椭圆管氟塑钢空气预热器烟气侧流动与换热特性数值研究

Numerical study on flow and heat transfer characteristics of flue gas side for a fluoroplastic steel air preheater with elliptical tubes

针对椭圆管氟塑钢空气预热器开展了烟气侧流动与换热特性的数值研究,分析归纳了椭圆率、横纵相对节距、内外氟塑料膜厚度以及空气膜厚度对传热与阻力的影响规律。计算结果表明:随着椭圆率的增大,平均对流传热系数与流动阻力均逐渐增加,而单位风机功率的传热速率逐渐下降;增加纵向相对节距和减小横向相对节距会增大平均对流传热系数与压降,不利于椭圆管空气预热器综合性能的提高;内外氟塑料膜厚度的增加均会导致换热量的减少,但内壁氟塑料膜对换热性能的影响更大;换热量随着空气膜厚度的增加快速降低,仅0.10 mm厚度的空气膜就可使换热量下降33.1%;氟塑料覆膜技术水平是椭圆管氟塑钢空气预热器推广应用的重要影响因素。

Numerical study is performed for the flow and heat transfer characteristics of flue gas side of a fluoroplastic steel air preheater with elliptical tubes.The influence laws of ellipticity,horizontal and longitudinal relative pitch,internal and external fluorine plastic film thickness and air film thickness on heat transfer and resistance are analyzed and summarized.The results show that,with an increase in the ellipticity,the mean convective heat transfer coefficient and resistance increase gradually while the heat transfer rate per unit fan power decreases gradually.Increasing the longitudinal relative pitch and decreasing the transverse relative pitch will increase the mean convective heat transfer coefficient and pressure drop,which is not conducive to the improvement of the comprehensive performance of the elliptical tube air preheater.The increase of internal and external fluorine plastic film thickness will lead to the decrease of heat transfer,but the inner fluorine plastic film has a greater effect on the heat transfer performance.The heat transfer decreases rapidly with the increase of the air film thickness.The heat transfer decreases by 33.1% with the air film thickness of 0.1 mm only.The technical level of fluorine plastic film covering is an important factor affecting the application of the elliptical tube fluorine plastic steel air preheater.