Experimental and simulated thermal resistance of thermogalvanic cells with triply periodic minimal surface structures

Abstract

Buildings release an abundance of waste heat that is left unused. Thermogalvanic cells (TGCs) can take advantage of waste heat to generate electricity with a low temperature gradient. Application of Triply Periodic Minimal Surface (TPMS) structures allow TGCs to potentially be used as building components for construction. TPMS in TGCs increase thermal resistance and the magnitude of increase varies by the type of TPMS used. Natural convection effects are one of the driving forces in TGCs, and those effects can be controlled with the use of TPMS structures while at the same time allowing the electrochemical process to occur. In this study, we ran multiple experiments for the TGCs with the Split P, Schwarz P, Gyroid, and IWP TPMS structures. Split P consistently gave relatively higher thermal resistances (0.012m−2KW) because of its higher surface area/volume ratio which effectively increased the temperature difference across the cell. The TGC containing the IWP structure had the least thermal resistance because of a low surface area as well as having large void spaces which increased heat transfer across the TGC. Furthermore, we simulated the thermal transport of the TGC containing the Schwarz P structure. By using the Boussinesq approximation, we were able to capture natural convection effects in our CFD simulations. The deviation of the ΔT from the experiment and simulation was due to the placement of the thermocouples at the top side of the electrode. This means that the measured electrode temperatures were overestimated since the warmer fluid was always present at the top while the simulated electrode temperature was calculated by taking the mean temperature of the electrode. The simulated thermal resistance matched the experimental values when the temperature was taken from the top sides of the electrodes, and was found to be 0.007 ±0.001m−2KW.