Faculty Publications
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Item Theoretical Computation of Performance of Sustainable Energy Efficient R22 Alternatives for Residential Air Conditioners(Elsevier Ltd, 2017) Vali, S.V.; Ashok Babu, T.P.A.The present paper focuses on theoretical investigation of various new R22 alternatives. In this study R407C and four new R22 alternative refrigerant mixtures composed of R1270, R290, RE170, R134a and R32 at different compositions are considered. All the four new refrigerants possess zero ODP and low GWP compared to R22.The chief objective of the present work is to compute the thermodynamic performance of a standard vapour compression refrigeration cycle with R22 and its alternative refrigerants. A MATLAB code is developed to compute the thermodynamic performance of all the considered refrigerants. Thermodynamic analysis of all the refrigerants are evaluated at the condensing and evaporating temperatures of 54.4°C and 7.2°C respectively. The results showed that COP for the refrigerant mixture R134a/R1270/RE170 (55/37.5/7.5 by mass percentage) is 5.35% higher among the R22, R407C and four studied refrigerants. The compressor discharge temperature for R134a/R1270/RE170 (55/37.5/7.5 by mass percentage) is 11.9°C lower when compared to R22 and hence this mixture indicates the durability of the compressor life. The energy spent by the compressor per ton of refrigeration for the mixture R134a/R1270/RE170 (55/37.5/7.5 by mass percentage) is 5.12% lower among R22, R407C and four investigated refrigerants. The GWP of R134a/ R1270/ RE170 (55/37.5/7.5 by mass percentage) is 716 which is low compared to GWP of R22 (1760). Therefore R134a/R1270/RE170 (55/37.5/7.5 by mass percentage) is a sustainable energy efficient refrigerant to replace R22 used in residential air conditioners from the stand point of COP, compressor discharge temperature, energy savings, GWP and ODP. And also in this study thermodynamic performance of refrigerants are computed at various evaporating temperatures by keeping condenser temperature as constant. © 2017 The Authors. Published by Elsevier Ltd.Item Thermodynamic performance analysis and flammability study of various new ozone friendly non azeotropic refrigerant mixtures as alternatives to replace R22 used in residential air conditioners(International Information and Engineering Technology Association info@iieta.org, 2018) Vali, S.V.; Ashok Babu, T.P.A.The present study investigates the theoretical thermodynamic performance analysis and flammability study of various new ozone friendly refrigerants as replacements to R22. In this work, five non azeotropic refrigerant blends comprising of R152a, R134a, R32, R290 and R1270, at various compositions were developed. Flammability study of all the five refrigerant mixtures considered were carried out by using Refrigerant Flammability (RF) number. The cycle followed during the performance investigation of refrigerants was the actual vapour compression refrigeration cycle. Thermodynamic performance characteristics of all the five investigated refrigerants were compared with the baseline refrigerant R22. Theoretical results showed that COP of refrigerant M40 was 0.51% higher, compared to R22 and the five refrigerants studied. Compressor discharge temperature of M40 was lowered by 11.6°C compared to R22. Power consumed to produce per ton of refrigeration of M40 was 0.52% lower, compared to R22 and the five refrigerants considered. Heat transfer rate through the condenser for M40 was 3.66% higher than R22. Volumetric refrigeration capacity of M40 was the highest among the five studied refrigerants and it was very close to the volumetric capacity of R22. Flammability analysis revealed that all the five investigated refrigerant mixtures were classified into the weakly flammable category. Overall, the thermodynamic performance of new ternary blend M40 (R32/R134a/R1270 5/60/35 by mass percentage) was higher than R22 with reasonable saving in power consumption and hence, M40 is a viable candidate to replace R22. © 2018 International Information and Engineering Technology Association. All Rights Reserved.Item Theoretical thermodynamic performance assessment of various environment-friendly novel refrigerants used in refrigeration systems(SAGE Publications Ltd info@sagepub.co.uk, 2020) Vali, S.S.; Ashok Babu, T.P.A.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. © IMechE 2019.