Experimental analysis of a new generation of membrane liquid desiccant air- conditioning (LDAC) system with free convection of desiccant for energy economic management

摘要

A new generation of membrane liquid desiccant air-conditioning (LDAC) system with free convection of desiccant is investigated experimentally. The free convection LDAC systems have benefits over conventional air conditioning (AC) systems with the added advantage of system operation with no circulating pump. The prototype system made up of mainly two externally cooled hollow fiber membrane (HFM) liquid-to-air energy exchangers worked as dehumidifiers and regenerators. The performance of the system studied under the standard summer air conditions, and a thorough study was done to reveal its behavior as an AC system in different airflow rates. The coefficient of performance (COP) of the system is 0.85 at the base condition, and the sensible heat factor (SHF) of the dehumidifier ranged between 0.24 and 0.4 for different operating conditions. The heat and moisture removal rate and sensible heat factor increased while the electrical and thermal coefficients of performance (ECOP and TCOP) decreased by the airflow rate increase. While the value of TCOP is approximately the same for all operating conditions, the ECOP is very sensitive to airflow rate, and its value reduced by 82% as the value of airflow rate tripled. It is inferred that unlike the forced energy transfer loops, it is mainly the solution side transfer coefficients that determine the system performance, and between the heat and moisture transfer coefficients, the latter is more effective on system performance.