Performance analysis of liquid-flow-window with submerged heat exchanger

Abstract

Liquid-filled glazing with submerged heat exchanger is a kind of building integrated solar thermal collector making full use of the transparent façade surface. This novel glazing is capable of preheating domestic water and reducing heat transmission to the indoor space, thus contributes to energy saving of the hot water system and the air-conditioning system. Dynamic thermal model of the glazing system has been developed by assuming uniform temperature and cellular flow in the window cavity. In this study, CFD analysis was employed to verify the assumed liquid flow pattern and temperature distribution. Then parametric study was carried out to assess the impact of several key influencing factors, including glass material, feed water flow rate, and cavity thickness on the thermal performance. The investigation supported an appropriate cavity thickness of 10 mm and feed water flow rate of 1000 ml/min per m2 glazed surface area for effective thermal performance. The use of two absorptive glass panes in the double-glazing gives the best thermal efficiency and electricity saving. The thermal performance of this new design was also compared with the buoyant-flow window design based on typical summer and winter conditions of Hong Kong. The results indicate its superiority and significance in green building development.