Cooling performance evaluation of a novel radiant ceiling panel containing phase change material (PCM)

This study analysed the behaviour and cooling performance of a novel ceiling panel with macro- encapsulated phase change material (PCM) and active discharge under different cooling loads. Unlike other constructions, the investigated panel features a pipe profile embedded and in direct contact with a thin PCM layer. A method to address modelling constraints was presented, aiding the development of alternative panel constructions. A model of the panel was validated and used to study the impact of various design parameters, namely supply water temperature, flow rate, and water circulation control, on the cooling performance. A design chart was developed which can simplify sizing and aid in early design phases. The investigation confirmed that the PCM panel has the potential to operate as a combined thermo active building system and radiant panel system. The panel can provide increased flexibility, up to 10 h of passive operation, if the PCM thermal capacity matches the cooling load. By altering the PCM thickness and hence the panel's thermal capacity, the cooled ceiling area can be varied which increases design flexibility although introducing operational differences. Furthermore, due to the panel's construction when the available thermal capacity is exceeded, water can be circulated through the pipes to cool the indoor space. This increases the average specific heat flux from 4-10 W/m2 (passive operation) to 45 W/m2 (active operation) in the tested conditions. Under the same conditions, a chilled supply water temperature between 16 and 19 degrees C led to a discharge duration ranging between 2 and 14 h.