THERMAL DESIGN OF AUTOMOBILE EXHAUST-BASED THERMOELECTRIC GENERATORS:OBJECTIVES AND CHALLENGES

摘要

The potential for thermoelectric power generation via waste heat recovery onboard automobilesto displace alternators and/or provide additional charging to a vehicle battery pack has increasedwith recent advances in thermoelectric materials processing. In gasoline fueled vehicles (GFVs),about 40% of the fuel energy is wasted in the exhaust heat [1], while a smaller amount of energy(30%) is rejected through the engine coolant. Therefore, exhaust-based thermoelectric generators(ETEG) have been in focus for GFVs applications since the late 1980s. Conversion efficiency ofmodern thermoelectric materials has increased more than three times in the last two decades [2] ;however, the disputes in thermal design of ETEG systems kept their overall efficiency at limitedinsufficient values. There are many challenges in thermal design of ETEG systems, represented inincreasing the efficiency of the heat exchangers (hot box and cold plate), maintaining sufficienttemperature difference across the TEMs during different operating conditions, and reducingthermal losses through the system as a whole. This paper is focused on reviewing the main aspectsof the thermal design of ETEG systems through the different investigations performed over thepast fifteen years. This paper is organized as follows: the construction of a typical ETEG is firstdescribed. The heat balance and efficiency of ETEG are then discussed. The third section of thispaper emphasizes the main objectives and challenges for designing efficient ETEG systems.Finally, a review of ETEG research activities through the last fifteen years is presented to focuson the methods used by research community to address such challenges.