十二烷微乳液冰浆制备与性能研究

Preparation and properties of dodecane microemulsion ice slurry

冰浆是一种传热性能良好的蓄冷剂和载冷剂。为了研究微乳液冰浆制备的特性,以十二烷为油相,己醇作为助表面活性剂,油酸钾、油酸钠和十二烷基硫酸铵及其混合物作为表面活性剂,制备了水包油(O/W)和油包水(W/O)型微乳液。采用了离心测试、粒径测试、电导率测试和导热率测试等方法对微乳液的性质和结构进行了表征与分析。采用恒温空气浴冷却结晶的方法进行了微乳液冰浆制备实验,根据过冷度与相变温度确定了微乳液冰浆最佳制备体系,并对该体系微乳液冰浆的生长过程进行了研究。研究结果表明,随着微乳液中油相比例的增加,形成稳定微乳液的表面活性剂的亲油性也随着增加。微乳液的油水比与己醇浓度影响冰浆过冷度和相变温度,油水比为1:9的O/W型微乳液制备冰浆的效果较好,过冷度不超过0.3℃,相变温度约为-0.1℃。利用冷热循环对微乳液及其冰浆制备过程的稳定性进行了验证,微乳液经历500次-5~25℃冷热循环后未发现分层现象,说明微乳液的稳定性良好,微乳液冰浆制备重复性好,可长期用于冰浆的制备。

Ice slurry is a kind of cold storage medium and secondary refrigerant with good heat transfer performance.Microemulsions of oil in water(O/W)and water in oil(W/O)are prepared to study ice slurry preparation using microemulsion.We used dodecane as the oil phase,hexanol as the cosurfactant,potassium oleate,sodium oleate,ammonium lauryl sulfate,and their mixtures as surfactants.We analyzed the properties and structures of the microemulsion through centrifugal,particle size,conductivity,and thermal conductivity tests.The optimum preparation system of the microemulsion ice slurry is determined according to the subcooling degree and phase change temperature,and its growth process is described.The experimental results show that the surfactant's lipophilicity to form stable microemulsions increases with the increase in the mass ratio of oil and water.The oil–water mass ratio and hexanol concentration of the microemulsion affect the supercooling degree and phase transition temperature of the ice slurry.O/W microemulsion with an oil–water mass ratio of 1:9 has a good performance for preparing ice slurry.Its subcooling degree is not more than 0.3℃,and the phase transition temperature is about−0.1℃.The stability of the microemulsion and its ice slurry preparation was verified by thermal cycling.After 500 thermal cycles between−5℃and 25℃,no stratification is found,indicating that the microemulsion has good stability.The microemulsion may be used to prepare ice slurry for a long time.