Integrating Phase Change Materials into automotive Thermoelectric Generators :An experimental examination and analysis of energetic potential through numerical simulation

Abstract

The heat exhausted by conventional combustion-engine vehicles during actual operation has shown highly transient properties. Therefore, automotive thermoelectric generators (TEG) are geared towards a particular operating state (design point). This, however, leads to two issues. Firstly, whenever the combustion engine runs at low load, the maximum operating temperature cannot be properly utilised, and secondly, a combustion engine at high load requires partial diversion of exhaust gas away from the TEG in order to protect the thermoelectric modules. One attractive means of homogenizing dynamic exhaust behaviour (thereby keeping the TEGs operating status at the design point as long as possible) is the use of latent heat storage, also known as phase change materials (PCM). By positioning PCM between module and exhaust heat conduit and choosing a material with a phase change temperature matching the module’s optimal operating temperature, it can be used as heat storage. This paper presents the results found during the institute’s examination of the influence of latent heat storage integration on the potential of automotive TEG to convert exhaust heat. The research resulted in the development of a concept based on the initial integration idea, followed by a proof of functionality through use of a specially created prototype. Additionally, the potential of energy gained by a PCM-equipped TEG was calculated. The simulations indicated a significant increase of the gained electrical energy in the selected test cycle.