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    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.
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    Theoretical Performance Investigation of Vapour Compression Refrigeration System Using HFC and HC Refrigerant Mixtures as Alternatives to Replace R22
    (Elsevier Ltd, 2017) Vali, S.V.; Ashok Babu, T.P.A.
    The present paper describes the theoretical thermodynamic performance of vapour compression refrigeration system using HFC and HC blends as an alternatives to replace the refrigerant R22. In this study thermodynamic analysis of window air conditioner with R431A, R410A, R419A, R134a, R1270, R290 and fifteen refrigerant mixtures consists of R134a, R1270 and R290 was carried out based on actual vapour compression cycle. All the investigated refrigerant mixtures are ozone friendly in nature and they possess GWP in the range of 0.0244 to 1.685 times the GWP of R22. Thermodynamic performance analysis of all the investigated refrigerant mixtures were evaluated at the condensing and evaporating temperatures of 54.4oC and 7.2oC respectively. The results show that COP for the refrigerant mixture R134a/R1270/R290 (50/5/45 by mass percentage) is 2.10% higher among the R22, R431A, R410A, R419A, R134a, R1270, R290, and fifteen studied refrigerant mixtures. The compressor discharge temperature of all the studied refrigerants were lower than that of R22 by 4.8oC-22.2oC. The power consumption per ton of refrigeration for the refrigerant mixture R134a/R1270/R290 (50/5/45 by mass percentage) is 2.01% lower among R22, R431A, R410A, R419A, R134a, R1270, R290, and fifteen studied refrigerant mixtures. Overall the thermodynamic performance of refrigerant mixture R134a/R1270/R290 (50/5/45 by mass percentage) is better than that of R22 with reasonable savings in the energy and hence it is an appropriate ecologically energy efficient alternative refrigerant to substitute R22 used in air conditioning applications. © 2017 The Authors.
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    Thermodynamic Performance Analysis of Eco friendly Refrigerant Mixtures to Replace R22 Used in Air Conditioning Applications
    (Elsevier Ltd, 2017) Vali, S.V.; Ashok Babu, T.P.A.
    In the present study theoretical thermodynamic performance of a 0.8 TR window air conditioner with ten binary refrigerant mixtures consists of propylene (R1270) and propane (R290) was investigated based on actual vapour compression refrigeration cycle. All the investigated refrigerant mixtures consist of zero ozone depletion potential. Global warming potential of R22 is 1760 whereas GWP of all the studied refrigerant mixtures were below three and also these mixtures are closer to azeotropic containing the temperature glide below 0.4oC. Thermodynamic performance of all the refrigerant mixtures are computed at the evaporating and condensing temperatures of 7.2oC and 54.4oC (ARI conditions) respectively. The results revealed that the coefficient of performance for the mixture R1270/R290 (75/25 by mass %) was closer to R22. The percentage variation in cop for the mixture R1270/R290 (75/25 by mass %) was least by 0.97% among the ten investigated refrigerant mixtures when compared to R22. Refrigeration capacity of all the considered refrigerant mixtures was similar to that of capacity of refrigerant R22. The compressor discharge temperature for all the studied refrigerants were reduced in the range of 5.6-8.4oC when compared to the reference refrigerant R22. The power required per ton of refrigeration for the refrigerant mixture R1270/R290 (75/25 by mass %) was least among the ten investigated refrigerant mixtures. Since refrigerant mixtures consist of hydrocarbons, therefore they had better miscibility with the mineral lubricant oil. Overall the thermodynamic performance of a refrigerant mixture R1270/R290 (75/25 by mass %) was nearest to R22 and hence it is a suitable environmentally alternative refrigerant to substitute R22 used in residential air conditioning applications. © 2017 The Authors.
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    Theoretical Evaluation of Energy Performance of a Vapour Compression Refrigeration System Using Sustainable Refrigerants
    (Springer, 2020) Vali, S.V.; Ashok Babu, T.P.
    The chief goal of this present investigation is to evaluate performance parameters of various sustainable refrigerants as R22 alternatives. In this investigation apart from R290, R134a and R22, twelve mixture refrigerants were developed at various composition. Results showed that energy efficiency ratio (EER) of mixture refrigerant MR40 (R290/R134a 95/5 in mass%) (4.546) stood greatest among twelve investigated alternatives and it was closer to the EER of R22 (4.602). Compressor discharge temperature of MR40 was lower than R22 by 16.020C. Volumetric refrigeration capacity of MR40 (3424 kJ/m3) was relatively lesser than R22 (3801 kJ/m3). Power spent per ton of refrigeration (PPTR) of MR40 (0.773 kW/TR) stood lowest among twelve investigated alternatives and it was fairly greater than R22 (0.764 kW/TR). Global warming potential (GWP100) of MR40 (68) was very low compared to R22 (1760). Overall, performance of MR40 was closer to R22, when compared with all the twelve investigated alternatives, and hence, it might be treated as a suitable replacement to refrigerant R22. © 2020, Springer Nature Singapore Pte Ltd.
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    Analytical computation of thermodynamic performance of various new eco-friendly alternative refrigerants applicable for air conditioners
    (Springer Science and Business Media Deutschland GmbH info@springer-sbm.com, 2021) Vali, S.V.; Ashok Babu, T.P.; Mahapatra, D.; Saboor, S.; Gorantla, K.K.; Sai Siva Subramanyam, V.
    The objective of the present investigation is to do the theoretical thermodynamic analysis of various new eco-friendly R22 substitutes used in vapour compression refrigeration (VCR) cycle. In this work, nine mixture refrigerants were considered at different compositions. Thermodynamic properties of all the considered refrigerants were developed and the same properties were used in the performance analysis of alternative refrigerants. Standard VCR cycle was considered for the thermodynamic assessment of alternative refrigerants. The working conditions considered are expressed as Te = 7.2 °C, Tk = 54.4 °C, ΔTsup = 11.1 °C and ΔTsub = 8.3 °C, respectively. Results revealed that the COP of mixture refrigerant MR20 (R600a/R134a/R1270 5/47.5/47.5 in mass%) was 2.02% higher than the COP of R22 and other nine investigated refrigerants. Discharge temperature of compressor obtained for MR20 was 11.79 °C lower compared to that of R22. Compressor power obtained for MR20 was 1.96% lower than that of R22. Volumetric refrigeration capacity obtained for MR20 was relatively closer to that of R22. GWP100 of MR20 (619) was lower compared to the GWP100 of R22 (1760). Overall, the performance of mixture refrigerant MR20 was better compared to all the considered R22 alternatives, and therefore it might be an appropriate candidate to replace R22 used in air conditioners. © Springer Nature Singapore Pte Ltd 2021.
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    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.
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    Computation of ecological properties, flammability properties and thermodynamic properties of sustainable refrigerant dimethylether (RE170) using Martin Hou equation of state (MHEOS)
    (International Information and Engineering Technology Association info@iieta.org, 2019) Vali, S.V.; Ashok Babu, T.P.S.A.
    The objective of present work is to investigate the thermodynamic properties, ecological properties and flammability properties of a refrigerant Dimethylether (RE170). Ecological properties such as ozone depletion potential (ODP) and global warming potential (GWP) were reported and validated with literature. Flammability properties such as upper flammability limit (UFL), lower flammability limit (LFL) and refrigerant flammability (RF) number were reported and validated with literature. Martin-Hou equation of state (MHEOS) is used while computing the thermodynamic properties of RE170. In this investigation, a MATLAB code was developed in order to compute the properties of RE170 over the wide temperature range about 131.6 K to 398.15 K and pressure up to 51.3 bar. The computed thermodynamic properties of RE170 were validated against REFPROP database, since its thermodynamic properties were not available in the existing literature. Therefore, REFRPROP can be considered as a reliable source as that of ASHRAE. Results showed that refrigerant RE170 has zero ODP and very low GWP (equals to one). Similarly RE170 has LFL of 3.34 vol%, UFL of 25.60 vol% and RF number of 51.05 kJ/g. Results of thermodynamic properties of RE170 revealed that the mean absolute deviation (MAD) between computed liquid and vapour phase enthalpy values and REFPROP values was 1.01 % and 0.32 %, respectively. Similarly MAD between computed liquid and vapour phase entropy values and REFPROP values was 1.05 % and 0.25 %. MAD of saturation pressure was 0.071 %. MAD between computed vapour specific volume, liquid density values and REFPROP values was 1.49 % and 0.25 %. Overall, computed thermodynamic, ecological and flammability properties of RE170 shows good agreement with literature. © 2019 International Information and Engineering Technology Association. All rights reserved.
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    Thermodynamic analysis of window air conditioner using sustainable refrigerant R290/RE170 and R1270/RE170 blends as substitutes to refrigerant R22
    (International Information and Engineering Technology Association info@iieta.org, 2019) Vali, S.V.; Setty, A.B.T.P.
    The present work emphasis on theoretical computation of thermodynamic performance of window air conditioner using various sustainable R290/RE170 and R1270/RE170 refrigerant mixtures as substitutes to R22. In this work, apart from R407C, twelve new binary mixtures comprising of R290, R1270 and RE170 at various compositions were developed. And also in this investigation, a MATLAB code was developed to compute the thermodynamic performance characteristics of various considered R22 alternatives at Tk=54.4 0C and Te=7.2 °C. The various performance characteristics computed are mass flow rate, refrigeration effect, compressor work, coefficient of performance (COP), pressure ratio, compressor discharge temperature, power consumed per ton of refrigeration, condenser heat rejection and volumetric cooling capacity. Results showed that the COP of refrigerant mixture RM7 (R1270/RE170 95/5 by mass %) was the highest among twelve refrigerants studied and it was 0.23 % higher than R22. Pressure ratio of RM7 (3.174) was 7.49 % lower than that of R22 (3.431). Compressor discharge temperature of all the twelve investigated refrigerants was lower in the range of 9.35 0C to 17.15 0C when compared with R22. Power consumed per ton of refrigeration of RM7 was 0.27 % lower than that of R22. Volumetric cooling capacity of RM7 (3833 kJ/m3) was very close to that of R22 volumetric capacity (3863 kJ/m3). Heat transfer through condenser of RM7 (6.372 kW) was similar to that of R22 (6.377 kW). Overall, thermodynamic performance of RM7 matches well with the performance of base line refrigerant R22 and hence, refrigerant RM7 can be considered as sustainable alternative to R22 used in air conditioners. © 2019 International Information and Engineering Technology Association. All rights reserved.
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    Theoretical energy performance assessment and environmental impact of various new ozone-friendly refrigerants used in residential air conditioners
    (SAGE Publications Ltd, 2020) Vali, S.V.; Ashok Babu, T.P.
    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. © IMechE 2020.
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    Investigation on thermodynamic performance analysis and environmental effects of various new refrigerants used in air conditioners
    (Springer Science and Business Media Deutschland GmbH info@springer-sbm.com, 2020) Vali, S.V.; Saboor, S.; Gorantla, K.; Mahapatra, D.; Setty, A.B.T.P.
    The main aim of this present investigation is to evaluate performance and environmental impact analysis of various novel mixture refrigerants as R22 replacements theoretically. Refrigerants with lower global warming potential (GWP) can be adequate for bringing down emissions which are concerned for air conditioners. In this investigation, twenty-seven refrigerants were developed at several compositions. Important studies such as computation of CO2 emissions using total equivalent warming impact (TEWI), toxicity and flammability analysis of various considered refrigerants were also carried out in this investigation. Performance analysis of refrigerants was conducted under different operating conditions. Results showed that the energy efficiency ratios (EERs) of refrigerants such as R1270, RM30 (R152a/R1270/RE170 of 25/71/4 by mass percentage) and RM50 (R152a/R1270/RE170 of 10/85/5 by mass percentage) were closer to that of R22 and they are relatively lower than R22 by 0.95%, 1.34% and 1.80%, respectively. Toxicity investigation exhibited that all the refrigerants studied were classified into nontoxic category (A) whereas flammability investigation revealed that all the novel refrigerant mixtures (RM10 to RM50) were classified into flammable category (A3). CO2 emissions (TEWI) released from air conditioner working with R1270, RM30 and RM50 were 7.41%, 6.85% and 6.51%, respectively, lower than that of R22. In terms of several thermodynamic aspects, the performance of refrigerants such as R1270, RM30 and RM50 were superior to those of R22 and its various considered alternatives working under different operating conditions, although their EERs are fairly lower than R22 and hence, these refrigerants could be considered suitable environment-friendly alternatives to R22 used in air conditioners. The present study gives essential information and a road map towards the development of low GWP R22 alternative refrigerant blends from the viewpoint of toxicity, flammability, performance aspects, environmental and safety aspects, respectively. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.