(535a) Roadway Deicing: A Pinch of Salt
AIChE Annual Meeting
2019
2019 AIChE Annual Meeting
Engineering Sciences and Fundamentals
Interfacial Transport Phenomena
Wednesday, November 13, 2019 - 12:30pm to 12:45pm
Roadway Deicing: A Pinch of Salt
Ice formation on roads
can have profound effects leading to car accidents. With approximately 70% of
U.S. roads being located in snowy regions, each winter >22 million tons of
salt is sprinkled on U.S. roads to keep them drivable. These road salts corrode
infrastructure and have detrimental effects on the environment. Inspired by the
semi-permeable biological membranes found in nature (e.g. our kidneys), we aim
to coat road salt within a polymer membrane which will maintain its deicing
functionality but prevent the environmental salt release. For this purpose, we have studied the
fundamentals of phase change of water to ice in the presence of a hygroscopic
material (such as salt), the resulting source-sink interactions between salt,
water, and water vapor and eventually develop scaling laws that govern the
deicing performance of a rock salt. We also have determined the freezing delay
potential of a number of other commonly used salts, subjected to different
environmental conditions. This methodical investigation is expected to
facilitate in choosing which salt performs best in a particular frigid outdoor
environment. The very fact that road salts are subjected to a myriad of
environmental conditions during their application in the winter season,
understanding the underlying physics that dictate their deicing performance is
crucial for efficiently salting roads by being beneficial for both
transportation safety and environmental sustainability.
Figure 1. Region of inhibited condensation around a sodium chloride salt
crystal chilled to -15°C
can have profound effects leading to car accidents. With approximately 70% of
U.S. roads being located in snowy regions, each winter >22 million tons of
salt is sprinkled on U.S. roads to keep them drivable. These road salts corrode
infrastructure and have detrimental effects on the environment. Inspired by the
semi-permeable biological membranes found in nature (e.g. our kidneys), we aim
to coat road salt within a polymer membrane which will maintain its deicing
functionality but prevent the environmental salt release. For this purpose, we have studied the
fundamentals of phase change of water to ice in the presence of a hygroscopic
material (such as salt), the resulting source-sink interactions between salt,
water, and water vapor and eventually develop scaling laws that govern the
deicing performance of a rock salt. We also have determined the freezing delay
potential of a number of other commonly used salts, subjected to different
environmental conditions. This methodical investigation is expected to
facilitate in choosing which salt performs best in a particular frigid outdoor
environment. The very fact that road salts are subjected to a myriad of
environmental conditions during their application in the winter season,
understanding the underlying physics that dictate their deicing performance is
crucial for efficiently salting roads by being beneficial for both
transportation safety and environmental sustainability.
Figure 1. Region of inhibited condensation around a sodium chloride salt
crystal chilled to -15°C