Analysis And Management Of Output Characteristics Of Thermoelectric Generator Based On Different Heat Transfer Boundary Conditions

Along with the large-scale use of fossil fuels,a large amount of waste heat resource accompanying with the gas and liquid dissipates to the surrounding environment.If this waste energy can be recovered effectively,it will greatly improve energy utilization efficiency.Thermoelectric power generation technology can convert heat into electricity and be applied in recovering different grade waste heat.In comparison to other waste heat recovery methods,thermoelectric power generation technology is especially recognized in that it is noiseless and reliable.However,the low conversion efficiency of thermoelectric generator(TEG)restricts its further application.Based on this background,this paper analyzed the output characteristics of TEG module by experimental analysis and numerical simulation.The influence of the Peltier effect on the output characteristics of TEG module was explored.The output performance of TEG module at different heat exchange boundaries was analyzed.In addition,the Maximum power point tracking(MPPT)technology was applied to manage the output energy of TEG module.The specific research contents of this paper are as follows:(1)In order to explore the influence of Peltier effect on the output performance of TEG under the fixed heat transfer boundary conditions,an experimental system was set up.In the experiment,the hot side of TEG was heated by a thermostatic heater which can keep the heating temperature constant,and the cold side was cooled through the convective heat transfer with water.The effect of cooling water flow rate on the open-circuit voltage was first analyzed and the optimum cooling water flow rate was confirmed.Furthermore,the influence of Peltier effect on the cold side temperature and output performance of TEG was investigated.The result showed that Peltier effect resulted in the less actual output power than the theoretical value and made the maximum power point deviate from the point where the load resistance equaled the internal resistance.The deviation value increased with the increase of hot side temperature of TEG module.(2)The finite element simulation software was used to investigate the boundary temperature distribution and output characteristics of TEG module under the third boundary condition.A simplified model of heat transfer of fins was established to calculate the equivalent heat transfer coefficient corresponding to different fin heights.Under the third boundary condition,the temperature of ceramics at both sides of the TEG module was uneven,and the nonuniformity of temperature increased with the increase of heat transfer coefficient.When both sides were convective heat transfer,the hot side temperature decreased and cold side temperature increased with the increase of current,which resulted in that effective temperature difference decreased with the current increasing.Under the same conditions,the enhancement of the cold side heat transfer was more beneficial to improve the output characteristics of TEG module.(3)The numerical simulation of TEG module output power management with the assistance of the MPPT technology was carried out.The models of TEG module connecting to the load resistance directly and the model of TEG module connecting to the load resistance through MPPT controller were built respectively.The influence of MPPT controller on the output voltage,current,power and efficiency of TEG module was analyzed.In addition,the direct connection was only suitable when the load resistance was near the internal resistance of TEG module,and the MPPT controller was more efficient for the load resistance far from the internal resistance of TEG,and the latter make TEG operate at maximum power point although it caused a little power loss.