IRJET- Modelling and Optimization of Heat Transfer Coefficients for Hot and Cold Sides of Thermoelec

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International Research Journal of Engineering and Technology (IRJET) Volume: 06 Issue: 08 | Aug 2019

www.irjet.net

e-ISSN: 2395-0056 p-ISSN: 2395-0072

Modelling and Optimization of Heat Transfer Coefficients for Hot and Cold Sides of Thermoelectric Generator (TEG) system R. Elankovan1, S. Suresh2, K Karthick3 123 Department

of Mechanical Engineering, National Institute of Technology, Tiruchirappalli, Tamil Nadu, India.

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Abstract – The race for exploring alternative energy source to replace the dependency of fossil fuels based energy is gaining significant attention due to the rise of global warming and other emission issues. Thermoelectric generator (TEG) is emerging as a promising member in alternative energy sources to restrict the consumption of fossil fuel for some extent. The advent of TEG to recover waste heat is a momentous in industrial applications. However, the thermal system of TEG for heat recovery applications need to be optimized to make it a viable option. This paper presents the impact of heat transfer coefficients (HTC) on the performance of TEG through simulation works carried out in ANSYS 17®. The impact of HTC on the hot side and cold side temperature of TEG couple is studied by varying heat source and heat sink temperatures for optimizing the performance of TEG. The results presented shows that the voltage and temperature difference will be higher with increase in cold side HTC rather than increasing hot side HTC. The percentage difference in voltage as well as for temperature is same for a set of hot side and cold side heat transfer coefficient. The maximum power output is generated for each heat transfer coefficient at a matched load resistivity of 0.00015 Ωm. In this study, the power output reaches saturation with increase in hot side heat transfer coefficient while the cold side heat transfer coefficient is approximately 50 times higher than that of hot side heat transfer coefficient. The drop in the voltage and difference in temperature also increases with increase in heat source temperature and heat sink temperature. Keywords: Thermal System Configuration, Heat Transfer Coefficient, Heat Source and Sink Temperature and Thermo electric generator (TEG)

1.INTRODUCTION The requisite for development of alternative energy sources to reduce the fossil fuel consumption has attained topmost priority to reduce the impact of emission of fossil fuel. The sole dependency of fossil fuel for power generation over the years has resulted in global warming, ozone depletion and other environmental degradation issues. The above said problem is the challenge for which there is an exorbitant rise of research interest is seen in the field of renewable energy over the last few years. At this context TEG acts as a promising member in the field of energy recovery. Although

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TEGs performance is greatly restricted due to less conversion efficiency, TEG continues to dominate in the field of waste heat recovery. Research suggests that 60% of the total energy is wasted in the form of heat which is in the form of low grade heat energy [1]. The application of TEG in converting waste heat into power output has gained attention all over the world and the research interest in this field has increased significantly over the last three decades. A thermoelectric generator (TEG) is a solid-state device, which can directly convert heat into electricity which is based on the discovery of Seebeck effect by which temperature difference is directly converted into heat. The heat to electricity conversion has an efficiency of less than 5% [2-3]. Therefore, the concern on improving the conversion efficiency of TEG is vital to use it as a viable tool to recover waste heat. The dominance of TEG on par with other sources of energy lies in the utilization of costless waste heat as energy input which makes it suitable for applications which are not affected by its low conversion efficiency [4]. The various applications of TEG range from recovering waste heat from fossil fuel fired boilers, automobile exhaust [5-9] to industrial operations such as biomass boiler [10], small scale pellet boiler [11], cement plants, marine waste incinerator [12], refineries, glass manufacturing, and foundries. Other areas of implementation include wood burning stoves [13], geothermal sites, solar salt ponds and solar concentrators [14]. The ill effects of fossil fuel burning can be mitigated and minimized to an extent by the effective introduction of the thermoelectric generators. The reliability of the thermoelectric effect in the electrification of waste heat has been validated by experiments conducted for different industrial process. The literature in the past indicates that the power output from TEG is directly proportional to the temperature difference between the hot and cold faces of the TEG. In a TEG thermal configuration system, the hot and cold face temperatures depend on the heat transfer coefficients on the respective sides. This paper emphasis the impact of variation in heat transfer coefficients on hot and cold sides of TEG through simulation using ANSYS 17® multi-physics software.

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