Effects of TiO2 Nanoparticle Morphology on Working Performances of Heat Pipes
To study the effects of medium morphology on working process of heat pipes,TiO2 nanoparticles with rod,flaky,and rhombus shape were prepared by using hydrothermal method,and TiO2-water nanofluids with three morpholo-gies were prepared by using two-step method.The thermal conductivity of working medium with different morphologies in heat pipes,start-up performance,isothermal performance,and thermal resistance of heat pipes working process were experimentally studied,and effects of TiO2 nanoparticle morphology on working performances of heat pipes were analyzed.The results show that the thermal conductivity of flaky TiO2-water nanofluids in heat pipes is greater than those of rhom-bus and rod-shaped TiO2-water nanofluids and base liquid water.When the heating power is same,the start-up tempera-ture of flaky TiO2-water nanofluid heat pipes is the lowest,which is(38.2±0.5)℃,and the average temperature difference between evaporation section and condensation section of the flaky TiO2-water nanofluid heat pipes is 2-3 ℃smaller than the corresponding average temperature difference of the rod and rhombus-shaped TiO2-water nanofluid heat pipes,and the total thermal resistance is reduced by 4.4％-28.3％.
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