Performance Improvement of Membrane Energy Exchanger Using Ultrasound for Heating, Ventilation, and Air Conditioning Application

Abstract

Air conditioning (AC) systems consume the maximum proportion of the total electricity used in the building sector. The demand for AC systems is expected to increase exponentially in the coming years due to various reasons such as climate change, and an increase in affordability and living floor space. A membrane-based liquid desiccant AC system along with energy recovery ventilating equipment is considered as a prospective alternative to the conventional air conditioning system (CACS). It has the potential to meet the increasing current and future AC demand in a sustainable manner. Its efficiency and energy-saving potential with respect to CACS depend on the performance of the membrane-based dehumidifier, regenerator, and energy recovery ventilating equipment, commonly referred to as membrane energy exchangers (MEEs). MEE is an indirect exchanger type in which a membrane separates the working streams. This intermediate membrane creates an additional resistance for the heat and mass transfer processes in the MEE. To reduce the resistance, this study experimentally and numerically investigate the influence of ultrasound on the performance of the MEE for dehumidification, humidification (applicable for membrane-based evaporative cooling and desiccant regeneration devices), and energy recovery processes. It is found that the vibration due to ultrasound has the potential to improve the mass transfer performance of MEE by the resistance at the air-membrane interface.