Click here to sign in with or
by Bob Yirka , Phys.org
A team of researchers from the Institute of Scientific Instruments working with a colleague from Charles University, both in the Czech Republic, has shown that heat flows more efficiently when the temperature of the material through which it is flowing oscillates, as opposed to remaining steady. In their paper published in the journal Physical Review Letters, the group describes experiments they conducted with heating and cooling helium in a container and its relevance to a theory proposed just two years ago.
In 1916, physicist John William Strutt, 3rd Baron Rayleigh, showed an example of oscillating heat flow. He filled a container with a fluid and then placed a heated coil below it and a cooling plate on top. This forced the liquid to rise and fall in the container. The effect has come to be known as Rayleigh-Bénard convection—it can be seen in the action of lava lamps. Two years ago, a team at the University of Twente proposed that heat flow in a Rayleigh-Bénard convection system would be more efficient if the heat coming from the base was oscillating. In this new effort, the researchers have shown this theory to be correct.
The work involved creating a container with a heating device at the bottom that could move through a temperature gradient over time. And like Strutt, they placed a cooling device on top. Unlike Strutt, however, they used a gas rather than a liquid—in their case, helium. They also carried out their experiments under cooler than ambient temperatures. To learn more about the impact of such oscillations on the heat flowing through the system, they conducted multiple runs during which the speed at of the oscillations ranged from 0.006 to 0.2 Hz.
They found that, as predicted, an oscillating heat source moved heat through the system more efficiently—as much as 25% more. Earlier theory suggested that the improvement in efficiency arises due to a destabilization between the boundaries of the liquids in the chamber, allowing the liquid areas in them to move past one another more easily. Explore further Innovative waste heat recovery experiment in Sweden More information: P. Urban et al, Thermal Waves and Heat Transfer Efficiency Enhancement in Harmonically Modulated Turbulent Thermal Convection, Physical Review Letters (2022). DOI: 10.1103/PhysRevLett.128.134502 Journal information: Physical Review Letters
More from Physics Forums | Science Articles, Homework Help, Discussion
Use this form if you have come across a typo, inaccuracy or would like to send an edit request for the content on this page. For general inquiries, please use our contact form. For general feedback, use the public comments section below (please adhere to guidelines).
Please select the most appropriate category to facilitate processing of your request
Thank you for taking time to provide your feedback to the editors.
Your feedback is important to us. However, we do not guarantee individual replies due to the high volume of messages.
Your email address is used only to let the recipient know who sent the email. Neither your address nor the recipient's address will be used for any other purpose. The information you enter will appear in your e-mail message and is not retained by Phys.org in any form.
Get weekly and/or daily updates delivered to your inbox. You can unsubscribe at any time and we'll never share your details to third parties.
Medical research advances and health news
The latest engineering, electronics and technology advances
The most comprehensive sci-tech news coverage on the web
This site uses cookies to assist with navigation, analyse your use of our services, collect data for ads personalisation and provide content from third parties. By using our site, you acknowledge that you have read and understand our Privacy Policy and Terms of Use.