Energy conservation benefit of water-side free cooling in a liquid desiccant and evaporative cooling-assisted 100% outdoor air system

• Impact of water-side free cooling on a LD-IDECOAS was investigated.
• A pilot system was installed and tested during hot and humid season.
• A supply air temperature range of 17–20 °C was achieved without chiller operation.
• Water-side free cooling provides significant energy savings in the proposed system.

The main purpose of this research was to experimentally investigate a liquid desiccant and evaporative cooling-assisted 100% outdoor air system. The proposed system was integrated with water-side free cooling in the desiccant solution and process air cooling to enhance its energy performance. The experimental results show that the required cooling water temperature for the desiccant solution is higher than the conventional cooling water supply temperature; that is, approximately 22–27 °C. Consequently, water-side free cooling was applied to produce the cooling water for the desiccant solution. The operation of the proposed system with the water-side economizer showed a 40–70% effectiveness of the indirect evaporative cooler, while that of the direct evaporative cooler was greater than 95%, and the supply air temperature ranged between 17 and 20 °C. The energy coefficient of performance (COP) of water-side free cooling applied to cool the desiccant solution was 8–17, whereas that of the conventional air-cooled chiller was 1–3. Economic consideration indicated that the operating energy savings might offset the penalty in the initial cost of the proposed system.