Academic administrator Jonathan Boreyko drives a group at Virginia Tech that has fabricated areas of strength for work with ice and water, investigating the opportunities for de-icing planes, building novel water collecting gadgets, and making snow globes out of air pockets. This knowledge of water has provided the group with serious areas of strength for its conduct in various states, prompting another undertaking that shows how ice extinguishes heat in contrast with water. The discoveries were distributed in Chem’s diary on April 14.
This project was carried out by master’s students Camryn Colón and Mojtaba Edalatpour. They looked into ways to remove heat from metal, which is a crucial step in applications like metallurgy and firefighting. In both cases, speed is required. While firefighters work to stop the destruction of property as quickly as possible, metallurgists need to quickly lower the temperature of a forged piece to achieve specific material properties. Extinguishing with water is successful only at a basic temperature; any higher and the water suspends its own fume and can never again reduce the intensity.
Boreyko’s group needed to check whether utilizing ice instead of water could sidestep the levitation issue and empower the extinguishing of super-hot surfaces.
“We would be able to directly compare the heat transfer of ice to that of cutting-edge boilers if you could quantify the steady-state heat flow at a constant temperature.”
Camryn Colón carried out this project.
Measuring, heating, and measuring again Edalatpour and Colón heated an aluminum stage and measured the difference between the cooling rates of water and ice for this study. To guarantee an immediate examination, they delivered a similar amount of water and ice onto the surface after it had been warmed to an ideal temperature.
Both the water and the ice successfully submerged the stage’s surface below 100°C when the stage’s initial surface temperature was between 100°C and 300°C. However, the ice achieved that outcome in half the time. Only ice quenching was successful at higher initial temperatures (300°C to 500°C). At these high temperatures, ice was 100 times more effective than liquid water at transferring heat.
What was the distinction? Water’s properties prevent it from reaching the optimal temperature for removing heat.
Because the steam that escapes in bubbles moves the heat away most effectively, the ideal temperature is boiling. Since water effectively suspends on its fume at high temperatures, it becomes protected from the surface, and the bubbling won’t ever happen. Ice acts in a different way. Ice melts because it absorbs a lot of heat when dropped on a hot surface. The problem of levitation is avoided because this reduces the amount of heat available for producing vapor bubbles. To put it another way, meltwater boils at higher temperatures because it boils at a slower rate than pure water.
Boreyko compared worker productivity to the unusual liquid behavior.
He advised, “Think about a workaholic who is always focused on their job.” They are initially extremely productive, but they quickly become exhausted and ineffective. Water behaves similarly when exposed to surfaces with extremely high temperatures, as it turns out: It experiences “burnout,” which is the scientific term for levitation and the catastrophic failure in cooling that results from being so focused and productive at boiling water into vapor. Therefore, ice prevails in the long run, like the patient tortoise. Although it does not produce vapor bubbles very well, this permits it to continue boiling and avoid levitation when temperatures rise.”
Following their recent discovery that ice does not levitate and lose its boiling capability until 550°C, in contrast to 150°C for water, the group’s hypothesis of using ice for quenching continues. The team led by Boreyko started a number of new projects that applied those findings. The first published outgrowth was this heat transfer.
Colón’s subsequent work incorporates estimating the cooling execution of ice when the surface is fixed at a consistent temperature as opposed to being permitted to chill off.
According to Colón, “you can measure the steady-state heat flux when you have a constant temperature, which would allow us to directly compare the heat transfer of ice versus state-of-the-art boilers.”
The group is likewise conceptualizing how to carry out a down-to-earth ice extinguishing framework.
According to Boreyko, “It remains to be seen exactly how to implement three-phase heat transfer for real-world applications, but we’re excited to figure it out over the next several years.” It might look more like releasing a pre-formed block of ice onto an overheated surface or making spray nozzles that can eject ice particles rather than water. Before this becomes a commercially available technology, there is a lot more to learn.”
More information: Jonathan R. Boreyko, Ice quenching for sustained nucleate boiling at large superheats, Chem (2023). DOI: 10.1016/j.chempr.2023.03.010. www.cell.com/chem/fulltext/S2451-9294(23)00129-8
