Compact Heat Exchangers (CHEs) are widely used in various applications in thermal fluid-systems including aerospace due to their compactness and light weight coupled with high effectiveness. Among the different types of CHEs for Aircraft Environmental Control System (ECS) and Avionics cooling applications, a cross-flow CHE with Lance & Offset fin is of special interest because of their high heat rejection capability. In the present work, the heat transfer coefficient of water based Al₂O₃ nano-fluid (NF) flowing in a Compact Plate-fin Heat Exchanger having Lance & Offset fins is studied experimentally. As part of experimental investigation a test setup is designed and developed. Experiments are conducted in the range of mass flux from 50 to 350 kg/s m² (100 ≤ Re ≤ 600) at room temperature as well as at higher temperatures up to 70 °C. In this study, Al₂O₃ volume concentration in water is varied from 0.255% to 0.51%. The variation of heat transfer coefficients and pressure drops of Al₂O₃ nano-fluid with respect to water are presented in graphical form for different mass fluxes. The heat transfer coefficient gets enhanced in low NF temperature regions (between 30 °C-45 °C) up to 25% for 1%NF and up to 35% for 2%NF, where as there is only a marginal improvement at higher operating temperatures (between 60 °C-75 °C). The uncertainty analysis is carried out for heat transfer coefficient based on sensors specification.

中文翻译：

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在带有水枪和偏置翅片的紧凑型热交换器中，用于水基Al 2 O 3纳米流体的传热系数和压降的测量

紧凑型热交换器（CHEs）的紧凑性，重量轻以及高效性，使其广泛用于包括航空航天在内的热流体系统中。在飞机环境控制系统（ECS）和航空电子冷却应用的不同类型的CHE中，带有长矛和偏置鳍片的错流CHE具有很高的散热能力，因此特别受到关注。在目前的工作中，实验研究了在带有兰斯和偏置翅片的紧凑型板翅式换热器中流动的水基Al ₂ O ₃纳米流体（NF）的传热系数。作为实验研究的一部分，设计并开发了测试装置。实验在50至350 kg / sm ²的质量通量范围内进行（100≤Re≤600）在室温以及最高70°C的高温下。在这项研究中，水中的Al ₂ O ₃体积浓度在0.255％至0.51％之间变化。对于不同的质量通量，以图形形式表示了Al ₂ O ₃纳米流体相对于水的传热系数和压降的变化。在低NF温度区域（在30°C-45°C之间），传热系数得到了提高，对于1％NF可达25％，对于2％NF可达35％，这是因为在较高的工作温度下仅有少量改善温度（介于60°C至75°C之间）。根据传感器规格对传热系数进行不确定度分析。