Study Of A Novel Solar Energy Device Combing Thermoelectric Chips With Heat Pipe Evacuated Tube

As an efficient,clean, non-pollution new energy source, all over the world has paid more attention to the development and utilization of solar energy now,many government have included it into the national energy development plan.The photo-thermal transformation application is the commonest,the maturest among all kinds of solar energy utilization, products of photo-thermal conversion are diverse in market.Solar water heater is the most important and effective utilization,due to the low cost,it is widelyused in our country.Especially,vacuum tube solar water heaters account for approximate95%in our market,their structure is simple,their price is inexpensive and they can obtain high efficiency relatively at low ambient temperature;They have better insulation effect,high pressure-bearing capacity,resistance to freezing and speed to start.The temperature of heat-pipe vacuum tube collector can be high,it may obtain excessive heat water in full solar irradiation,the water can not be fully utilized which result in a waste of energy.So we combine thermoelectric chips with heat-pipe vacuum solar collector,we can generate electricity and get heat water simultaneously using seebeck effect.It can be easily assembled,so as a small thermoelectric generator, there are many similar new applications continuing to emerge.In this paper,an experimental platform of new solar energy utilization which combine heat-pipe vacuum tube with thermoelectric chips is designed and manufactured,the theoretical analysis and experimental research are carried out.Through programs calculating,we can make simulation to mathematical model of the generator.the impact of external load,outdoor environment temperature,outdoor wind speed and water velocity to system are analyzed.The external load should be larger than internal load when device achieve the maximum output power.When the irradiation of1000w/m2,the maximum instantaneous electrical efficiency is3.2%,the simulation results show that the outdoor wind speed and ambient temperature have little effect on the electrical properties,the water velocity of lower header has obvious effect on the electrical properties,because the heat of thermoelectric chips cold junction can be taken away quickly,so the cold junction temperature can not be high.the data analysis about actual weather data in HeFei indicate that the maximum temperature difference is175℃at noon,the maximum instantaneous power efficiency is2.8%at this time.The experiment test of the performance of this system have been done.In generating mode,the maximum open circuit voltage is22V when the temperature difference of thermoelectric is110℃.The system have the maximum output power when the load resistance is about25Ω.When the day’s average temperature difference of thermoelectric is80℃,the theoretical temperature difference is88℃,the average generation efficiency of the experimental system is1.2%,the theoretical electrical efficiency is1.3%and thermal efficiency is39%in the same time.The thermal efficiency is47%in heating priority mode,in other word,the higher part to generating mode is used to generate electricity. Meanwhile the day thermal efficiency of the system which does not contain thermoelectric chips is about53%.