An Investigation On Falling Horizontal Film Absorption Process For The Absorber Of A Lithium-Bromide Absorption Chiller By Simulation And Experiment

It is known that a Lithium-bromide absorption chiller is mainly composed of the components such as a generator, a condenser, an evaporator, an absorber and some heat exchangers. The absorber is one of the most important components for the chiller as its absorbing characteristics directly influences the performance of the whole chiller. It has been indicated that the absorbing effect and cooling capacity could be improved by increasing the solution concentration, lowering the solution temperature or lowering the temperature of cooling water inlet. However, it is not always happened that the coefficient of performance (COP) of the chiller would be improved along with the methods above-mentioned, because the parameters above are always influenced by each other, for example, the heating amount needed would be increased as the generating temperature goes up. So it is necessary to investigate the connection between the parameters of absorption and the COP of the chiller. In this paper, based on the principle of double effect Lithium-bromide absorption chiller and the mechanism of falling film absorption on horizontal tubes, the theoretical models of falling film absorption on single tube and falling film absorption on horizontal row tubes have been established. A series of programs which are used for computing the theoretical mathematical models have been programmed, including program of Lithium-bromide absorption system simulation, programs of falling film absorption on single tube and falling film absorption on horizontal row tubes. Thus, the impact of absorber parameters on both the heat transfer and mass transfer characteristics of absorber and the performance of the lithium-bromide absorption chiller could be discussed, and the models have been validated correctly with experiments.The experimental equipment is composed of a loop of heat source, a loop of chilling water, a cycle of absorbing refrigerating effect, a vacuumed system and a set of data-measuring device. The experimental rig was improved in oil heating circulation loop and a few of heat exchangers in order to ensure these experiments could running smoothly and the test data could be picked up exactly. According to the experimental rig, the impact of solution concentration and temperature, temperature of cooling water inlet and sprinkling density of Lithium Bromide solution on the characteristics of heat transfer and mass transfer to the absorber and the performance of overall Lithium-Bromide absorption chiller have been discussed.