Fig. 14.01

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Fig. 14.01
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Laws of Themodynamics 0th. Zeroth U
internal energy U1 U2 if T1 T2 1st ?U
Q W Q Heat W Work 2nd It is impossible
for an engine working IN A CYCLE to produce no
other effect than that of extracting heat from a
reservoir and performing an equivalent amount of
work. (The Kelvin-Planck statement of the 2nd law
of thermodynamics) (Some of the energy, Qu, MUST
be lost to heat ?S Qu / T) Energy can
only be changed in one direction that is from
usable to unusable, from available to
unavailable, or from ordered to
disorderedEntropy is the measure of the extent
to which available energy in any subsystem of the
universe is transformed into an unavailable form.
(The Rifken statement of the 2nd law, p. 46)
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Turbine converts work, W, to kinetic energy of a
magnet in a solenoid, to electrical energy.
Boiler Change in energy, ?U, from change in
chemical potential energy of a fuel, or nuclear
energy, is stored in P-V work and latent heat of
phase change from water to steam.
W
Heat loss to waterways. Condensers are usually
water cooled from local streams, lakes, and
oceans.
?U
Q
Condenser re-compresses expanded gas by
exploiting a phase change from steam to water.
Latent heat of phase change, Q, is released to
the environment.
Q
Heat loss to atmosphere
Rankine cycle for power generation By the 2nd
law, for an engine working in a cycle, not all of
the energy from a fuel can be converted to work
(W). Some must be lost as heat (Q).
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The Entropy Bill (Rifken, p.46)

• Waste heat, Q, is a pollutant in the environment.
  The main problem is that it reduces dissolved
  oxygen in water, stressing or killing aquatic
  life (i.e. fish).

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