Abstract :
[en] The Building integrated with phase change material (PCM) creates a large thermal barrier between the indoor thermal environment and the ambient, usually resulting in an overheating problem in summer. Dynamic insulation system (DIS) based on airflow is introduced into PCM to form a composite structure featured with switchable thermal resistance to address this issue. The theoretical model is built according to the phase transition of PCM and heat transfer between PCM and flowing air. The result indicates that thermal resistance can be modified by natural convection and forced turbulence of air. Forced turbulence case obtains the lowest thermal resistance, orderly followed by natural convection and closed cases. Temperature and phase change contour indicate that turbulent air enables to the promotion of uniformity of temperature and phase transition distribution. The larger H/L ratio and height of the PCM cavity inducing more intensive air flow are favorable to heat transfer between air and PCM. A DIS-PCM module with a low flowing rate or large inputted heat flux produces a rapid heat transfer rate and early PCM melting. The Built DIS-PCM module is then coupled with the multilayer hollow wall component to investigate potential applications in relieving building overheating issues. The lower average temperature of the interior wall and higher heat dissipation rate from the indoor thermal environment verify that the DIS-PCM module enables to resolve of building overheating under constant or variable ambient temperature, even at slight temperature differences between indoor and ambient temperatures. Indoor thermal comfortable temperature can be accurately adjusted according to the air-flowing rate. In conclusion, the novel DIS-PCM system eliminates building overheating issues through its thermal resistance switch in response to various working scenarios, with substantial benefits to the development of latent heat thermal energy storage available for building energy conservation.
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