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首页> 外文期刊>International Journal of Heat Exchangers >Heat and Mass Transfer in Longitudinal Flow Helical Tube Heat Exchangers
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Heat and Mass Transfer in Longitudinal Flow Helical Tube Heat Exchangers

机译：纵向流量螺旋管换热器的传热传质

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摘要

At present an enhancement of heat and mass transfer in different channels due to flow swirling is among one of the more promising way to design compact heat exchangers. For suppression of azimuthal nonuniformities of velocity and temperature that develop in the lateral entrance of heat carrier flow the helical-tube twisted bundle heat exchanger can be used. In this device, a helical tube bundle is twisted relative to the longitudinal axis of bundle. For investigating heat and mass transfer in these bundles the original methods of zone heating and of heat diffusion from point source were used. The heat transfer from a system of linear finite-size heat sources is considered for determining an effective diffusion coefficient using the homogenized flow model and statistical methods. Heat transfer in bundles was investigated by method of local similitude. The experimental data on heat transfer in a typical helical tube bundle is generalized in the form of second order multi-terms in logarithm coordinates for geometrically nonsimilar bundles. The data on the interchannel flow mixing for helical tube bundles and for helical tube twisted bundles are represented by the same relations. The cross mixing coefficients in these bundles exceed by 10 times the turbulent diffusion coefficients near the axis of circular tube. The twisting bundle of helical tubes enhances heat transfer compared to a typical helical tube bundle. It is concluded that use of twisted helical tube allows enhancing heat transfer and transverse flow mixing and decreasing of temperature nonuniformity over the bundle cross-section.
机译：目前，由于流动涡流而引起的在不同通道中的传热和传质的增强是设计紧凑型热交换器的更有希望的方法之一。为了抑制在载热体的侧向入口处产生的速度和温度的方位角不均匀性，可以使用螺旋管绞束式换热器。在该装置中，螺旋管束相对于束的纵轴扭曲。为了研究这些束中的传热和传质，使用了区域加热和从点源进行热扩散的原始方法。考虑使用均质流动模型和统计方法确定线性扩散有限热源系统的传热，以确定有效扩散系数。采用局部相似性方法研究了束中的热传递。关于典型螺旋管束中传热的实验数据以几何非相似束的对数坐标中的二阶多项形式概括。螺旋管束和螺旋管扭曲管束的通道间流动混合数据用相同的关系表示。这些束中的交叉混合系数超过圆形管轴附近湍流扩散系数的10倍。与典型的螺旋管束相比，螺旋管的扭曲束增强了热传递。可以得出结论，使用扭曲的螺旋管可以增强传热和横向流混合，并降低束横截面上的温度不均匀性。

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