A Cool Solution

THE MAGAZINE DEVOTED TO NICKEL AND ITS APPLICATIONS July 2004 Volume 19, Number 3

LOCATED ON LAKE ONTARIO, the City of Toronto is taking advantage of cold lake water to reduce the cost of cooling office buildings during the summer months.

LAKE WATER AT a chilly 4°C helps to remove heat from office air which originates from people, lights and office equipment.

PARALLEL FLOW heat exchangers, made of S31600 nickel-containing stainless steel.

THIRTY-SIX HEAT EXCHANGERS like this one are being supplied in the $4-million project.

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Stainless steel heat exchangers are key to energy-efficient air conditioners.

By Virginia Heffernan

Nickel Magazine, July 2004 -- Austenitic stainless steel is playing a central role in an effort to replace conventional air conditioning in downtown office buildings. New "greener" systems use lake water as a cooling medium and therefore only 25% of the electricity that would normally be needed by conventional air conditioners.

Toronto's lake-water cooling project, the largest of its kind in the world, takes icy water from a depth of about 83 metres in Lake Ontario and circulates it through office buildings via a network of underground pipes. The chilly water is used in customers' cooling systems through heat exchangers provided by APV Solutions & Services, a division of London-based Invensys.

Under a C$4-million dollar contract with Enwave District Energy Ltd., APV is supplying 36 heat exchangers made of S31600 stainless steel to the project.

Enwave, one of North America's largest district energy providers, selected APV's Paraflow plate heat exchangers for the task. They provide a 93% recuperation rate (meaning only 7% of the chill is left behind in the water, an excellent recovery) while complying with the National Sanitation Association's requirements for potable water systems, says Osama Shenouda, process engineer for APV.

The Paraflow units (so-called because the flow regimes on either side of the plates are parallel to one another) are designed to operate in challenging chemical and industrial environments. They come is a variety of materials and styles depending on the application and the harshness of the process fluids. Typical application environments include steel plants, bauxite to alumina operations and coke oven plants. S31600 can be fully recycled at the end of the 40-to-50-year expected operating life of the units.

According to Enwave, more than half of Toronto's annual cooling load goes to counteract the heat produced by people, lights, and equipment in office buildings all year long. But the city is in a unique position to replace conventional, energy-guzzling air conditioning with deep-water cooling because its cluster of downtown towers sit beside a large, deep body of water.

The C$165-million project, which carries water at 4°C through 5-kilometre-long intake pipes to an onshore pumping station, will eventually produce enough cooling to service more than 1.8 million square metres of office space, the equivalent of about 100 towers.

Once the water has relinquished its chill, it will continue on its way to become part of Toronto's municipal water distribution system supply.

"This will be the largest lake water cooling service in the world, and the first of its kind in Canada," says Dennis Fotinos, president and CEO of Enwave. "It will meet up to 40% of the air-conditioning requirements for Toronto's downtown core, use up to 75% less energy than conventional electric chillers and eliminate forty-thousand tonnes of carbon dioxide and lower levels of pollution."

Few district energy systems have taken advantage of this abundant and renewable source of air conditioning. In 2002, Cornell University in New York replaced central campus chillers with a new source based on the cold deep waters of nearby Cayuga Lake - an initiative which earned it a Technology Award from the American Society of Heating, Refrigerating and Air-Conditioning Engineers. The other deep-water cooling systems are found in Stockholm, where salty water from the Baltic Sea passes through titanium plate heat exchangers, Halifax, Nova Scotia, Canada, where ocean water cools two commercial buildings along the waterfront, and the National Energy Lab at Keahole Point in Hawaii, U.S.A.

Virginia Heffernan is a Toronto-based freelance writer.

PHOTOS: APV Solutions & Sevices

Osama Shenouda Process Engineer APV Solutions & Services 3280 Langstaff Rd. Concord, Ontario Canada L4K 4Z8 Tel: 1 905 760 1852 Fax: 1 905 760 1865 E-mail: Web site:

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