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中南大学学报(自然科学版)

Journal of Central South University

第44卷    第9期    总第229期    2013年9月

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文章编号:1672-7207(2013)09-3904-07
来流速度分布对径向热管换热器性能影响的数值模拟
涂福炳,马士伟,高晟扬,刘庆赟,毛建丰

(中南大学 能源科学与工程学院,湖南 长沙,410083)

摘 要: 利用FLUENT软件对径向热管换热器壳程进行数值计算,研究烟气入射角和速度均匀度对换热器流场、温度场和单位压降换热系数的影响规律。研究结果表明:当来流速度均匀时,入射角增大使热管背风侧回流区发生偏移,下游管束被上游管束尾迹覆盖,减少烟气与管束的碰撞,降低烟气压力损失,换热效率降低,在同一横截面上烟气温度分布较均匀;当来流速度不均匀时,换热器壳程烟气出现明显的高速区与低速区,使温度场均匀性变差,出现低温区,且不均匀因子τ越大,温度场均匀性越差,低温区范围也越大;单位压降换热系数α/?p随烟气入射角的增大而逐渐增大,在45°时达到最大值,此时换热器整体性能最好;此后,随入射角进一步增大,α/?p急剧减小,换热器性能恶化;当因子τ较小时,多股扰流能提高换热器整体性能,而少股扰流将降低换热器整体性能,且因子τ越大,换热器整体性能越差;壳程温度模拟结果与测试结果相比,相对误差在5%以内。

 

关键字: 径向热管换热器;数值模拟;速度分布;入射角;单位压降换热系数;换热性能

Numerical simulation of radial heat pipe heat exchanger under different velocity distribution inflows
TU Fubing, MA Shiwei, GAO Shengyang, LIU Qingyun, MAO Jianfeng

School of Energy Science and Engineering, Central South University, Changsha 410083, China

Abstract:The characteristics of the flow field, temperature field and heat transfer coefficient of unit pressure drop were analyzed under different inclination angles and velocity evenness by simulating the shell side of a radical heat pipe heat exchanger with the software FLUENT. The results show that when the velocity inflows are evenly distributed, the inclination angles with increment cause the migration of the reflux zones behind the heat pipes and make the wake of the upper pipes cover the lower pipes, so the collision between the flue gas and the heat pipes abates, the pressure loss drops and the heat exchange rate decreases, while a uniform temperature reaches at the same cross section. When the velocity inflows are unevenly distributed, sensible high velocity zone and low velocity zone emerge in the shell side of the heat exchanger, the uniformity of temperature field becomes worse with low temperature zone, and the larger the unevenness factor τ is, the worse the uniformity of temperature field is, the larger the low temperature zone is. The heat transfer coefficient of unit pressure drop α/?p increases gradually as the inclination angle enlarges and culminates at 45° where the thermal performance of the heat exchanger gets its optimum, since then α/?p decreases rapidly and the thermal performance of the heat exchanger deteriorates remarkably. Inflows with more interference flows and smaller τ factor can improve the integrity performance of the heat exchanger, but inflows with less interference flows will decrease the integrity performance, and the larger the τ factor is, the more deterioration. The relative error of the temperature simulation results in the shell side to experimental results is less than 5%.

 

Key words: radial heat pipe heat exchanger; numerical simulation; velocity distribution; inclination angle; heat transfer coefficient of unit pressure drop; thermal performance

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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