The Analysis of Heat Exchangers Geometry in Thermoelectric Generators for Waste Heat Utilization

Abstract

The paper presents results of the analysis and comparison of the hot-side heat exchangers (HHXs) dedicated for the thermoelectric generators (TEGs). Efficient operation of TEG depends on, i.a. proper design of the HHX. Six geometries of the heat exchangers’ cross-section have been investigated and analysed in view of heat transfer effectiveness (ηTH) and pressure drop (ΔP). As an assumption, useful heat exchange surface has been set up as 2400 cm2, maintaining heat exchanger (HX) length as 30 cm, which is enough for the placement of the 32 thermoelectric modules able to generate at least 160 W of the electrical power. The source of waste heat are flue gases, in the analysis approximate as an air. Cold-side heat exchanger (CHX) has been simplified and calculated as a water flow around the casing of the HHX to achieve comparable results. As a base, circular profile has been presented. Numerical calculations provide results suggesting which shape is most suitable for specified application. Results could be the first guidelines for selecting and designing the HX for the TEG. Further investigation will focus on optimization of the chosen HX in view of increasing ηTH and minimizing ΔP.