Most power plants in the United States are built alongside bodies of water to meet the demands of their cooling systems. Some of that water is lost through evaporation in cooling towers. In other cases, warmer water is pumped back into lakes, rivers, or bays, which can raise the ambient temperature, killing fish and other aquatic organisms and creating toxic algae blooms. Scientists call this “thermal pollution.”
University of Cincinnati (UC) researchers have developed enhanced metal fins with a unique geometric design that favorably alters the air flow over them. This provides far better heat convection to cool the steam in the air-cooled condenser. The flow of air gets disrupted with more mixing and more efficient heat transfer compared to traditional fins. The design was the result of carefully controlled experimentation coupled with computational modeling. Modeling gives an understanding of the physics and experiments give the results that can be used to optimize design.
Shedding more heat increases the efficiency of the power plants, which means they can produce more electricity. And since the cooling system is more effective, it doesn’t have to be as big and costly to build. Laboratory-scale tests suggested the researchers’ system can reduce the cooling temperature from 140 degrees to as low as 115 degrees.
The engineers are also working on a solution to one of the energy industry’s biggest conundrums. In the summer, electricity demand typically peaks during the hottest part of the day when a plant’s cooling systems are least efficient. They are developing a system to pre-cool the circulated air using a heat sink that captures cooler temperatures at night.
Air-cooled power plants will become increasingly valuable in arid parts of the world in the face of growing industrialization and climate change, said UC engineer Raj Manglik. “There is already a water shortage, exacerbated by the global need for energy,” he said. “We will need a substantially larger number of new power plants if the rest of the world begins to consume energy at the rate we do in the United States.”