Effects of Design Parameters on Fuel Economy and Output Power in an Automotive Thermoelectric Generator

Abstract

The need for more sustainable mobility promoted research into the use of waste heat to reduce emissions and fuel consumption. As such, thermoelectric generation is a promising technique thanks to its robustness and simplicity. Automotive thermoelectric generators (ATEGs) are installed in the tailpipe and convert heat directly into electricity. Previous works on ATEGs mainly focused on extracting the maximum amount of electrical power. However, the back pressure caused by the ATEG heavily influences fuel consumption. Here, an ATEG numerical model was first validated with experimental data and then applied to investigate the effects that modifying the main ATEG design parameters had on both fuel economy and output power. The cooling flow rate and the geometrical dimensions of the heat exchanger on the hot side and the cold side of the ATEG were varied. The design that produced the maximum output power differed from that which maximized fuel economy. Back pressure was the most limiting factor in attaining fuel savings. Back pressure values lower than 5 mbar led to a < 0.2% increase in fuel consumption. In the ATEG design analyzed here, the generation of electrical output power reduced fuel consumption by a maximum of 0.5%.

NOx Emissions below the Prospective EURO VII Limit on a Retrofitted Heavy-Duty Vehicle

“…These systems can convert waste heat, downstream of the after-treatment system, into electricity, and store it into a battery for later use. Many theoretical models [11,[31][32][33][34] and experimental prototypes [12,[35][36][37][38] have been developed which demonstrate the feasibility of this idea. Other authors have studied the use of ATEGs in heavy duty engines with a power production up to 1kW [39][40][41].…”

Experimental study of the potential for thermal energy recovery with thermoelectric devices in low displacement diesel engines

“…Recently, several studies focused on the heat recovery potential of TEGs implemented in commercial and heavy-duty vehicles [27,28,29]. Studies discussing the application of TEGs focus on the influence of operational variables like the temperature of the surface s and the pressure drop, other aspects like the heat exchanger materials, or the characteristics of TEMs, on the overall conversion efficiency of TEGs [30,31]. Accordingly, Liu et al [32] discussed the flow distribution effects on temperature gradient and performance metrics of the heat exchanger.…”

Electrical Modelling and Mismatch Effects of Thermoelectric Modules on Performance of a Thermoelectric Generator for Energy Recovery in Diesel Exhaust Systems

“…Some recent works have managed to reduce this trend [26][27][28][29][30], but these have not been validated under realistic working temperatures inherent to a TEG working for a light-duty vehicle. Cózar et al [29] stated that there is an optimum number of TEMs from which an increase of the number of TEMs diminishes the power output.…”