The quantum afterburner

The quantum afterburner
4 February 2002

Quantum mechanics could be used to improve the efficiency of
heat engines, according to Marlan Scully of Texas A&M
University in the US. Scully has calculated that exhaust energy
from an engine could be used to power a laser. This would
improve engine performance beyond that of the ideal Otto
cycle without violating the laws of thermodynamics (M Scully
2002 Phys. Rev. Lett. 88 050602).

Scully considered a simplified version of the Otto cycle, a sequence
of operations similar to that carried out by a standard car engine.
In this four-step cycle, a hot gas expands in a cylinder doing
useful work before it loses heat to its surroundings; then it is
compressed and heated again.

But Scully added two extra steps. After the heat has dissipated
the gas is passed through a laser-maser cavity at constant
temperature, where it deposits useful energy. This cavity is then
reheated once the system as a whole has been reheated, again
at a constant temperature.

The crux of Scully’s system is that the heating of the cavity does
not raise the kinetic energy of the atoms in the gas, as the normal
heating stage does. Instead it increases the internal energy
levels of the atoms, making them emit photons. Scully calculated
that this liberated quantum energy was greater than the extra
work that would have been produced if the additional heat had
instead been ploughed into a normal four-stage cycle.

Scully points out that this result does not violate any laws of
thermodynamics. He also analysed an equivalent system in a
Carnot cycle – which, unlike the Otto cycle, runs at the highest
efficiency permitted by thermodynamics – and found that quantum
mechanics could not be used to improve the engine’s

He hints that he has already worked out how to test his idea in
the lab and that he has conceived several novel laser systems.
His idea has been dubbed a ‘quantum afterburner’ because of its
parallel with the devices that extract useful energy from the
exhaust of a jet engine.

Edwin Cartlidge is News Editor of Physics World
au>The quantum afterburner

Видывал я разных изобретателей дармой энергии/работы. Большинство погорело на полном неумении пользоваться элементарными измерительными приборами. А некоторые не могли даже правильно оперировать табличными данными.

А за текстик - спасибо.

в начало страницы | новое
Поддержи форум!
ЯндексЯндекс. ДеньгиХочу такую же кнопку
Твиттер сайта