Heat engines transform heat into mechanical energy with the corresponding efficiency of an Otto engine amounting to only about 25 percent, which is what your automobile gets.
The efficiency of heat engines powered by thermal heat reservoirs is determined by the second law of thermodynamics, one of the fundamental concepts in physics. It was as far back as 1824 that Frenchman Nicolas Carnot calculated the maximum possible efficiency limit of such engines, now known as the Carnot limit.
Now imagine a heat engine that consists of just a single calcium ion. Such a nano-sized heat engine would be far more efficient than your car engine or a coal-fired power plant because we can theoretically exceed the classic Carnot limit by manipulating the heat baths and exploiting non-equlibrium states.
A prototype of such a single-ion heat engine is currently being constructed at Mainz University.
Simulation of an Otto cycle of a single ion heat engine: The enclosed area pictures the produced work that is significantly increased by way of squeezing. Credit: Quantum, Mainz University
Calculations and simulations from last year showed for the first time that the thermo-dynamic flow in an internal combustion engine could be reproduced using individual ions. The idea was to use a calcium 40 ion, which has a diameter a million times smaller than that of a human hair, for this purpose. "Individual ions can basically act as the piston and drive shaft or, in other words, represent the entire engine," explained Johannes Roßnagel of the Quantum, Atomic, and Neutron Physics (QUANTUM) work group of the JGU Institute of Physics.
Individual ions have already been captured in Paul traps and, using laser beams and electrical fields, not only cooled and heated but also compressed.
"This means we are able to manipulate the pulse location distribution for optimum efficiency," added Roßnagel. "Exceeding the Carnot limit for a standard heat engine thus does not violate the second law of thermodynamics but instead demonstrates that the use of specially prepared, non-thermal heat reservoirs also makes it possible to further improve efficiency."
In their article, the physicists calculated the general Carnot limit for this situation. As the mechanical capacity of a single ion machine is extremely low, it can probably only be used in heating or cooling nano systems.
A single trapped ion in a linear Paul trap with special geometry: The heat engine is being realized by the divergent bars; the squeezing is being caused by establishing special electrical fields. © Quantum, Mainz University
The intention is now to actually develop the proposed single ion heat engine in initial experiments and construct a prototype in the laboratory.
Citation: Johannes Roßnagel et al. , 'Nanoscale Heat Engine Beyond the Carnot Limit', Physical Review Letters, 22 January 2014 DOI: 10.1103/PhysRevLett.112.030602
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- Unregulated Genetic Testing Websites Still Causing Concerns
- War On Doping And The Hypocritical Treatment Of Lance Armstrong
- Mindfulness Meditation May Improve Sleep Quality
- Tautological Description-Relativistic Metaphysics IS The Theory Of Everything
- What Antidepressants Do To Healthy People
- The New York Times On Drugs - Wrong, Naive Or Misleading?
- Oxytocin Nasal Spray Causes Men To Eat Fewer Calories
- "Let me explain exactly why you or your family member reacted as they did, why the test subjects..."
- "One guy runs a red light and is stopped and confesses. One guy runs a red light and says he didn't..."
- "To the author: Before you write a story and assert that the treatment of Lance Armstrong was hypocritical..."
- "Above the author writes: Leipheimer was only banned for six months, and out of season so he did..."
- "I worked in cycling during the Armstrong period. Lance Armstrong was banned from cycling not so..."
- Antidepressants linked to improved cardiovascular outcomes
- Bee Bailout: If dollars rule the world, why shouldn't bees be too big to fail?
- Antidepressants linked with improved cardiovascular outcomes
- How healthy is genetically modified soybean oil?
- Healthier males help infertile obese females conceive