Boiling and condensation, a kind of convective heat transfer characterized by high heat fluxes, are widely encountered in many engineering applications. Fluids are the main heat carriers in heat transfer applications, and hence performance of a thermal system is remarkably linked with the working fluid's thermophysical properties. In thermal systems, nanofluids have been embarked upon to use as a working fluid because of their improved specifications. Pool boiling and condensation heat transfer characteristics of a new kind nanofluid consisting of hexagonal boron nitride nanoparticles and dichloromethane base fluid were investigated experimentally. Experiments were performed with dichloromethane and hexagonal boron nitride/dichloromethane nanofluid solutions to specify nanoparticles' effect on thermal performance. Nanofluid solutions were prepared at varying volumetric concentrations ranging from 0.5% to 1.5% to analyze the impacts of nanoparticle concentration rate. Experiments were conducted under varying input powers ranging from 50 W to 350 W. Boiling curves, the changes in pressure versus heat flux, heat transfer coefficients both in boiling and condensation processes were determined. Viscosity was also measured for each working fluid. It was figured out that nanoparticle addition to the base fluid dramatically affected thermal characteristics. Some enhancements of 27.6% and 17.65% for boiling and condensation processes have been achieved.

中文翻译：

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六方氮化硼/二氯甲烷纳米流体的核沸腾沸腾和冷凝传热特性

沸腾和冷凝是一种以高热通量为特征的对流换热，在许多工程应用中都广为使用。流体是传热应用中的主要载热体，因此，热系统的性能与工作流体的热物理性质显着相关。在热系统中，由于其改进的规格，已开始将纳米流体用作工作流体。实验研究了一种由六方氮化硼纳米粒子和二氯甲烷基流体组成的新型纳米流体的池沸腾和冷凝传热特性。用二氯甲烷和六方氮化硼/二氯甲烷纳米流体溶液进行了实验，以说明纳米颗粒对热性能的影响。制备了浓度范围从0.5％到1.5％的纳米流体溶液，以分析纳米颗粒浓缩率的影响。实验是在50 W至350 W的不同输入功率下进行的。沸腾曲线确定了压力与热通量的变化，沸腾和冷凝过程中的传热系数。还测量了每种工作流体的粘度。已经发现，向基础流体中添加纳米颗粒显着影响了热特性。对于沸腾和冷凝过程，已实现了27.6％和17.65％的增强。测定沸腾曲线，压力与热通量的变化，沸腾和冷凝过程中的传热系数。还测量了每种工作流体的粘度。已经发现，向基础流体中添加纳米颗粒显着影响了热特性。对于沸腾和冷凝过程，已实现了27.6％和17.65％的增强。测定沸腾曲线，压力与热通量的变化，沸腾和冷凝过程中的传热系数。还测量了每种工作流体的粘度。已经发现，向基础流体中添加纳米颗粒显着影响了热特性。对于沸腾和冷凝过程，已实现了27.6％和17.65％的增强。