Abstract Understanding heat transfer to endothermic hydrocarbon fuels (EHFs) with pyrolysis at high heat flux is a challenging issue for the design of regenerative cooling panels in the fuel-cooled thermal management technology of advanced aircrafts. In this work, the convective heat transfer of supercritical EHFs in presence of pyrolysis reactions was experimentally investigated in horizontal tubes at the heat flux up to 1.836 MW/m2 under 3.5 MPa. A CFD model with an improved kinetics (Chem Eng Sci 2019, 207, 202-214) has been developed and extensively validated to get detailed information on the coupling mechanism of heat transfer and pyrolysis. The heat transfer rate can be enhanced by pyrolysis reactions at relative low heat flux (below 400 kW/m2). With increasing heat flux, the rapid and high-degreed pyrolysis near-wall considerably changes the local composition and thus the thermophysical properties, resulting in the significant heat absorption differences in the cross section and local heat transfer deterioration. Typically, Nub decreases from 108.8 to 73.4 (about 30%) when the heat flux increases from 426 to 758 kW/m2. The possible reasons may be attributed to the weakened near-wall turbulence by the increased fluid viscosity in presence of secondary products, as well as the increased thermal boundary layer effect attributed to the high near-wall heat absorption and huge radial property gradient at high heat flux.

中文翻译：

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水平管中超临界碳氢燃料的传热：高热通量下近壁热解的影响

摘要 了解在高热通量下热解吸热碳氢燃料 (EHF) 的热传递是先进飞机燃料冷却热管理技术中再生冷却板设计的一个具有挑战性的问题。在这项工作中，在 3.5 MPa 下，在水平管中以高达 1.836 MW/m2 的热通量对存在热解反应的超临界 EHF 的对流传热进行了实验研究。已经开发并广泛验证了具有改进动力学的 CFD 模型 (Chem Eng Sci 2019, 207, 202-214)，以获得有关传热和热解耦合机制的详细信息。在相对较低的热通量（低于 400 kW/m2）下，热解反应可以提高传热率。随着热通量的增加，近壁面的快速和高度热解显着改变了局部组成，从而改变了热物理性质，导致横截面的显着吸热差异和局部传热恶化。通常，当热通量从 426 增加到 758 kW/m2 时，Nub 从 108.8 减少到 73.4（约 30%）。可能的原因可能是由于存在二次产物时流体粘度增加导致近壁湍流减弱，以及高温下近壁吸热高和径向性能梯度大导致热边界层效应增加。通量。当热通量从 426 增加到 758 kW/m2 时，Nub 从 108.8 减少到 73.4（约 30%）。可能的原因可能是由于存在二次产物时流体粘度增加导致近壁湍流减弱，以及高温下近壁吸热高和径向性能梯度大导致热边界层效应增加。通量。当热通量从 426 增加到 758 kW/m2 时，Nub 从 108.8 减少到 73.4（约 30%）。可能的原因可能是由于存在二次产物时流体粘度增加导致近壁湍流减弱，以及高温下近壁吸热高和径向性能梯度大导致热边界层效应增加。通量。