Influence of ellipticity and tube inclination angle on thermal performance of tube-fin heat exchanger
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摘要: 建立管翅式换热器模型，在雷诺数Re为500~1600时，对不同椭圆率和管倾角下的管翅式换热器热工性能在3D CFD软件中进行数值分析. 分析椭圆率（0.45~0.85）和管倾角（0o~45o）对管翅式换热器的流动和传热特性以及Colburn因子j、摩擦因数f和效率指数j/f的影响. 结果表明，j、f随着Re的增大而降低，而j/f随Re的增大而上升，并逐渐趋于平缓；适当地倾斜椭圆管，有利于产生更多的湍流，强化对流换热. 当管翅式换热器的椭圆率为0.75，管倾角为15o~25o时，最有利于换热和流体流动特性.Abstract: The model of tube-fin heat exchanger was established, and thermal performances of tube-fin heat exchanger with different ellipticities and tube inclination angles were analyzed by 3D CFD sfotware when the Re was 500~1600. The effects of ellipticities (0.45~0.85) and tube inclination angles (0o~45o) on flow and heat transfer characteristics, colburn factor j, friction factor f and efficiency index j/f of tube-fin heat exchanger were analyzed. The results show that j and f decrease with the increase of Re, while j/f increase with the increase of Re and tend to be gentle. Proper tilt angle is beneficial to generate more turbulence and strengthen convective heat transfer. When the ellipticity of tube-fin heat exchanger is 0.75 and the inclination angle of the tube between 15o and 25o, the heat transfer and fluid flow characteristics are the most favorable.
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Key words:
- ellipticity /
- tube inclination angle /
- Colburn factor /
- friction factor /
- efficiency index
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图 4 椭圆率为0.75和雷诺数为 1000 的中间平面速度等值线
Figure 4. Velocity contours of the middle plane with ellipticity 0.75 and Re 1000
图 6 椭圆率为0.75和雷诺数为 1000 的中间平面压强等值线
Figure 6. Pressure contours of the middle plane with ellipticity 0.75 and Re 1000
图 5 椭圆率为0.75和雷诺数为 1000 的中间平面温度等值线
Figure 5. Temperature contours of the middle plane with ellipticity 0.75 and Re 1000
图 7 Colburn因子相对于椭圆率和雷诺数的变化
Figure 7. Variation of Colburn factor j with respect to ellipticity e and Re
图 8 摩擦因数相对于椭圆率和雷诺数的变化
Figure 8. Variation of friction factor f with respect to ellipticity e and Re
图 9 效率指数相对于椭圆率和雷诺数的变化
Figure 9. Variation of efficiency index j/f with respect to ellipticity e and Re
表 1 椭圆管翅式换热器流体的相关参数
Table 1. Related parameters of elliptical tube-fin heat exchanger fluid
参数 数值 材料 空气 流体密度ρf·/(kg·m−3) 1.185 比热容/(J·kg−1·K−1) 1049 导热系数/(W·m−1·K−1) 0.0261 动力黏度/(kg·m−1·s−1) 1.831×10−5 
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