圆管内对流换热过程中潜热型功能流体流动阻力特性的实验研究

Experimental study on flow characteristics of latent functionally thermal fluid in circular tube

实验研究了由正十四烷和尿素甲醛树脂制成的相变微胶囊和水混合制成的潜热型功能流体在流过恒热流圆管进行对流换热时的流动阻力特性,获得了压降随流速的变化关系、摩擦阻力系数和表观黏度随R e的变化关系。并在同样条件下用单相水进行了对比实验。相变微胶囊的加入导致流体流动阻力较单相流体有显著增大。管路中扰动件导致单相流体的流动阻力特性在低R e条件下呈湍流特征;功能流体则呈不同规律,扰动仅导致流动阻力进一步增大,而流动阻力特性仍呈层流特征。

An experimental study on the flow characteristics of microencapsulated phase-change material （MCPCM） suspension flow in a circular tube was conducted under the heat transfer condition of constant wall heat flux. The MCPCM particles consist of tetradecane as the phase-change material and a polyoxymethylene urea wall. The variation of pressure drop with mean velocity, the variation of friction factor and the variation of apparent viscosity with Reynolds number were obtained. The comparison study was also conducted under the same conditions by using the pure water as the fluid. The employment of MCPCM particles significantly increases the pressure drop of the flow through the tube. The disturbance in the tube introduces that the friction factor for the pure water flow exhibits turbulent characteristics when the Reynolds number is smaller. For the suspension flow of MCPCM particles, on the contrary, the disturbance only causes the pressure drop increases, but the friction factor exhibits laminar characteristics.