Inger Palsgaard Bach

Irreversible transfer processes of thermoelectric generators

We discuss a novel tool based on heat flow diagrams for analyzing irreversible processes associated with thermoelectric devices and discuss some ambiguous descriptions and errors in related investigations. We consider thermoelectric generators as a paradigm of a heat engine cycle and determine the heat flow distribution by treating the one-dimensional heat transfer differential equation. Representative heat flow diagrams are used to study the influence of internal and external irreversible processes of heat conduction and Joule heat generation.

Transient Behavior Study of Thermoelectric Generators through an Electro-thermal Model Using SPICE

A thermoelectric generator (TEG) usually works in dynamic operating conditions due to the time change, in real applications, of the electric load and hot or cold temperatures. Thus understanding transient thermal and electrical behavior of the device, besides the steady-state behavior, is important in order to investigate the global device performance. The major objective of this work is to describe the transient behavior of TEG operating in high temperature environments through a SPICE model based on an electrothermal analogy. The SPICE model presented is derived from a one dimensional (1-D) heat transfer differential equation. An important feature of the model is its ability to calculate the temperature profile taking the real temperature dependence of the materials properties into account. This feature is essential in simulating TEG exposed to a large temperature difference. In combination with considering the finite heat transfer rate at the interface between TEG and thermal ambient, the model is able to reflect the thermo-electric coupled multi-field system effect of TEG. A test rig is developed for verifying the proposed model. Commercially available TEG is tested with respect to stabilizing time under sharply changed electric load. The preliminary results of experiments and modeling are analyzed. It is expected that the model presented can assist, not only in the optimal design of TEG itself, but also in the evaluation of the whole energy system

Multi-physics simulation of thermoelectric generators through numerically modeling

The governing equations taken from the assumption of local equilibrium and the heat transfer rate form of Onsager flux have been compared with those based on classical heat transfer formulation by a simplified one dimensional (1-D) thermoelectric generator (TEG) model. In this paper, the simulation of coupled multi-physics effects in a TEG is realized in a three dimensional (3-D) way, based on the heat transfer formulation, through finite-difference numerical method and PSPICE computational tool. The feature to take the real temperature dependence of the materials properties into account is included in the computation.