Thermodynamic Analysis of Vapour Compression Refrigeration System with Sustainable Refrigerant Blends as Alternatives to Replace R22

The phase out schedule of a hydrochlorofluorocarbon refrigerant R22 demands the development of ecofriendly refrigerants. Since R22 has adverse ecological effects like high ODP and high GWP. Hence the present paper emphasis on the thermodynamic analysis of vapour compression refrigeration system with various ozone friendly refrigerant blends as an alternatives to R22. In this work eight refrigerant mixtures composed of R290, R134a, R152a, R125 and R32 at various compositions are developed. All the developed refrigerants possess zero ODP and low GWP compared to R22. The main objective of the present work is to compute the thermodynamic performance parameters of R22 and its alternatives based on actual vapour compression refrigeration cycle. The performance parameters of all the eight investigated refrigerants are computed at evaporating and condensing temperature of 7.2oC and 54.4oC respectively by using a MATLAB code. The results showed that COP of a refrigerant mixture RM40 (3.541) is higher among eight studied refrigerants and it is 0.2 % higher than the COP of R22 (3.534). GWP of RM40 (10) is lowest among the R22 and eight studied refrigerants. The compressor discharge temperature of RM40 is lower among the eight studied refrigerants and it is reduced by 6.6oC when compared to R22. Power spent per ton of refrigeration of RM40 (0.992 kW/TR) is lower among the eight studied blends and it is marginally lower than that of R22 (0.994 kW/TR). Volumetric refrigeration of capacity of RM40 (2837 kJ/m3) is higher among the eight investigated refrigerant blends and it is closer to that of volumetric capacity of R22 (3086 kJ/m3). Overall the thermodynamic performance of new binary blend RM40 (R290/R152a 95/5 by mass %) is very close to R22 and hence it is a sustainable alternative refrigerant to replace R22

Theoretical Development of Thermodynamic Properties of Environmental Friendly Refrigerant RE170 by Using Martin Hou Equation of State

This paper deals with the theoretical development of thermodynamic properties of an environmental friendly refrigerant dimethylether (RE170). Since hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) are going to be phase out and phase down as per Montreal and Kyoto protocol respectively. Refrigerant RE170 has zero ozone depletion potential (ODP) and very low global warming potential (GWP) which is less than two. Hence RE170 is considered as a viable option to replace for the refrigerants with high global warming potential (GWP) like HCFCs and HFCs. RE170 can be used as blend component with other ecofriendly refrigerant. The main objective of the present study is to compute the thermodynamic properties of RE170 by using Martin Hou equation of state. Thermodynamic properties are useful to do the thermodynamic analysis of vapour compression refrigeration cycle. The properties computed are saturation vapour pressure, liquid density, specific volume, enthalpy and entropy (both in the saturated liquid and vapour state). In the present study a MATLAB code is developed to compute the above considered thermodynamic properties from the temperature about 133K-363K and pressure up to 27.2 bar. The computed properties of dimethylether is compared with NIST REFPROP database. Since thermodynamic properties of RE170 is not available in ASHRAE hand book and also in literature. Therefore NIST REFRPROP can be considered as reliable source as that of ASHRAE. The results shows that deviation of liquid and vapour phase enthalpy from that of NIST is -0.058 to 2.55%. Similarly deviation of liquid and vapour phase entropy from that of NIST is -0.037 to 1.88%. Deviation of specific volume and liquid density from that NIST is 0.10 to -2.54% and -0.42 to 0.008% respectively. Variation of saturation pressure is less than -0.65%. Overall the computed thermodynamic properties of RE170 by using Martin-Hou equation of state shows good agreement with NIST for the temperature range (133K-363K) and pressure up to 27.2 bar

Theoretical energy performance assessment and environmental impact of various new ozone-friendly refrigerants used in residential air conditioners

This study focuses on energy performance investigation and environmental impact analysis of various new ecofriendly refrigerant blends as alternatives to high global warming potential refrigerant R22 theoretically. In this study, 23 refrigerants were considered at various composition. The present work considered the practical vapour compression refrigeration cycle for the performance assessment of various R22 alternatives. Essential studies such as toxicity, flammability, and total equivalent warming index of various novel refrigerants were also conducted in this study. Results obtained from practical vapour compression refrigeration cycle revealed that the energy efficiency ratio of refrigerants such as R1270 (2.860) and RB03 (R290/R152a of 60/40 in mass %) (2.854) was closer to the energy efficiency ratio of R22 (2.940). Volumetric refrigeration capacity (VRC) of R1270 (3293 kJ/m3) was similar to that of R22 (3297 kJ/m3) whereas VRC of RB03 (2908 kJ/m3) was almost similar to that of R407C (2925 kJ/m3) which was an alternative to R22. Compressor discharge temperature of RB03 was 15.78 ℃ lower when compared to R22. Flammability study revealed that all the new refrigerant blends (RB01 to RB04) were classified into weakly flammable (A2) and flammable (A3) category refrigerants whereas toxicity study revealed that all the investigated refrigerants were classified into non-toxic group (A). Refrigerant blend RB03 was less flammable compared to R1270. Total equivalent warming index analysis revealed that the environmental impact of R422A was 27.88% higher than R22 whereas RB03 has 4.97% lower environmental impact compared to R22. Overall, performance of refrigerant blend RB03 was better compared to 23 investigated refrigerants and it was very nearer to the performance of R22 and hence, it could be considered as an ecofriendly alternative to replace high global warming potential refrigerant R22 used in air conditioners. </jats:p

Theoretical thermodynamic performance assessment of various environment-friendly novel refrigerants used in refrigeration systems

The present investigation focuses on theoretical performance of various new environment-friendly refrigerant mixtures as substitutes to high global warming potential refrigerant R22. In this investigation, 34 refrigerants were considered at various composition. In this work, both complex vapor compression cycle (actual cycle) and standard vapor compression cycle (ideal cycle) was considered for the performance assessment of refrigerants. Vital studies such as flammability, toxicity, and environmental impact of various novel refrigerants were also carried out in this study. Results obtained from actual cycle showed that the coefficient of performance of refrigerant mixture RM40 (R1270/R134a 90/10 in mass %) (2.728) was the greatest among 34 investigated alternatives and it was closer to the coefficient of performance of R22 (2.770). Compressor discharge temperature of RM40 was 13.36 ℃ lower when compared with R22. Volumetric refrigeration capacity of RM40 (3335 kJ/m3) was slightly higher than that of R22 (3297 kJ/m3). Power spent per ton of refrigeration of RM40 (1.288 kW/TR) was marginally higher than that of R22 (1.269 kW/TR). Global warming potential (GWP100) of RM40 (133) was very low compared to the GWP100 of R22 (1760). Total equivalent warming index (environmental impact) of RM40 was 5.61% lower than R22. However, performance results obtained from standard cycle for various investigated refrigerants were better than actual cycle, since various losses occur were neglected in the standard cycle. Overall, thermodynamic performance of refrigerant mixture RM40 (R1270/R134a 90/10 in mass %) obtained from both actual and standard cycle was the highest among 34 investigated refrigerants and it was very closer to the performance of R22 and hence, it could be considered as an environment-friendly alternative to replace high GWP refrigerant R22 used in refrigeration systems. </jats:p

Performance computation of window air conditioner with very low GWP near azeotropic refrigerant mixtures as a drop in Substitutes to R22

The principal objective of the present study is to compute the thermodynamic performance of window air conditioner based on standard vapour compression refrigeration cycle using R22, R407C and nineteen refrigerant mixtures. In this work nineteen R290/R1270 blends at different compositions are developed. A MATLAB code is developed to compute the thermodynamic performance parameters of all the studied refrigerants at condensing and evaporating temperatures of 54.4°C and 7.2°C respectively. The performance parameters are cooling effect, compressor work, COP, compressor discharge temperature, power per ton of refrigeration and volumetric cooling capacity respectively. Analytical results revealed that COP of new binary mixture R290/R1270 (90/10 by mass %) is 2.82% higher among R22, R407C and nineteen studied refrigerants. Energy required by the compressor per ton of refrigeration for R290/R1270 (90/10 by mass %) is 2.73% lower among R22, R407C and nineteen studied fluids. The discharge temperature of the compressor for all the nineteen investigated blends are reduced by 6.0-8.9oC compared to R22. Overall thermodynamic performance of window air conditioner with R290/R1270 (90/10 by mass %) is better than R22 with significant savings in energy consumption and hence it is an energy efficient ecofriendly refrigerant mixture as a drop in substitute to R22