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在压力为10~28 MPa、质量流速为500~1 220 kg/(m2.s)、热负荷为140~400 kW/m2的工况范围内,在试验台上进行了直径38.1 mm、厚度7.5 mm垂直上升内螺纹管的传热特性研究.结果表明:在亚临界压力区,内螺纹管的旋流作用使内螺纹管具有明显的传热强化效果;随着压力的升高,特别是在近临界压力区,由于汽-液比体积的差值减小,内螺纹管的旋流作用降低,所以强化传热效果降低.在超临界压力区,管内流体属于单相流体,当管中心处工质温度与贴壁处工质温度均低于拟临界温度时,管中心工质与管内贴壁处工质之间的比体积相差很小,使得内螺纹管的旋流作用降低,管壁温度升高较快,传热恶化;当管中心工质温度低于拟临界温度、而贴壁处工质温度高于拟临界温度时,两处工质之间的比体积差增大,使得内螺纹管的旋流作用增强,传热强化,壁温降低.
At a pressure of 10 ~ 28 MPa, a mass flow rate of 500 ~ 1 220 kg / (m2.s) and a heat load of 140 ~ 400 kW / m2, a diameter of 38.1 mm and a thickness of 7.5 mm vertical rising tube.The results show that in the subcritical pressure zone, the swirling effect of the internally threaded tube makes the internally threaded tube have a significant heat transfer enhancement effect; with the increase of the pressure, especially in the In the near critical pressure zone, due to the decrease of the vapor-liquid specific volume, the swirling flow of the internally threaded tube decreases, so the heat transfer enhancement effect is reduced.In the supercritical pressure zone, the fluid in the tube belongs to a single-phase fluid, When the temperature of working fluid and the working temperature of the adherent wall are both lower than the quasi-critical temperature, the specific volume difference between the working fluid in the pipe center and the wall of the pipe is small, so that the swirling effect of the internally threaded pipe is reduced. When the temperature of the working fluid in the pipe center is lower than the quasi-critical temperature and the working fluid temperature at the adhensive wall is higher than the quasi-critical temperature, the specific volume difference between the two working materials increases, making the The swirling effect of the internally threaded pipe is enhanced, the heat transfer is enhanced and the wall temperature is reduced.