A Comparative Study Of Two Liquid Desiccant For Dehumidification And Regeneration

Compared with the traditional air condensation dehumidification,the liquid desiccant dehumidification system(LDAS) has the advantages of higher dehumidifying efficiency, and can effectively use the waste heat, thus it is used more and more frequently in air condition system in the LDAS, the liquid desiccant is directly contacted with the air to exchange heat and mass, and then achieve the purpose of dehumidification.Therefore, the efficiency and energy consumption of dehumidifying are influenced by the properties of liquid desiccant. At present,the research about the LDAS is more concerned with the design of the system, while the properties of the liquid desiccant are neglectted. Consequently, this paper researched the LDAS using two different liquid desiccants of lithium bromide and lithium chloride.Firstly, in view of two different liquid desiccants, solution of lithium bromide and lithium chloride,we established a mathematical model of heat and mass transfer, which is based on the gas-liquid flow form of cross-flow. In order to verify the correctness of the mathematical model, the simulation results were compared with the experimental data of other scholars, the results showd that the error of the simulation results is within ±10%.Secondly, the study separately calculated the changes of two liquid desiccants' ability of dehumidification and regeneration using the established model, when the solution's concentration/temperature and flow rate were changed. And the difference between the abilities for dehumidification and regeneration of lithium bromide and lithium chloride was compared under the same conditions.Finally, under the circumstances of making sure the moisture content of the infoor air keeps constant in cooling season, using the method of changing liquid desiccant's flow rate. The dehumidificatioand regeneration load and water pump's energy consumption of the LDAS using two different liquid desiccants were studied, when we changed the desiccant solution's temperature or concentration. Then, the difference of the energy consumption between lithium bromide and lithium chloride were compared under the same conditions.The following conclusions are obtained in this study:(1)With the dropping of desiccant solution's temperature, the increase of concentration and flow rate, the dehumidifying capacity of the LDAS was enhanced; on thecontrary, the regenerate capacity of the LDAS was enhanced.(2) The dehumidifying capacity of the lithium chloride was better than the lithium bromide under the same conditions, while the regenerate capacity was worse.(3)Throughout the whole cooling season, the overall energy consumption of the LDAS decreased as the solution's concentration decreased, the temperature of the dehumidification process dropped and the temperature of the regeneration process increased.(4) The LDAS using the lithium bromide had better energy performance than the one using lithium chloride under the same conditions.