Modelling transient states of thermoelectric systems

The paper deals with simulations of transient states of systems equipped with thermoelectric modules. Such a system is described analytically taking account of thermal resistance of the contact layers and the thermal capacity of the heat exchangers. The model was implemented in an in-house software that enables a comprehensive analysis of the performance of thermoelectric systems. The developed software was validated based on the results of experimental tests conducted using commercially available thermoelectric modules on a dedicated test bench and own measurement approach. The calculations carried out demonstrated how the performance of thermoelectric processes can be influenced in cooling work conditions by the supply current and the leg height, where both parameters were optimized to achieve the minimum cooling temperature, in the steady and transient states. Additionally, an effect of a change in the thermal capacity of the upper heat exchanger on the energy recovered under transient conditions was presented. Next, to reach the preset level of generated electric power at the system cold start-up, an optimization leading to shortening the heating process by 27% was proposed. Optimization showed that results considering contact thermal resistance led to the cooling temperature about 17% higher by 38% higher leg and slightly lower current.