ENERGY CONSERVATION OF BUILDINGS BY USING PHASE CHANGE MATERIAL

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Latent heat storage is a kind of heat storage technology by using phase change materials (PCM). Authors proposed Mn(NO_3)_2・6H_2O mixed with MnCl_2・4H_2O as a new PCM for storing cold energy during night time for cooling system and Mg(NO_3) _2・6H_2O mixed with MgCl_2・6H_2O as a new PCM for storing urban waste heat such as surplus heat from co-generation system. It was clarified that chloride salts are adequate to modulate the melting point without drop of the latent heat. In addition, although only small super cooling was observed for these substances in a small vessel, that is not problem in the actual cases. Also, heat exchanging rates and stabilities of these PCM were examined. From these tests, great possibility was obtained as a PCM for thermal energy storage system.Next, a direct heat exchange system between granulated PCM and air was proposed. PCM is consisted from granulated porous media and paraffin. Its particle diameter is about 1〜3mmφ. Advantage of this system is that heat transfer coefficient is kept relative large and continuous during phase change. Column experiments related with heat exchange between PCM and air were conducted. Also, a computer simulation program was made and phase change period was discussed by the proposal non-dimensional time. Next, applications this new principal to stabilization the outdoor air temperature for the ventilation system and to the under floor air conditioning system were examined