Design And Thermal Performance Analysis Of Solar Water Heating System With Heat Pipe Evacuated Tube And Flat Plate Collector In Lanzhou Area

With the development of social industrialization,China's economy is growing rapidly.However,our country's economy grows rapidly at the cost of the massive consumption of fossil power and air pollution.Because our country's economy is highly dependent on the high energy consumption industry,energy shortage and environmental pollution have become a serious obstacle to Chinese economic development and improvement.At present,building energy consumption has reached more than 30% of the total energy consumption in the whole society.Therefore,various sectors of society should pay more attention to the development and utilization of new energy in the building.Among them,the more mature and more common application of new energy combined with building technology is the solar water heating technology.It has been widely studied and applied in the field of building energy saving.Solar collector is an important apparatus for solar energy absorption and conversion.The thermal performance of the solar collector plays a key role in the solar water heating system.In this paper,the flat plate collector and the heat pipe evacuated tube collector as the solar collector,numerical study and comparative analysis of thermal performance of solar water heating system in Lanzhou are performed.The main research contents and results are as follows:1.In this paper,the numerical model is established by TRNSYS software based on the experiments of heat pipe evacuated tube and flat plate collector solar water heating system.The experiments were done by Ayompe et al.in Dublin,Ireland.Comparing the numerical results of the collector outlet temperature,heat gain of collector,heat gain of storage tank with experimental data,it is found that the obtained results are in good agreement with experimental data.Therefore,the simulation is correct and numerical study on the practical application of solar water heating system can be carried out.2.Using TRNSYS software to build two numerical simulation models of solar water heating system of a residential villa in Lanzhou.For two types of solar water heating system,heat pipe evacuated tube collector and flat plate collector is used as solar collector,respectively.Meanwhile,two sets of solar water heating systems are indirect forced circulation water heating system are used in the same project under the same weather conditions in Lanzhou.The receiving solar radiation,effective heat gain,solar fraction and system efficiency of two types of solar water heating system are obtained by dynamic simulations.The results show that the solar fractions of two types of solar water heating system are between 20%~70%,and the efficiencies of two systems are between 20%~60%.Regardless of the weather conditon is under high solar radiation intensity or low solar radiation intensity,the solar fraction and the system efficiency of the heat pipe evacuated tube collector water heating system are higher than those of the flat plate collector water heating system.It is also found that the heat pipe evavuated tube collector is more resistant to the external environment than the flat plate collector and the energy conversion ability of heat pipe evavuated tube collector is higher than that of flat plate collector.