Impingement and vaporization of a 5-millimeter water droplet onto a 3-millimeter film of hot canola oil. The image to the right, shot just half a second after the water first contacts the oil, shows a plethora of droplets that are released. Some droplets are submicron and can remain airborne for more than 30 minutes. Source: Marston Research Group, Texas Tech UniversityImpingement and vaporization of a 5-millimeter water droplet onto a 3-millimeter film of hot canola oil. The image to the right, shot just half a second after the water first contacts the oil, shows a plethora of droplets that are released. Some droplets are submicron and can remain airborne for more than 30 minutes. Source: Marston Research Group, Texas Tech UniversityHot oil droplets that often leap from the frying pan as we cook have the potential to not only cause painful burns. They also have the potential to contribute to indoor air pollution, according to a recent study.

Researchers from Texas Tech University and Utah State University are presenting their findings at the American Physical Society's Division of Fluid Dynamics, being held Nov. 19-21, 2017, in Denver, Colorado.

"We've discovered that a very large number of small oil droplets are released when even a single, small droplet of water comes into contact with hot oil," said Jeremy Marston, an assistant professor at Texas Tech University.

Using a thin layer of canola, peanut or soybean oil, the researchers measured the temperature with a thermocouple as part of their experiment.

“Then, we inject a small droplet of water and record the event with a high-speed video camera," Marston said. "The resulting phenomena is dramatic — you can see the explosive release when the water, trapped under the oil, vaporizes all of a sudden. This causes the oil film to rupture and sends oil droplets flying."

The team determined that the oil droplets can be hazardous because they are small enough to inhale.

"It's known that millions of deaths worldwide occur due to indoor air pollution, but we don't know yet how much cooking in poorly ventilated kitchens contributes to it," Marston said. "We're planning to conduct a detailed study to quantify how much impact kitchen-based aerosols have on indoor air pollution. Ultimately, we hope that our research can guide designs for improved ventilation systems to remove these ultrafine aerosols."

Marsten continued: "To explore the fundamental science, we'll perform three-dimensional volumetric imaging and thermal imaging to assess the dispersion of the aerosols released in cooking," he said. "We'll also perform some preliminary trials using a new air curtain that could be integrated into current ventilation systems. And since some of the droplets are inhalable and potentially hazardous, we're also planning to use an 'aerosol particle sizer' that can measure down to the nanometer sizes to see just how small these particles can be."

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