Experimental Research On Heat Pipe Flat-Plate Solar Collector With Insulating Glazing Cover

The flat-plate solar collector has got global attention for its high thermal efficiency, low price and facilitating to integrate with buildings. It takes account about 95% share of solar collector market in the world with an exception of China. However, its spreading and application are being affected to a certain extent for its poor performance in anti-freezing in China. Poor performance in anti-freezing has become the main factors on spreading and application of the flat-plate collector. Solving the problem of its poor performance in anti-freezing is favorable for the development of solar energy development in China, especially in northern cold areas.Instead of using usual flat absorber, the heat pipe collector uses heat pipe flat absorber, which enhances its performance in anti-freezing. This paper mainly studies the differences between the heat pipe flat-plate solar collector with insulating glass cover and the usual flat-plate solar collector with heat exchanger and insulating glass cover through comparing experiments. This paper can provide reference for the application possibility of heat pipe flat-plate solar collector in cold area.This paper introduces the relevant knowledge about gravity heat pipe and builds the mathematic models of the heat pipe flat-plate solar collector with insulating glass cover and the usual flat-plate solar collector with heat exchanger and insulating glass cover. Particularly, this paper derivates the formulas of integrated absorption rate for the glasses and absorbers in both single-glass-absorber system and double-glazing-absorber system by strict theoretical deduction.In order to study the heat collecting performance of heat pipe flat-plate solar collector with insulating glazing cover, this paper tests the working performance of the heat collecting system in typical weather conditions, gets the performance data of transient efficiency and daily average efficiency, draws the curves, and compare the heat collecting performance between the heat pipe flat-plate solar collector with insulating glass cover and the usual flat-plate solar collector with heat exchanger and insulating glass cover. The results show that heat pipe flat- plate solar collector has a lower heat collecting performance, and its daily average efficiency is low within 3%. So it draws a conclusion that heat pipe flat-plate solar collector can be used in northern cold area. This paper also gives the main methods of improving the performance of heat pipe flat-plate collector.