Boiling heat transfer with pure fluids deteriorates significantly under downward-facing heater (−1g) and in narrow gaps/confined spaces where surface tension dominates over buoyancy. The addition of amphiphilic additives such as surfactants and ionic liquids in water is well known to enhance boiling heat transfer under the downward-facing heater. However, the potential of amphiphilic additives to enhance boiling heat transfer in confined spaces is not explored much in the literature. In this work, confined pool boiling experiments were performed with aqueous surfactant solutions under various subcoolings, heater orientations, and confinement gaps (0.2 mm to 2.8 mm). Results are compared with corresponding experiments with pure water. In comparison to water, where bubble coalescence was prevalent in confined spaces, aqueous surfactant solutions suppressed coalescence and facilitated bubble removal sideways away from the heater surface, increasing the wetted area. This phenomenon with surfactant solutions was observed at all orientations that enhanced heat transfer in comparison to water. A maximum of 120% increase in heat transfer coefficient (HTC) and 280% increase in critical heat flux with surfactant was observed in comparison to the baseline case of pure water. Further, we demonstrated boiling heat transfer performance in a closed confined chamber, where significant enhancement in HTC was observed with the aqueous ionic liquid solution in comparison to water. We believe the results presented in this work can be utilized to develop boiling-based miniaturized thermal management and energy systems.

中文翻译：

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在密闭空间中促进池沸腾传热的两亲性添加剂

在朝下的加热器下（-1 g）和狭窄的间隙/密闭空间中，其中表面张力在浮力上占主导地位。众所周知，在水中添加两亲性添加剂（例如表面活性剂和离子液体）可增强朝下加热器下的沸腾传热。然而，两亲性添加剂增强密闭空间中沸腾传热的潜力在文献中并未得到太多研究。在这项工作中，使用表面活性剂水溶液在各种过冷，加热器方向和限制间隙（0.2毫米至2.8毫米）下进行了有限的池沸腾实验。将结果与纯水的相应实验进行比较。与密闭空间中气泡聚结比较普遍的水相比，表面活性剂水溶液抑制了聚结并有助于从加热器表面侧向去除气泡。增加润湿区域。与水相比，在所有方向上都观察到了表面活性剂溶液的这种现象，该现象增强了热传递。与纯水的基线情况相比，使用表面活性剂的传热系数（HTC）最多增加了120％，临界热通量最多增加了280％。此外，我们证明了在密闭密闭室中的沸腾传热性能，与水相比，离子液体水溶液在HTC中观察到显着增强。我们认为，这项工作中提出的结果可用于开发基于沸腾的微型热管理和能源系统。与纯水的基线情况相比，使用表面活性剂的传热系数（HTC）最多增加了120％，临界热通量最多增加了280％。此外，我们证明了在密闭密闭室中的沸腾传热性能，与水相比，离子液体水溶液在HTC中观察到显着增强。我们认为，这项工作中提出的结果可用于开发基于沸腾的微型热管理和能源系统。与纯水的基线情况相比，使用表面活性剂的传热系数（HTC）最多增加了120％，临界热通量最多增加了280％。此外，我们证明了在密闭密闭室中的沸腾传热性能，与水相比，离子液体水溶液在HTC中观察到显着增强。我们认为，这项工作中提出的结果可用于开发基于沸腾的微型热管理和能源系统。与水相比，使用离子液体水溶液观察到的HTC显着提高。我们认为，这项工作中提出的结果可用于开发基于沸腾的微型热管理和能源系统。与水相比，使用离子液体水溶液观察到的HTC显着提高。我们认为，这项工作中提出的结果可用于开发基于沸腾的微型热管理和能源系统。