Research On Thermoelectric Device And Its Application In Waste Heat Collection Of Iron And Steel Works

With the expansion of the world population and the continuous development of science and technology,the contradiction between the development and utilization of energy and environmental protection has become increasingly prominent.Therefore,the development of new energy and energy-saving technology is the key to break through the current energy problem.Thermoelectric power generation is a kind of clean power generation method,which transforms low-grade heat sources such as industrial waste heat and exhaust heat into electric energy.In recent years,it has been highly concerned by many scholars.However,there are still some problems such as low efficiency of thermoelectric conversion,unstable operation of array system and easy damage of components.In this paper,based on the application of thermoelectric power generation system in steel production line,theoretical and practical research is carried out to solve the practical problems of low power generation efficiency and unstable system power output in the application process of thermoelectric power generation system.Firstly,the thermoelectric generator(TEG)is theoretically analyzed from the perspective of thermal power and external electrical characteristics.Based on the equivalent model of the thermoelectric generator,the preconditions for the operation of the thermoelectric generator at the maximum power point are derived.On this basis,the traditional MPPT method is improved,and a new MPPT method is proposed.Compared with the traditional short-circuit current MPPT method,this method does not need to disconnect the temperature difference chip from the main circuit,saving energy and reducing the risk of converter failure.Besides,there is no problem of TEG output power oscillation and static error.The short-circuit current can be calculated only by collecting the inductive current and processing the sampling data.The effective value of the inductive current is controlled at 1 / 2 of the short-circuit current by PI controller,and then the maximum power point tracking is realized.The simulation and experimental results show that the maximum power point tracking method proposed in this paper can effectively track the maximum power point,and the control algorithm is simple and reliable,which can effectively improve the overall efficiency of the system.The array system of thermoelectric power generation is the key to the large-scale application of thermoelectric generation,and also the future development direction of thermoelectric power generation.This paper analyzes the basic electrical characteristics and power mismatch of TGA,the characteristics of system output power reduction,and draws a conclusion that the power characteristics of TGA are complex,multi peak,low efficiency and so on under the condition of uneven local temperature distribution.In view of the electrical characteristics of the branch of the thermoelectric generation system,this paper proposes a power compensation method of the thermoelectric generation array based on the series controlled voltage source of the branch.Through the step-down compensation of the system output voltage to the array branch,each branch can run at the maximum power point to improve the overall output power of the thermoelectric generation system.The simulation results show that the proposed power compensation scheme is feasible,effective and has high practical value.In order to study the thermoelectric generation system better,this paper designs a highpower thermoelectric generation platform,whose full load output power can reach 900 W.At the same time,a set of thermoelectric generation system is designed and tested in a steel plant.The test results show that the system can be used in the industrial production site and can fully collect waste heat to convert it into electrical energy and incorporate it into the plant power grid.It is of great significance for the promotion and application of thermoelectric generation system.