PCM cooling ceilings in the Energy Efficiency Center – Regeneration behaviour of two different system designs

Abstract

The regeneration behaviour of two different cooling ceilings with PCM was monitored and analysed with two different methods an analysis of the measured PCM temperatures as well as an analysis of the measured heat fluxes into and out of the PCM modules. The temperatures and heat fluxes then were compared to the measured enthalpy curves of the PCM. Both analysis methods determined the solid fraction of PCM after the regeneration period and yielded very similar results. While the PCM in the cooling ceiling system with the PCM on top of the water pipes was completely liquid only during 5% of the investigated days after the daily heat absorption from the room, the PCM in the cooling ceiling system with the PCM below the water pipes was completely liquid during more than 60% of the investigated days. The regeneration results reflect this differing starting behaviour with typical solid fractions of 90–100% for ceiling type PCM on top and only 80–95% for ceiling type PCM at the bottom. However, since both values are quite high the regeneration behaviour of both PCM cooling ceiling constructions must be considered as very good.