SOLAR HEATING AND COOLING SYSTEM WITH LOW TEMPERATURE LATENT HEAT STORAGE

摘要

Heat activated chillers are integrated into solar thermal systems in order to provide solar heating and cooling. During the cold season solar heat serves for space heating. During the warm season solar heat is converted into useful cooling by utilizing the solar heat as driving heat for the sorption cooling device, simultaneously avoiding overheating of the solar thermal system. A favourable situation is given when radiative heating and cooling facilities. e.g. floor or wall heating systems or activated ceilings, are applied for transferring heating and cooling to the room at moderate heating and cooling temperatures, respectively. A low-temperature latent heat storage based on phase-change-material can be applied to cope with the given system requirements: During heating operation the latent heat storage balances heat generation by the solar system and other heat sources and the supply to the consumer. Thus a low operating temperature of the solar thermal system is accomplished yielding efficient operation with optimum solar gain. In cooling mode the latent heat storage serves as a reject heat sink for the absorption chiller in addition to a dry cooling system. By that means heat rejection of the chiller is shifted to periods with lower ambient temperatures, i.e. night time or off-peak hours, and thus the necessity of a wet cooling tower is eliminated allowing for a substantial reduction in operational effort, water consumption, and cost. A discussion of the system concept and of the thermal design of the latent heat storage is given. Experimental results of a functional model of the heat storage and operational experience of a first full-scale demonstration of the solar heating and cooling system incorporating a recently developed compact water/lithiumbromide absorption chiller are presented.