Improving high-rise hot water distribution

Researchers from the University of Toronto are collaborating with local startup FlowMix to study technology that could improve hot water distribution for the 1.9 million Canadians who live in condominiums, potentially eliminating cold showers and accidental scalding. 

“The problem of hot water delivery in condos or highrise buildings can be substantial. Not much has changed since mechanical valves – driven by pressure and temperature difference – were introduced over a century ago,” says Pierre Sullivan, a professor in the department of mechanical and industrial engineering in the Faculty of Applied Science & Engineering who is also director of the Turbulence Research lab.

Sullivan combines experimental and computational tools to better understand fluid physics. His research has spanned aerodynamic control, wind power, small aircraft and weather gauges.

In residential buildings, where hot water must be supplied to multiple residents, there are inevitable demand spikes, such in the morning when people are getting ready for work. Extended periods when water is not in use, including overnight or while residents are at work, can also cause issues. During these down times hot water lines cool, which can lead to a chilly morning shower.

FlowMix, a company that designs hot water control systems, has developed a method that maintains a cycle of hot water in residential water delivery systems. Sullivan and his team reviewed the FlowMix design and, through testing and modelling, showed the effectiveness of the company’s solution.

“Simulations helped us to understand the flow structure inside the device for the purpose of improving the performance. We also modeled traditional mixing devices to compare the performance of these devices with FlowMix,” said Ali Rahmatmand, a former post-doctoral researcher in the Turbulence Research lab.

“We also provided an AI model to predict the supply temperature of a building based on a basic demand and cold-water temperature to improve the control system,” said Marin Vratonjic, another former post-doctoral researcher.

With the team’s recommendations, the startup was able to optimize their system for both new construction and retrofits of highrise buildings. This collaboration also means FlowMix can now quantify its impact on energy savings and CO2 emission reduction, which could help inform decisions made by condominium boards.

By Lynsey Mellon

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