Experimental Investigation On The Feasibility Of Electro-Osmotic-Dehumidification

In order to improve the treating capacity on latent heat of air-conditioning system,to realize independent control of temperature and humidity and further to achieve energy-saving,a novel heat exchanger-dehumidification fin coupled with electro-osmotic dehumidification technology is proposed.The dehumidification fin is expected to realize the moisture regulation of processed air by utilizing the electro-osmotic flow formed in the micro-pore of porous materials.To further explore the feasibility of electro-osmotic-dehumidification in the air-conditioning system,an experimental study is introduced in this thesis to investigate the variations of electro-osmotic flow and the impact factors in solid desiccants with different degree of saturation.Starting with the selection,preparation and performance testing of porous adsorption materials,a series of fabricating procedures of single material samples,composite material samples and curing material samples are determined respectively.The adsorption performance of different types of material is determined by static adsorption test,and the structural stability of material is determined by mechanical strength test.Based on the test results,macro-porous silica gel,activated alumina and zeolite are optimal desiccants selected as single material samples.By impregnating with 20-40 wt%calcium chloride solution and combing with water-soluble curing agent such as PVA,the single materials can further be prepared as composite material samples and curing material samples.After determining the test materials,two types of experimental systems are designed for measuring electro-osmotic dehumidification rate.One for testing samples with high degree of saturation and the other one for testing samples with low degree of saturation.The sample in the high saturation test is directly contacted with liquid water to simulate extreme conditions,which can highly enhance the electro-osmotic regeneration effect and provide sufficient observations on the impact factors.The sample in low saturation test is directly contacted with a humid chamber to simulate conventional conditions,which will be used to estimate the dehumidification potential when applied in the normal air conditioning system.Based on the designed methods and the instrument selected in the system,the measurement uncertainty of high saturation and low saturation systems are±0.35%and±0.35%,respectively.Based on the experimental results of the electro-osmotic flow rate derived in samples with different degree of saturation,the main conclusions are summarized as follows.In high saturation test,the macro-porous silica gel indicates higher electro-osmotic flow rate,but worse structural stability which leads to abnormal fluctuation and behavior of test results.The average particle size of three porous materials is negatively correlated with the electro-osmotic flow rate;the voidage of three porous materials is positively correlated with the electro-osmotic flow rate;the relationship between the applied field intensity and the electro-osmotic flow rate varies in different samples.Within the range of factors studied in this paper,the optimum parameters of particle size,voidage and applied field intensity to obtain higher electro-osmotic flow rate are 0.05-0.1mm(three kinds of materials),11.4%(activated alumina),40.3%(macro-porous silica gel),23.0%(zeolite),and 2.81V/mm(activated alumina),3.04V/mm(macro-porous silica gel),2.28V/mm(zeolite),respectively.In low saturation test,the different average pore sizes of activated alumina and zeolite barely affect the electro-osmotic flow rate;the voidage of materials is non-monotonic change with the electro-osmotic flow rate;the applied field intensity is positively correlated(activated alumina)and negatively correlated(zeolite)with the electro-osmotic flow rate,respectively.The optimum parameters of voidage and applied field intensity to obtain higher electro-osmotic flow rate are 10.0%(activated alumina),20.5%(zeolite),and 7.66V/mm(activated alumina),3.31V/mm(zeolite),respectively.In general,the electro-osmotic flow rate at high saturation and low saturation can reach 10~3 times and 10 times of the lowest dehumidification rate of air conditioning system.It is full of potential to apply porous adsorption materials coupled with electro-osmotic effect in dehumidification unit of air conditioning system.