Experimental and numerical study of dew-point indirect evaporative coolers to optimize performance and design

Abstract

Dew-point indirect evaporative coolers (DIEC) allow to significantly reduce air temperature from supply air flow and require a low energy consumption, so they could be an interesting alternative to conventional air-cooling system. In the present work, the optimal geometric design and the optimal operational parameters of DIEC systems to achieve cooling conditions and comply with the European ventilation regulations were determined. Hence, the experimental energy performance of a DIEC under different inlet air conditions was studied, and a detailed DIEC model based on the ε-NTU method was developed and validated. The experimental results showed very high DIEC dew-point effectiveness values, up to 0.87. Additionally, the numerical results obtained with the detailed DIEC model were in very good agreement with the experimental results, so this model can be adequately used to analyse and optimise DIEC systems. The optimal geometric designs and operational parameters of the DIEC systems depended on the type of space to be conditioned and the ventilation category. The maximum COP values were always obtained for low values of volumetric air flow rate, 50.26 for an office application, 44.19 for the restaurant application and 37.14 for the auditorium application. However, the highest compactness of the DIEC designs were achieved for medium and high values of volumetric air flow rate ratio, between 0.45 and 0.8. The results obtained could significantly help to achieve the objectives of sustainable cooling and ventilation of spaces in the frame of Nearly Zero Energy Buildings.