Phase change slurries in panel cooling systems for buildings

The energy demand for space cooling and air conditioning at the commercial sector (hospitals, office buildings and stores) is growing fast in the last decades . A better building insulation decreases the need of heating and cooling. Contrary to that, the increasingly use of electronic devices and the tendency to a transparent architecture rises the cooling demand. One option to cover these demands is space cooling by capillary tubes in floors, walls, and ceilings offering a large surface for heat exchange. Phase Change Slurry (PCS) is a binary system consisting of a PCM (paraffin) dispersed in a continuous fluid phase (water). Paraffin, as typical organic PCM (Phase Change Material), absorbs or releases energy during the solid liquid phase transformation. The latent and the sensible he at capacity of the paraffin, together with the sensible heat of the water can be used to store or to transfer heat. The paraffin/water-dispersion remains liquid and therefore pumpable even when the paraffin is solid. This contribution describes a panel cooling concept combined with a PCS cold storage. Due to its large surface area, the heat transfer can be done with relatively small temperature differences. Such a system enables the production and use of cold at advantageous conditions. In spring and autumn, it is mostly possible to load the cold storage passively by using only the low ambient temperature at night time. In the summer time the energy consumption for active cooling is lower than without storage. A cooling machine with lower cold capacity is sufficient, due to better condit ions for the heat rejection.