Performance Research On Industrial Air-dehumidifier By Liquid Desiccant

Supplied air should be dehumidified in many industrial processes. However, asincreasing demand for the dry air and dehumidification depth, it will cause a hugewaste of energy by solely relying on compression refrigeration dehumidification. Inthis paper, liquid desiccant dehumidification technology was recommended inindustry, and the industrial liquid desiccant dehumidification unit was proposed. Anexperimental platform for the unit model was designed and contributed, and the studyof performance of regenerator was conducted through the experimental and numericalsimulation methods. This paper carried out the research including the followingaspects:Firstly, an experimental platform for the unit model was designed andcontributed. Progressively, the process and parameters of the liquid desiccant systemwas determined, non-standard equipment was designed and machined, standardequipment was selected, and finally the electrical control system and experimentalmeasurement system were designed and installed. The entire bench of the liquiddesiccant system is divided into four processes as the air handling process, the outsidesolution cycle process, the inner solution cycle process, and hot/cold water cycleprocess. All devices of the bench were controlled to run and stop, and wantedparameters of the air, solution, and cold/hot water were measured and acquired. It wasthe foundation of conducting experimental study and helped to optimize the design byproviding an experimental platform.Secondly, experiments were carried out based on the platform, and theexperimental study was to reveal the impact of operating parameters on theregenerator performance and overall system cycle. The inlet solution temperature, theinlet solution and air flow rate were divided into three levels of single factorexperiment. Experimental results showed that: volumetric mass transfer coefficient ofthe packing, with the same variation of regeneration rate, can reflect regenerationcapacity of using this packing, increasing in pace with the regeneration temperature ofthe solution, inlet solution flow rate, and liquid to gas ratio increases. The higherregeneration solution temperature was not conducive to the average mass transfercoefficient and regeneration of the packing, but helped to enhance the enthalpyefficiency of regeneration. Best regeneration performance can be obtained at thehigher inlet solution flow rate and lower air speed through the packing (high liquid-gas rate). Outside inputs of heat and cold capacity to the system was increasedas the regeneration temperature increased, along with the effect of the energy savingof economizer was more remarkable. Also, through the regression of mass transfercoefficient, the empirical formula of regeneration Sherwood number was obtained.This helped to provide a basis and reference for theoretical research and applications.Finally, a cross-flow regenerator mathematical model was established to simulatethe regeneration performance with different regenerator inlet parameters. Themathematical model is applicable as the simulation results agreed well with theexperimental results. The distribution of temperature and humidity of the air,temperature and concentration of the solution inside the packing during regenerationprocess was analyzed and resulted that higher solution concentration was got at theoutlet of the solution close to the inlet of the air. Using the model to control the outletconcentration of the solution in the regenerator, it can be significantly enhanced byincreasing the inlet solution temperature, at the rate of0.013%/℃. This provided areference for the simulation study and manipulation of the regenerator.