Transient cooling characteristics of radiant cooling tiles under airflow variations in dual-evaporator refrigeration system

: This work focuses on the design of cooling tiles integrated with a domestic refrigerator to efficiently deliver thermal comfort within an enclosed space. An auxiliary evaporator cools water stored in an insulated tank, which is subsequently circulated through heat exchangers embedded in the tiles. The system achieves space cooling predominantly through radiant heat transfer, supplemented by overhead air supply and warm air extraction. Experimental investigations were conducted under varying operating durations and air velocities to evaluate key performance metrics, including coefficient of performance (COP), heat transfer rate, temperature distribution, humidity, and energy consumption. The results indicate a temperature reduction of 10°C across the tiles and 6.4 °C within the cooling space for the velocity of air equal to 8 m/s. The measured system COP, refrigeration COP, heat transfer rate, and energy consumption were 5.77, 3.44, 514.56 W, and 100 W, respectively. Rise in the velocity of air enhanced the rate of heat transfer and COP ratio by 276.47% and 46.07%, without compromising the performance of the domestic refrigeration unit when adapted to a dual-evaporator configuration. Furthermore, it was observed that extending the operating time from 50 to 60 minutes enabled the system to approach steady state conditions. The optimization analysis indicates that the cooling space temperature is maintained within the thermal comfort zone, the experimental duration is curtailed by 38.33%, and a 25% reduction in air velocity engenders a 7% decrease in energy consumption. Overall, it was found that system was able to achieve the steady state conditions. system approaches a quasi-steady state, with only very minor residual temperature variations in the final phase of operation