Water-cooling construction progresses

Construction of a cooling plant directly across from Building 39 on Vassar Street is nearing completion, and the new cold-water chiller is expected to be available for standby service in early June.

In addition, a new cooling tower behind the Central Utility Plant (CUP) on Albany Street should be completed in July. It will increase cooling tower capacity by 72 percent.

"The facility will be fully operational in automatic control in August," said Peter L. Cooper, assistant director for utilities at Physical Plant.

This is the first chiller addition to the CUP since 1972. The East Campus chilled water plant (Building E40) was installed in 1980.

The blue machine visible through the open steel at the Vassar Street construction site is a 5,000-ton chiller made by York Co. The two cylindrical vessels, one above the other, are heat exchangers. In one, cold expanded refrigerant cools the chilled water; in the other, cooling tower water cools the hot compressed refrigerant. This is similar to the thermodynamic cycle used in a home refrigerator.

One ton in a cooling context is not a measure of weight; it is the amount of cooling provided by melting a ton of ice in one hour. This is equal to 12,000 BTU/hr, about the capacity of a large window air conditioner.

The compressor, driven by a 4,200-horsepower steam turbine, increases the CUP chiller capacity by 48 percent.

The steam to drive all the chiller compressor turbines at the CUP is provided primarily by the cogeneration water heat boiler, with Boilers 3,4 and 5 on standby.

The CUP, constructed as a coal-fired steam and electric generating plant in 1915, has been transformed several times during its existence due to technological changes, utility requirements, fuel availability and cost.

It was converted to oil in 1933. In 1938, Cambridge Electric Light Co. became the primary source of electricity. The co-generation plant went on line in 1995.

A version of this article appeared in MIT Tech Talk on May 21, 1997.

Topics: Campus services

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