Abstract
Waste heat recovery using a thermoelectric generator (TEG) is a promising approach for vehicle original equipment manufacturers to reduce fuel consumption and lower CO2 emissions. A TEG can convert otherwise wasted thermal energy from engines to electricity directly for use in the vehicle systems. This paper focuses on the development of a dynamic model of TEG system designed for vehicle waste heat recovery, which is made up of counter-flow heat exchangers (HXRs) and commercial thermoelectric modules (TEMs). The model is built from thermoelectric materials into a TEM and then into a TEG system. Compared to other TEG models, the tuning and validation process of the proposed model is more complete. Experiments are done on both a TEM test rig and a heavy-duty diesel engine, which is equipped with a prototype TEG on the exhaust gas recirculation (EGR) path. Simulations of steady-state operating points as well as the response to typical engine cycle test show good agreement with experimental data.A TEG installed upstream of the after-treatment system in a heavy-duty truck has been modelled to predict the temperatures and power output in a dynamic driving cycle. The simulation results of temperatures show the model can be used as a basis to develop a control system for dynamic operation to ensure safety operation of TEG and efficient operation of the after-treatment system. A comparison of power output of the systems under different scenarios underlines the importance of integration of TEM with HXRs. Based on the simulation results, around 20% average power output increase can be expected by optimizing the thermal contact conductance and the heat transfer coefficient of hot side HXR.
Highlights
Driven by CO2 legislation and fuel cost, car original equipment manufacturers have emphasised the efficiency of the engine and drivetrain
This paper focuses on the development of a dynamic model of thermoelectric generator (TEG) system designed for vehicle waste heat recovery, which is made up of counter-flow heat exchangers (HXRs) and commercial thermoelectric modules (TEMs)
This dynamic model serves two major purposes: performance prediction and as a basis for developing temperature control strategies. These two applications are presented. To fully present these two application, the validated TEG model is integrated with other exhaust system components in the model of a heavy duty engine with the TEG model located upstream of the aftertreatment system
Summary
Driven by CO2 legislation and fuel cost, car original equipment manufacturers have emphasised the efficiency of the engine and drivetrain. For the typical energy flow path of an internal combustion engine (ICE), approximately one third of the energy is discharged by exhaust gas. Interest in waste-heat recovery (WHR) has flourished in recent years [1,2,3,4]. Thermoelectric generator (TEG), as one of the WHR methods, has attracted substantial interest because of its advantages of silent operation and compactness. The performance of current TEG systems is largely decided by the thermoelectric modules (TEMs). Significant strides have been made in the materials of TEMs and recent work is beginning to translate those material improvements into TEG performance [4]
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