Applicability of a heat-pump-driven liquid-desiccant air-conditioning system in energy-efficient buildings

Abstract

Building trend is toward energy-efficiency by reducing building sensible load, while neglecting latent load. A heat-pump-driven liquid-desiccant (HPLD) air-conditioning system has emerged for effectively handling building latent load in energy-efficient buildings with low indoor sensible heat ratio. However, previous studies only investigated one building type, failing to account for the increase in building energy-efficiency. This study estimates building thermal loads of four different energy-efficient high latent load buildings, simulating building trend. Then, as energy-efficiency of buildings increases, the changes in indoor thermal comfort and energy consumption of the HPLD air-conditioning system and reference vapour compression system are compared. Simulation results show that in building with the highest energy-efficiency, the reference system can only maintain thermal comfort for 43.3% and 24% of summer operating hours when primarily meeting supply-air target temperature and humidity, respectively. Contrastingly, the proposed system can maintain thermal comfort in all building types for almost 100% of summer operating hours due to decoupled control of air temperature and humidity. Additionally, the proposed system saves up to 33.2% of operating energy when both systems achieve the same thermal comfort satisfaction. In conclusion, the HPLD air-conditioning system with decoupled control is more applicable as energy-efficiency of buildings increases.