Development and validation of thermal performances in a novel thermoelectric generator model for automotive waste heat recovery systems

Abstract

Integrated thermoelectric generators (TEGs) and heat exchangers (HEX) can transform heat into electrical power by converting temperature gradients between heat sources and cold sinks. Predicting TEG thermal performances with compact HEX is crucial to designing efficient TEGs for automotive waste heat recovery. However, previous investigations mainly concentrated on TEG electrical performance, neglecting the thermal performances under high Reynolds numbers (Re) of exhaust gasses. This study utilizes the model-based development (MBD) method to develop a novel 1D TEG model, focusing heat transfer coefficient α and pressure drop ΔP inside a louvered corrugated fin HEX, component temperatures, and boundary heat flux, which affect electrical power from thermoelectric modules (TEM). The performance data are measured from 36 tests under different fin pitches Fp = 1.0 - 2.0 mm, Re = 4,000–14,000, and inlet gas conditions. Two methods are used to develop the model using user-defined functions (UDFs) for friction coefficient Cf and α, accounting for actual fin geometries. In Method 1, UDF multipliers for each Fp are required to calibrate the TEG model. In Method 2, simplified UDFs for Cf and α are implemented. Method 1 shows that the model is well-calibrated with maximum average relative errors δa< 6.7% but requires model fitting for each Fp. The fast-predictive TEG model with the novel calibration Method 2 can reproduce the thermal and electrical performances with δa< 20% without model tuning, which can be used for TEG redesign and integrated into vehicle-level MBD with a conventional and electrified powertrain, leveraging a fast driving-cycle simulation.