Categories
Energy

4: Air conditioners that operate with water

Problem:

Leaking CFC and HCFC-based air conditioners contribute to GHG and ozone depletion.

Solution:

In 2018 a team of scientists at the National University of Singapore announced the development of a prototype of a sustainable air conditioning unit which uses water instead of refrigerants, and consumes 40 % less electricity to operate, and can cool a space to as low as 18° Celsius.

After four years of government-funded research on Project Drawdown, Dr. M. Kum Ja, Dr. Bui Duc Thuan, Associate Professor Ernest Chua, and Dr. Md Raisul Islam have produced two new technologies.

The first is a membrane dehumidifier which uses special water-absorbing materials and a difference in air pressure to extract water from ambient air as it is passed through the membrane.

The water removed is potable and almost as pure as bottled drinking water.

The drier air is then passed through what is called the counter-flow dew-point evaporative cooler, the team’s second invention.

This device removes heat through evaporative cooling, the same process that reduces body temperature through perspiration. Instead of relying on HCFCs, the drawdown air conditioner can cool a room using rain water.

It requires 2 pints (one liter) of water to cool a master bedroom unit for 15 to 20 hours. While regular air conditioners expel hot air as a by-product, the prototype releases humid air that is still likely to be cooler than ambient temperatures.

This helps to avoid disrupting the urban microclimate outside.

If a city replaces all its compressor-based coolers with this innovative air-conditioner, then it reduces its electrical demand enormously. Cities may slash their need for new power plants in developing countries, with a resource found wherever humans thrive.

In October 2018, team member Ernest Chua was conferred the Best Paper Award at the IEEE-organised “International Conference on Green Energy for Sustainable Development held in Phuket, Thailand. He also presented a paper in January 2019 at the World Economic Forum Annual Meeting at Davos.

He has emphasised that the 5 ft. (1.6 m) tall prototype was not the finished version, and his team is now looking to create a more compact and commercially viable product for the market in three to five years’ time. (nus.edu.sg)

Ernest Chua,“A hybrid air conditioning system employing membrane dehumidification and dew-point cooling” International Conference on Green Energy for Sustainable Development, October 2018

Discover solution 5: a bus that takes particles OUT of the air as it travels.

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