双面膜反转强化吸收过程传热传质

Heat and mass transfer enhancement during absorption process with double-side film-inverting configuration

提出了一种双面液膜反转方案,竖直布置2组或2组以上交叉双尺度波纹板束为传热面,在上板束各对板底部设置耙形导流器,交叉地将上板束各对板两侧的液膜引至下板束异侧,然后利用液膜与具有水平沟槽的波纹板片上的表面张力作用使反转后的下降液膜均匀化,以此实现液膜反转和交叉双尺度波纹板技术的复合强化。建立了溴化锂水溶液在2段光滑平板上降膜反转吸收过程的传热传质数学模型并进行了数值计算。给出了反转液膜前后液膜内流场、温度场、质量分数分布计算结果,并讨论了溴化锂水溶液降膜吸收传热和传质过程中反转次数对传热和传质系数的影响。

Film-inversion is an effective way recently developed to enhance heat and mass transfer in absorbers. However, only one side of round or rectangular tube i. e. half of the total heat transfer area is used to form film inverting configuration in the published literatures. This paper presents a double-side film-inverting scheme, which consists of two plate bundles with two-scale crosswise corrugations and a set of comb shaped conjunctions for leading the film from both sides of each couple of the upper plate bundle to the opposite sides of the bottom one. The horizontal corrugation can make film distribution uniform before and after inversion with the surface tension effect, and thus increase the heat and mass transfer coefficients of the absorption process. A mathematic model for heat and mass transfer in absorption process with aqueous Li Br solution falling film-inverting on two sequential vertical plane plates was established and calculated numerically. The velocity profiles, temperature and concentration distribution inside the solution film were obtained. The influence of the number of inversion on heat and mass transfer characteristics was analyzed. The calculation results show that the heat and mass transfer coefficients of the once-film-inverting scheme increased by about 58% and 73% respectively over these of the none filminverting scheme.