Silver nanofluids with three different volume fractions are prepared by a one-step chemical reduction method(Ultra-sound-assisted Membrane Reaction(UAMR)).The convective heat transfer and friction characteristics of s...Silver nanofluids with three different volume fractions are prepared by a one-step chemical reduction method(Ultra-sound-assisted Membrane Reaction(UAMR)).The convective heat transfer and friction characteristics of silver nanofluid in micro-pin fin heat sink are investigated experimentally.The results indicate that the pressure drops of nanofluids with different volume fractions have little difference.Compared to the base fluid(polyvinylpyrrolidone(PVP) solution),the pressure drop of nanofluids increases slightly at the same volume flow rate.When the flow rate is small,the increment is not obvious.The in-troduction of surfactant increases the fluid viscosity,so the pressure drops of nanofluids are larger than those of pure water,under the same flow rate.However,the maximum difference is no more than 10%.The volume fraction of silver nanoparticles significantly affects the convection heat transfer coefficient of micro-pin fin heat sink.The presence of nanoparticles improves significantly the heat transfer performance.However,high viscosity of the nanofluids hinders the heat transfer strengthening effect of nanofluids.In the present work,when the volume fraction of silver particles reaches to 0.012%,the thermal resistance of nanofluid gradually becomes lower than that of deionized water,which indicates the integrated heat transfer enhancement of nanofluids.展开更多
The heat transfer coefficient in a multidimensional heat conduction problem is obtained from the solution of the inverse heat conduction problem based on the thermographic temperature measurement. The modified one-dim...The heat transfer coefficient in a multidimensional heat conduction problem is obtained from the solution of the inverse heat conduction problem based on the thermographic temperature measurement. The modified one-dimensional correction method （MODCM）, along with the finite volume method, is employed for both two- and three-dimensional inverse problems. A series of numerical experiments are conducted in order to verify the effectiveness of the method. In addition, the effect of the temperature measurement error, the ending criterion of the iteration, etc. on the result of the inverse problem is investigated. It is proved that the method is a simple, stable and accurate one that can solve successfully the inverse heat conduction problem.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 51176002)National Basic Research Program of China (Grant No. 2011CB710704)funding Project for Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality (Grant No. PHR200906104)
文摘Silver nanofluids with three different volume fractions are prepared by a one-step chemical reduction method(Ultra-sound-assisted Membrane Reaction(UAMR)).The convective heat transfer and friction characteristics of silver nanofluid in micro-pin fin heat sink are investigated experimentally.The results indicate that the pressure drops of nanofluids with different volume fractions have little difference.Compared to the base fluid(polyvinylpyrrolidone(PVP) solution),the pressure drop of nanofluids increases slightly at the same volume flow rate.When the flow rate is small,the increment is not obvious.The in-troduction of surfactant increases the fluid viscosity,so the pressure drops of nanofluids are larger than those of pure water,under the same flow rate.However,the maximum difference is no more than 10%.The volume fraction of silver nanoparticles significantly affects the convection heat transfer coefficient of micro-pin fin heat sink.The presence of nanoparticles improves significantly the heat transfer performance.However,high viscosity of the nanofluids hinders the heat transfer strengthening effect of nanofluids.In the present work,when the volume fraction of silver particles reaches to 0.012%,the thermal resistance of nanofluid gradually becomes lower than that of deionized water,which indicates the integrated heat transfer enhancement of nanofluids.
文摘The heat transfer coefficient in a multidimensional heat conduction problem is obtained from the solution of the inverse heat conduction problem based on the thermographic temperature measurement. The modified one-dimensional correction method （MODCM）, along with the finite volume method, is employed for both two- and three-dimensional inverse problems. A series of numerical experiments are conducted in order to verify the effectiveness of the method. In addition, the effect of the temperature measurement error, the ending criterion of the iteration, etc. on the result of the inverse problem is investigated. It is proved that the method is a simple, stable and accurate one that can solve successfully the inverse heat conduction problem.
