oC). The performance of the VCS was analyzed using the parameters of coefficient performance, compressor work, and pull-down time (PDT). The experimental result shows that the vapour compression system obtained its best PDT, enhanced coefficient of performance, and energy reduction when the ambient temperature was 20 °C.

Theoretical performance studies on environment friendly refrigerants used in refrigeration units

European Union regulations stipulate that household refrigeration systems must operate with fluid refrigerants that possess low global warming potential (GWPs). In this work, theoretical performance of six binary and one ternary mixture (which consists of R13I1, R290, R161, R32, R1234yf, and R1234ze(E)) was investigated. The performance parameters such as coefficient of performance (COP), refrigeration effect (RE), volumetric cooling capacity (VCC), discharge temperature, pressure ratio, and specific power consumption of all considered refrigerant mixtures is studied with respect to the evaporator temperature range of -18 to 18⁰C and the condenser temperature range of 40 to 55⁰C. The properties corresponding to different operating conditions for the refrigerants considered in this study are estimated using REFPROP 10. The findings demonstrated that, when compared to R134a, all the investigated refrigerants exhibited very low specific power consumption (apart from M9, M10, and M14-M16), and high volumetric cooling capacity (VCC) (apart from M11 and M13) under the operating conditions of evaporator temperature -18⁰C and condenser temperature 40⁰C. M1-M3 and M11-M13 gave similar and within 10% deviation in coefficient of performance, while M3 and M11-M13 refrigerant mixtures offer significantly low discharge temperatures when compared to R134a. Refrigerant mixtures M2 and M11 consistently exhibited a better performance in comparison to R134a in the aspect of majority of the performance parameters considered in this study. Finally, it is understood that M2 and M11 are two possible alternative refrigerants to conventional refrigerants used in small refrigeration units (R134a and R22). Further, it is also identified that these mixtures are non-flammable, possess zero ODP and low GWP values.

Internal Heat Exchanger Influence in Operational Cost and Environmental Impact of an Experimental Installation Using Low GWP Refrigerant for HVAC Conditions

The use of an internal heat exchanger in vapor compression refrigeration systems of one stage is a common practice because it helps to increase the cooling capacity in the evaporator. Furthermore, the use of refrigerants with low global warming potential is becoming more frequent due to environmental regulations worldwide. Thus, this paper presents an evaluation of the improvement produced by the inclusion of an internal heat exchanger cycle (IHXC) in an experimental installation from the viewpoint of exergy, economic and environmental through to exergy, exergoeconomics, and Specific Life Cycle Climate Performance (SLCCP) studies. The tests were conducted using R1234ze(E) as a replacement alternative to R134a in three evaporating temperature conditions: 4 °C, 9 °C, and 14 °C. Comparisons were made considering R134a in BRC mode versus R1234ze(E) in BRC and IHXC modes. Results show that a lower environmental impact is produced by an evaporating temperature of 14 °C with a reduction in SLCCP of 13.3% using IHXC and R1234ze(E). Moreover, the highest increase in exergy efficiency was observed for an evaporating temperature of 4 °C, with this increase being 9%, while the lowest increase in the total cost rate was observed for the same evaporating temperature, being 12.3% and 21.2% for BRC and IHXC modes using R1234ze(E), respectively.