Experimental performance evaluation of isothermal dehumidification and indirect evaporative cooling-assisted dedicated outdoor air system

Abstract

A novel dedicated outdoor air system integrated with vacuum membrane dehumidification technology was developed to experimentally evaluate its cooling, dehumidification, and energy performance at the pilot scale. While previous studies on vacuum membrane dehumidification have largely remained at the proof-of-concept stage using theoretical modeling or small-scale apparatus, this study advances the field by constructing and testing a pilot-scale air-conditioning system that integrates vacuum membrane dehumidification with indirect evaporative cooling to address latent and sensible loads, respectively. Experiments were conducted under annual climate-based operating sequences to examine seasonal characteristics by monitoring transient thermal behaviors across four modes. The cooling capacity and coefficient of performance (COP) of the proposed system were also examined. Results showed that the proposed system achieved target supply air conditions across all modes, enabled by separate control of latent and sensible loads and partial-load operation of the vacuum membrane dehumidifier according to the outdoor latent load. In terms of energy efficiency, the proposed system exhibited a COP of 0.35-0.7 in the total cooling and dehumidification modes, and 4.25-4.5 in the sensible cooling and heat recovery modes, highlighting both the promise and the limitations of the current vacuum membrane dehumidification technology. For future building applications, performance improvements were discussed through comparative analysis with previous studies on vacuum membrane dehumidification.