Thermoelectric Generators for Automotive Waste Heat Recovery Systems Part I: Numerical Modeling and Baseline Model Analysis

Abstract

A numerical model has been developed to simulate coupled thermal and
electrical energy transfer processes in a thermoelectric generator (TEG)
designed for automotive waste heat recovery systems. This model is capable
of computing the overall heat transferred, the electrical power output, and
the associated pressure drop for given inlet conditions of the exhaust gas and
the available TEG volume. Multiple-filled skutterudites and conventional
bismuth telluride are considered for thermoelectric modules (TEMs) for
conversion of waste heat from exhaust into usable electrical power. Heat
transfer between the hot exhaust gas and the hot side of the TEMs is
enhanced with the use of a plate-fin heat exchanger integrated within the
TEG and using liquid coolant on the cold side. The TEG is discretized along
the exhaust flow direction using a finite-volume method. Each control volume
is modeled as a thermal resistance network which consists of integrated
submodels including a heat exchanger and a thermoelectric device. The
pressure drop along the TEG is calculated using standard pressure loss
correlations and viscous drag models. The model is validated to preserve
global energy balances and is applied to analyze a prototype TEG with data
provided by General Motors. Detailed results are provided for local and
global heat transfer and electric power generation. In the companion
paper, the model is then applied to consider various TEG topologies using
skutterudite and bismuth telluride TEMs.