Study on the performance of tube evaporative cooling dehumidifier based on CFD

Abstract

Most of the existing numerical models for falling film dehumidifiers consider two-dimensional adiabatic-type models. However, the performance of the adiabatic type dehumidifier is relatively poor, in addition to the fact that the two-dimensional model cannot well represent the flow process of liquid desiccant and the dehumidification process in the actual operation of the dehumidifier. Therefore, in order to better study the falling film of liquid desiccant and the heat and mass transfer process inside the tube, this paper established a three-dimensional model of the evaporative cooling falling film dehumidifier with higher dehumidification performance outside the tube based on CFD technology. The results showed that the simulation results of the constructed model were in good agreement with the experimental results, and the average relative error about 12 %. The out-of-tube evaporative cooling system cooled the dehumidifier through the combined effect of droplet evaporation and low-temperature liquid film on the outer wall surface. Under the baseline conditions: the dehumidification performance of the solution outlet section was better than that of the solution inlet section. The best cooling effect and dehumidification performance was achieved when the flow rate of shower water was 0.25 kg/(m2·s) and the flow rate of evaporative cooling air was 0.3 m/s. The dehumidification performance at a solution inlet velocity of 0.01 m/s was 79 % of that at 0.06 m/s; even if the solution flow rate was small, evaporative cooling dehumidifier still had a good dehumidification performance. The results of this paper provided a reference for the design of evaporative cooling type solution dehumidifier.