This paper is concerned with the forced convective heat transfer of dilute liquid suspensions of nanoparticles （nanofluids） flowing through a straight pipe under laminar conditions. Stable nanofluids are formulated ...This paper is concerned with the forced convective heat transfer of dilute liquid suspensions of nanoparticles （nanofluids） flowing through a straight pipe under laminar conditions. Stable nanofluids are formulated by using the high shear mixing and ultrasonication methods. They are then characterised for their size, surface charge,thermal and rheological properties and tested for their convective heat transfer behaviour. Mathematical modelling is performed to simulate the convective heat transfer of nanofluids using a single phase flow model and considering nanofluids as both Newtonian and non-Newtonian fluid. Both experiments and mathematical modelling show that nanofluids can substantially enhance the convective heat transfer. Analyses of the results suggest that the non-Newtonian character of nanofluids influences the overall enhancement, especially for nanofluids with an obvious non-Newtonian character.展开更多
The long-term safe operation of high-power equipment and integrated electronic devices requires efficient thermal management,which in turn increases the energy consumption further.Hence,the sustainable development of ...The long-term safe operation of high-power equipment and integrated electronic devices requires efficient thermal management,which in turn increases the energy consumption further.Hence,the sustainable development of our society needs advanced thermal management with low,even zero,energy consumption.Harvesting water from the atmosphere,followed by moisture desorption to dissipate heat,is an efficient and feasible approach for zero-energy-consumption thermal management.However,current methods are limited by the low absorbance of water,low water vapor transmission rate(WVTR)and low stability,thus resulting in low thermal management capability.In this study,we report an innovative electrospinning method to process hierarchically porous metal–organic framework(MOF)composite fabrics with high-efficiency and zero-energy-consumption thermal management.The composite fabrics are highly loaded with MOF(75 wt%)and their WVTR value can be up to 3138 g m^(-2) d^(-1).The composite fabrics also exhibit stable microstructure and performance.Under a conventional environment(30℃,60%relative humidity),the composite fabrics adsorb water vapor for regeneration within 1.5 h to a saturated value Wsat of 0.614 g g^(-1),and a corresponding equivalent enthalpy of 1705.6 J g^(-1).In the thermal management tests,the composite fabrics show a strong cooling capability and significantly improve the performance of thermoelectric devices,portable storage devices and wireless chargers.These results suggest that hierarchically porous MOF composite fabrics are highly promising for thermal management of intermittent-operation electronic devices.展开更多
基金supported by Chinese Heilongjiang Postdoctoral FoundationChinese Heilongjiang Postdoctoral Science Funding No.LBH-Q07036+1 种基金the Science Creative Foundation for Distinguished Young Scholars in Harbin (Grant No. 2008RFLG005)Project Supported by Natural Scientific Research Innovation Foundation in Harbin Institute of Technology No.HIT.NSRIF. 2008.43.
文摘This paper is concerned with the forced convective heat transfer of dilute liquid suspensions of nanoparticles （nanofluids） flowing through a straight pipe under laminar conditions. Stable nanofluids are formulated by using the high shear mixing and ultrasonication methods. They are then characterised for their size, surface charge,thermal and rheological properties and tested for their convective heat transfer behaviour. Mathematical modelling is performed to simulate the convective heat transfer of nanofluids using a single phase flow model and considering nanofluids as both Newtonian and non-Newtonian fluid. Both experiments and mathematical modelling show that nanofluids can substantially enhance the convective heat transfer. Analyses of the results suggest that the non-Newtonian character of nanofluids influences the overall enhancement, especially for nanofluids with an obvious non-Newtonian character.
基金supported by the National Natural Science Foundation of China(51877132,U19A20105,and 52003153)the Program of Shanghai Academic Research Leader(21XD1401600)。
文摘The long-term safe operation of high-power equipment and integrated electronic devices requires efficient thermal management,which in turn increases the energy consumption further.Hence,the sustainable development of our society needs advanced thermal management with low,even zero,energy consumption.Harvesting water from the atmosphere,followed by moisture desorption to dissipate heat,is an efficient and feasible approach for zero-energy-consumption thermal management.However,current methods are limited by the low absorbance of water,low water vapor transmission rate(WVTR)and low stability,thus resulting in low thermal management capability.In this study,we report an innovative electrospinning method to process hierarchically porous metal–organic framework(MOF)composite fabrics with high-efficiency and zero-energy-consumption thermal management.The composite fabrics are highly loaded with MOF(75 wt%)and their WVTR value can be up to 3138 g m^(-2) d^(-1).The composite fabrics also exhibit stable microstructure and performance.Under a conventional environment(30℃,60%relative humidity),the composite fabrics adsorb water vapor for regeneration within 1.5 h to a saturated value Wsat of 0.614 g g^(-1),and a corresponding equivalent enthalpy of 1705.6 J g^(-1).In the thermal management tests,the composite fabrics show a strong cooling capability and significantly improve the performance of thermoelectric devices,portable storage devices and wireless chargers.These results suggest that hierarchically porous MOF composite fabrics are highly promising for thermal management of intermittent-operation electronic devices.
