The new solution to indoor overheating is to use a heat accumulation module with a system of capillary pads. This newly developed system not only enables a room during summer to be passively cooled, but also gives us an opportunity to provide rooms with low heating in winter. Today this technical solution has already been legally protected in the Czech Republic as a utility model.
The main technological components that compose the pre-built system consist of a base plate, a foam polystyrene panel and a pad made of capillary tubes which lead to the feeding and return pipeline, positioned along both the top and bottom edge of the module. The pad is placed in a layer of plaster with a 30% share of micro-pellets with a phase-changing material (PCM).
Figure 1: Diagram showing a series of linked panels with capillary pads and plaster, together with a cooling source. The ground plan and section illustrate the practical application in an experimental room inside the Institute of Building Structures at the Faculty of Civil Engineering, Brno University of Technology
Schéma rozmístění panelů - Drawing of panel layout, Půdorys - Ground plan, Detail kapilárního chlazení - Detail of capillary cooling, Řez - Cut, Spoj kapilár - Connection of capillaries, Schéma panelů - Diagram of panels
The system functions so that excessive daytime heat indoors is accumulated in the heat accumulation layer of plaster containing the PCM micro-pellets, and then at night, when the temperature in the room falls below the temperature of PCM crystallization, heat is released spontaneously from the plaster back into the room. Thus radiant heating of the room occurs, bringing with it extra energy savings. The principle can be advantageously applied during the so-called transitional period. However, if summer temperatures are high both day and night, the effective removal of accumulated energy must be realized in some way other than radiation to the interior.
In order to guarantee sufficient discharge of accumulated energy from PCM micro-pellets at night a capillary pad is used. In order to increase the capacity of heat accumulation, this pad is permanently flooded with water, which advantageously cools down the accumulation medium, particularly at night and during off-peak hours. Screw threads on the distribution tubes enable other modules to be easily connected into a particular distribution loop. The distribution pipelines are emptied into a distributor and a collector. The outlet line from the air-water cooler, where cooling water is prepared during off-peak electricity rates, is connected to the distributor. The collector outlet is connected to the return line to the cooling source.
The main advantages of a pre-built system of capillary pads compared to systems already established is that this innovative system uses the reversible phase changes of PCM for heat accumulation and, in particular, that the system allows for dry assembly thanks to welded screw connections - not provided by the other known systems. Another advantage is that in winter the system can be used as capillary heating: the cooling source is replaced with a heater to warm up the feeding water. The set of modules then produces radiant heating. Both for cooling and heating, it is economically most advantageous to use a heat-pump powered by off-peak electric energy.
