Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Heat Engines01:10

Heat Engines

3.9K
A heat engine is a device used to extract heat from a source and then convert it into mechanical work used for various applications. For example, a steam engine on an old-style train can produce the work needed for driving the train.
Whenever we consider heat engines (and associated devices such as refrigerators and heat pumps), we do not use the standard sign convention for heat and work. For convenience, we assume that the symbols Qh, Qc, and W represent only the amounts of heat transferred...
3.9K
The Carnot Cycle01:30

The Carnot Cycle

4.4K
Converting work to heat is an irreversible process, and the purpose of a heat engine is to reverse the effect partially. Heat engines aim to increase the efficiency of the reversal, that is, maximize the work retrieved from heat. If the efficiency of a heat engine were 100%, it would imply reversing the process completely without introducing any other effect. Thus, it would violate the second law of thermodynamics.
What could be the theoretical limit to the efficiency of a heat engine? The...
4.4K
The Carnot Cycle and the Second Law of Thermodynamics01:20

The Carnot Cycle and the Second Law of Thermodynamics

4.1K
The Carnot engine works between two heat reservoirs of fixed temperatures. The Carnot cycle begs the following question: Is it possible to devise a heat engine that is more efficient than a Carnot engine between two fixed temperatures? The answer lies in designing a Carnot refrigerator.
Since the individual steps in a Carnot cycle can be reversed, the entire cycle is, thus, reversible. If a Carnot cycle is reversed, it becomes a Carnot refrigerator. It extracts heat Qc from a cold reservoir at...
4.1K
Otto and Diesel Cycle01:27

Otto and Diesel Cycle

4.4K
An Otto engine is a four-stroke engine that uses a mixture of gasoline and air as the working fuel. The fuel is injected into the cylinder, and the piston is moved completely down so that the cylinder is at maximum volume. By moving the piston up, adiabatic compression takes place. The spark plug ignites the gasoline-air mixture, and the burning fuel adds heat to the system at a constant volume. The heated mixture expands adiabatically and gets further cooled by exhausting heat, and this cyclic...
4.4K
Mechanical Efficiency of Real Machines01:14

Mechanical Efficiency of Real Machines

1.4K
The mechanical efficiency of a machine is a fundamental concept that describes how effectively a machine can convert input work into output work. According to this concept, the efficiency of a machine is equal to the ratio of the output work to the input work. An ideal machine, meaning a machine that has no energy losses, has an efficiency of one. This implies that the input work and the output work are equal.
However, in reality, no machine can be truly ideal, and all of them experience some...
1.4K
Efficiency of The Carnot Cycle01:16

Efficiency of The Carnot Cycle

3.9K
The hypothetical Carnot cycle consists of an ideal gas subjected to two isothermal and two adiabatic processes. Since the internal energy of an ideal gas depends only on its temperature, which is the same before and after the completion of the Carnot cycle, there is no change in its internal energy. Hence, using the first law of thermodynamics, the total heat exchanged by the ideal gas equals the total work done. Thus, we can quantify the efficiency of the Carnot cycle via the heat exchanged...
3.9K

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

On-Site Potential Creates Complexity in Systems with Disordered Coupling.

Physical review letters·2023
Same author

Mpemba effect in driven granular Maxwell gases.

Physical review. E·2020
Same author

Precooling Strategy Allows Exponentially Faster Heating.

Physical review letters·2020
Same author

Rapid laser solver for the phase retrieval problem.

Science advances·2019
Same author

Quantum thermodynamics from the nonequilibrium dynamics of open systems: Energy, heat capacity, and the third law.

Physical review. E·2018
Same author

Microcanonical work and fluctuation relations for an open system: An exactly solvable model.

Physical review. E, Statistical, nonlinear, and soft matter physics·2013
Same journal

Erratum: Bacterial Turbulence at Compressible Fluid Interfaces [Phys. Rev. Lett. 136, 138301 (2026)].

Physical review letters·2026
Same journal

Unveiling Light-Quark Yukawa Flavor Structure via Dihadron Fragmentation at Lepton Colliders.

Physical review letters·2026
Same journal

Adaptable Route to Fast Coherent State Transport via Bang-Bang-Bang Protocols.

Physical review letters·2026
Same journal

Topological Transition and Emergence of Elasticity of Dislocation in Skyrmion Lattice: Beyond Kittel's Magnetic-Polar Analogy.

Physical review letters·2026
Same journal

Pound-Drever-Hall Method for Superconducting-Qubit Readout.

Physical review letters·2026
Same journal

Coupling a ^{73}Ge Nuclear Spin to an Electrostatically Defined Quantum Dot in Silicon.

Physical review letters·2026
See all related articles

Related Experiment Video

Updated: Mar 21, 2026

A Rapid Method for Modeling a Variable Cycle Engine
04:58

A Rapid Method for Modeling a Variable Cycle Engine

Published on: August 13, 2019

8.1K

Geometric Heat Engines Featuring Power that Grows with Efficiency.

O Raz1, Y Subaşı1, R Pugatch2

  • 1Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA.

Physical Review Letters
|May 7, 2016
PubMed
Summary
This summary is machine-generated.

Researchers developed a geometrical method to optimize heat engine performance. This approach allows for designing protocols that achieve maximum power and efficiency, even at fast cycle times, and proves Carnot efficiency is unattainable at non-zero power.

More Related Videos

Improving the Combustion Performance of a Hybrid Rocket Engine using a Novel Fuel Grain with a Nested Helical Structure
07:58

Improving the Combustion Performance of a Hybrid Rocket Engine using a Novel Fuel Grain with a Nested Helical Structure

Published on: January 18, 2021

6.6K
A Modeling and Simulation Method for Preliminary Design of an Electro-Variable Displacement Pump
09:04

A Modeling and Simulation Method for Preliminary Design of an Electro-Variable Displacement Pump

Published on: June 1, 2022

3.7K

Related Experiment Videos

Last Updated: Mar 21, 2026

A Rapid Method for Modeling a Variable Cycle Engine
04:58

A Rapid Method for Modeling a Variable Cycle Engine

Published on: August 13, 2019

8.1K
Improving the Combustion Performance of a Hybrid Rocket Engine using a Novel Fuel Grain with a Nested Helical Structure
07:58

Improving the Combustion Performance of a Hybrid Rocket Engine using a Novel Fuel Grain with a Nested Helical Structure

Published on: January 18, 2021

6.6K
A Modeling and Simulation Method for Preliminary Design of an Electro-Variable Displacement Pump
09:04

A Modeling and Simulation Method for Preliminary Design of an Electro-Variable Displacement Pump

Published on: June 1, 2022

3.7K

Area of Science:

  • Thermodynamics
  • Statistical Mechanics
  • Non-equilibrium Physics

Background:

  • Classical thermodynamics defines limits on heat engine efficiency (Carnot limit) but not on output power or its dependence on cycle time.
  • Understanding heat engine performance under non-equilibrium conditions and fast driving is crucial for developing advanced energy technologies.

Purpose of the Study:

  • To develop a geometrical framework for analyzing heat engine power and efficiency as functions of cycle time.
  • To design protocols that achieve maximal power and efficiency in the fast driving limit.
  • To investigate the attainability of Carnot efficiency at non-zero power output.

Main Methods:

  • Development of a geometrical description for heat engine power and efficiency.
  • Application of this geometrical framework to a class of heat engine models.
  • Design and analysis of engine protocols under varying cycle times.

Main Results:

  • A geometrical method was established to describe heat engine power and efficiency concerning cycle time.
  • Protocols were designed to achieve maximal power and efficiency at the fast driving limit.
  • It was proven that exact Carnot efficiency cannot be reached at non-zero power output.

Conclusions:

  • The geometrical approach provides a powerful tool for optimizing heat engine performance.
  • Maximal power and efficiency can be simultaneously achieved in the fast driving limit.
  • The findings clarify fundamental limitations of heat engines operating out of equilibrium.