World's smallest steam engine comes to life
Posted on December 12, 2011 - 05:11 by Kate Taylor on TG Daily
"German physicists say they've built a heat engine measuring only a few
micrometers across which works as well as a normal-sized version - although it
sputters, they admit.
Researchers at the University of Stuttgart and the Max Planck Institute for
Intelligent Systems say that the engine does basically work, meaning there's
nothing, in principle, to prevent the construction of highly efficient, small
heat engines.
"We've developed the world's smallest steam engine, or to be more precise the
smallest Stirling engine, and found that the machine really does perform work,"
says Clemens Bechinger of the University of Stuttgart.
"This was not necessarily to be expected, because the machine is so small that
its motion is hindered by microscopic processes which are of no consequence in
the macroworld." The disturbances cause the micromachine to run rough and
sputter.
The researchers couldn't construct the tiny engine in the same way as a
normal-sized one. In the heat engine invented almost 200 years ago by Robert
Stirling, a gas-filled cylinder is periodically heated and cooled so that the
gas expands and contracts. This makes a piston execute a motion with which it
can drive a wheel, for example.
However, the working gas in the new engine consists of just one individual
plastic bead measuring three micrometers, which floats in water. Since the
colloid particle is around 10,000 times larger than an atom, researchers can
observe its motion directly in a microscope."
http://www.tgdaily.com/general-sciences-features/60148-worlds-smallest-steam-engine-comes-to-life
