水基石墨烯纳米流体在矩形小槽道内的流动换热特性
|
摘要
测试了水基石墨烯纳米流体的部分热物性,研究了不同浓度、雷诺数(Re)和加热功率条件下水基石墨烯纳米流体作为换热工质在设计的矩形结构小槽道内的对流换热性能。结果表明,层流状态(Re=500～2000)下,矩形槽道壁面温度随Re增大逐渐降低,随加热功率增大逐渐升高,与常规流体换热特性一致;在相同Re和换热功率条件下,随纳米流体浓度增大,壁温逐渐减小;水基石墨烯纳米流体的换热强度比基液去离子水提升较大,Re=2000、加热功率为210W时,浓度为0.03wt%的水基石墨烯纳米流体的平均努塞尔数(Nu)为9.3,比基液水提升48.8%;受入口效应影响,沿槽道长度局部对流换热系数逐渐减小,最高可达25674.5 [W/(m2·℃)],较基液水最大可提高39.1%;Re=500～1 400时,石墨烯纳米流体的流动换热强度随Re增大明显增强;由实验数据结合理论模型拟合了适用于石墨烯纳米流体对流换热强度的计算式,计算结果与实验结果最大相对误差不超过25%,平均相对误差仅为4.8%。
A small rectangular channel was designed and fabricated. The convective heat transfer properties of water-based graphene nanofluids in the channel were experimentally investigated by using it as the heat transfer medium under different experimental conditions [different mass concentrations, Reynolds numbers(Re) and heating powers], and some thermal properties of water-based graphene nanofluidswere tested. The experimental results showed that the temperature along the wall of rectangular channel decreased with the increase of Re and increased with the increase of heating power under laminar flow(Re=500～1000). This change regulation was consistent with the heat transfer characteristics of conventional fluids, however, with the increase of mass concentration of nanofluids at same Re and heating power, the wall temperature decreased gradually because of the Brownian motion of graphene nanoparticles, the enhancement of scrambling by mixing of particles and the enhancement of thermal properties of nanofluids. The heat transfer intensity of water-based graphene nanofluid was higher than that of deionized water. When Re was 2 000 and heating power was 210 W, the average Nusselt number(Nu) of water-based graphene nanofluids with 0.03 wt% concentration was 9.3, which was 48.8% higher than that of the based water under the same conditions. Under the influence of inlet effect, the local convective heat transfer coefficient along the channel length decreased gradually, and the maximum local heat transfer coefficient of nanofluid increased by 39.1% compared with the deionized water. The flow heat transfer intensity of graphene nanofluids was obviously enhanced by the Brownian motion of graphene particles at certain Re(500～1400). In order to describe the heat transfer characteristics of water-based graphene nanofluids more clearly, a heat transfer relation was fitted by combining experimental data and theoretical models. Compared with the experimental results, the maximum relative error(MRE) was less than 25%, and the mean relative error was only 4.8%.
A small rectangular channel was designed and fabricated. The convective heat transfer properties of water-based graphene nanofluids in the channel were experimentally investigated by using it as the heat transfer medium under different experimental conditions [different mass concentrations, Reynolds numbers(Re) and heating powers], and some thermal properties of water-based graphene nanofluidswere tested. The experimental results showed that the temperature along the wall of rectangular channel decreased with the increase of Re and increased with the increase of heating power under laminar flow(Re=500～1000). This change regulation was consistent with the heat transfer characteristics of conventional fluids, however, with the increase of mass concentration of nanofluids at same Re and heating power, the wall temperature decreased gradually because of the Brownian motion of graphene nanoparticles, the enhancement of scrambling by mixing of particles and the enhancement of thermal properties of nanofluids. The heat transfer intensity of water-based graphene nanofluid was higher than that of deionized water. When Re was 2 000 and heating power was 210 W, the average Nusselt number(Nu) of water-based graphene nanofluids with 0.03 wt% concentration was 9.3, which was 48.8% higher than that of the based water under the same conditions. Under the influence of inlet effect, the local convective heat transfer coefficient along the channel length decreased gradually, and the maximum local heat transfer coefficient of nanofluid increased by 39.1% compared with the deionized water. The flow heat transfer intensity of graphene nanofluids was obviously enhanced by the Brownian motion of graphene particles at certain Re(500～1400). In order to describe the heat transfer characteristics of water-based graphene nanofluids more clearly, a heat transfer relation was fitted by combining experimental data and theoretical models. Compared with the experimental results, the maximum relative error(MRE) was less than 25%, and the mean relative error was only 4.8%.
引文
[1]He Y R,Jin Y,Chen H S,et al.Heat transfer and flow behaviour of aqueous suspensions of TiO2 nanoparticles(nanofluids)flowing upward through a vertical pipe[J].International Journal of Heat&Mass Transfer,2007,50(11/12):2272-2281.
[2]Kayhani M H,Soltanzadeh H,Heyhat M M,et al.Experimental study of convective heat transfer and pressure drop of TiO2/water nanofluid[J].International Communications in Heat&Mass Transfer,2012,39(3):456-462.
[3]Rayatzadeh H R,Saffar-Avval M,Mansourkiaei M,et al.Effects of continuous sonication on laminar convective heat transfer inside a tube using water-TiO2 nanofluid[J].Experimental Thermal&Fluid Science,2013,48(7):8-14.
[4]Ding Y L,Alias H,Wen D S,et al.Heat transfer of aqueous suspensions of carbon nanotubes(CNT nanofluids)[J].International Journal of Heat&Mass Transfer,2006,49(1/2):240-250.
[5]Chen H S,Yang W,He Y R,et al.Heat transfer and flow behaviour of aqueous suspensions of titanate nanotubes(nanofluids)[J].Powder Technology,2008,183(1):63-72.
[6]Garg P,Alvarado J L,Marsh C,et al.An experimental study on the effect of ultrasonication on viscosity and heat transfer performance of multi-wall carbon nanotube-based aqueous nanofluids[J].International Journal of Heat&Mass Transfer,2009,52(21/22):5090-5101.
[7]Saeedinia M,Akhavan-Behabadi M A,Nasr M.Experimental study on heat transfer and pressure drop of nanofluid flow in a horizontal coiled wire inserted tube under constant heat flux[J].Experimental Thermal&Fluid Science,2012,36(1):158-168.
[8]Wang J L,Zhu J J,Zhang X,et al.Heat transfer and pressure drop of nanofluids containing carbon nanotubes in laminar flows[J].Experimental Thermal&Fluid Science,2013,44(44):716-721.
[9]Naghash A,Sattari S,Rashidi A.Experimental assessment of convective heat transfer coefficient enhancement of nanofluids prepared from high surface area nanoporous graphene[J].International Communications in Heat&Mass Transfer,2016,78:127-134.
[10]Baby T T,Ramaprabhu S.Enhanced convective heat transfer using graphene dispersed nanofluids[J].Nanoscale Research Letters,2011,6(1):1-9.
[11]Sobti A,Wanchoo R K.Thermal conductivity of nanofluids[J].Materials Science Forum,2013,757:111-137.
[12]Tuckerman D B,Pease R F W.High-performance heat sinking for VLSI[J].IEEE Electron Device Letter,1981,2(5):126-129.
[13]吴信宇,吴慧英,屈健,等.纳米流体在芯片微通道中的流动与换热特性[J].化工学报,2008,59(9):2181-2187.Wu X Y,Wu H Y,Qu J,et al.Flow and heat transfer characteristics of nanofluids in silicon chip microchannels[J].CIESC Journal,2008,59(9):2181-2187.
[14]周继军,申盛,徐进良,等.微槽道内单相流动阻力与传热特性[J].化工学报,2005,56(10):1849-1855.Zhou J J,Shen S,Xu J L,et al.Single-phase flow and heat transfer in micro-channels[J].CIESC Journal,2005,56(10):1849-1855.
[15]李孝军,屈健,韩新月,等.微槽道脉动热管的启动及传热特性[J].化工学报,2016,67(6):2263-2270.Li X J,Qu J,Han X Y,et al.Start-up and heat transfer performance of micro-grooved oscillating heat pipe[J].CIESC Journal,2016,67(6):2263-2270.
[16]Peng X F,Peterson G P.The effect of thermofluid and geometrical parameters on convection of liquids through rectangular microchannels[J].International Journal of Heat&Mass Transfer,1995,38(4):755-758.
[17]Peng X F,Peterson G P.Convective heat transfer and flow friction for water flow in microchannel structures[J].International Journal of Heat&Mass Transfer,1996,39(12):2599-2608.
[18]Kim B.An experimental study on fully developed laminar flow and heat transfer in rectangular microchannels[J].International Journal of Heat&Fluid Flow,2016,62(Part B):224-232.
[19]刘东,舒宇,何蔚然,等.微针肋槽道内去离子水换热特性[J].强激光与粒子束,2018,30(4):25-30.Liu D,Shu Y,He W R,et al.Heat transfer characteristics of mini pin-fin channels[J].High Power Laser and Particle Beams,2018,30(4):25-30.
[20]Drew D A,Passman S L.Theory of multicomponent fluids[M].Berlin:Springer,1999:600.
[21]Nield D A,Bejan A.Convection in porous media[M].Berlin:Springer,2011:284-290.
[2]Kayhani M H,Soltanzadeh H,Heyhat M M,et al.Experimental study of convective heat transfer and pressure drop of TiO2/water nanofluid[J].International Communications in Heat&Mass Transfer,2012,39(3):456-462.
[3]Rayatzadeh H R,Saffar-Avval M,Mansourkiaei M,et al.Effects of continuous sonication on laminar convective heat transfer inside a tube using water-TiO2 nanofluid[J].Experimental Thermal&Fluid Science,2013,48(7):8-14.
[4]Ding Y L,Alias H,Wen D S,et al.Heat transfer of aqueous suspensions of carbon nanotubes(CNT nanofluids)[J].International Journal of Heat&Mass Transfer,2006,49(1/2):240-250.
[5]Chen H S,Yang W,He Y R,et al.Heat transfer and flow behaviour of aqueous suspensions of titanate nanotubes(nanofluids)[J].Powder Technology,2008,183(1):63-72.
[6]Garg P,Alvarado J L,Marsh C,et al.An experimental study on the effect of ultrasonication on viscosity and heat transfer performance of multi-wall carbon nanotube-based aqueous nanofluids[J].International Journal of Heat&Mass Transfer,2009,52(21/22):5090-5101.
[7]Saeedinia M,Akhavan-Behabadi M A,Nasr M.Experimental study on heat transfer and pressure drop of nanofluid flow in a horizontal coiled wire inserted tube under constant heat flux[J].Experimental Thermal&Fluid Science,2012,36(1):158-168.
[8]Wang J L,Zhu J J,Zhang X,et al.Heat transfer and pressure drop of nanofluids containing carbon nanotubes in laminar flows[J].Experimental Thermal&Fluid Science,2013,44(44):716-721.
[9]Naghash A,Sattari S,Rashidi A.Experimental assessment of convective heat transfer coefficient enhancement of nanofluids prepared from high surface area nanoporous graphene[J].International Communications in Heat&Mass Transfer,2016,78:127-134.
[10]Baby T T,Ramaprabhu S.Enhanced convective heat transfer using graphene dispersed nanofluids[J].Nanoscale Research Letters,2011,6(1):1-9.
[11]Sobti A,Wanchoo R K.Thermal conductivity of nanofluids[J].Materials Science Forum,2013,757:111-137.
[12]Tuckerman D B,Pease R F W.High-performance heat sinking for VLSI[J].IEEE Electron Device Letter,1981,2(5):126-129.
[13]吴信宇,吴慧英,屈健,等.纳米流体在芯片微通道中的流动与换热特性[J].化工学报,2008,59(9):2181-2187.Wu X Y,Wu H Y,Qu J,et al.Flow and heat transfer characteristics of nanofluids in silicon chip microchannels[J].CIESC Journal,2008,59(9):2181-2187.
[14]周继军,申盛,徐进良,等.微槽道内单相流动阻力与传热特性[J].化工学报,2005,56(10):1849-1855.Zhou J J,Shen S,Xu J L,et al.Single-phase flow and heat transfer in micro-channels[J].CIESC Journal,2005,56(10):1849-1855.
[15]李孝军,屈健,韩新月,等.微槽道脉动热管的启动及传热特性[J].化工学报,2016,67(6):2263-2270.Li X J,Qu J,Han X Y,et al.Start-up and heat transfer performance of micro-grooved oscillating heat pipe[J].CIESC Journal,2016,67(6):2263-2270.
[16]Peng X F,Peterson G P.The effect of thermofluid and geometrical parameters on convection of liquids through rectangular microchannels[J].International Journal of Heat&Mass Transfer,1995,38(4):755-758.
[17]Peng X F,Peterson G P.Convective heat transfer and flow friction for water flow in microchannel structures[J].International Journal of Heat&Mass Transfer,1996,39(12):2599-2608.
[18]Kim B.An experimental study on fully developed laminar flow and heat transfer in rectangular microchannels[J].International Journal of Heat&Fluid Flow,2016,62(Part B):224-232.
[19]刘东,舒宇,何蔚然,等.微针肋槽道内去离子水换热特性[J].强激光与粒子束,2018,30(4):25-30.Liu D,Shu Y,He W R,et al.Heat transfer characteristics of mini pin-fin channels[J].High Power Laser and Particle Beams,2018,30(4):25-30.
[20]Drew D A,Passman S L.Theory of multicomponent fluids[M].Berlin:Springer,1999:600.
[21]Nield D A,Bejan A.Convection in porous media[M].Berlin:Springer,2011:284-290.