December 13, 2017

PhD graduate's research to improve air conditioning systems for health, environment

Mechanical engineer Yi Guo investigates how developments in air conditioning technology could help mitigate humidity and disease

With hotter than average summer days forecast, air conditioning is becoming an even greater necessity during our Australian summers.

PhD student Yi Guo is researching how this every day technology can be further developed to have a positive impact on the environment and our health.

A research assistant at UOW’s Sustainable Building and Research Centre, Yi has called on her passion for mechanical engineering to develop and create a model for an Advanced Electrodialysis-assisted Liquid Desiccant Dehumidification Air-conditioning System.

The liquid desiccant solution contacts the air as part of the dehumidifying process before the air is sent into the cooling system. The dehumidification of the air combining with the evaporative cooling significantly reduces the amount of electricity required, which is also environmentally friendly compared to current air conditioners on the market.

Experimental research shows by adding liquid desiccant dehumidification to the vapour compression air-conditioning system, the performance efficiency of the traditional vapour compression system can be increased by 68 per cent under typical operating conditions.

Yi said this liquid desiccant air-conditioning works particularly well in locations where there is high humidity, such as Darwin or Singapore, as the liquid desiccant efficiently absorbs water vapour in the air, which reduces the latent load of cooling.

Her motivation behind the research spawned from many years of tolerating uncomfortable humid conditions, often responsible for certain respiratory-related illnesses.

“My hometown is in Sichuan province in China, where the humidity is very high. And high humidity is related to many diseases like asthma and arthritis,” Yi said.

“Liquid desiccant dehumidification air-conditioning provides a healthier indoor environment by controlling the air humidity. And humidity control has become more important for indoor health and thermal comfort because of concerns over the quality of indoor air due to diseases such as fungal rhinitis, hypersensitivity pneumonia, acute respiratory conditions and asthma that are related to humidity.

“Occupants in a building with a high humidity ratio may feel uncomfortable, and that may influence their productivity – that’s where the liquid desiccant dehumidification air-conditioning system comes into its own.

“In my PhD thesis, we are trying to improve the performance of the liquid desiccant air conditioning system by using Electrodialysis technology - a type of membrane technology. The improvement of the performance will help promote this type of air conditioning in the market.”

In 2013, Yi experienced an early career highlight after assisting with the design of the air conditioning system for the Illawarra Flame house, a sustainable building which won the first place in the Solar Decathlon competition in Datong, China.

Last year, she was even more motivated to pursue her research after being named runner up in the iAccelerate pitch. It was here she introduced the concept of the membrane-assisted liquid desiccant air-conditioning system.

“I explained how humidity control is very important to us which is normally ignored by people. Most people probably feel they don’t have a good temperature during wet days. And this is not their fault, it’s because of the high humidity. It is hard to sweat.

“It further affects your metabolism, the release of hormones, and blood circulation. And these all together make you feel uncomfortable. Besides, a humid environment is a breeding place for many types of microscopic organisms that can harm your health. Dust mites also prefer the humid environment, and they are one of the major triggers of asthma and allergies,” she said.

Having successfully completed her PhD over the last four years, Yi plans to return to China where she has intends to pursue the research she has started here in Wollongong.

“I have accepted a research position at Xi'an Jiaotong University in China. I would like to continue my work there to promote the development of liquid desiccant air-conditioning systems.

“Hopefully the mature product of this can be easily purchased in the market in the near future.”