Design And Optimization Of The Thermoelectric Generator For Utilizing Dissipated Heat From An Aluminum Reduction Cell's Sidewalls

The aluminum reduction cell is the main equipment for aluminum production in industry, which consumes direct electricity as much as 13000kWh for each ton of aluminum. Therefore, it makes sense to study the method to reduce the energy consumption of aluminum reduction cell. In this paper, a thermoelectric generator using heat dissipated from the sides of an aluminum reduction cell was designed to reduce its energy consumption. The device is quiet with simple structure, small size, light weight, long life, high reliability, no mechanical moving parts and no pollution; moreover, it requires low heat source temperature. So it is suitable for recycling the low-grade heat sources and has wide application prospects.In this paper, major work and achievements are so follows:(1) By considering the thermal contact resistance and electrical contact resistance of the ceramic sheet and the deflector plate, a correlation for the thermoelectric generator's output power, conversion efficiency and temperature difference was proposed, and the temperature difference between the two sides of semiconductor galvanic arms was also calculated. This relationship provides a foundation for optimizating output power and conversion efficiency.(2) The load corresponding to the maximum output power was calculated, and it is not equal to but is a bit greater than the internal resistance. The increase of the load resistance caused the decrease of the loop current and the Peltier effect, which increased the effective heat flux through the thermoelectric generator and the temperature difference and its gradient.(3) The numerical simulation and experiments of the thermoelectric generator were carried out and were compared with the calculation results. The calculated output power agreed well with the numerical and experimental results, revealing the variation of internal resistances and neglect of heat loss have little effect on the results. The calculated and numerical conversion efficiencies are close, but the experimental results were greater than both of them after the peak value. The irreversible heat loss and the error caused by physical parameter of materials varing with temperature is neglected so that the calculated output power was smaller than its true value.(4) The feasibility of application of the thermoelectric generation to the aluminium electrolysis process was examined through calculating the dissipated heat and testing the heat flux and temperature of the aluminum cell's sidewalls. Thermoelectric generators were designed and fabricated according to the structure of the aluminum cell and the requirement of the thermoelectric generation. The output power and conversion efficiency of the thermoelectric generators were tested, and the results indicate that the thermoelectric generators for each aluminum cell can convert 3000W heat energy to the electric power which accounts for about 5.2% in the total dissipated heat from the aluminum cell's sidewall, and the generators can output electric power 25 kWh per ton aluminum.