竖直管外降膜吸收传热传质过程强化的研究

Study on the Heat-mass Transfer in Falling Film outside the Vertical Tube for Water Vapor Absorption into Aqueous Lithium Bromide

对LiBr溶液在光滑管和四种换热强化管竖直管外降膜吸收过程进行了实验研究,得到了实验条件下的最佳管型。分析了非绝热吸收过程中传热传质相互作用、相互影响的关系; 建立了竖直管外降膜吸收热-质传递过程的数学模型,并对该过程进行了数值计算。模型计算值与实验结果的比较证明该模型具有较好的适用性。

The falling-film absorption for water-lithium bromide system on vertical tubes was studied experimentally. The DND tube was proved to be the best one in heat transfer property among one smooth tube and four kinds of heat transfer enhancement tubes. The heat transfer property of the other four kinds of tubes is in the following order: DAC tube >ND tube>XC tube>GH tube. The existence of low-ribs, fins, as well as the leaning channels intensifies the Marangoni effect and increases the surface area of tube. The geometric shape inside the heat transfer enhancement tubes affects heat transfer property more significantly than the geometric shape outside the tubes. The relationship of the inter-action and inter-affection between heat and mass transfer in a process of non-insulated absorption was theoretically analyzed. A model was proposed to describe the coupled heat and mass transfers in vertical falling-film absorption and the results indicated that model simulations are in good agreements with the experimental data.