TY - JOUR

T1 - Experimental Investigation of Coupled Transport Mechanisms in a PEM Based Thermoelectric Energy Converter

AU - Willke, Maike

AU - Rahm, Nils Eric

AU - Kabelac, Stephan

N1 - Funding Information: The authors gratefully acknowledge the financial support by the Deutsche Forschungsgemeinschaft (project no. 449554201).

PY - 2023/7/17

Y1 - 2023/7/17

N2 - Thermoelectric energy converters based on galvanic cells (TGC) offer the possibility of direct conversion of low-temperature waste heat into electrical energy and could therefore be a promising approach for an increase in the overall efficiency of energy conversion. Due to an externally applied heat source, a temperature gradient across the electrolyte is induced, leading to a gradient in the chemical potential of the species and an electrical potential difference between the electrodes. The aim of approaching an internal equilibrium state leads to various coupled molecular transport mechanisms taking place in the electrolyte, impacting the open circuit voltage (OCV) and the performance of the TGC. By applying the theory of non-equilibrium thermodynamics (NET) to describe these coupled processes, the interactions that occur can be characterized in more detail. In this work, a polymer electrolyte membrane (PEM)-based TGC with two H2/H2O electrodes of different temperatures and gas compositions is experimentally investigated. By controlling the gradients in temperature and concentration, different impacts on the resulting OCV can be identified. In addition, we present the measured coupling coefficient, representing the singular relation between the transport of the hydrogen ions inside the membrane and the electrical potential difference between the electrodes for a wide variety of working conditions.

AB - Thermoelectric energy converters based on galvanic cells (TGC) offer the possibility of direct conversion of low-temperature waste heat into electrical energy and could therefore be a promising approach for an increase in the overall efficiency of energy conversion. Due to an externally applied heat source, a temperature gradient across the electrolyte is induced, leading to a gradient in the chemical potential of the species and an electrical potential difference between the electrodes. The aim of approaching an internal equilibrium state leads to various coupled molecular transport mechanisms taking place in the electrolyte, impacting the open circuit voltage (OCV) and the performance of the TGC. By applying the theory of non-equilibrium thermodynamics (NET) to describe these coupled processes, the interactions that occur can be characterized in more detail. In this work, a polymer electrolyte membrane (PEM)-based TGC with two H2/H2O electrodes of different temperatures and gas compositions is experimentally investigated. By controlling the gradients in temperature and concentration, different impacts on the resulting OCV can be identified. In addition, we present the measured coupling coefficient, representing the singular relation between the transport of the hydrogen ions inside the membrane and the electrical potential difference between the electrodes for a wide variety of working conditions.

KW - coupled molecular transport mechanisms

KW - energy conversion

KW - non-equilibrium thermodynamics

KW - polymer electrolyte membrane

KW - thermogalvanic cell

UR - http://www.scopus.com/inward/record.url?scp=85166172776&partnerID=8YFLogxK

U2 - 10.3390/en16145434

DO - 10.3390/en16145434

M3 - Article

AN - SCOPUS:85166172776

VL - 16

JO - ENERGIES

JF - ENERGIES

SN - 1996-1073

IS - 14

M1 - 5434

ER -