Calculation of Efficiency and Power Output by Considering Different Realistic Prospects for Recovering Heat from Automobile using Thermoelectric Generator

Abstract

In this work, we are developing the theoretical prototype and improving the technique for installing the Thermoelectric Generator (TEG) set up in automobiles. We have considered a linear curve fit from a zigzag curve of reported mass flow rate and temperature variation at the hot gas inlet. Accordingly, the temperature of the coolant is also varied linearly at the inlet from 300 K to 320 K and corresponding the mass flow rate of coolant. Circular fin is installed around each circular layer of Thermoelectric Materials (TEM) after the water jacket. The heat loss through each fin is calculated as 24 W. Energy balance is done at each and every TEM and correspondingly calculated the amount of power transferred through each segment of TEG as 32 W. We have calculated the length of TEM sample for attaining the respective temperature range for the hybrid of $Bi_2Te_3$ and $TiO_{1.1}$. This calculation is done by considering the compatibility factor derived as $s =\frac{\sqrt{1+ ZT}-1}{\alpha T}$ which is a ratio of current density to conduction heat flux. The length obtained for this particular combination is $\sim$8 mm. To this end, we have reported the efficiency with respect to mass flow rate of hot flue gas from the automobile for different layers of TEG for the above-mentioned combination. Here, we have explored the possibility of installing a number of different layers TEG module which can be installed throughout the lateral surface area of exhaust chamber. Thermal mismatching criteria are also discussed at the adjoining surface of TEM because of high temperature. To maintain the thermal expansion or contraction of TEM, spring and bolt arrangement is provided, which is fixed over the aluminium oxide ceramic substrate. For automobile, if temperature of source is considered as 800 K, so for the temperature range of 300 K to 800 K the ideal power output is obtained as 58 W.