Simulation and experimental studies on the liquid desiccant dehumidification of horizontal tubes having a staggered arrangement

Field synergy theory has been widely used in the field of single-phase heat transfer, which is of importance to heat transfer optimization. However, few scholars apply the field synergy theory to the field of mass transfer, especially to the field of liquid desiccant dehumidification. The innovation of this paper is the application of the technology of the falling-film evaporation of a horizontal tube and the theory of field synergy to liquid desiccant dehumidification. The objective of this paper is to study the falling film liquid dehumidifier and get the dehumidification performance and mass transfer synergy angle under the influence of multiple factors. The heat and mass transfer characteristics of the system are studied in simulation and experimentally. The mass transfer synergy angle comprising the velocity vector and concentration gradient vector is taken as a standard to measure the mass transfer synergy, while the moisture content of the outlet air is taken as a standard to measure the dehumidification performance of the system. Fluent simulation software is used to simulate the dehumidification process of the equipment with staggered horizontal pipes, establish physical and mathematical models and analyze the velocity field and moisture content field in the model. The moisture content of the outlet air and the distribution of the mass transfer angle are obtained. The mass transfer angle of the system is about 96°. The effects of various factors on the air moisture content at the outlet of the equipment are studied experimentally. Results show that the dehumidification amount decreases with an increase in air velocity. Increases in the solution concentration, air inlet moisture content and solution flow rate increase the amount of dehumidification, following the same trends as in simulation. A comparison of the simulation results with the experimental results shows the relative error is within 20%. This study shows that it is feasible to combine the field synergy theory with liquid desiccant dehumidification. On the basis of this study, researchers in related fields can further study the effect of mass transfer synergy angle on mass transfer synergy in liquid desiccant dehumidification system.