径向热管换热器壳程数值模拟及结构参数优化

利用FLUENT软件,对同轴径向热管换热器壳程进行模拟计算,分析烟气速度、温度及局部对流换热系数沿壳程的变化规律,并寻求换热器结构参数优化值。研究结果显示:换热器壳程,离热管管壁越近,温度梯度越大;烟气流经管束时,在管束尾部形成一个楔形的涡流区,速度在流体出现脱体的地方达到最大;湍流强度在涡流中心区域也达到最大值,中心区域的换热强度明显高于热管两侧边缘处,管束尾部的烟气温度低于管边缘处的烟气温度。将模拟结果与测试结果进行比较,误差在10%以内。通过改变换热器结构参数,对换热器壳程烟气对流换热进行分析研究,得到径向热管换热器结构优化参数:横向管距为114~120 mm;纵向管距为120~125 mm;翅片高度不应高于26.5 mm;翅片间距为6 mm。

Numerical simulation and structural parameters optimization in shell side of radial heat pipe heat exchanger

By simulating the shell side of radial heat pipe heat exchanger with the software FLUENT,the characteristics of smoke velocity,temperature and local convection heat transfer coefficient along the shell side of heat exchanger were analyzed,and the structural parameters were optimized.The results show that on the shell side of heat exchanger,the closer area to the heat pipe,the bigger the temperature gradient is;a wedge eddy is formed in the rear of heat pipe as smoke flows through heat pipe,the velocity maximizes when detached fluids appears;in the central region,turbulence intensity is the biggest,and the heat transfer intensity is obviously higher than that of the edge,and the smoke temperature at the rear of heat pipe is lower than that at the edge of heat pipe.Comparing the simulation results with the test results,the errors are within 10%.Then by changing structural parameters,the shell side convective heat transfer of radial heat pipe heat exchanger were studied,and the structural parameters optimization were established: transverse space of heat pipe is from 114 to 120 mm;longitudinal space of heat pipe is from 120 to 125 mm;fin height is below 26.5 mm;and fin space is 6 mm.