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STEM SIGHTS: The Concordian who recycles ‘thermal garbage’

PhD candidate Mahmood Joybari is developing ways to reuse heat released from high-rise buildings
October 23, 2017
By Kenneth Gibson

Mahmood Mastani Joybari: “Numerous systems operate in an inefficient manner.” Mahmood Mastani Joybari: “Numerous systems operate in an inefficient manner.”

A quick search on Google Maps will show you satellite imagery of the top of any high-rise in downtown Montreal — Place Ville Marie, KPMG Tower, even Concordia’s Henry F. Hall Building. Look closely and you’ll see a large number of cooling towers, which resemble giant fans.

Cooling towers are the primary way that the air-conditioning systems of large buildings release their waste heat, or “thermal garbage” as Mahmood Mastani Joybari calls it.

Joybari, who recently defended his dissertation in the Department of Building, Civil and Environmental Engineering, believes there is a better way to use the waste heat from cooling systems.

The research he conducted for his PhD looked at using phase-change materials — substances that absorb and release thermal energy during the process of melting and freezing — to create thermal energy storage units. These could hold the waste heat from high-rise cooling systems to be used later to heat a building’s water.

The replacement of cooling towers with this kind of thermal energy storage system would have far-reaching impacts on global warming, by simultaneously eliminating the dumping of heat into the atmosphere and reducing the energy consumption associated with water heating.

Photo by Christian Barette (Flickr Creative Commons) Photo by Christian Barette (Flickr Creative Commons)

‘Solutions to energy inefficiencies can help save the planet’

How does this specific image relate to your research at Concordia?

Mahmood Mastani Joybari: Most people have seen the vapour released from the top of high-rise buildings on cold winter days. Conversely, air-conditioning systems remove heat from indoor spaces and dump it into the environment by means of cooling towers.

Besides being aesthetically unpleasant, one of the major concerns regarding the use of cooling towers is the possibility of bacterial growth if they are not maintained carefully. A bacterium called legionella can grow in cooling towers and can cause a life-threatening respiratory infection known as legionnaires’ disease.

Moreover, dumping heat into the air has effects on global warming. My research focuses on ways to take heat that is currently released into the atmosphere and recover it for hot water preheating.

What is the hoped-for result of your project? And what impact could you see it having on people's lives?

MMJ: Global warming is an inevitable consequence of greenhouse gases, particularly carbon dioxide. In Quebec, for example, it is predicted that there will be an average temperature increase of two to seven degrees Celsius in the next 55 years. Under such conditions, thermal garbage from equipment such as cooling towers is unacceptable.

Additionally, hot water supplies in buildings are a major source of energy consumption. Distribution systems are known to be inefficient, compounding the problem of energy use.

Thus, my research seeks to reduce global warming by both eliminating the heat dumping of a building’s cooling system and then using that heat to reduce the amount of external fuel required to warm its water.

What are some of the major challenges you face in your research?

MMJ: Creating change in a major industry is always hard, especially if it is a well-established one like that of air conditioning. In my case, the change requires replacing an existing component with a thermal energy storage unit.

Inherently, thermal storage is a slow process, which must be enhanced to be able to catch up with the requirements of air-conditioning systems. My research focuses on methods for such an enhancement and provides recommendations for this application.

What person, experience or moment in time first inspired you to study this subject and get involved in the field?

MMJ: Several cases of legionnaires’ disease have been reported throughout the world in recent years, resulting in numerous lives lost.

Canada witnessed two major outbreaks in Toronto in 2005 and Quebec City in 2012, which resulted in 34 deaths among 307 cases. These tragic events inspired me to engage in replacing cooling towers by thermal storage to save lives.

From a bigger-picture perspective, of course, many lives will also be saved if my research can contribute to stopping the advance of global warming. 

What advice would you give STEM students who might be interested in getting involved in this line of research? 

MMJ: Numerous systems operate in an inefficient manner. With the case of climate change, in my opinion, simple solutions to these sorts of inefficiencies can help save the planet.

I invite interested STEM students to take a look at the world around them and identify potential systemic improvements that can increase energy efficiency and sustainability.

What do you like best about being at Concordia?

MMJ: I like being located in the heart of downtown Montreal, one of the most vibrant neighbourhoods in the city. Additionally, Concordia offers the opportunity to thrive both scientifically, by providing all required tools and academic support, and non-scientifically, through its diverse, multicultural and friendly environment.

Are there any partners, agencies or other funding/support attached to your research?

MMJ: I have received funding through the Concordia University Research Chair for Energy and Environment as well as the Natural Sciences and Engineering Research Council Discovery Grant and Collaborative Research and Training Experience programs. This project was part of the Canadian contribution to a project sponsored by the International Energy Agency (IEA - ECES Annex 31).

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