Performance evaluation of counter flow dew-point evaporative cooler with a three-dimensional numerical model

Abstract

• A three-dimensional numerical model of a regenerative dew-point evaporative cooler was developed; • The effects of operating conditions were comprehensively analyzed; • The influence of none-even water distribution position was revealed; • The existing of none water area deteriorated the cooler’s effectiveness; • The water distribution at the entrance or outlet of the wet channel affected the cooler’s performance more prominent. Dew-point evaporative cooling is a promising low-emission cooling technique. It applies latent heat from water evaporation with a special humidity manipulation process, which owns a high efficiency and is environmentally friendly. The influences of its operation and design conditions were comprehensively discussed with current one-dimensional or two-dimensional model previously. However, air flow is regarded as constant along the direction of channel width and the previous models assume that the water film is even-distributed in the wet channels, which deteriorates the accuracy of numerical model. In this paper, a three-dimensional model was developed to simulate the air flow and moisture content transport of a regenerative dew-point evaporative cooler. Different from previous models, this study focusses on the effects of non-even water distribution on cooler performance. Results show that the deviation between experimental test and present three-dimensional numerical simulation was less than 3.77% under different inlet conditions, and the three-dimensional model improved the simulation accuracy by 5.46% compared with the conventional two-dimensional model, which demonstrated the superiority of three-dimensional simulation. Based on the proposed three-dimensional numerical model, the influences of inlet conditions, air intake velocity and working air ratio were parametrically analyzed. Last but not least, the effect of water distribution was revealed. The existence of none water distribution area led to poor cooling performance in general, and it had prominent influences on water evaporation when the positions of none water distribution area were near the entrance or outlet of the wet channel. The developed three-dimensional model and the analysis of water distribution effects can benefit the future design of dew-point evaporative coolers.