采用计算流体力学方法对螺旋隔板套管式换热器壳侧的传热和阻力特性进行模拟,建立了螺旋升角为40°、螺旋隔板高度分别为b,3b/4,b/2,b/4和b/8(b为螺距)的换热器模型,分析了螺旋隔板高度对壳程流体传热的影响.结果表明,相同壳程工质体积流量下,换热器的壳程总换热量、换热系数和阻力系数随隔板高度增加而增加,单位长度压降随隔板高度增加而减小.隔板高度为b,3b/4和b/2时比隔板高度为b/8时的换热系数分别提高7.83,3.68和3倍,壳程进出口压降分别减少98%,97%和95%,但阻力系数却分别提高34,15.3和5.3倍.为提高螺旋隔板强化单管换热器的壳侧综合换热性能,其隔板高度应为1/2b-3/4b.
Heat transfer performance and flow resistance of shell side of the double-pipe heat exchanger with helical baffle were investigated by using CFD numerical simulation software. 5 heat exchangers with the helical baffle at the helical angle of 40°, and baffle space heights of b, 3b/4, b/2, b/4 and b/8 (b refers to the helix pitch) were simulated, and the influence of baffle space height on fluid flow and heat transfer of the shell side was examined. The results indicated that under the same volume flow rate, the heat transfer per unit area, heat transfer coefficient and friction factor increased with the increase of baffle space, but the pressure gradient decreased with the increase of baffle space. The heat exchange coefficient of heat exchangers with partition height of b, 0.75b and 0.5b was enhanced over 7.83, 3.68 and 3 times than that with partition height of 0.125b, and the pressure drop reduced by 98%, 97% and 95%, but the resistance coefficient was enhanced over 34, 15.3 and 5.3 times, respectively. In order to enhance the comprehensive heat exchange of shell side of single-tube heat exchanger with helical baffle, the partition height should be between 0.5b and 0.75b.