使用高温金属盐/膨润土颗粒状定型复合材料的重力热管式蓄热器蓄放热特性试验研究

In this paper, a novel gravity-assisted heat pipe type high-temperature heat storager is presented, in which the composite granular solid-liquid PCM is piled up as the porous medium layer. The composite PCM, phase change at the temperature of 200-250℃, is compounded of mixed metal salt and inorganic bentonite. Naphthalene is presented as the phase change heat transfer medium of the gravity-assisted heat pipe type heat storage. In the period of heat storage, the heat source working medium, naphthalene vapor, condenses on the surface of the granular in the heat storage layer and releases large of latent heat of vaporization which is transferred to the PCM. And the liquid naphthalene from condensation stays in the gap of the porous media. In the period of heat release, the liquid naphthalene evaporates after absorbing heat from the granular PCM, then the vapor rises to the surface of the condenser pipe in the upper heat storage and condenses again. And the liquid naphthalene from condensation drops to the granular PCM. The mechanism of heat storage/release above is similar to that of the gravity-assisted heat pipe, which is different from any past heat storager, no matter direct-contact or indirect-contact. The heat transfer between PCM and the heat resource or cold resource in this paper carries out in the form of cyclic phase change of the working medium which directly happens on the surface of those materials. This noval design that uses evaporation and condensation of the working medium instead of conduction and convection between materials slips the leash resulted from low thermal conductivity of the PCM and endows the heat storager with extremely outstanding heat tranfer performance. In this paper, a series of experements are carried out firstly to learn the properties of the new heat storager. Then a series of theoretial analysis, such as heating time, power distribution, temperature difference between the inside and outside of the granular PCM and between the surface of the PCM and the vapor around, is carried out. The result shows that the temperature difference of the granular PCM and the working medium is very small, the temperature change almost simultaneously and the whole system has an excellent heat storage/heat radiation performance.