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Engineering students to help power plant improve efficiency

by Nan Cooper - September 8, 2008

Three engineering students, under the supervision of chemical engineering professor Douglas Cooper, began a research study over the summer aimed at helping the UConn power plant perform more efficiently.

The team seeks to fine-tune the operation of the plant, which is already highly efficient, with the goal of reducing consumption of natural gas and fresh water while still meeting the electrical, heating, and cooling requirements of the Storrs campus.

The combined-cycle cogeneration plant supplies electricity to the entire campus, from dorms and academic buildings to administration and service facilities. It also provides steam heating in the winter and chilled water cooling in the summer. Before the plant came online in 2006, the University purchased electricity from a utility company, and steam was generated on-campus in an old-style boiler house.

The student team includes Rachelle Howard, a doctoral candidate in chemical engineering, and two undergraduate students, seniors Michelle Przybylek, an environmental engineering major, and Melissa Tweedie, a chemical engineering major.

The research team will collaborate with the plant utilities manager Ronald Gaudet and power plant supervisor Tim Grady to: reduce natural gas usage and carbon emissions through improvements in overall plant efficiency; reduce water usage through identification of alternative designs and operational practices; and lengthen equipment life and reduce equipment maintenance costs through decreased cycling.

“This effort promotes University President Michael Hogan’s objective of a more environmentally-sustainable campus,” says Cooper. “It reinforces UConn’s position as a leader in researching, demonstrating, and supporting solutions to urgent global challenges.”

The in-plant performance study is supported by the Office of the Associate Vice President for Administration & Operations.

Gaudet says a combined cycle power plant burns fuel – natural gas or fuel oil – only once but generates electricity in two ways. At the UConn cogen plant, the fuel is first burned in what are essentially jet engines – three large gas turbines – turning electric generators in the process.

The hot exhaust gases exiting each turbine then enter steam boilers, called heat recovery steam generators, to produce both high pressure and low pressure steam. The high pressure steam turns a steam turbine generator to produce additional electricity, without burning extra fuel.

Engineering students Melissa Tweedie, seated, Rachelle Howard, left, and Michelle Przybylek, in the control room of the cogeneration plant.
Engineering students Melissa Tweedie, seated, Rachelle Howard, left, and Michelle Przybylek, in the control room of the cogeneration plant.
Photo by Mohamed Faizal

Howard’s tasks focus on the control system, testing and documenting new methods for plant performance evaluation and loop tuning where the cogeneration plant operation is the primary focus and beneficiary. The control system is the computer “brain” of the plant.

It receives hundreds of temperature, pressure, flow, and other sensor signals, and rapidly adjusts valves, pumps, compressors, and other elements so the plant runs safely and efficiently.

Howard has developed a method for analyzing control signals and improving control system performance without the need to “bump” or deliberately disrupt the plant as required by current industrial practice.

Przybylek, an honors student, will perform an overall energy and carbon balance analysis that will form the basis of her senior honors thesis.

Tweedie will build upon her experience as a summer intern with UTC Power to perform an overall water balance analysis. Both will participate in other tasks as needed to the benefit of the plant.

Lee Langston, professor emeritus of mechanical engineering, who encouraged the University to build the cogeneration plant, explained that after electricity generation, there is plenty of low-pressure steam left over to heat campus buildings, kitchens, and laboratories in the winter.

During the warmer months, when heating loads are greatly reduced, the low-pressure steam drives refrigeration compressors to supply chilled water to air conditioning units in these buildings.

“The result,” says Cooepr, “is that UConn’s new facility is among the most versatile and efficient academic cogeneration plants in the country.”

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