Research On Liquid Desiccant Process With [EMIM][DEP] Aqueous Solution

Because of the defects of the traditional liquid desiccant,such as LiBr aqueous solution and three glycol,the further development of liquid dehumidification technology is limited.It is a hotspot to find a new type of liquid desiccant.The ionic liquid 1-Ethyl-3-methyl-imidazolium Diethyl phosphate([EMIM][DEP])has potential to be a new liquid desiccant due to its unique physicochemical property.In order to study the dehumidification performance of ionic liquid [EMIM][DEP] aqueous solution,two aspects of numerical simulation and experimental research are studied in this paper.Firstly the heat and moisture transfer model of the counter-flow dehumidifier is established to investigate the dehumidification performance of [EMIM][DEP] aqueous solution by using the finite difference method.Then,a set of experimental system is designed.The dehumidification capacity of [EMIM][DEP] aqueous solution is investigated and the mathematical model is verified by using the experimental system under different conditions such as wet air flow rate,solution temperature,solution flow rate and solution concentration.The results show that increasing the wet air flow rate,decreasing the solution temperature,increasing the solution flow rate and increasing the solution concentration can increase the dehumidification capacity of [EMIM][DEP] aqueous solution.It is proved that the mathematical model is reasonable through the comparison of the experimental and simulated values.Additionally,the variation law of dehumidification capacity with inlet parameters is explained from the perspective of internal mass transfer.Based on this model,the desiccant effect on the lithium bromide(Li Br)aqueous solution and [EMIM][DEP] aqueous solution were simulated and compared under different working conditions.Meanwhile,the effect of inlet parameters on the dehumidification effect of the two kinds of liquid desiccant is analyzed.The inlet parameters include the inlet temperature of wet air,the mass flow of wet air,the mass flow of liquid desiccant and the inlet humidity of wet air.The results show that the average dehumidifying capacity of ionic liquid [EMIM][DEP] aqueous solution is 60%~64% of the Li Br solution;changing the inlet temperature of wet air has little effect on the dehumidification effect of two kinds of liquid desiccant;changing the influences of the mass flow of wet air,the mass flow of liquid desiccant and the inlet humidity of wet air on the dehumidification effect of two kinds of liquid desiccant are remarkable.Compared with Li Br aqueous solution,the dehumidification effect of [EMIM][DEP] aqueous solution is slightly inadequate,but it has the advantages of no corrosion,green environmental protection,stable chemical properties and so on.Therefore,the [EMIM][DEP] aqueous solution has a better application prospect as a liquid desiccant.Based on the numerical simulation and experimental study on the dehumidification process of ionic liquid [EMIM][DEP] aqueous solution,the variation law of [EMIM][DEP] aqueous solution dehumidification capacity is obtained under different working conditions.It is helpful for the application of [EMIM][DEP] aqueous solution as a new liquid desiccant to engineering practice.