Faculty Publications
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Item Study of Optimum Inward Glass Tilt Angle for Window Glass in Different Indian Latitudes to Gain Minimum Heat into Buildings(Elsevier Ltd, 2015) Gorantla, K.K.; Ashok Babu, A.B.T.Modern buildings use glass materials for building enclosures. Extensive use of glass in building envelopes increases the heat gain, which in turn increases the energy demand to maintain the building at comfortable conditions. This paper presents experimentally measured spectral optical properties of four different glass materials such as, clear, bronze, green and reflective glasses. The solar optical properties were computed using spectral optical properties. The effect of inward glass tilts to gain minimum heat into buildings for different latitudes of India with four different glass materials for energy efficient glass window design was studied. The optimum glass tilt for different Indian latitudes such as, 90, 130, 170, 210, 250 and 290 in all orientations of the window glass (E, W, N, S, NE, NW, SE and SW) were computed. From the results it is observed that at 90 and 170 N latitudes minimum heat gain is found to be in south direction for the vertical position of all the glasses. For 130 N latitude, 40 inward tilt of the glass is observed to be optimum in south direction. For latitudes 210 and 250 N, 20 inward tilt of the glass is efficient in south orientation. 290 N latitude requires an inward tilt of 60 for glass materials to eliminate solar radiation passing through the glasses in south direction. © 2015 The Authors. Published by Elsevier Ltd.Item Simulation of various wall and window glass material for energy efficient building design(Trans Tech Publications Ltd ttp@transtec.ch, 2016) Gorantla, K.K.; Saboor, S.; Ashok Babu, A.B.T.Buildings consume huge amount of energy for forced ventilation and artificial day lighting. Use of appropriate material combinations for walls and window glass can help in reducing energy consumption for cooling and lighting. This paper presents the thermal properties of four building materials such as, laterite stone, dense concrete, burnt brick and mud brick. It also presents the experimentally measured optical properties of glass materials such as, clear glass, bronze glass, green glass and reflective. In this study building of size 5m × 5m × 3.2m with four wall materials and four glass materials were designed using design builder software. The thickness of the wall was considered as external wall with thickness 0.22m. All the walls covered with cement plaster on either side. Roof of the building is made of reinforced cement concrete and floor is dense concrete. Thermal analysis was carried out using by Energy plus software. Single sized glass windows were placed in south direction (Due to less heat gain in south direction) for Mangalore city (12.87°N, 74.88°E), Karnataka, India. Different window to wall ratios (20%, 40%, 60%, 80% and 100%) were maintained for buildings. Total eighty building models were investigated for heat gain into buildings. From the results, it is observed that irrespective of the window to wall ratio, mud brick walls with reflective window glass were observed to be energy efficient from the lower heat gain point of view, and laterite stone wall building with clear glass windows were observed to be the worst due to their higher heat gain values. At 60% window to wall ratio mud brick walls with reflective window glass have 24.93kWh heat gain and dense concrete walls with clear glass have 32.9 kWh heat gain. The results of the study help in establishing the best combination of wall and glass materials for minimum heat gain into buildings. © 2016 Trans Tech Publications, Switzerland.Item Optimizing Vertical Air Gap Location Inside the Wall for Energy Efficient Building Enclosure Design Based on Unsteady Heat Transfer Characteristics(Springer, 2020) Saboor, S.; Nagaraju, S.; Rizvan, S.M.; Gorantla, K.K.The chief principle of this paper is to optimize the location of vertical air space within composite walls based on thermal unsteady response state parameters that include admittance, transmittance, attenuation factor, and time lag. For computation of these parameters, a MATLAB code has been generated. This code solves 1-D heat flow diffusion equation with convective periodic boundary conditions. Six building construction materials such as laterite stone, burnt brick, mudbrick, reinforced brick, fly ash brick, and concrete block were selected and computations were made for 42 configurations of the composite walls. From this, it is concluded that composite walls with air space located at the outer side of the external wall and the mid-center of the external wall are energy efficient from higher time lag, higher thermal admittance, and lower thermal transmittance perspective and the composite walls with air space located at outer and inner sides of the external walls are the best from the lower decrement factor perspective, among seven studied configurations. The results of the study reduce the air conditioning loads in buildings. © 2020, Springer Nature Singapore Pte Ltd.Item 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.Item Day lighting and thermal analysis using various double reflective window glasses for green energy buildings(International Information and Engineering Technology Association info@iieta.org, 2018) Gorantla, K.K.; Saboor, S.; Setty, A.B.T.P.R.The objective of this research work is to identify the best double reflective window glass which provides adequate daylighting by controlling solar heat gain as per the requirement of summer and winter seasons of composite climatic zone in India. To attain this objective an investigation of spectral characteristics of different reflective glasses such like gold, sapphire blue, opal blue, grey, green and bronze reflective glasses is carried out experimentally using Shimadzu UV 3600 spectrophotometer in the entire solar spectrum wavelength range from 300 nm to 2500 nm based on ASTM E 424 standards.The measured spectral characteristics were used to compute the visible optical properties in the visible zone and solar optical properties in solar spectrum zone by using International standard method with a MATLAB code. The computed optical properties transmittance, reflectance and absorbance are used in the simulation tool for heat gain and daylight calculations for a school room building. As far as both hottest and coolest days are concerned double gold reflective window glass (DGLDRGW) is found to be the best in the South orientation. During hottest day, DGLDRGW gains minimum heat of 2.13 kWh with adequate daylight factor (2.049% at 9 A.M. and 2.025% at 4 P.M.) and also it gains maximum heat of 8.55 kWh with adequate daylight factor (2.729% at 9 A.M. and 2.732% at 4 P.M.) for school room building among six studied double reflective window glasses. © 2018 International Information and Engineering Technology Association. All Rights Reserved.