Sensitivity study of heat-pipe-ring embedded building façade for solar absorption

Abstract

Solar thermal utilization is a promising way for building energy conservation, especially by integrating with the building façade in a large area. Studies on the solar-absorbing façade have been made continuously through innovative and integrative technologies. The metallic module with the embedded heat pipe ring (HPR) array is newly proposed to work as the building-integrated solar thermal collector for water preheating and to prevent thermal transmission to indoor space simultaneously. Besides, this façade module can meet the aesthetic requirement of modern buildings and avoid the risk of being frozen. The study aims to investigate the implications of its major operating and design parameters on energy performance using a validated numerical model. In particular, the effects of feed water flow rate, absorber coating, and front glazing on the proposed façade panel are analyzed systematically via steady-state and dynamic simulations in this sensitivity study. It is found that increasing the feedwater flow improves thermal efficiency and therefore the electricity-saving in hot water supply, yet with diminishing return; and a feedwater flow of 4000 ml/min per m2 front surface area is recommended for both glazed and unglazed designs. At a favorable water flow rate, the selective coating and glass cover options are not beneficial for vertical HPR modules in five climate zones of China. For sloped arrangement, the tilted façade module with inclination angle close to the local latitude as the norm is again appropriate.