Faculty Publications

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    Analytical computation of thermodynamic performance parameters of actual vapour compression refrigeration system with R22, R32, R134a, R152a, R290 and R1270
    (EDP Sciences edps@edpsciences.com, 2018) Vali, S.S.; Setty, T.P.; Babu, A.
    The present work focuses on analytical computation of thermodynamic performance of actual vapour compression refrigeration system by using six pure refrigerants. The refrigerants are namely R22, R32, R134a, R152a, R290 and R1270 respectively. A MATLAB code is developed to compute the thermodynamic performance parameters of actual vapour compression system such as refrigeration effect, compressor work, COP, power per ton of refrigeration, compressor discharge temperature and volumetric refrigeration capacity at condensing and evaporating temperatures of 54.4oC and 7.2oC respectively. Analytical results exhibited that COP of both R32 and R134a are 15.95% and 11.71% higher among the six investigated refrigerants. However R32 and R134a cannot be replaced directly into R22 system. This is due to their higher compressor discharge temperature and poor volumetric capacity respectively. The discharge temperature of both R1270 and R290 are lower than R22 by 20-26oC. Volumetric refrigeration capacity of R1270 (3197 kJ/m3) is very close to that of volumetric capacity of R22 (3251 kJ/m3). Both R1270 and R290 shows good miscibility with R22 mineral oil. Overall R1270 would be a suitable ecofriendly refrigerant to replace R22 from the stand point of ODP, GWP, volumetric capacity, discharge temperature and miscibility with mineral oil although its COP is lower. © The Authors, published by EDP Sciences, 2018.
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    Effect of Various External Shading Devices on Windows for Minimum Heat Gain and Adequate Day lighting into Buildings of Hot and Dry Climatic Zone in India
    (EDP Sciences edps@edpsciences.com, 2018) Gorantla, G.; Saboor, S.; Talanki Setty, P.R.; Babu, A.
    Glass is the major component of the building envelope to provide visual comfort to inside the buildings. In général clear and bronze glass was used as a main building envelope for both residential and commercial buildings to provide better day lighting into the buildings. If we use more glass area as a building envelope more radiation allows into the buildings. So that it is necessary to reduce more solar radiation and provide sufficient daylight factor inside the building's through glass windows with the help of external devices called shading devices. In this work four shading devices was tried on bronze glass window to find the heat gain and daylighting into buildings. This paper presents the experimental measurement of spectral characteristics of bronze glass which include transmission and reflection in entire solar spectrum region (300nm-2500nm) based on ASTM standards. A MATLAB code was developed to compute visible and solar optical properties as per the British standards. A building model was designed by design builder software tool. 40% window to wall ratio was considered for building models, thermal and day lighting analysis of buildings through windows was carried out in Energy plus software tool for hot and dry climatic zone of India. © The Authors, published by EDP Sciences, 2018.
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    Performance computation of window air conditioner with very low GWP near azeotropic refrigerant mixtures as a drop in Substitutes to R22
    (EDP Sciences edps@edpsciences.com, 2018) Vali, S.S.; Setty, T.P.; Babu, A.
    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. © The Authors, published by EDP Sciences, 2018.
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    A Review on Methods for Analysis of Laterally Loaded Piles
    (Springer Science and Business Media Deutschland GmbH, 2022) Babu, A.; Nayak, S.
    Pile foundations are often subjected to lateral loads and moments due to forces such as wind, waves and earthquake. The lateral response of a single pile is one among the main complex soil-structure interaction problems in foundation engineering. The behavior of the soil-pile system is mainly nonlinear, making the problem more complicated. The lateral load resistance of pile is influenced by the soil pile interaction, which in turn depends on soil properties, pile material, diameter of the pile, pile length, loading type etc. Several methods have been used for the analysis of vertical piles subjected to lateral loads, some of which have gained significant experience in applying the theory to practical situations. Realistic soil-pile interaction and pile behavior under lateral load can be simulated using software based on finite element analyses. A comprehensive literature review of different methods for the analysis of laterally loaded piles is discussed in this paper. The applicability, advantages, limitations and comparison of various methods are also included in the study. For the better understanding the entire review is segregated into different subsections on the basis of nature of analyses. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
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    Thermal and energy saving analysis by using tinted double window glass combinations for heat gain in buildings
    (Regional Energy Resources Information Center (RERIC) rericjournal@ait.ac.th, 2018) Gorantla, K.; Saboor, S.; Babu, A.; Ranga, P.; Setty, T.
    Buildings consume large amount of energy to accommodate thermal and visual comforts, in which glass windows play an important role as we used as building envelope. Universally clear glass is used as chief building envelope for buildings. As clear glass is having more transmission property it permits more radiation and day light into the buildings which creates uneasy feeling to the occupants. This paper presents the experimental measurement of spectral characteristics of three tinted glasses which include transmission and reflection in entire solar spectrum wavelength region from 300nm to 2500nm as per ASTM standards by using UV 3600 Shimadzu spectrophotometer. These measured spectral characteristics were used to compute solar optical properties as per British standard by using MATLAB code. To find the total solar radiation through double tinted window glass combinations GC1 to GC6 place as building envelopes of New Delhi climatic zone by using MATLAB code and to find the monthly solar radiation passing into the building which is helpful to calculate the cost energy saving annually for cooling and heating loads. From the results GC6 combination windows are saving cost i.e. 61.16 (US Dollars/year) in south, 60.54 (US Dollars/year) in south east and 59.23 (US Dollars/year) in south west orientations annually than other combination windows.
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    Experimental and theoretical studies of various solar control window glasses for the reduction of cooling and heating loads in buildings across different climatic regions
    (Elsevier Ltd, 2018) G, K.K.; Saboor, S.; Kumar, V.; Kim, K.-H.; Babu, A.
    The glass material and position/orientation of windows are very important to control the heat gain in buildings. In this article, we studied the effect of different window glazing materials (such as bronze, green, grey, bronze-reflective, green-reflective, grey-reflective, gold-reflective, opal blue-reflective, and sapphire blue-reflective glass) in controlling the heat gain by the buildings. The spectral data of diverse window glasses have thus been measured in solar spectrum range of 300–2500 nm. Moreover, the MATLAB codes have been developed to compute solar optical properties (including transmittance, reflectance, and absorbance), solar heat gain coefficient (SHGC), and heat transfer through the glazing material. Thermal analysis was carried out using a total of nine window glasses in eight coordinal directions (E, W, N, S, SE, SW, NE, and NW) against three climatic conditions (hot and dry, warm and humid and composite) in India. In terms of net annual cooling and heating cost savings per window, the grey reflective glass was found to be the most energy saving glass among all glasses tested in this study. The grey reflective glass exhibited the highest cost saving in net annual cooling and heating in all eight orientations across three climatic regions. The grey reflective glass saved the net cost of heating and cooling by $ 61.24 per annum in the south orientation of Jodhpur climatic conditions. © 2018 Elsevier B.V.