Purpose

The purpose of this study is to experimentally and numerically scrutinize the heat transfer enhancement in pool boiling and condensation by changing the hydrophilicity or hydrophobicity properties of the working fluid, i.e. by use of nanofluid solution.

Design/methodology/approach

For specifying the effects of nanoparticle concentration on heat transfer properties, two different nanofluid solutions (h-BN/DCM and SiO₂/DCM) at three different volumetric concentrations were prepared and tested under different heat flux conditions. Boiling curves, alterations in pressure with heat flux and heat transfer coefficients for both boiling and condensation processes were obtained and viscosity measurements were performed for dichloromethane (DCM) and each working fluid was prepared. In addition, a series of numerical simulations, via computational fluid dynamics approach, was performed for specifying the evaporation–condensation phenomena and temperature and velocity distributions.

Findings

Nanoparticle addition inside the base fluid increased the thermal characteristics of the base fluid significantly. For the experimental results of h-BN/DCM nanofluid, the increment rate in heat transfer coefficient for saturation boiling, after-saturation boiling and condensation processes was found as 27.59%, 14.44% and 15%, respectively.

Originality/value

The novelty of this comparison study is that there is no such experimental and numerical comparison study in literature for DCM fluid, which concentrates on thermal performance enhancement and compares the effect of different kinds of nanoparticles on heat transfer characteristics for boiling–condensation processes.

中文翻译：

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使用h-BN / DCM和SiO2 / DCM纳米流体增强池沸腾和冷凝中的传热：实验和数值比较

目的

这项研究的目的是通过改变工作流体的亲水性或疏水性，即使用纳米流体溶液，在实验上和数值上仔细研究池沸腾和冷凝过程中的传热增强。

设计/方法/方法

为了说明纳米颗粒浓度对传热性能的影响，制备了三种不同体积浓度的两种不同的纳米流体溶液（h-BN / DCM和SiO ₂ / DCM），并在不同的热通量条件下进行了测试。获得了沸腾曲线和冷凝过程的沸腾曲线，压力随热通量和传热系数的变化，并对二氯甲烷（DCM）进行了粘度测量，并制备了每种工作流体。此外，还通过计算流体动力学方法进行了一系列数值模拟，以指定蒸发冷凝现象以及温度和速度分布。

发现

在基础流体内部添加纳米颗粒显着提高了基础流体的热特性。对于h-BN / DCM纳米流体的实验结果，发现饱和沸腾，后饱和沸腾和冷凝过程的传热系数增量分别为27.59％，14.44％和15％。

创意/价值

这项比较研究的新颖之处在于，在文献中没有针对DCM流体的实验和数值比较研究，该研究专注于提高热性能，并比较了各种纳米颗粒对沸腾-冷凝过程中传热特性的影响。