环形小通道内水单相换热特性的实验研究

Heat-transfer characteristics of single-phase water flow in small annular channel

采用自行设计的环形小通道换热装置,对双面加热环形小通道内单相水处于流动充分发展下的对流换热特性进行了实验研究,通过热电偶、流量计测量内外壁面温度、水温和水流量,分析单相水处于不同热流密度下内外壁面热流密度、流量与对流传热系数之间的关系特性,结果表明:通道内外壁单独加热时的壁面对流传热系数均随加热热流密度的增大而增大,当加热热流密度一定时,内壁面对流传热系数随流量的增大而增大,外壁面对流传热系数随流量的增大变化不明显;内外壁同时加热时,随着内、外壁加热热流密度比的增大,内壁面的对流传热系数先减小后增大,而外壁面的对流传热系数一直增大。

An experimental study was carried out to investigate the convective heat-transfer characteristics of single- phase water in the self-designed device with small bilaterally-heated annular channel under the condition of fully developed flow. By measuring the temperature with thermocouples and the flow velocity with flowmeters, the relationship between heat flux, flow velocity and convective heat-transfer coefficient was investigated at the different heat fluxes. The results show that when the outer or inner wall is heated separately, the convective heat-transfer coefficient of the wall increases with the increase of heat flux; and keeping the heat-flux, the convective heat. transfer coefficient of the inner wall increases with the increase of water flow, the outer wall does not change significantly; when the outer and inner walls are heated together, the convective heat-transfer coefficient of the inner wall reduces first, and then increases, and the outer wall keeps increasing.