Review and Trends of Thermoelectric Generator Heat Recovery in Automotive Applications

Automotive vehicles with internal combustion engines, such as conventional gasoline and electric hybrid vehicles, exhibit inherent irreversibilities that hinder them from achieving high efficiencies. These irreversibilities manifest themselves in the form of thermal losses in the engine and contribute to the total energy consumption in the transportation sector. Waste heat recovery is a method to increase the overall fuel efficiency of vehicles by recovering thermal energy that would be lost from the engine to the environment and converting it to useful energy for the vehicle. In the past years, thermoelectric generators have been intensively investigated for waste heat recovery in vehicles because they are solid-state devices that convert heat directly into electricity and hence have no moving parts, operate quietly, are relatively small, and require low maintenance. This paper presents a review of the literature on waste heat recovery in vehicles through the implementation of thermoelectric generators. First, potential sources or locations in a vehicle for waste heat recovery are presented. Second, the available thermoelectric technology for vehicle applications is reviewed. Then, the components required to create a waste heat recovery system are discussed. The approach for modeling thermoelectric generators to predict the power output is then considered. Finally, experimental investigations by researchers are presented as well as the future trends observed for waste recovery via thermoelectrics.