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首页> 外文期刊>Journal of Heat Transfer >Heating And Ignition Of Metal Particles In The Transition Heat Transfer Regime
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Heating And Ignition Of Metal Particles In The Transition Heat Transfer Regime

机译：过渡传热条件下金属颗粒的加热和着火

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摘要

This paper considers the heating and ignition of small metallic particles in hot gases for a range of Knudsen numbers, for which the continuum description of heat transfer is not valid. Modified Fuchs' model for the transition heat transfer analysis was adapted to treat diatomic gas with properties changing as a function of temperature. The dimensionless heat transfer coefficient, Nusselt number, was calculated as a function of the particle diameter for the transition heat transfer regime. Heat transfer rates in the transition regime are somewhat different from one another for the cases of particle heating and cooling while the absolute values of the particle-gas temperature difference are the same. This effect does not exist for the continuum heat transfer model. It is observed that the applicability of the continuum heat transfer model for particles of different sizes depends on pressure and particle-air temperature difference. For example, for particles at 300 K heated in air at 2000 K, the continuum heat transfer model can be used for particle diameters greater than 10 μm and 1 μm at the pressures of 1 bar and 10 bars, respectively. Transition heat transfer model must be used for the analysis of heat transfer for nanosized particles. For calculating the ignition delay, the continuum model remains useful for particle diameters greater than 18 μm and 2 μm for 1 bar and 10 bars, respectively. The sensitivity of the transition heat transfer model to the accommodation coefficient is evaluated. It is found that for metallic particles, the accommodation coefficient has a relatively weak effect on the heat transfer rate.
机译：本文考虑了在一定范围的努德森数下热气体中小金属颗粒的加热和着火，因此连续传热描述无效。改进的Fuchs模型用于过渡传热分析，适用于处理性质随温度变化的双原子气体。计算无量纲的传热系数，努塞尔数，作为过渡传热方案的粒径的函数。对于颗粒加热和冷却的情况，在过渡状态下的传热速率彼此之间有些不同，而颗粒-气体温度差的绝对值相同。对于连续传热模型不存在这种效果。可以看出，连续传热模型对不同尺寸颗粒的适用性取决于压力和颗粒空气温度差。例如，对于在2000 K的空气中加热的300 K的颗粒，连续传热模型可以分别在1 bar和10 bar的压力下用于直径大于10μm和1μm的颗粒。必须使用过渡传热模型来分析纳米颗粒的传热。为了计算点火延迟，对于1 bar和10 bar分别大于18μm和2μm的粒径，连续模型仍然有用。评估了过渡传热模型对调节系数的敏感性。发现对于金属颗粒，调节系数对传热速率的影响相对较弱。

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