Nav: Home

Thermal siphon effect: heat flows from low temperature to high temperature

September 27, 2019

Heat energy spontaneously goes from higher temperature to lower temperature. However, recently, a team from China and the USA (Kezhao Xiong and Zonghua Liu from East China Normal University, Chunhua Zeng from Kunming University of Science and Technology, and Baowen Li from University of Colorado Boulder) revealed that in some complex network structures, heat energy can transfer from a node with lower temperature to another node with higher temperature, which we call thermal siphon effect. The team even discovered that this effect becomes more evident with the decrease of network assortativity.

To understand this abnormal phenomenon (Figure a), the team studied power spectra of the nodes (Fig c and d), and the transport of the energy within the spectra range. They found that, within the power spectrum range, heat energy still transfers from (effective) high temperature node to (effective) low temperature node.

Moreover, an optimal network structure is discovered, that displays a small thermal conductance and a large electrical conductance simultaneously.

It is well known that realistic systems for heat management and control are not regular lattices but complex networks such as the thermal devices of nanotube and nanowire networks, whose topologies are fundamentally different from the cases of 1D and 2D lattices. In particular, the ideal materials for thermoelectric applications are phonon glass and electric crystal, namely good electric conduction and poor thermal conduction.

Therefore, the study may shed a new light on the search of good thermoelectric materials.
See the article:

Thermal siphon phenomenon and thermal/electric conduction in complex networks
Kezhao Xiong, Zonghua Liu, Chunhua Zeng, Baowen Li
Natl Sci Rev, 2019, doi: 10.1093/nsr/nwz128

Science China Press

Related Energy Articles:

Mandatory building energy audits alone do not overcome barriers to energy efficiency
A pioneering law may be insufficient to incentivize significant energy use reductions in residential and office buildings, a new study finds.
Scientists: Estonia has the most energy efficient new nearly zero energy buildings
A recent study carried out by an international group of building scientists showed that Estonia is among the countries with the most energy efficient buildings in Europe.
Mapping the energy transport mechanism of chalcogenide perovskite for solar energy use
Researchers from Lehigh University have, for the first time, revealed first-hand knowledge about the fundamental energy carrier properties of chalcogenide perovskite CaZrSe3, important for potential solar energy use.
Harvesting energy from walking human body Lightweight smart materials-based energy harvester develop
A research team led by Professor Wei-Hsin Liao from the Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong (CUHK) has developed a lightweight smart materials-based energy harvester for scavenging energy from human motion, generating inexhaustible and sustainable power supply just from walking.
How much energy do we really need?
Two fundamental goals of humanity are to eradicate poverty and reduce climate change, and it is critical that the world knows whether achieving these goals will involve trade-offs.
New discipline proposed: Macro-energy systems -- the science of the energy transition
In a perspective published in Joule on Aug. 14, a group of researchers led by Stanford University propose a new academic discipline, 'macro-energy systems,' as the science of the energy transition.
How much energy storage costs must fall to reach renewable energy's full potential
The cost of energy storage will be critical in determining how much renewable energy can contribute to the decarbonization of electricity.
Energy from seawater
A new battery made from affordable and durable materials generates energy from places where salt and fresh waters mingle.
Shifts to renewable energy can drive up energy poverty, PSU study finds
Efforts to shift away from fossil fuels and replace oil and coal with renewable energy sources can help reduce carbon emissions but do so at the expense of increased inequality, according to a new Portland State University study
Putting that free energy around you to good use with minuscule energy harvesters
Scientists at Tokyo Tech developed a micro-electromechanical energy harvester that allows for more flexibility in design, which is crucial for future IoT applications.
More Energy News and Energy Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Clint Smith
The killing of George Floyd by a police officer has sparked massive protests nationwide. This hour, writer and scholar Clint Smith reflects on this moment, through conversation, letters, and poetry.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at