Balla Hyder H, Abdullah Shahrir, Mohdfaizal Wan, Zulkifli Rozli, Sopian Kamaruzaman
Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, UniversitiKebangsaan Malaysia, Malaysia.
J Oleo Sci. 2013;62(7):533-9. doi: 10.5650/jos.62.533.
A numerical simulation model for laminar flow of nanofluids in a pipe with constant heat flux on the wall was built to study the effect of the Reynolds number on convective heat transfer and pressure loss. The investigation was performed for hybrid nanofluids consisting of CuO-Cu nanoparticles and compared with CuO and Cu in which the nanoparticles have a spherical shape with size 50, 50, 50nm respectively. The nanofluids were prepared, following which the thermal conductivity and dynamic viscosity were measured for a range of temperatures (10 -60°C). The numerical results obtained were compared with the existing well-established correlation. The prediction of the Nusselt number for nanofluids agrees well with the Shah correlation. The comparison of heat transfer coefficients for CuO, Cu and CuO-Cu presented an increase in thermal conductivity of the nanofluid as the convective heat transfer coefficient increased. It was found that the pressure loss increases with an increase in the Reynolds number, nanoparticle density and particle volume fraction. However, the flow demonstrates enhancement in heat transfer which becomes greater with an increase in the Reynolds number for the nanofluid flow.
建立了一个用于模拟纳米流体在壁面具有恒定热流的管道中层流的数值模拟模型，以研究雷诺数对对流换热和压力损失的影响。对由CuO-Cu纳米颗粒组成的混合纳米流体进行了研究，并与CuO和Cu纳米颗粒进行了比较，其中纳米颗粒呈球形，尺寸分别为50、50、50nm。制备了纳米流体，随后测量了一系列温度（10 - 60°C）下的热导率和动态粘度。将获得的数值结果与现有的成熟关联式进行了比较。纳米流体的努塞尔数预测与Shah关联式吻合良好。CuO、Cu和CuO-Cu的传热系数比较表明，随着对流换热系数的增加，纳米流体的热导率增加。研究发现，压力损失随着雷诺数、纳米颗粒密度和颗粒体积分数的增加而增加。然而，流动显示出传热增强，随着纳米流体流动雷诺数的增加，传热增强变得更大。
