矩形窄缝通道内水稳态和瞬态流动换热特性实验

Experimental Study on Steady and Transient Characteristics of Heat Transfer and Flow for Single-phase Water Flow in Narrow Rectangular Channel

以去离子水为工质,在压力0.5～5.0 MPa的范围内,对矩形窄缝通道内水稳态及瞬态流动换热特性进行了实验研究。结果表明:矩形窄缝通道在水平和竖直放置以及稳态和瞬态条件下,水的流动换热特性呈现出基本相同的规律。层流向紊流过渡区域的雷诺数(Re)为900<Re<1300,比常规通道提前,单相摩擦阻力系数比常规通道大;采用Dittus-Boelter公式的形式拟合得到了新的换热实验关联式,其系数较Dittus-Boelter公式的系数约小11.3%。在稳态条件下,紊流区换热系数随质量流速的增加而增大,增大趋势比较明显;换热系数随热流密度的变化不明显;压力对单相强迫对流换热特性基本没有影响。

Single-phase water characteristics of flow and heat transfer in steady and transient conditions were experimentally investigated in the horizontal and vertical rectangular channels with the pressure ranging from 0.5MPa to 5.0MPa..The experimental results indicated the characteristics of single-phase water flow and heat transfer in transient conditions were similar to that in steady conditions. So were the experimental results for horizontal and vertical narrow rectangular channels. The single-phase water frictional resistance coefficient in narrow rectangular channel were larger than that of normal channels, and the transition region from laminar flow to turbulence flow had a small Reynolds number relative to Qonventional channels. The critical Reynolds number at the transition region was in the range 900 ≤Re ≤1300. Based on Dittus-Boelter correlation, the experimental correlations of heat transfer were obtained, and the coefficients of the new experimental correlations were less about 11.3% than that of Dittus-Boelter correlation. In steady conditions, the heat transfer coefficient at turbulence flow region increased observably with the mass flux, it also increased slightly with the heat flux, and it had slight relationship with the pressure.