Journal of the Korean Solar Energy Society ISSN:1598-6411(Print) 2508-3562(Online) 한국태양에너지학회 논문집

Considering the values acquired from thermal bridge performance indicators developed based on a design stage may differ from the actual thermal bridge performance values, it is essential to quantitatively assess their performance in-situ. When the surface temperature of the internal walls of a thermal bridge is measured in-situ to evaluate the performance, a time delay is observed in the transfer of the effect of external conditions to the internal surfaces. The shape of the thermal bridge components exhibit either 2D or 3D boundary conditions, and hence, multiple time lags can occur depending on the surface condition of the thermal bridge, which affects the accuracy of the performance of thermal bridges during evaluations in-situ. Therefore, in this study, we analyzed the effect of time lag of the thermal bridge components on the thermal bridge performance using heat transfer simulations. It was observed that the relative error was approximately 25.35% with an average of 9.22% as compared to the steady-state thermal bridge. Furthermore, the approximate time lag values of each component surface were calculated based on their surface temperatures. As a result, the time lag difference between the thermal and non-thermal bridge components was approximately 10 h and 30 min, respectively. On eliminating the time lag difference from all surfaces of the thermal bridge components using the calculated time lag, the relative error decreased to 19.97% with an average of 7.69%, as compared to the steady-state thermal bridge. Therefore, the relative error increased by 1.53% with an average of approximately 5.40%, owing to the time lag of the thermal bridge.