Changing cooling in Hong Kong through dehumidifying in addition to chilling

ABSTRACT

Much of the residential housing in Hong Kong is cooled by compressive air conditioning wall units using hydrofluorocarbons (HFCs) as refrigerants. The recent Kigali Agreement in Rwanda has proposed the rapid phasing out of HFCs, a global warming gas that is 1400 times more heat trapping than carbon dioxide. Such air conditioning is ineffective in hot and humid Hong Kong. Condensing humidity also causes irritating dripping onto pedestrians. This paper proposes compressing hot and humid air directly using a recently invented Hui turbine, instead of the displacement pressurisation of the refrigerant. Compressed air is cooled in a condenser with humidity condensing out, releasing a substantial amount of heat of condensation. The cooled pressurised air is expanded in the Hui turbine, producing chill and recovering work. This innovative air conditioning method which does not use a refrigerant is called Firefly Air. This paper looks at the thermodynamic heat pump cycle of this cooling and dehumidifying process, comparing it with the usual Rankine cycle heat pump process which employs a refrigerant. Chill production is more than doubled and the resulting chilled air has greatly reduced humidity, while irritating dripping is avoided.

KEYWORDS:

• Air conditioning
• thermodynamic heat pump
• cooling and dehumidifying process
• Hui turbine
• Firefly Air

Acknowledgements

Mr Ng Cheuk Hei Michael prepared the figures based on the information gathered from the Internet.

ORCID

Mark H C Chan http://orcid.org/0000-0002-9669-1584

Additional information

Notes on contributors

Joseph Y Hui

Prof Joseph Y Hui obtained his B.Sc., M.Sc. and Ph.D. degrees in Electrical Engineering from the Massachusetts Institute of Technology in 1981, 1981 and 1983, respectively. He was the International Switching Symposium (ISS) Chair of the Department of Electrical, Computer, and Energy Engineering at the Arizona State University, and became a Professor Emeritus in 2014 in order to take on the role of the President and CEO of the Monarch Power, an R&D company devoted to solving the 3Es of human needs: energy, environment, and education. Prof Hui holds more than 40 patents in communication, networking, cloud computing, and renewable energy. He has received many awards, such as the Institute of Electrical and Electronics Engineers (IEEE) Fellow, the IEEE William Bennett Prize Paper Award, and the NSF Presidential Young Investigator Award. He is the author of many papers and books, including the seminal textbooks Integrated Switching and Traffic Theory for Integrated Broadband Networks (Kluwer Academic) and What’s the Matter with Energy! (Solar Man Press).

Mark H C Chan

Ir Dr Mark H C Chan obtained his B.Sc. and M.Sc. degrees in Civil Engineering, and Sc.D. degree in Geotechnology from the Massachusetts Institute of Technology in 1979, 1981 and 1986, respectively. He has about 30 years of academic and industrial experience in the US, the UK, Canada and Hong Kong in numerical analysis, geotechnical design and construction. He is a Research Fellow of The Hong Kong Polytechnic University and has worked on various R&D projects and geotechnical control at the Geotechnical Engineering Office (GEO) of the Civil Engineering and Development Department (CEDD) of the HKSAR Government. He has been a member of a working group of the Geotechnical Division Committee of The Hong Kong Institution of Engineers (HKIE) since 2006 and is the leader of the Geotechnical Computer Program Users Group. Ir Dr Chan has organised and spoken at geotechnical seminars of the HKIE, the American Society of Civil Engineers (ASCE), the Association of Geotechnical and Geoenvironmental Specialists (AGS) and the GEO.