Solid absorbent dispersion in an inert fluid for solar refrigeration applications

One of the most significant factors limiting the performance of solar powered solid absorption refrigeration systems is the low rates of heat and mass transfer within the absorbant pellet. Solutions to these problems are discussed in this paper. They include the use of suitable additives or treatments, and the dispersion of the absorbent in an inert liquid which has a high absorption capacity for the refrigerant without impeding the absorption and generation reactions. With particular reference to the calcium chloride/ammonia system, the experimental investigation of the idea of dispersing the absorbent in an inert liquid is reported here. The tests were performed by simulating the absorption and generation reactions in two mild steel pressure vessels, one acting as the absorber/generator, and the other as the receiver of the condensed refrigerant. Normal heptanol was used as the inert liquid. The novel feature of the investigation is the use of a bubble agitation device in order to dispense with mechanical stirring of the dispersion. Heating was done electrically, pressure, temperature and mass measurements being taken. The results indicate that the absorption and generation reactions were at least five times faster with the dispersion. The practical problems of utilizing the absorbent in this form in solar refrigeration systems are considered.