Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Department of Thermal and Energy Engineering

This experimental work deals with the measurement of the contact angle of the nanocomposites made of phase change material (PCM) OM 08 and multi-wall carbon nanotubes (MWCNTs) with different volume concentrations namely, 0.05%, 0.1%, 0.3%, 0.5%. Two different types of copper substrate, namely copper plate with and without shot blasting, were used in this study. It was identified that the droplet contact angles of the nanocomposites were increased with the increase in volume concentration. Also, an increase in the droplet contact angle was more predominant at the higher volume concentration of MWCNTs. The nanocomposite with 0.5 vol.-% of MWCNT has a maximum droplet contact angle of 42.1° and 40.01° respectively on the normal and SBS copper substrate. The use of the highly roughed SBS effectively reduced the contact angle of the nanocomposite by 2° and 2.3° during the first and second passes respectively. © 2021 Institute of Materials, Minerals and Mining Published by Taylor & Francis on behalf of the Institute.

World University root node

School of Mechanical Engineering

Vellore Campus

Surface Engineering

Effect of shot blasting on droplet contact angle of carbon aided phase change nanocomposites

This article deals with the photothermal conversion performance of solar glycol – multiwall carbon nanotubes based nanofluids were studied with various weight concentrations and time. A broad investigation was performed with various nanofluid samples with the help of a sun simulator. The measurement was conducted with solar glycol-MWCNTs based nanofluids with 0.1%, 0.2%, and 0.3% volume concentration respectively. The heat loss was reduced by insulation material, whereas the nanofluid samples were heated with the help of a sun simulator. The difference in temperature of 7.7°C was attained for the 0.3 vol.% nanofluid as compared with solar glycol. Compared with solar glycol the temperature of MWCNT-SG based nanofluid at the volume concentration of 0.3% was augmented by about 69.21% with a light irradiation time of 10 min. The experimental results confirm that the SG\MWCNTs based can be used as the right replacement for heat transfer fluids for direct absorption solar collector system applications. © IMechE 2020.

Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering

Experimental investigation on photothermal conversion using solar glycol/MWCNTs based nanofluids

Fulltext

World Electric Vehicle Journal

Design and Analysis of a Solar-Powered Electric Vehicle Charging Station for Indian Cities

In this work, simulation has been carried out for multipass Gas tungsten Arc Welding of SS316L and their effects were studied for thermal and residual stresses and compared with experimental results. The sequentially coupled thermo-mechanical, transient thermal and static structural analysis was modelled using ANSYS with relevant Ansys Parametric Design Language coding. Infrared thermography camera was used to obtain the real time temperatures during the welding. The effect of temperatures and the induced residual stresses of the weldment is measured with X-Ray diffraction technique. Tensile residual stresses have been identified at fusion zone and compressive stresses at heat affected zone. Pass wise temperature measurements were taken from analysis and experiment the agreement with 7.24%. The agreement of measured and analysed residual stress had an agreement with 16.66%.

Analysis of thermal stresses and its effect in the multipass welding process of SS316L

The analysis of the Permanent Magnet Synchronous Machine, especially with the high power density and more efficient cooling system is of great practical significance to lower greenhouse gas, to lessen climate change. This paper gives a detailed review of advanced cooling methods and applications to the permanent magnet synchronous motors, as well as presents experimental and analytical analyses of the cooling methods and design problems for permanent magnet synchronous motors applications. The main authors' claims and objectives focus on water jacket cooling methods and their requirements of efficient permanent magnet synchronous motors cooling system. Also, the water-cooling system with cryogenic, Potting silicon gelatine (PSG) and phase change materials (PCM) methods are identified investigated. First, the different heat sources are and the various temperature effects together with their influences on the permanent magnet synchronous motors performances are studied. The main part of the work includes an evolution overview of the water-cooling methods with thermal-performance analysis. Also, the PMSM temperature control main benefits are investigated and some unsolved problems regarding optimal motor cooling model design are commented on. Finally, recent advances in the permanent magnet synchronous motors cooling methods and future scope are presented.

Sadhana - Academy Proceedings in Engineering Sciences

Water cooling, PSG, PCM, Cryogenic cooling strategies and thermal analysis (experimental and analytical) of a Permanent Magnet Synchronous Motor: a review

This paper presents convective heat transfer characteristics of liquid-liquid horizontal pipe flow. Experiments are carried out in a stainless-steel pipe of diameter 1.59 cm with L/D ratio of 377. Three different oils with varying properties (viscosity: 630 mPa-s, 202 mPa-s and 1.95 mPa-s and density: 919 kg/m3, 901 kg/m3 and 790 kg/m3 respectively) are employed as oil phase and the other fluid phase being water. The experiments are conducted for four oil-water flow patterns-stratified flow, stratified flow with droplets at the interface, dispersed oil-in-water and dispersed water-in-oil with fluid fractions ranging 0 to 1 at different fluid velocities. A constant temperature heat supply, using jacketed hot water flowing over the test pipe, is maintained. The analysis of heat transfer experiments indicates that the heat transfer process in liquid-liquid flow depends on the same dimensionless terms, the Reynolds number and the Prandtl number, that signifies single-phase flow heat transfer. Accordingly, it is found that the established and existing single-phase heat transfer correlations, modified according to flow regime, flow pattern and fluid flow and thermal properties, are also applicable for liquid-liquid flow. The heat transfer in liquid-liquid flow found to be influenced by the fluid fraction. Effectively, for stratified flow, the heat transfer in the liquid-liquid flow is the sum of heat transfer of the individual fluid phases. However, for dispersed flow, the presence of additional fluid phase is incorporated by employing the effective Reynolds number and effective Prandtl number. Using this methodology, more than 85% of stratified flow and 92% of dispersed flow heat transfer characteristics are predicted within ±20% of experimental data. © 2021 Elsevier B.V.

Journal of Petroleum Science and Engineering

Predictive correlations for heat transfer characteristics of oil-water horizontal pipe flow-an experimental study

Solar energy is clean, renewable, abundant and free. The light and heat energy can be harnessed by using several technologies such as solar heating, photovoltaic cell and photosynthesis. Solar collectors are used for collecting solar thermal energy by heating and reheating a stream of water. This paper focuses on improving performance of solar flat plate collector using twisted tape. Flat plate collectors have a wide range of usage in industrial, public as well as residential sectors. Solar water heaters are environment-friendly, cheap to operate and need very little when compared with other solar applications. Many researchers are working to enhance the thermal efficiency of solar water heaters. The thermal efficiency enhancement can be done by modification of design of parts of solar flat plate collector such as absorber plate, STs, working fluid, thermal insulation, efficiency of fin and selective coating of an absorber plate. Use of twisted tape is an efficient method to increase the thermal efficiency by increasing the heat transfer by increasing the contact surface area between the water and metal tubes (inserted tape tubes) and also by promoting turbulence of flow. © Springer Nature Singapore Pte Ltd 2021.

Lecture Notes in Mechanical Engineering

Analysis of thermal efficiency of solar flat plate collector using twisted tape

Buildings contribute greatly to global energy use and consumption. The energy consumption of buildings is significant due to the integration of heating, ventilation, and cooling systems. Evidently, the utilization of phase change materials (PCMs) in building design can adequately reduce air-conditioning costs of buildings by diminishing external heat gains and losses. Moreover, the adoption of natural, eco-friendly, and cost-effective materials, such as terracotta bricks, can be valuable from an environmental point of view. This paper intends to assess the air-conditioning cost-saving potential of several PCM stuffed terracotta brick configurations. In that respect, the encapsulated PCMs were filled in the hollows of terracotta bricks. For the aims of this study, five different types of PCMs were considered, in relation to the thermophysical properties of their solid and liquid state (OM18: Organic mixture, HS22: Hydrated salt, OM29, OM32, and OM37). In addition, three PCM-stuffed terracotta brick configurations were examined with reference to the number of the PCM layers (PCMTB-A with one PCM layer, PCMTB-B with two PCM layers, and PCMTB-C with three PCM layers). Therefore, fifteen PCM-stuffed terracotta brick configurations were analysed numerically, related to environmental conditions that refer to two different scenarios in India (hot dry and composite climates). Results have unveiled that the OM32 PCM assemblies have shown better thermoeconomic performance compared to the other types of PCM. With respect to the most advantageous number of PCM layers, the evidence of this analysis has exposed that the PCMTB-C case has shown the highest annual air-conditioning cost-savings and the highest yearly carbon emission mitigations in both climates (Ahmedabad and Lucknow). In hot-dry climates, the PCMTB-C with OM32 PCM exhibited the highest annual air-conditioning cost-saving ($ 74.7), the highest annual carbon emission mitigation (1.43 ton/kWh), and the moderate payback period (22.5 years) compared to the other cases. To conclude, the findings of this study suggest a suitable way to improve the decision-making process of building design, while bridging the performance gap in terms of energy efficiency and sustainability. © 2021 A. Chelliah et al.

Advances in Civil Engineering

Thermal Behaviour Analysis and Cost-Saving Opportunities of PCM-Integrated Terracotta Brick Buildings

This paper gives a comprehensive review of advanced cooling schemes and their applications to the permanent magnet synchronous motors (PMSMs), as well as investigating the electrical motor’s topologies its thermal design issues, materials and performances. Particularly, the electromagnetic and electric performances, machine sizing, together with the structural design, are given. In addition, the work addresses the motor’s material design and properties along with its insulation performance, which is the main goal of optimization. Mainly, thermal mapping with analysis is provided according to the different cooling methods, including air-cooling, water-cooling, oil-cooling, heat-pipe-cooling, potting silicon gelatin cooling, and as well as cooling strategies for tubes and microchannels. The most common special features and demands of the PMSMs are described in the appearance of the motor’s failures caused by uncontrolled temperature rise. In addition, heat sources and energy losses, including copper loss, core loss versus motor speed, and output power, are analyzed. The review of the proposed cooling methods that will achieve the required heat transfer of the PMSM is presented with numerical simulations and measurements data. A review of numerical methods and results, including the finite element methods (FEM), such as the Ansys CFD software, to obtain a high-accuracy thermal mapping model of the PMSM system is given. The revived methods and design requirements due to PMSM temperature profile and cooling flow at different rotor speeds and torque loads are investigated. Finally, the motor design recommendations, including the newly developed cooling solutions, which enable it to effectively redistribute the temperature and heat transfer, increasing the efficiency of the PMSM machine, are laid out. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/ 4.0/).

Department of Energy and Power Electronics

School of Electrical Engineering

Energies

Thermal mapping of a high-speed electric motor used for traction applications and analysis of various cooling methods⇔a review

Evaluating the improvement in efficiency and heat transfer rate in heat exchangers using additives has been the centre of attraction for many researchers. In this study, a solar flat plate water heater is modelled using ANSYS Fluent, and the simulated results are compared with experimental data. For the simulation, a single-phase model is used with equivalent correlations for the thermo-physical properties of the nanofluid. Using water as the working fluid, the performance was evaluated for a set flow rate and solar insolation. The study is extended by modelling the same in ANSYS Fluent and using water and CuNP mixture as working fluid to analyse the enhancement of heat transfer in thermal absorbers. The pressure drop in the system is analysed and the data is used to justify the usage of nanoparticles in solar thermal absorbers. The efficiency of the system for various volume fractions of nanoparticles is optimized by introducing an efficiency index. © 2021, Springer Nature Singapore Pte Ltd.