|Budget Amount *help
¥1,500,000 (Direct Cost : ¥1,500,000)
Fiscal Year 1992 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1991 : ¥1,000,000 (Direct Cost : ¥1,000,000)
In order to use solar thermal energy and low-quality energy effectively, a means of energy storage is required. One method under study involves heat storage in the latent heat of solid-liquid phase change. It is known that paraffin waxes exhibit desirable characteristics as a phase change material for heat storage. On the other hand, paraffin waxes have some undesirable proper-ties such as: 1) low thermal conductivity, 2) relatively large volume change in phase change due to the high solubility of air in the liquid phase. Both give rise to the low heat transfer rate in charging and discharging processes. To improve this problem, it has been proposed to utilize metallic fillers, fins, and capsules. However, these techniques are not always effective.
In the present study, we considered to use paraffin wax-water emulsion as a new heat storage material, which has fluidity in solid phase and relatively high thermal conductivity and fusion heat. The experiments of charging and discharging for two kinds of emulsion and water as a reference were performed by using a shell-and tube type heat storager. Time-changes of temperature of heat storage material and working fluid were measured under varied conditions of flow direction, mass flow rate, and inlet temperature of working fluid. Enthalpies charged and discharged were evaluated and compared. As a result, it was found that emulsion is a suitable and effective heat storage material to enhance heat transfer. Effects of operation condition on characteristics of charging and discharging were made clear.