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通过系统的数值模拟计算,在准确确定甲烷的热力学和传输物性变化的情况下,详细分析了两种热流密度下超临界压力对低温甲烷的湍流传热过程的影响,揭示了对流换热Nusselt数的变化规律。计算结果表明:在超临界压力下,热力学和传输物性对湍流传热现象会造成很大的影响,尤其在甲烷的临界区域附近,由于物性的剧烈变化会导致传热过程的恶化现象;在高热流密度情况下(如7MW/m2),增大管内压力有利于提高对流换热强度;现有的常用变物性湍流传热公式不能适用于超临界压力下低温甲烷的对流换热计算。
Through numerical simulation of the system, the influence of supercritical pressure on the turbulent heat transfer process of methane at low temperature under two heat fluxes is analyzed in detail under the condition of accurately determining the thermodynamics and the change of transport properties of methane. It is revealed that the convective heat transfer Nusselt number The law of change. The calculation results show that under the supercritical pressure, the thermodynamics and transport properties have a great influence on the turbulent heat transfer. Especially in the vicinity of the critical area of methane, due to the drastic change of physical properties, the heat transfer process will worsen. At high In the case of heat flux density (eg 7MW / m2), increasing the pressure in the tube is beneficial to increase the convective heat transfer strength. The existing heat transfer equation of variable physical turbulence can not be applied to the calculation of the convective heat transfer of methane at low temperature under supercritical pressure.