Abstract

Using a system of differential equations of heat and mass transfer written in a cylindrical coordinate system with volumetric interphase sources of heat and mass transfer, a mathematical model of heat and mass transfer in film blocks of cooling tower irrigators has been developed. Expressions describing the interphase sources of heat and mass transfer and correlations for calculation of their parameters are presented. The parameters of the sources, i.e., the coefficients of heat and mass transfer, are related with the hydraulic resistance of irrigator blocks and can be calculated with both uniform and nonuniform distribution of air and water. The calculated volumetric coefficients of mass transfer were calculated and compared with the experimental data for regular mesh packing made of polyethylene and sheet-type metal packing. The numerical solution of the system of differential equations yielded the distribution of water, air, and air humidity content along the height of a packing block. The thermal efficiency of water cooling was calculated. It agrees satisfactory with the experimental data for spraying blocks made of polyethylene mesh. The causes of nonuniform distribution of phases among the packing blocks, which decreased the thermal efficiency of the cooling tower, were examined. The numerical investigations revealed that nonuniform air supply has the most significant influence decreasing the thermal efficiency of water cooling by as much as 35% or more compared with uniform phase distribution. The presented mathematical model can be used for estimating the cooling capacity of existing cooling towers at thermal power stations (TPSs) and industrial plants as well as in upgrading or developing high-efficient spraying blocks for film-type apparatuses.

中文翻译：

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考虑水和空气分布不均匀性的传热传质效率的数值估计

摘要

利用写在圆柱坐标系中的热与质量传递的微分方程组以及体积和体积间的热与质量传递源，开发了冷却塔灌溉机膜块中热与质量传递的数学模型。给出了描述相间传热和传质来源以及用于计算其参数的相关性的表达式。源的参数，即传热系数和传质系数，与灌溉模块的水力阻力有关，可以通过均匀分布和不均匀分布的空气和水进行计算。计算出传质的体积系数，并将其与聚乙烯制成的常规网状填料和片状金属填料的实验数据进行比较。微分方程系统的数值解产生了沿着填料块高度的水，空气和空气湿度含量的分布。计算出水冷的热效率。它与聚乙烯网状喷涂块的实验数据相吻合。检查了填料块之间的相分布不均匀的原因，这降低了冷却塔的热效率。数值研究表明，与均匀的相分布相比，不均匀的空气供应具有最大的影响，使水冷的热效率降低多达35％或更多。