Browsing by Author "Mahapatra, D."

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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 TeÂ =Â 7.2Â Â°C, TkÂ =Â 54.4Â Â°C, Î”TsupÂ =Â 11.1Â Â°C and Î”TsubÂ =Â 8.3Â Â°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 11.79Â Â°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. Â© Springer Nature Singapore Pte Ltd 2021.
Effect of Solar Optical Properties of Building Envelope on Time Lag, Decrement Factor and Energy Saving of Buildings
(Springer Nature, 2020) Mahapatra, D.; Ashok Babu, T.P.A.
World has been suffering from energy crisis since 1970. This is because of the increased population and industrialization. Buildings have a significant contribution to total energy consumption across the globe. The increased urbanization leads to boom in construction of buildings. The materials used for the construction of buildings affect the climate of the city up to a great extent and affect the energy consumption as well. So, construction materials should be chosen wisely. The surface temperature of the building envelope is affected by the coatings used. Cool coatings help in reducing the surface temperature of the building envelope. Time lag and decrement factor are the indicators of energy saving in building. In this paper, the effect of cool coating on time lag and decrement factor was studied. Values of time lag and decrement factor were evaluated in different climatic zones of India. It has been found that as the absorptivity of the building envelope increases, the decrement factor increases. By changing the absorptivity from 0.2 to 0.73, a minimum change of 16% (New Delhi) in decrement factor and 11.75% (Jodhpur) in surface temperature was observed. The maximum change in decrement factor was 56.44% (Jodhpur). The maximum change in surface temperature was 39.02% (Bangalore). So, it should always be practised to keep the absorptivity of the building envelope as low as possible. © 2020, Springer Nature Singapore Pte Ltd.
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.
Mechanical and dynamic thermal performance evaluation of rice husk blended cement plaster when used with different bricks
(Elsevier Ltd, 2024) Mahapatra, D.; Madav, V.; Talanki Puttaranga Setty, A.B.
The construction industry is known for its significant environmental impact during the construction and operational phases. This study aims to explore the potential of rice husk, an abundant agricultural waste, as a partial replacement for sand in cement mortar. The research evaluates the thermo-mechanical properties, including compressive strength, water absorption, thermal conductivity, specific heat, and thermal diffusivity, of cement mortar by conducting a series of laboratory experiments. One of the critical novel aspects of this study is the evaluation of the dynamic thermal performance of the cement mortar when used with different bricks. The dynamic thermal performance was assessed using a MATLAB code based on the Charted Institute of Building Service Engineers (CIBSE) 2006 standard. By increasing the percentage of rice husk as a replacement for sand, the compressive strength of the cement mortar decreases, while the thermal conductivity decreases and the water absorption capacity increases. Notably, the results reveal that a 12 % reduction in thermal conductivity can be achieved by replacing just 7 % of the sand with rice husk. Furthermore, the study establishes a linear relationship between the dynamic thermal performance of the cement mortar and its volumetric heat capacity. These findings contribute to the development of eco-friendly solutions for energy-efficient buildings. The outcomes of this research can help engineers, architects, and policymakers in the decision-making processes regarding sustainable construction practices, promoting the use of rice husk as a viable alternative to sand. © 2023 Elsevier Ltd
Thermal and cost analysis of various air filled double glazed reflective windows for energy efficient buildings
(2020) Kirankumar, G.; Saboor, S.; Vali, S.S.; Mahapatra, D.; Talanki, Puttaranga, Setty, A.B.; Kim, K.-H.
The enormous amount of energy is being consumed by buildings in an attempt to deliver thermal comfort in buildings. This paper aims at reducing/increasing the total solar heat gain through various combinations of double glazed reflective windows of buildings. The spectral characteristics of six reflective glasses namely bronze, green, grey, opal blue, sapphire blue and gold-reflective glasses at a normal angle of incidence by using UV-3600 Shimadzu spectrophotometer according to ASTM E 424 standards were experimentally measured. The solar optical properties of the glasses were deduced by developing a MATLAB code using spectral data which was obtained from experiments in the solar spectrum wavelength range of 300 nm 2500 nm. Thirty air-filled double-glazed reflective windows have been studied for both thermal and cost analysis in the Indian composite climatic zone (New Delhi 28.580 N, 77.200 E). The configuration C13 (Grey reflective glass-Air gap 10 mm-Gold reflective glass) is observed to be the best air-filled double glazed window from the highest annual cost savings ($ 79.29 per annum in SE direction) and lower payback period (1.42 years) point of views among thirty double-glazed reflective glasses studied. The results of this paper are useful in the design of sustainable passive solar buildings. 2019 Elsevier Ltd
Thermal and cost analysis of various air filled double glazed reflective windows for energy efficient buildings
(Elsevier Ltd, 2020) Gorantla, G.; Saboor, S.; Vali, S.S.; Mahapatra, D.; Talanki Puttaranga Setty, A.B.; Kim, K.-H.
The enormous amount of energy is being consumed by buildings in an attempt to deliver thermal comfort in buildings. This paper aims at reducing/increasing the total solar heat gain through various combinations of double glazed reflective windows of buildings. The spectral characteristics of six reflective glasses namely bronze, green, grey, opal blue, sapphire blue and gold-reflective glasses at a normal angle of incidence by using UV-3600 Shimadzu spectrophotometer according to ASTM E 424 standards were experimentally measured. The solar optical properties of the glasses were deduced by developing a MATLAB code using spectral data which was obtained from experiments in the solar spectrum wavelength range of 300 nm–2500 nm. Thirty air-filled double-glazed reflective windows have been studied for both thermal and cost analysis in the Indian composite climatic zone (New Delhi 28.580 N, 77.200 E). The configuration C13 (Grey reflective glass-Air gap 10 mm-Gold reflective glass) is observed to be the best air-filled double glazed window from the highest annual cost savings ($ 79.29 per annum in SE direction) and lower payback period (1.42 years) point of views among thirty double-glazed reflective glasses studied. The results of this paper are useful in the design of sustainable passive solar buildings. © 2019 Elsevier Ltd
Variation of Time Lag, Decrement Factor and Inside Surface Temperature with Solar Optical Properties of Building Envelope in Different Climatic Zones of India
(Springer, 2020) Mahapatra, D.; Ashok Babu, T.P.
Maintenance of thermal comfort inside buildings requires a significant amount of energy. According to the Centre for Science and Environment, the energy spent on achieving thermal comfort in commercial buildings and in residential buildings are 31% and 7%, respectively. Considering the energy crisis that world has been suffering; every individual should try to save energy by some means. The increase in urbanization over the last few years gave rise to boom in constructions. Choosing the materials used for the construction of buildings wisely can contribute towards energy saving. The solar optical properties of building envelope affect the surface temperature up to a great extent which in turn affects the energy used for thermal comfort. In this paper, the effect of solar optical properties on time lag decrement factor and inside surface temperature is studied in different Indian climatic zones. Â© 2020, Springer Nature Singapore Pte Ltd.