Improving the performance of indirect evaporative cooler for energy recovery from the perspective of nozzle configuration : a CFD model analysis

Abstract

As a sustainable cooling technology, indirect evaporative cooling (IEC) has been widely recognized as an effective means of achieving carbon neutrality based on its low energy consumption and high efficiency in central air conditioning (AC) systems of buildings. In contrast to the conventional arrangement, IECs as heat recovery units are often arranged in a diamond shape inside the air handling units (AHUs) of data centers (DCs), an approach that facilitates the flexible use of space and integration within the units in a more compact form. The use of CFD simulations allows an integrated analysis of the coupling of hydrodynamic, thermal and mass properties helps to improve the evaporation performance of IECs. In this study, a 3D simulation model of a diamond-shaped IEC containing the water spray system was developed to compare and analyze the air-water arrangement options in IEC systems currently used in DCs, and the corresponding characteristics are explored from the perspective of CFD techniques to determine the effect of nozzle configurations on the formation and evaporation of water film within the wet channels. Then, parametric analysis of nozzle setup schemes based on performance metrics showed that the nozzle arranged in top-side configuration and paired with the air-water counterflow form had the best performance, with 59.2% and 27.4% improvement in water film coverage area and temperature drop, respectively, over the worst scheme (bottom configuration) at a water supply flow rate of 65 L/s. Finally, the effectiveness of the enhanced approach was simulated and analyzed for hydrophilic and fiber coatings, and it was found that the water film coverage increased by 14.5% and 31.6%, respectively, while the coefficient of performance (COP) increased by 7.4% and 16.1%.