The researchers test site shows photovoltaic panels (foreground) providing power to a battery-storage system and concrete panels (background). Photo: University of Arkansas
Engineering researchers at the University of Arkansas
are developing an anti-icing system that could make airport runways safer and
less expensive to maintain during winter months. The approach uses a
conventional photovoltaic system to supply energy to a conductive concrete slab
that would function as a surface overlay on runways. Energy conducted
throughout the slabs allows them to continually maintain temperatures above
freezing and thus prevent accumulation of snow and ice.
“Major U.S. airports do a good job of keeping runways safe and
clear of ice and snow,” says Ernie Heymsfield, associate professor of civil
engineering. “But this is a labor-intensive and expensive process, especially
for northern airports. The St. Paul,
Minn., airport, for example,
budgets approximately $4 million annually for snow removal. For various
reasons, including the fact that it is grid-energy independent, our system
could put a huge dent in this budget.”
After initial design, Heymsfield now leads a team of
researchers who are testing the slab at the university’s Engineering
in south Fayetteville.
The slab consists of two layers above existing soil and a gravel base.
The bottom layer—the first layer above the gravel base—is a
20-ft by 24-ft base slab that does not contain any conductive properties. Above
the base slab is a surface layer that consists of twelve overlay panels, each 4
ft by 10 ft. Ten of these panels are made with a special concrete mix that
conducts heat much like a cast-iron skillet exposed to a stove burner. Two
control panels made of conventional concrete mix provide a basis for comparison
to the conductive panels.
The photovoltaic system supplies DC power to electrodes
embedded within the conductive concrete panels. The components of the
photovoltaic system include an array of cells that convert sunlight into
energy, a battery storage bank and a regulator to control energy between the
array and the batteries. Energy is transferred from the batteries to the
electrodes. The intrinsic thermal-mass properties of the concrete mix also
enable the slab to absorb large amounts of heat from ambient temperature
conditions, which minimizes the cost of the photovoltaic system.
Preliminary tests showed that although heat flow was
non-uniform and concentrated on an area near the energy source, the conductive
panels responded much faster to extreme surface temperature reductions after
the researchers applied a thin layer of ice. Heymsfield says the non-uniformity
and concentration of heat flow will be corrected by modifying the electrode
configuration. The researchers will continue testing the system through the
2011 and 2012 winter season.
If successful, the modified pavement could be an alternative
to current snow and ice-removal methods, which include plowing, blowing and
applying chemicals. There are various pavement de-icing methods, including
chemical, thermal, electric, and microwave, but these methods are expensive
because they rely on grid power or require a high number of airport personnel.
SOURCE – University of Arkansas