CH-24-C055 - Field Study of a Heat-Pump-Driven Liquid-Desiccant Air-Conditioning System Applied in a Public Building with High Latent Load

The importance of humidity control in buildings with high latent loads has increased owing to the inefficiency of conventional vapor compression cooling (VCC) systems in terms of energy use and maintaining a thermally comfortable room. To address this, an innovative approach is proposed: a heat-pump-driven liquid-desiccant (HPLD) air-conditioning system, which integrates a liquid-desiccant system dehumidifying air based on vapor pressure difference with a heat pump controlling both desiccant-solution and air temperatures. Both the proposed and conventional systems are installed in a high-latent-load public building in Seoul, South Korea. The VCC system operates solely by setting a target room temperature; reference case 1 is set at 25°C (77°F), while reference case 2 is set at 18°C (64.4°F). The proposed system operates by setting both the target room temperature and humidity at 25°C (77°F) and 0.0105 kg/kg (0.0105 lb/lb), respectively. In cold and humid weather during the summer rainy season, reference cases 1 and 2 achieve thermal comfort satisfaction ratios for only 0 and 12% of operating hours, respectively. In contrast, the proposed case maintains a thermally comfortable room for 99% of operating hours. Reference cases 1 and 2 and the proposed case record the energy consumed to maintain the thermally comfortable room for 1 h as infinity, 536, and 41 kWh/h (infinity, 1829, and 140 kBtu/h), respectively. In hot and humid weather, the thermal comfort satisfaction ratio of operating hours is recorded as 2, 79, and 94% for reference cases 1 and 2 and the proposed case, respectively. The corresponding energy consumed to maintain comfort for 1 h is recorded as 2072, 72, and 64 kWh/h (7070, 246, and 218 kBtu/h) for reference cases 1 and 2 and the proposed case, respectively. Field-test results reveal that the conventional VCC system struggles to maintain comfort energy-efficiently in high-latent-load buildings, relying solely on achieving the target room temperature in the operation. In contrast, the proposed system excels in maintaining comfort while using energy efficiently, independently controlling the air temperature and humidity based on both set parameters in the operation. This advantage is particularly noticeable during the rainy season, highlighting the superior applicability of the proposed system in high-latent-load buildings compared with the reference system.