Abstract
Structure and heat losses of an evacuated flat-plate type solar collector are discussed in this study. High performance and light weight are features of the collector. Heat losses from the absorber plate to the glass cover and the rear plate were measured and examined under several low pressure conditions from 2.5 to 10^5Pa. The measured result shows that the plateau range in the continuum region between 10^2 and 4×10^4Pa. From the result, the inside pressure level lower than 10^4 Pa is required for the proper operation of the flat-plate collector. Thermal efficiency of the evacuated flat-plate collector was calculated. The compared result indicates that the performance of the evacuated flat-plate collector is higher than that of the evacuated tube type collector in range of ΔT/q_<sun><0.14Km^2/W.
