压水堆核电厂温差发电模块热电特性耦合分析

[Background] The thermoelectric power generation technology is effective at utilizing low-grade heat. Recovery of waste heat from the Pressurized Water Reactor (PWR) nuclear power plant (NPP) using the thermoelectric generators can save energy and protect the ecological environment of the surrounding ocean. [Purpose] This study aims to propose a simplified model of the thermoelectric generator and carry out the coupling analysis of the power generator module in PWR NPP. [Methods] Firstly, based on COMSOL code, a single Thermoelectric Generator Model (TEG) model was established to carry out the 3D numerical simulation. The structured mesh generated by the sweep method was used to obtain the temperature and potential contours of the single TEG model. The complex single TEG model was reduced to a thin plate with one type of material so as to reduce the computing resources required for the multi-physics coupling calculation. The formula for calculating the equivalent thermal conductivity of the reduced model was derived. Thereafter, the numerical simulation under multiple temperature differences was carried out by using the original model for the single TEG to obtain the relation of the output power, the equivalent thermal conductivity and the temperature of the hot side and the cold side. These results in the form of discrete points were processed by the bilinear interpolation method. The reduced model was implemented in FLUENT through the user-defined function (UDF). The model of the thermoelectric generator module with typical structure consisted of hot-side water, hot channel wall, cold-side water, cold channel wall and 22 TEGs was established, and numerical simulation of this model was carried out using FLUENT. Subsequently, the computational domain included multiple regions of 2 fluid domains and 22 solid domains, and the unstructured mesh was used for the fluid domains to represent the hot-side water and cold-side water. Finally, the structured mesh was used for the solid domains with regular geometry, which was beneficial to reduce the mesh number and improve the mesh quality, and the sensitivity analysis was performed on the influence of hot-side fluid parameters on the output power. [Results] Results of thermal-electric coupling analysis of the single TEG show that the thermal-electric coupling analysis of the single TEG is carried out. The temperature drop is mainly concentrated on the semiconductor materials. When the temperature difference between the hot side and the cold side is 200 K, the calculated voltage is 3.884 8 V. The result fits well with the reference value, which validates the applicability of this model. The coupling analysis of the thermoelectric generator module is carried out. The temperature distribution and the total output power are obtained by simulation. When the temperature difference between the inlets of hot-side water and cold-side water is 173.15 K, the total output power of the 20 TEGs is 108.66 W. The output power is positively correlated with the temperature and velocity of the hot-side fluid. [Conclusions] The simplified model of the single TEG in this study is applicable to the coupling simulation for the thermoelectric generator module utilizing the heat source from the PWR NPP, providing reference for the utilization of waste heat in NPP using other type of reactor and the design of thermoelectric generator modules.