Harnessing Heat: A New Wave in Energy Recovery

At the University of Guelph, Dr. Mostafa H. Elsharqawy from the School of Engineering leading a project to improve home energy efficiency. His team is developing an innovative drain water heat recovery (DWHR) system to reduce energy waste in residential and commercial buildings. This technology could soon become a staple in both residential and commercial buildings, offering a sustainable and cost-effective solution to energy waste.  

A Fresh Look at Energy Recovery 

With a rich background in mechanical engineering and extensive experience in clean energy and water systems, Elsharqawy brings unparalleled expertise to this project. His recent research focuses on developing a novel design for a DWHR device that recovers heat from wastewater, which is the warm water that goes down the drain when you take a shower or use hot water in the sink. The idea is simple yet powerful: instead of letting this energy go to waste, the device captures it and uses it to preheat incoming cold water, reducing the energy needed to heat water for everyday use. This deep well of knowledge underpins his latest endeavor in DWHR, reflecting his commitment to sustainable solutions. 

The Magic Inside: How It Works 

The new DWHR device features a unique design that ensures maximum heat recovery. As warm water flows through the device, it comes into contact with a coiled pipe where cooler water flows in the opposite direction. The key innovation lies in the material and structure. Traditional devices use copper, which is bulky, expensive, and not very efficient in short-duration uses like hand washing. Elsharqawy's team uses polymers (plastics) that heat up and cool down much faster than copper. 

Inside the device, warm drain water flows over a series of plastic fins and a coiled pipe that carries the incoming cold water. The fins increase the surface area for heat exchange, making the process more efficient. The polymer material not only reduces cost but also improves the device’s performance in short-duration uses, such as dishwashing. By utilizing 3D printing technology, they can produce these devices at a fraction of the cost, making them accessible to more people.  

Breaking Down Barriers: New Solutions for Old Problems 

One of the major challenges the team faced was ensuring the device's performance under different conditions. “Our new device is made of plastic and we eliminated a lot of material, which significantly improves its transient performance. Additionally, we created a transparent model of the device to study how water flows and transfers heat, optimizing the design to work well with typical plumbing systems found in homes and buildings,”  says Elsharqawy.  

With a cheaper and more efficient DWHR device, homeowners can save on energy bills, and builders can include these devices in new constructions to meet higher energy efficiency standards.  

"This technology also has significant potential in commercial settings, like restaurants and food processing facilities, where a lot of hot water is used and wasted. By making these devices affordable, we can open up the market to many more users," says Elsharqawy. 

Elsharqawy and his team are now working on patenting their design and hope to see it commercialized soon. They believe this innovation will play a crucial role in making energy recovery more mainstream and accessible, contributing to a more sustainable future. 

Inspiring the Next Generation 

Elsharqawy encourages students interested in renewable energy and sustainable technologies to pursue research in these areas. "Our work shows that even simple changes in how we manage energy can have a big impact. I invite students to join us in exploring new ways to make our world more efficient and sustainable," he says. 

Through their pioneering research, Elsharqawy and his team at the University of Guelph are paving the way for a future where energy waste is minimized, and sustainability is a standard, not an exception. 

This story was written by Mehran Bozorgi as part of the Science Communicators: Research @ CEPS initiative. Mehran is a PhD candidate in the School of Engineering under Dr.s Syeda Humaira Tasnim and Shohel Mahmud. His research focus is on the development of sustainable cooling systems to achieve thermal comfort conditions in buildings in different climate conditions. 

Funding Acknowledgement: This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC–Grant #401366). 

References: E. Ovadia, T. Alam, A. Duran, and M. H. Sharqawy, “Thermal Performance of Conventional-Metal and Novel-Plastic Drain Water Heat Recovery Device,” Heat Transf. Eng., vol. 0, no. 0, pp. 1–14, Jun. 2024, doi: 10.1080/01457632.2024.2362542. 

E. Ovadia and M. H. Sharqawy, “Transient behavior of a falling-film drain water heat recovery device, thermal and economic performance assessments,” Case Stud. Therm. Eng., vol. 48, no. December 2022, p. 103096, Aug. 2023, doi: 10.1016/j.csite.2023.103096. 

M. Salama and M. H. Sharqawy, “Experimental investigation of the performance of a falling-film drain water heat recovery system,” Appl. Therm. Eng., vol. 179, no. February, p. 115712, Oct. 2020, doi: 10.1016/j.applthermaleng.2020.115712.