多壁碳纳米管水基纳米流体重力热管传热特性数值模拟

Numerical simulation of heat transfer characteristics of multi-walled carbon nanotubes water-based nanofluids applied in gravity heat pipes

为揭示多壁碳纳米管水基纳米流体应用在重力热管中的传热特性,基于多相流模型(VOF)建立其重力热管数值模型,并将数值结果与实验数据进行对比验证。以热阻作为性能评价指标,改变加热功率和充液率,讨论二者对热管换热性能的具体影响。通过添加传热传质源项来编写用户自定义函数(UDF)完成内部流体蒸发冷凝过程中的相变模拟。模拟结果表明:该数值模型能够较好模拟多壁碳纳米管水基纳米流体应用重力热管内部复杂的流动与传热过程;在选定的加热功率及充液率参数范围内,该重力热管的整体热阻随蒸发段加热功率的增大而减小,随充液率的增大而增大。

In order to reveal the heat transfer characteristics of multi-walled carbon nanotubes (MWCNTs) water-based nanofluids applied in gravity heat pipes, a numerical model of MWCNTs gravity heat pipes was established based on the multiphase flow model (VOF), and the numerical results were compared with the experimental data. Taking thermal resistance as performance evaluation index, the specific effects of heating power and liquid filling rate on heat transfer performance of heat pipe are discussed. User-defined function (UDF) is compiled by adding heat and mass transfer source term to simulate phase transition in evaporation and condensation of internal fluid. The simulation results show that the numerical model can well simulate the complex flow and heat transfer process of multi-walled carbon nanotube waterbased nanofluids applied in gravity heat pipes. Within the selected heating power and filling rate parameters, the overall thermal resistance of the gravity heat pipe decreases with the increase of heating power in the evaporation section and increases with the increase of filling rate.