Upward Flow Boiling to DI-Water and Cuo Nanofluids Inside the Concentric Annuli
Upward Flow Boiling to DI-Water and Cuo Nanofluids Inside the Concentric Annuli
复制标题
DOI：
10.18869/acadpub.jafm.67.223.19404
复制
发表时间：
2015-10
影响因子：
1
通讯作者：
M. Sarafraz;F. Hormozi;S. Peyghambarzadeh;N. Vaeli
中科院分区：
文献类型：
--
作者：
M. Sarafraz;F. Hormozi;S. Peyghambarzadeh;N. Vaeli
本文对去离子水和氧化铜水基纳米流体在不同工况下的流动沸腾换热系数进行了实验测量和比较。液体在环形空间中流动。根据实验结果，可以看到两个具有不同机理的传热区域，即强制对流区和核沸腾区。结果表明，随着热流密度的增加，两种工质在两个换热区域的流动沸腾换热系数均增大。此外，通过增加流体的流速，在两个区域处的传热系数显著增加。流体入口温度作为一个复杂的参数对环空的影响进行了研究和简要讨论。结果表明，随着入口温度的升高，核态沸腾区和强制对流区的边界逐渐被取代，在较低的热流密度下，随着入口温度的升高，核态沸腾区逐渐占据主导地位。此外，由于气泡和局部搅拌的相互作用，可以获得更高的传热系数。对Chen型模型进行了热物性修正，并对实验数据进行了检验。结果表明，实验数据与关联式计算结果吻合较好，偏差在30%以内。
In this work, flow boiling heat transfer coefficients of deionized water and copper oxide water-based nanofluids at different operating conditions have been experimentally measured and compared. The liquid flowed in an annular space. According to the experiments, two distinguished heat transfer regions with two different mechanisms can be seen namely forced convective and nucleate boiling regions. Results demonstrated that with increasing the applied heat flux, flow boiling heat transfer coefficient increases for both of test fluids at both heat transfer regions. In addition to, by increasing the flow rate of fluid, the heat transfer coefficient dramatically increases at both regions. Influence of inlet temperature of fluid to the annulus as a complicated parameter has been investigated and briefly discussed. Results showed that inlet temperature of fluid displaces the boundary between forced convection and nucleate boiling areas such that with increasing the inlet temperature, nucleation mechanism become dominant mechanism at lower heat fluxes. Furthermore, higher heat transfer coefficient can be obtained due to interactions of bubbles and local agitations. Also, Chen type model was modified in terms of thermo-physical properties and examined to experimental data. Results showed that experimental data are in a good agreement with those of obtained by the correlation with deviation up to 30%.