Effects of Module Spatial Distribution on the Energy Efficiency and Electrical Output of Automotive Thermoelectric Generators

Ivan Ruiz Cózar,Lino Montoro,Samir Ezzitouni,Albert Massaguer,Martí Comamala,Toni Pujol,Jose Ramon González,Eduard Massaguer

doi:10.3390/en14082232

Ivan Ruiz Cózar, Lino Montoro + Show 6 more

Open Access

https://doi.org/10.3390/en14082232

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Journal: Energies	Publication Date: Apr 16, 2021
Citations: 5	License type: CC BY 4.0

Affiliation: University of Girona, University of Castilla-La Mancha

Abstract

Automotive thermoelectric generators (ATEGs) are devices used to harvest waste energy from the exhaust gases of internal combustion engines. An ATEG is essentially formed by three main elements: (1) heat absorber in contact with exhaust gases; (2) thermoelectric modules that directly convert heat into electricity; (3) heat sink to increase the heat transfer through the system. Thermoelectric modules (TEM) are commonly based on small-scale commercial units, with tenths of them needed to assemble a full ATEG device. Thus, several thermal and electrical connections between TEMs can be implemented. Previous studies focused on the implications on the output power. Here, we investigated the effects of using different module connections on the energy efficiency and on the electrical outputs (voltage and current). The study was carried out numerically with ATEGs that used from 4 to 100 individual TEMs. Series, parallel and square connections were investigated under two different engine operating points. The maximum output power was obtained with overall energy conversion efficiencies on the order of 3%. Though the series connection provided the highest output power, the square configuration was the best compromise between output power and electrical characteristics (voltage and current) to successfully integrate the ATEG into the vehicle management system.

Highlights

The shift towards an electrified mobility will imply the coexistence of transportation modes based on different powertrains
The numerical model was based on GT-SUITE software from Gamma Technologies [22]. This multi-physics CAE system has been successfully applied in a wide variety of studies focused on the exhaust gases of internal combustion engines, including those involving waste heat recovery systems such as organic Rankine cycles [23], turbocompounding [24] and Automotive thermoelectric generators (ATEGs) [25]
We carried out the same procedure as that developed in Cózar et al [15], who defined the ATEG as a set of submodels each one corresponding to an individual Thermoelectric modules (TEM)

Summary

Introduction

The shift towards an electrified mobility will imply the coexistence of transportation modes based on different powertrains. In the mid-term, the long-distance road transport of goods will continue relying on vehicles with internal combustion engines [1]. Several calls of the European Union funding programmes have tackled different aspects involved in the issue of green mobility of road vehicles [2]. It is well known that approximately 1/3 of the fuel primary energy employed in internal combustion engines is lost through the exhaust gases [3]. Commercial thermoelectric generator modules (TEMs) consist of pairs of n-type and p-type semiconductor legs electrically connected in series and thermally in parallel. A single TEM of dimensions 40 × 40 × 3.5 mm may contain on the order of 100 legs, being able to generate < 10 W with a 240 Wm−2 heat flux and an overall energy efficiency below 5% (see, e.g., [4])

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