Design and Operating Performance of a Heat Pump-driven Liquid Desiccant Air-conditioning System for Residential Buildings

Abstract

In this study, a workable design of a small-scale heat-pump-driven liquid-desiccant (HPLD) air-conditioning system was proposed for residential buildings. By composing the system with only one set of feasibly decoupled controlling both the sensible and latent loads, the proposed system enhances the system compactness and practicality contributing to the system to be widespread used. The proposed system consists of a liquid-desiccant (LD) unit for removing the latent load of process air and a heat-pump (HP) unit for removing the sensible load of process air and also removing the desiccant-solution cooling and heating loads. The solution dual sumps that showed energy saving potential by reducing the solution cooling and heating loads was adopted for LD unit in this study. A prototype of the proposed system was constructed, and its operating performances for various operating modes and energy efficiencies for representative summer and winter modes were experimentally investigated. Based on the established sequence of operation capable of handling the annual indoor sensible and latent load variations, the proposed system showed ideal and reliable air (temperature and humidity) and desiccant-solution (temperature and concentration) behaviors for each operating mode. The energy efficiencies were evaluated to 7.72 EER for summer and 2.51 COP for winter which both satisfy the approved minimum efficiency requirements. In conclusion, the proposed system demonstrated its great application potential for residential buildings in terms of not only system compactness and practicality but also operating performances including energy efficiency.