Experimental Study On Thermoelectric Module Performance Based On LNG Cold Energy Power Generation

Natural gas is attracting widespread attention as a transitional energy between green renewable energy and polluting traditional fossil fuels.Liquefied natural gas（LNG）is a common natural gas transportation method,and the regasification process releases a large amount of cold energy,which needs to be recycled.Thermoelectric generators（TEG）have the advantages of no noise,no vibration,small size,long life,etc.The combination of thermoelectric power generation technology and cold energy recovery can effectively solve the complex system and inability to flexibly respond to natural gas when thermal cycle is used for cold energy power generation.supply fluctuations.The performance of the thermoelectric module mainly depends on the thermoelectric material,and different thermoelectric materials have their own optimal operating temperature range.Due to the lack of commercial thermoelectric materials for low temperature conditions,when using existing thermoelectric modules for cold energy power generation,the physical parameters of the thermoelectric modules under low temperature conditions are needed as a basis.Therefore,it is necessary to study the physical parameters and power generation performance of existing thermoelectric modules in different temperature ranges.Since the change of thermal resistance of each part in the thermoelectric module is not clear,the temperature difference between the cold and hot ends of the pn junction cannot be accurately measured.This paper designs and builds a thermoelectric module performance test system in two temperature ranges,low temperature and normal temperature.The thermal resistance of each part of the TEG is measured through experiments,and the temperature of the cold and hot ends of the pn junction is obtained by means of the thermal resistance network analysis method.Combined with the measurement results of the open circuit voltage,output voltage,and current of the thermoelectric module,the physical parameters（Seebeck coefficient,thermal conductivity,electrical conductivity and figure of merit）of the thermoelectric module in the low temperature and normal temperature range are calculated,as well as the output characteristics（output power,efficiency）.（1）Four kinds of thermoelectricity of No.1（TEHP1-12656-0.3,Bi₂Te₃）,No.2（KTGM161-18,Bi₂Te₃）,No.3（TEC1-12706,Pb Te）and No.4（TEC1-12706,Bi₂Te₃）were measured experimentally Low temperature physical properties of the module.From the results,as the temperature decreases,their Seebeck coefficients decrease rapidly,and the Seebeck coefficients of modules 1,2,and 4 decrease from124.6～206.48μV/K to 49.3～70.9μV/K;Reduced from 207.31μV/K to 92.66μV/K.With the decrease of temperature,the thermal conductivity of modules 1,3,and 4 all increased,from 0.404 to 0.72 W/m K to 0.551 to 1.08 W/m K;the thermal conductivity of module 2 decreased from 0.384 W/m K to 0.314 W/m K.The conductivity of all four modules increases with decreasing temperature.The measurement results of the output power and efficiency of No.1～4 modules at low temperature show that the output characteristics of No.2 module are the best,the maximum output power can reach0.0195 W,and the efficiency can reach 0.45%.（2）The performance parameters of four types of thermoelectric modules in the normal temperature range were measured.It can be seen from the results that in the temperature range of 290-340 K,the Seebeck coefficients of modules 1,2 and 4decrease from 279.75～333.46μV/K to 202.05～309.09μV/K as the temperature decreases;The coefficient is reduced from 285.14μV/K to 258.37μV/K.As the temperature decreases,the thermal conductivity of the four modules increases,from0.3～0.51 W/m K to 0.33～0.62 W/m K.The measurement results of the output power and efficiency of the four modules in the normal temperature range show that the No.1module has the best output characteristics at low temperature,the maximum output power can reach 0.021 W,and the efficiency can reach 0.365%.