Hongji Zhu

This paper focuses on the problem of thermoelectric cooler waste heat recovery and utilization, and proposes taking the waste heat together with the original heat source as the input heat source of the integrated thermoelectric generation–cooling system. By establishing an analytic model of this integrated thermoelectric generation–cooling system, the steady-state and transient thermal effects of this system are analyzed. The steady-state analysis results show that the thermoelectric generator’s actual heat source is about 20% larger than the intrinsic heat source. The transient analysis results prove that the current of thermoelectric power generation and the cold end temperature of the system show a nonlinear change rate with time. The cold end temperature of the system has a maximum value. Under different intrinsic heat sources, this maximum value can be reached between 1 s and 2.5 s.

In complex flight conditions, due to the large amount of unusable heat generated by aerodynamic heating, the thermal protection system of an aircraft needs to withstand a large temperature shock, which brings great challenges to the design of the structure. In order to effectively utilize the irregular aerodynamic heat, and improve structural heat conduction, a composite structure is formed by using phase change energy storage materials on the basis of the thermoelectric structure, which transforms the aerodynamic waste heat into stable electric energy for the internal system. Through the study of the response of nonlinear transient energy, it is found that the thermoelectric and mechanical properties of the new structure can be improved by adding phase change energy storage materials. Under actual flight conditions, the new structure can reduce the maximum temperature by 180 K and the maximum thermal stress by 110 Mpa. The mechanical properties of the structure are effectively improved, the service life of the structure is prolonged, and the waste heat can be converted into stable electrical energy output to improve the thermoelectric output performance. On the premise of ensuring conversion efficiency, the output power of the new structure has been improved by 64.8% through structural optimization under actual flight conditions.

Phase change material (PCM) is an excellent heat storage material which can absorb a large amount of heat in the form of latent heat and can be used to improve the power generation effect of thermoelectric generator (TEG) in a fluctuating thermal environment. The thermal conductivity of PCM plays a key role. In this paper, graphene films as thermal conductive fillers were introduced into graphene foams through the ice-templated method. The composite structure can increase the thermal conductivity of paraffin by 44 times to 11.594 W/mK, and the corresponding mass fraction is only 1.14 wt%. On the other hand, the influence of thermal conductivity of PCM on TEG under periodic heat flux condition was analyzed through simulation. The results indicate that increasing thermal conductivity helps the PCM to better play a buffering effect, and significantly reduce the fluctuation of the power generation voltage.