Study On The Formation Characteristics Of Dodecane Microemulsion Ice Slurry

Ice slurry is usually a solid-liquid two-phase solution formed by mixing ice crystal particles with an average diameter of less than 1 mm and water or aqueous solution.The cooling capacity of ice slurry is 5 ～ 6 times higher compared with conventional chilled water.An air conditioning system with ice slurry as a cold storage medium can realize "peak shifting and valley filling" and balance power grid load,which is an effective means of power demand side management at present.Supercooling method is a common method to prepare ice slurry,but the ice slurry prepared by the supercooling method also has some problems,such as low ice content,easy adhesion to the wall,and ice blockage.Therefore,the preparation of ice slurry using emulsion has attracted much attentions,but the emulsion ice slurry is prone to delamination during freezing /melting process.The stability of emulsion is poor,which affects its long-term use.Microemulsion with better stability and repeatability than emulsion was prepared in this thesis to solve the problem of poor stability and repeatability of emulsion ice slurry.Ice slurry is prepared with the microemulsion as base liquid,and the properties of different types of microemulsion ice slurry were studied.The microemulsion is a transparent or translucent thermodynamically stable system composed of oil,water,surfactant,cosurfactant,and other components,which has good fluidity.The hydrophilicity and lipophilicity(HLB value)of the surfactant were adjusted by the mixed surfactant.Dodecane as the oil phase,and hexanol was used as cosurfactant to prepare microemulsions with oil-water mass ratios of the microemusion is 1:9,2:8,and3:7,respectively.The stability of microemulsion is tested by centrifugation.The properties and structure of microemulsion were characterized and analyzed by particle size test,electrical conductivity test,and thermal conductivity test.The experimented results show that the HLB value of surfactant used for forming microemulsion decreases with the increase of the mass ratio of oil to water.The average particle sizes of microemulsions with oil-water mass ratios of 1:9,2:8,and 3:7 are 50.6 nm,67.89 nm,and 58.92 nm,respectively.The thermal conductivity of oil-in-water(O/W)microemulsion decreases with the increase of surfactant HLB,while that of water-in-oil(W/O)microemulsion increases with the increase of surfactant HLB value.The microemulsion remained stable without delamination after 500 times of demulsification and self-emulsification recovery.O/W type microemulsion and W/O type microemulsion are used to prepare ice slurries.The phase transition temperature,supercooling degree,cooling discharge rate,ice storage rate,stability,and viscosity of ice slurry are studied.The phase transition temperature of W/O type microemulsion is lower than that of O/W type microemulsion,and the undercooling degree is higher than that of O/W type microemulsion.When the oil-water mass ratio is the same,the ice discharge rate of the same type of microemulsion ice slurry is faster when the surfactant addition amount is 15%.For different types of microemulsion ice slurry,the O/W type has a faster cooling release speed.The growth rate of W/O microemulsion ice slurry is slower than that of O/W microemulsion because surfactant and hexanol inhibit the growth of ice crystals.300 freezing/melting thermal cycle experiments were carried out on the microemulsion.The supercooling degree of the microemulsion is stable,the change of phase transition temperature was not more than0.2℃,the formation process of microemulsion ice slurry is stable,and it can be used for a long time.