论文部分内容阅读
采用3种导热性能不同的固体颗粒为填充物,以空气为介质,在床层被加热的情况下,研究了固定床中内置圆管的错流传热.采用最小二乘法对实验数据进行拟合,得到以床层对壁的平均给热系数、气体的导热系数和床层中被加热圆管的管径计算的Nusselt准数经验关联式:Nuf=31(lb0/ls)1.4(Db/Dp)0.2Rep0.33Pr0.62,Rep=10~180,Db/Dp=28~116,lb0/ls=0.5~0.2.Reynolds数以固体颗粒的等外表面积当量直径进行计算.结果表明,在错流传热过程中,表征气体流动特性的参数Rep仍是错流传热的重要影响因素,Nusselt准数除与床层的结构参数Db和颗粒的当量直径Dp有关外,还与颗粒的导热系数ls和床层的导热系数lbo密切相关.
Three kinds of solid particles with different thermal conductivities were used as filling materials, and the air was used as a medium to study the cross-flow heat transfer of the built-in circular tubes in a fixed bed with heating of the bed.The experimental data were fitted by the least square method , The Nusselt number calculated from the average bed-to-wall heat supply coefficient, the thermal conductivity of the gas, and the diameter of the heated tube in the bed is empirically derived: Nuf = 31 (lb0 / ls) 1.4 (Db / Dp ) 0.2Rep0.33Pr0.62, Rep = 10 ~ 180, Db / Dp = 28 ~ 116, lb0 / ls = 0.5 ~ 0.2 The number of Reynolds is calculated as equivalent surface area equivalent diameter of solid particles. In the thermal process, the parameter Rep, which characterizes the gas flow characteristics, is still an important influencing factor for the cross-flow heat transfer. The Nusselt quasi-number is related to the structural parameter Db of the bed and the equivalent diameter Dp of the particles, Layer thermal conductivity lbo is closely related.