Abstract

Many studies have been conducted on PCMs' material character, thermal comfort, and energy savings. However, PCM is more expensive than most sensible heat storage materials (e.g., water and concrete). Thus, it is necessary to develop a relatively cheaper solution. A floor heating system is developed using PCM and an under-floor chamber. A home air conditioner or a pneumatic solar thermal collector is used as a heat source. By sending warm air into the insulated under-floor chamber, heat is transferred to a storage tank adhered to the flooring material. The heat storage layer is composed of PCM on the flooring side and a water-filled layer on the chamber side. A spring-effect heat-conductive metal plate (SHP) adheres the heat storage layer to the backside of the flooring material. Made of an inexpensive sheet metal bent into a certain shape, the SHP realizes a spring effect with the strength needed to ensure adhesion. By installing this system between floor joists, it becomes possible to install a heat storage layer adhered to the backside of the floor without changing the ordinary floor structure. In addition, we present a simulation and a diagram for design purposes. A floor, composed of phase-change materials and a water pack, is represented using a mass-point model. The model formulated with differential equations is solved using the backward difference method. For the four cases, time-series fluctuation of heat storage and heat release is simulated. Regarding the phase change material, we express the nonlinear tendency of heat release and storage. Line charts for the proposed system are presented. We define system optimization, which is to maximize the length of time the floor surface temperature is stably maintained with respect to the unit heat storage amount. By conducting simulations using the model of Chapter 3, we develop diagrams that derive the PCM specifications (i.e., phase-change temperature and thickness) based on the designed room temperature and the floor surface temperature lower-limit value.

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