Development, Performance Evaluation and Design Optimisation of an Air-to-air Membrane Enthalpy Exchanger

A significant fraction of energy demand within the built environment results from the unsustainable design and intensive use of Heating, Ventilation and Air Conditioning (HVAC) systems. The introduction of energy efficient technologies into HVAC systems has therefore gained extensive attention in recent years as a means to increase building energy efficiency and sustainability. Air-to-air membrane enthalpy exchangers (MEEs) are among a wide range of environmentally friendly devices that have been increasingly used to recover waste energy from the exhaust air stream released from buildings. This exhaust air is a result of the need to bring fresh ventilation air into the building to maintain good indoor air quality (IAQ). MEEs can also improve indoor air quality in other ways, for example, by reducing the risk of the spread of infectious diseases, such as COVID-19 or influenza, through facilitating greater dilution of such contaminants by clean outdoor air. Although MEEs have been extensively studied from a number of different research perspectives over many years, quantification of MEE performance improvement and design optimisation have been less thoroughly investigated. The membrane is the key component of an MEE, and improving its properties can significantly enhance the overall performance of such devices. On the other hand, cross flow MEEs have historically had relatively poor heat and moisture transfer effectiveness, and the development of new hybrid air flow configurations (e.g. a combination of cross, counter and/or parallel flow configuration) for MEEs represents an opportunity to improve their performance and market share. There is also a knowledge gap in respect of the design optimisation of MEEs.