Thermal performance of two heat exchangers for thermoelectric generators

W Li,M.C Paul,J Siviter,A Montecucco,A.R Knox,T Sweet,G Min,H Baig,T.K Mallick,G Han,D.H Gregory,F Azough,R Freer

doi:10.1016/j.csite.2016.06.008

Abstract

The thermal performance of a heat exchanger is important for the potential application in an integrated solar cell/module and thermoelectric generator (TEG) system. Usually, the thermal performance of a heat exchanger for TEGs is analysed by using 1D heat conduction theory which ignores the detailed phenomena associated with thermo-hydraulics. In this paper, thermal and momentum transports in two different heat exchangers are simulated by means of a steady-state, 3D turbulent flow k-ε model with a heat conduction module under various flow rates. In order to simulate the actual working conditions of the heat exchangers, a hot block with an electric heater is included in the model. The TEG module is simplified by using a 1D heat conduction theory, so its thermal performance is equivalent to a real TEG. Natural convection effects on the outside surfaces of the computational domains are considered. Computational models and methods used are validated under transient thermal and electrical experimental conditions of a TEG. The two heat exchangers designed in this paper have better thermal performance than an existing heat exchanger for TEGs. More importantly, the fin heat exchanger is more compact and efficient than the tube heat exchanger.

Highlights

The thermal performance of a heat exchanger is important for the potential application in an integrated solar cell/module and thermoelectric generator (TEG) system
A plate heat exchanger with undulated surfaces was optimized with a computational fluid dynamics (CFD) package, ANSYS CFX 10.0, as well as with a response surface method conducted by Kanaris et al [5]
A tetrahedral mesh is generated in the solid domains of the heat exchanger and the hot block as well as in the fluid domains, a hexahedral mesh is created in the solid domain of the TEG

Summary

Introduction

The thermal performance of a heat exchanger is important for the potential application in an integrated solar cell/module and thermoelectric generator (TEG) system. For the spiral heat exchanger, experiments were carried out to confirm the analytical temperature difference across the TEG module at varying water flow rate As evidenced, this 1D simulation method may provide useful information but clearly ignores the effects associated with combined thermal and hydraulic occurrences within systems. A plate heat exchanger with undulated surfaces was optimized with a CFD package, ANSYS CFX 10.0, as well as with a response surface method conducted by Kanaris et al [5] Their chosen computational model was a 3D narrowed channel with inclined triangular undulations in herringbone pattern. Elliptical finned-tube heat exchanger thermal-hydraulic performance was optimized by using Fluent and response surface method based on seven design variables proposed by Sun and Zhang [7]. The cooling oil flow rate is assumed to be distributed uniformly from one finned cannel to another

Methods

Results

Discussion

Conclusion