水平管外壁薄膜蒸发侧表面传热系数

采用智能化薄膜厚度测试仪，在考察液体负荷、蒸发侧沸点、蒸发侧传热温差、传热管管径等因素对水平光滑传热管外液膜厚度及其波动状况影响的基础上，研究了蒸发侧表面传热系数随液膜厚度的概率分布和平均厚度变化的趋势，讨论了多种操作参数对蒸发侧表面传热系数的影响。针对水平管降膜蒸发流动的波动特性，定义了G (δ⁺)和h (α)⁺₂，得到蒸发侧表面传热系数的关系式，突出了液膜波动的影响，为进一步揭示蒸发侧表面传热系数的影响因素以及进行工业设计提供实验依据.

HEAT-TRANSFER FILM COEFFICIENTS OUTSIDE TUBE OF FALLING FILM HORIZONTAL-TUBE EVAPORATOR

The film thickness distribution and average thickness outside a horizontal test tube were measured by using a film-thickness meter. The effects of liquid load, evaporation boiling point, evaporation temperature difference and tube diameter on film thickness, waving intensity and, as a result, the heat-transfer film coefficients outside the horizontal-tube were studied experimentally. Experiments of the heat-transfer coefficient of horizontal-tube evaporation were conducted with various operation parameters. Wave function G(δ⁺) for describing the wave characteristics of the film on the surface of horizontal-tube and dimensionless evaporation heat-transfer film coefficient h(α⁾⁺₂ were specifically defined. Equations of evaporation heat-transfer coefficient were set up by regression of experimental data. Some literature models of evaporation heat-transfer coefficients do not give satisfactory results, because film waving is not considered in the models. This shortcoming is overcome in the present models. These results provide a basis for further developing high efficiency heat-transfer process and novel evaporators.