Design And Research On Heat Source Adapted To Microminiature Semiconductor Thermoelectric Generator With Combustion

Modern military equipments are changing into this direction: more electroniclize, miniaturization and invisible, and the demands for smaller generators are increasing. Currently, the most common military power generation equipment is mainly composed of diesel generators, gasoline generators, fuel cells, batteries and other components. Micro Electro Mechanical System(MEMS) is in the frontiers of scientific research, and it has great potential value in many fields, such as MAV(Micro Air Vehicles),UAVs(Micro-Unmanned Aerial Vehicles), portable energy(the battery systems of portable computer, mobile phones, GPS receivers), the future war(meet the goal of Land Warrior System battery weight), at the same time as for energy density characteristics , it is also 20~30 times better than the current best battery systems . The demand for micro-power with small size, light weight and long life is due to the appearance of micro-electronic mechanical system.Because of the development of the semiconductor thermoelectric generation materials and the superiority of thermal energy devices, military generator using semiconductor thermoelectric generation system attain more and more attention. As for the small-sized chamber of semiconductor thermoelectric generation, the energy is utilized by the way of flame combustion. Within the scope of the same diameter of flameout, the gas will not burn out, and the heat taken out from the combustion chamber is limited, so it causes the combustion heat too centralized in the combustion chamber inside, and it makes the temperature distribution non-uniform. And then creat new problem: firstly, the generation power using semiconductor materials is unstable; secondly, the internal temperature gradient of semiconductor material is too large, and the corresponding, thermal stress is large, so the life-span is lower. Moreover, due to temperature extreme point, it will directly burn semiconductor materials, the fuel needs to be reduced, but at the same time, generation efficiency and power are decreased, and burning also loses stability.The paper is based on the Swiss-roll model which is studied by Li Junwei and Zhong Beijing. In the paper, in order to acquire the heat structure which is suitable for the thermoelectric generation material, the structure of single combustion chamber and multi combustion chamber was designed. Then we used computational fluid dynamics software FLUENT to simulate the 2d and 3d micro-combustion of the mixture of gas and air in various models. The contents of this paper are divided into the following section:1. Based on the characteristics of micro combustor, the right physical model and mathematical calculation method were needed, including control equations, chemical reaction kinetics, material transfer theory, numerical algorithms and reasonable boundary conditions, and then the initial ideas and the specific implementation ways about the mutative pipe structure of single-chamber and multi chamber were proposed.2. Based on this thinking, four structure assumptions about the inlet and outlet of single chamber were made. Theoretical basis of the heat source could be used to set a premixed gas flow conditions and the same boundary conditions, then conclused the appropriate model. Meanwhile, studied the equivalence ratio and the range of this model, compared the temperature field and internal heat transfer traits with non-mutative pipe. According to the structure assumption of multi-chamber, simulated the four combustors. Then the comparison of the temperature uniformity was also performed between non-mutative pipe and mutative pipe, meanwhile found that: based on the changed passage, the temperature field of four combustors was more even than the single one.3. With more practical factors, 3d model was applied to the burner of single combustion chamber. According to different flow velocities, we made the numerical simulation for the 3d model. As a result, we found that in the same case of heat transfer coefficient, the scope of security combustion exited 3d model which is different from 2d plane.4. Tried two kinds of methods for the fabrication of burners, and finally selected CNC engraving as an appropriate way. Then set up the experiment rig and proceeded the debugging of the test.