圆管束与椭圆管束换热、磨损及积灰特性的数值研究

Numerical Study on Heat Transfer, Wear and Fouling Performance of Circular Tube Bundle and Elliptical Tube Bundle

为了从换热特性、流阻特性、磨损及积灰等方面综合分析对比烟气横掠圆管束和椭圆管束的性能,利用数值模拟的方法先是对圆管束、椭圆管束的换热及流阻特性进行了数值计算,验证了烟气横掠管束数学模型的正确性,然后对圆管束、椭圆管束的磨损及积灰情况进行了气固两相流冷态数值模拟。计算结果表明：与圆管束相比,椭圆管的换热系数减小7.72%,流动阻力降低了66.71%,椭圆管束的综合性能优于圆管束;椭圆管束具有更好的抗飞灰磨损性能,并且在工况较恶劣的环境下,椭圆管束的各排管子可降低磨损量21%~73%;由于椭圆管束具有更小的低速回流区域,更小的管壁低速区域,更优化的流场分布等优点,椭圆管束具有更好的抗积灰特性。因此,相比于圆管束,椭圆管束不仅具有更好的综合换热性能,还具有更优的防磨性能及抗积灰性能。

To analyze the performance of the flue gas transversely flowing through the circular tube bundle or the elliptical tube bundle from the aspects of heat exchange characteristics, wear and fouling, the numerical simulation of the heat transfer characteristics of the circular tube bundle and the elliptical tube bundle was carried out by using the numerical simulation method. The correctness of the mathematical model of the flue gas transversely flowing through the bundle was verified, and then numerical simulation of two - phase flow in cold state was carried out to simulate the wear and fouling of the circular tube bundle and the elliptical tube bundle. The results show that, compared with the circular tube bundle, the heat transfer coefficient of the elliptical tube is reduced by 7.72%, the flow resistance is reduced by 66.71%, and the comprehensive performance of the elliptical tube bundle is better than that of the circular tube bundle. Elliptical tube bundle resist to ash wear better than the circular tube bundle under the low flow rate, small particle size ash condition, and in the harsh environment, the wear of elliptical tube bundle different rows can be reduced by 21% to 73%. In addition, due to the advantages of elliptical tube bundles with smaller, low velocity recirculation zones, smaller lower velocity regions on the tube wall, and more optimized flow field distributions, elliptical tube bundle has better anti-fouling performance. In conclusion, compared with the circular tube bundle, elliptical tube bundle not only has a better overall heat transfer performance, but also has better anti-wear performance and anti-fouling performance.