The Representative Thermal Conductivity of Wickless Heat Pipes in a Thermoelectric Generator Module Design via Computational Numerical Analysis

Abstract

Thermoelectric generator (TEG) cells are capable of producing electricity from the flow of heat through semiconductor materials via the Seebeck effect. A TEG module (TEM) was developed through the integration of TEG cells, heat pipes, and heat sinks with the function to recover low-temperature waste heat for combined heat and power outputs. The mechanics of heat transport through the components have a distinctive impact on overall performance. Wickless heat pipes were used in the design, and it is difficult to directly evaluate the convection heat transfer coefficient within the heat pipes. Computational numerical analysis usually simplifies the heat pipe by modelling it as a solid copper pipe, where the thermal conductivity of the pipe replaces the actual value of heat transfer coefficient. To determine the representative thermal conductivity of the wickless heat pipe, a computational numerical model of the TEM was developed. Experiment data of the TEM operation, where the cold-side air inlet temperature inlet was at 20.7°C while the hot-side waste heat inlet temperature was at 70.0°C, was used to validate the computational model. The representative thermal conductivity value for the wickless heat pipe was found to be 500 W/m.K, at which the percentage difference for the hot-side and cold-side TEG surface temperatures, and the TEG surface temperature differences were below 5%. The approach has been proven suitable to analyse the representative heat pipe thermal conductivity for simplified thermoelectric generator modules.