超临界压力下水在倾斜管内传热特性的研究

I HEAT TRANSFER CHARACTERISTICS OF SUPERCR TICAL WATER FLOWING IN INCLINED TUBES

以水为工质,在倾角α=14°和10°、压力22.0～28.OMPa、质量流速600～1400kg/(m^2·s)、内壁热负荷250～410kW/m^2的参数范围内,研究了水(特别是在大比热区附近)的传热特性.针对微倾斜管中,内壁面既非定壁温也非定热流的边界条件下,成功地提出了二维温度场计算方法,从而获得了传热系数、努赛尔特数等.分别在传热恶化前及传热恶化后两个区域内关联了传热系数数据.对于超临界流体在最大比热区附近呈现的特殊传热特性规律进行了分析,并研究了倾斜管中由于浮升力引起的自然对流对各参数沿周向分布的影响.

Investigations are made of heat transfer with supercritical water flowing in inclined tubes. A comprehensive set of data is obtained at pressure from 22. 0 to 28. 0 MPa, mass flow rate from 600 to 1400 kg/(m2· s), he at fluxes from 250 to 410kW/m, and inclinations of 10°and 14°. A new method of calculating two dimensional wall temperature field for non - vertical tubes is presented at the inside wall condition of neither temperature constant nor heat flux constant. Then heat transfer coefficients and Nusselt number are also obtained. Heat transfer coefficient data for normal heat transfer region and heat transfer deterioration region is correlated respectively. Special heat transfer behavior near the pseudocriti-cal region is analysed. Parameter distribution along the circumference induced by natural convection is also studied.