Experimental analysis of thermal storage tank configurationin a solar cooling installation with an absorption chiller

摘要

The use of air conditioning systems in Spanish dwellings is gaining popularity, as the installed units grows by 0,8 million per year. The most popular air conditioning system today is the vapor-compression cycle. This kind of system consumes a considerable amount of electric energy as it incorporates a mechanical compressor in its cycle and utilizes refrigerants that can be dangerous to the environment. A solution to this kind of equipment can be found in Solar Facilities configured to produce cold water for air conditioning purposes by means of an absorption chiller. This kind of equipment can be driven by a heat input produced by the solar facility. This machine consumes a very low amount of electric energy and presents great advantages for the environment. Nevertheless, the need of a heat reservoir to operate in the afternoon hours, where solar radiation is not enough to drive the chiller, is indispensable in a solar facility. To serve this purpose, the introduction of a thermal storage tank has to be made.There are two basic internal configurations of a thermal storage tank in a solar cooling facility. These are Stratification and Well-mixed configuration. Experimental results show that for solar cooling applications, having a homogeneous mixture temperature in the thermal storage tank produce more daily cooling energy than in an stratified one, although the solar field efficiency is lower. This gives the facility more autonomy of operation in the afternoon, when the sun goes down and radiation is not enough for the application. Effects on the facility produced by Well-mixed configuration are: efficiency reduction on the solar collector’s field , 0,27, higher daily COP’s, 0,33, and extended solar cooling time of about two hours.