Power, water and refrigeration in one box
Engineers at the University of Florida have developed and built a system that can provide power, water and refrigeration from a single unit. This project, funded by the U.S. Army, will lead to units small enough to fit inside a military jet or a large truck. The prototype system is already more efficient than conventional turbines. And it is also environmentally friendly because it can use traditional fossil fuels as well as biomass-produced fuels or hydrogen and releases only small amounts of pollutants. This kind of system could be used as a mobile unit in case of hurricanes or wars. But it might also be connected to the normal power grid in fixed locations. Read more...
This project was led by William Lear and S.A. Sherif from the University of Florida.
Below is a picture of William Lear standing in front of the prototype system that can provide power, water and refrigeration (Credit: Kristen Bartlett/University of Florida). Here is a link to a larger version.
Now let's look at the reasons why this system was built.
Both the Federal Emergency Management Agency and the military now rely on large generators to produce electricity in hazard zones. For cooling, they either haul in ice or electricity-hogging refrigerators. Depending on the location and emergency, imported fresh water may be another major logistical challenge and expense.
As the U.S. Army wanted to simplify this process, it decided to fund the project initiated by Lear and Sherif, who already have published several academic papers on such a system.
The engineering researchers' solution: a small system that ties a novel gas turbine power plant to a heat-operated refrigeration system. The refrigeration makes the gas turbine more efficient, while also producing cool air and potable water. The turbine can run on conventional fossil fuels as well as biomass-produced fuels or hydrogen.
And as traditional gas turbines lose efficiency when not operated at full power and in warm temperatures, Lear and Sherif tried to build a more efficient device.
[Lear] rerouted the path of gases passing through the turbine, cooling them via heat exchangers. Sherif, an expert in refrigeration, then tied the system to absorption units, cooling the gases still more. Users can either tap all the cooling power to obtain peak efficiency for the turbine, or divert some for refrigeration or air conditioning. "You can decide how much of one you want versus how much of the other, depending on your needs," Sherif said.
But how more efficient is this system when compared to current ones?
Lear said his experiments and computer models suggest that with all the cooling devoted to the turbine, it will be 5 percent to 8 percent more efficient than traditional turbines. With some cooling siphoned for other purposes, it was still 3 percent to 5 percent more efficient than the turbines. Contrasting traditional gas turbines, the system maintains its efficiency whether operated at peak or partial power.
A few percentage points might not seem like much, but it makes a big difference when fuel is scarce or expensive, particularly if refrigeration and water are added bonuses, Lear said. "Power companies would kill for a 1 percent gain," he said.
The two engineers are still working on a more compact system that would be moveable -- if not portable. And they will present a paper about their progress at the next International Mechanical Engineering Congress & Exposition which will be held in November at Chicago, Illinois.
Finally, Lear and Sherif are receiving the U.S. Army money through a small company based in Gainesville, Florida, Triad Research. So it's only normal that the Gainesville Sun wrote about this new system. Here is a short quote from Lear.
"I hope it will be part of the power grid of the future, whether just in Florida or elsewhere," Lear said. "It, along with other changes to the design grid, make for a much more robust system, especially with hurricanes and other emergencies. Florida is the initial focus, but it could have applications worldwide."
Sources: University of Florida News, via EurekAlert!, August 2, 2006; and various web sites
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