Thermal performance of ceiling radiant cooling panel with a segmented and concave surface: Laboratory analysis

Radiant heating/cooling systems are thermally efficient and economically feasible alternatives to conventional ventilated air conditioning. This study experimentally investigates the thermal performance of the ceiling radiant cooling panel (CRCP) with a segmented and concave surface by evaluating the thermal conditions inside a laboratory-scale room equipped with this new panel. The experiments were carried out under various operating conditions, where the fluid inlet temperature and fluid flow rate were controlled independently. The indoor air temperature, air velocity, and humidity ratio were recorded and analyzed, and the temperatures of the upper and lower panel surfaces and the surrounding surfaces were also measured. Subsequently, the heat transfer properties were calculated and summarized. When the inlet water temperature decreased from 24 degrees C to 15 degrees C at the same flow rate of 4 L/min, the average air temperature decreased by over 1.5 degrees C, and the total heat flux increased by 50%. The heat flux changed significantly with variations in the inlet water temperature, while changing the flow rate had a smaller impact. The radiant heat transfer coefficient of the panel was determined to be 5.0 W/(m2.K), while the convective heat transfer coefficient exhibited an exponential relationship with the temperature difference between the surface of the panel and the surrounding air. Moreover, the proposed panel enhanced the convective heat flux by 2.6 times and the total heat flux by 45%, compared with a flat panel, and achieve the same improvement as the panel with inclined fins, but with a smaller surface area. In addition, the panel achieved the same air temperature with a lower flow rate, which shows the potential for energy saving.

Automated summary

Research shows that the ceiling radiant cooling panel with a segmented and concave surface performs well in terms of thermal efficiency in a laboratory-scale room, as lowering the inlet water temperature can effectively reduce the average air temperature and increase the total heat flux. The heat flux of the panel varies significantly with changes in inlet water temperature, while changes in flow rate have a smaller impact.