In what seems a counter-intuitive maneuver, Dr. Homayun Navaz, professor of Mechanical Engineering at Kettering University, turned down the velocity of cold air and raised the temperature to 32 degrees to improve energy efficiency in a refrigerated display case. Ironically, it worked. Energy savings went up and the food got colder.

“You would think more air coming faster would work better, but the decreased velocity improved infiltration, which resulted in the food being one degree colder because the cold air was distributed more efficiently inside the display case,” explained Navaz.

Using a machine called the "Proof of Concept Air Curtain" (POCAC), designed and built at Kettering, a matrix of tests were performed and the resulting 3,000 data was correlated through a computer program based on an Artificial Neural Network (ANN).

By reducing the velocity by 30 percent, infiltration was reduced by 12 percent and the power required was reduced by 13 percent.

Infiltration represents 83 percent of the cooling load and is the biggest energy draw for refrigerated display cases. Less energy use equals real cost savings of about $13 million for the state of California alone, according to Navaz.

This kind of energy savings also reduces CO2 emissions that cause green house gases, he said. The nationwide savings for reduced infiltration rate version of just open vertical display cases can be calculated to be about $170 million to $200 million a year with a reduction in carbon dioxide emissions of more than 500,000 tons.

Manufacturers implementing changes based on the Kettering research are already seeing better than predicted results, according to Navaz, and so far it hasn’t cost them anything to implement the recommended changes.

“This is not something we are promising,” said Navaz, “it is something we have done and proven.”

The Department of Energy and the California Energy Commission and Edison underwrote the research project that began in 1998. The total cost of the project came in just under $500,000, according to Navaz.

Partnering organizations for the cold air curtain project included: The Technology Test Center (TTC) at Edison; Public Interest Energy Research (PIER) at California Energy Commission.

“Imagine if we could save 10 to 15 percent in all refrigeration units, what an impact what would make on energy consumption world wide," Navaz said.

Navaz is currently attempting to form a consortium with Edison to expanded the research and create jobs in Michigan by starting a center for Efficient Refrigeration Technology.

More at www.kettering.edu , More about Navaz's research at this link..