Influence factors on thermal conductivity of ammonia-water nanofluids  

作　　者：杨柳 杜垲 张小松 

机构地区：[1]School of Energy and Environment,Southeast University

出　　处：《Journal of Central South University》2012年第6期1622-1628,共7页中南大学学报（英文版）

基　　金：Projects(51176029,50876020) supported by the National Natural Science Foundation of China;Project(2011BAJ03B00) supported by the 12th Five-Year National Science and Technology Support Key Program of China; Project(ybjj1124) supported by the Foundation of Graduate School of Southeast University,China

摘　　要：In order to investigate the mechanism of nanoparticles enhancing the heat and mass transfer of the ammonia-water absorption process,several types of binary nanofluids were prepared by mixing Al2O3 nanoparticles with polyacrylic acid(PAA),TiO2 with polyethylene glycol(PEG 1000),and TiN,SiC,hydroxyapatite(noodle-like) with PEG 10000 to ammonia-water solution,respectively.The thermal conductivities were measured by using a KD2 Pro thermal properties analyzer.The influences of surfactant and ammonia on the dispersion stabilities of the binary nanofluids were investigated by the light absorbency ratio index methods.The results show that the type,content and size of nanoparticles,the temperature as well as the dispersion stability are the key parameters that affect the thermal conductivity of nanofluids.For the given nanoparticle material and the base fluid,the thermal conductivity ratio of the nanofluid to the ammonia-water liquid increases as the nanoparticle content and the temperature are increased,and the diameter of nanoparticle is decreased.Furthermore,the thermal conductivity ratio increases significantly by improving the stabilities of nanofluids,which is achieved by adding surfactants or performing the proper ammonia content in the fluid.In order to investigate the mechanism of nanoparticles enhancing the heat and mass transfer of the ammonia-water absorption process, several types of binary nanofluids were prepared by mixing Al2O3 nanoparticles with polyacrylic acid （PAA）, TiO2 with polyethylene glycol （PEG 1000）, and TiN, SiC, hydroxyapatite （noodle-like） with PEG 10000 to ammonia-water solution, respectively. The thermal conductivities were measured by using a KD2 Pro thermal properties analyzer. The influences of surfactant and ammonia on the dispersion stabilities of the binary nanofluids were investigated by the light absorbency ratio index methods. The results show that the type, content and size of nanoparticles, the temperature as well as the dispersion stability are the key parameters that affect the thermal conductivity of nanofluids. For the given nanoparticle material and the base fluid, the thermal conductivity ratio of the nanofluid to the ammonia-water liquid increases as the nanoparticle content and the temperature are increased, and the diameter of nanoparticle is decreased. Furthermore, the thermal conductivity ratio increases significantly by improving the stabilities ofnanofluids, which is achieved by adding surfactants or performing the proper ammonia content in the fluid.

关 键 词：binary nanofluids AMMONIA-WATER thermal conductivity size effect dispersion stability 

分 类 号：TB383.1[一般工业技术—材料科学与工程]