Experimental investigation of thermal performance of a heating system combining solar air collector with hollow ventilated interior wall

Abstract

A novel heating system combining solar air collector with hollow ventilated interior wall (SAC-HVIW) has the ability to supply thermal energy for the nighttime heating and improve the nighttime thermal comfort in residential buildings on Tibetan Plateau. In this paper, a test chamber is constructed to investigate the heating performance of this system. Nine cases with different ventilation rates and supply air temperatures in the channel are measured under steady-state conditions. Results show that the heating capacity of the hollow ventilated interior wall increases with the logarithmic mean temperature difference (LMTD). U-value of the interior wall changes smoothly with the ventilation rate and the LMTD of the system, but the effectiveness of the interior wall almost keeps constant for all cases with the mean value of 0.85. The radiant heat transfer coefficient of the hollow ventilated interior wall keeps the constant of 5.43 W/(m2•K), whereas the convective heat transfer coefficient increases smoothly with the ventilation rate and the inlet air temperature. Radiant heat transfer is dominant with the weight of more than 60%. Experimental data are used to evaluate the heating performance of HVIW, and it is also beneficial to the design of this system.