Preparation, thermal performance and application of shape-stabilized PCM in energy efficient buildings

Shape-stabilized phase change material (PCM) is a kind of novel PCM. It has the following salient features: large apparent specific heat for phase change temperature region, suitable thermal conductivity, keeping shape stabilized in the phase change process and no need for containers. The preparation for such kind material was investigated and the thermophysical properties of various samples developed by us were measured. Several applications of such material in energy efficient buildings (e.g., in electric under floor space heating system, in wallboard or floor to absorb solar energy to narrow the temperature swing of a day in winter) were studied. Some models of analyzing the thermal performance of the systems were developed, which were validated with our experiments. The following conclusions are obtained: (1) The applications of the novel PCM we put forward are of promising perspectives in different climate regions; (2) By using different paraffin, the melting temperature of shape-stabilized PCM can be adjusted; (3) The optimal composition of paraffin in shape-stabilized PCM is about 80%; (4) The heat of fusion of it is in the range of 62-138 kJ/kg; (5) For PCM floor or wallboard to absorb solar energy to narrow the temperature swing in a day in winter, the suitable melting temperature of PCM should be a little bit higher than the average indoor air temperature of the room without PCM for the period of sunshine; (7) For the electric under-floor space heating system, the optimal melting temperature can be determined by simulation; (8) PCM layer used in the aforementioned application should not be thicker than 2 cm; (9) For given conditions, the numerical models developed by us can provide the prediction and optimal design for the applications of shape-stabilized PCM in buildings.

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