Nav: Home

Improving heat recycling with the thermodiffusion effect

July 15, 2019

Absorption heat transformers can effectively reuse the waste heat generated in various industries. In these devices, specialised liquids form thin films as they flow downward due to gravity. These liquid films can absorb vapour, and the heat is then extracted by a coolant so that it can be used in future processes. So far, however, there has been little research into how the performance of these films is influenced by the thermodiffusion effect - a behaviour seen in mixtures, where different types of mixture respond differently to the same temperature gradient. In a study recently published in EPJ E, researchers from the Fluid Mechanics group at Mondragon University and Tecnalia in Spain, led by M. M. Bou-Ali at Mondragon University, pooled their expertise in transport phenomena and absorption technology. Together, they explored for the first time the influence of the thermodiffusion property on the absorption, temperature and concentration profiles of falling films.

With the industrial sector currently producing vast amounts of waste heat, the study is part of a growing effort to increase its efficiency by recycling unused heat. The researchers discovered that when the mass transfer of different mixture components varies due to the thermodiffusion effect, as is seen in a liquid with a negative thermodiffusion coefficient (water-lithium bromide), the absorption of surrounding vapours can be increased. They also found that the absorption in the films changes significantly as they flow down, due to widely varying temperatures and concentrations. The team arrived at their conclusions by incorporating a variety of thermodiffusion effect equations into numerical models, and subsequently calculating the resulting degrees of vapour absorption in the films.

Since a third of our total energy consumption is currently in industrial processes, heat exchange devices are becoming more and more important to increasing their efficiency by recycling large amounts of heat. The work, therefore, offers valuable new insights into how the performance of falling film absorbers could be improved in the future.
-end-
Reference

P. Fernandez de Arroiabe, A. Martinez-Urrutia, X Peña, M. Martinez-Agirre, M. M. Bou-Ali (2019), On the thermodiffusion effect in vertical plate heat exchangers, Eur. Phys. J. E 42:85. DOI 10.1140/epje/i2019-11850-7

Springer

Related Research Articles:

More Research News and Research Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Risk
Why do we revere risk-takers, even when their actions terrify us? Why are some better at taking risks than others? This hour, TED speakers explore the alluring, dangerous, and calculated sides of risk. Guests include professional rock climber Alex Honnold, economist Mariana Mazzucato, psychology researcher Kashfia Rahman, structural engineer and bridge designer Ian Firth, and risk intelligence expert Dylan Evans.
Now Playing: Science for the People

#540 Specialize? Or Generalize?
Ever been called a "jack of all trades, master of none"? The world loves to elevate specialists, people who drill deep into a single topic. Those people are great. But there's a place for generalists too, argues David Epstein. Jacks of all trades are often more successful than specialists. And he's got science to back it up. We talk with Epstein about his latest book, "Range: Why Generalists Triumph in a Specialized World".
Now Playing: Radiolab

Dolly Parton's America: Neon Moss
Today on Radiolab, we're bringing you the fourth episode of Jad's special series, Dolly Parton's America. In this episode, Jad goes back up the mountain to visit Dolly's actual Tennessee mountain home, where she tells stories about her first trips out of the holler. Back on the mountaintop, standing under the rain by the Little Pigeon River, the trip triggers memories of Jad's first visit to his father's childhood home, and opens the gateway to dizzying stories of music and migration. Support Radiolab today at Radiolab.org/donate.