By Sally Pobojewski
New and Information Services
A U-M experiment on the space shuttle Endeavour, launched in late June, will help scientists learn more about what happens when liquids boil.
The objective of the experiment, according to Herman Merte Jr., professor of mechanical engineering, is to understand the basic mechanisms that control what scientists call the nucleate pool boiling process.
“Anyone who has ever boiled water on a stove is familiar with nucleate pool boiling,” Merte says. “Even though it’s an everyday event, scientists don’t understand precisely how it works, because Earth’s gravity influences how bubbles form and grow in boiling liquids.”
Using automated cameras and temperature sensors, Merte recorded images and data from about two quarts of a liquid called R-113 (a type of freon) as it boiled during an eight-hour series of experiments.
The 175-pound self-contained experimental apparatus, tucked inside a garbage can-sized canister in the payload bay, was activated by shuttle astronauts just before their first sleep period during the mission. The pool boiling experiment had to take place while the astronauts sleep. Otherwise, vibrations from movement inside the shuttle would distort the boiling process, according to Merte.
“NASA is interested in results from this experiment, because boiling liquids generate bubbles which are very efficient at transferring large amounts of heat,” Merte explains. “Finding new ways to dissipate heat from the space shuttle or future manned space platforms will be vital to the success of long-term missions.”
According to Merte, there are potential benefits closer to home as well, including more effective air conditioning and refrigeration systems and improvements in power plants that could reduce the cost of generating electricity.
The experiment was funded by NASA and administered by NASA’s Lewis Research Center in Cleveland, Ohio. Robert B. Keller, associate professor of mechanical engineering, and graduate student Ho-Sung Lee assisted with the experiment.
