Power plants – Motor operated by expansion and/or contraction of a unit of... – Unit of mass is a gas which is heated or cooled in one of a...
Reexamination Certificate
2001-05-11
2004-03-02
Nguyen, Hoang (Department: 3748)
Power plants
Motor operated by expansion and/or contraction of a unit of...
Unit of mass is a gas which is heated or cooled in one of a...
C060S526000
Reexamination Certificate
active
06698200
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to thermodynamic heat engines, in particular to improved efficiency thermodynamic heat engines of at least three cycle steps.
BACKGROUND OF THE INVENTION
Prior thermodynamic engines of the Stirling cycle exchange a fluid that can be heated (or cooled) and compressed (or expanded) and have at least two different volumes or segregated portions or regions of a common volume in which the fluid is contained and moved. Typically, the fluid is generally heated to a first temperature T
1
by a temperature source, cooled to a lower temperature T
2
by a temperature sink and mechanical work extracted as a result of the displacement and expansion and compression of the fluid as it is cyclically exposed to the temperature source and sink. Notably, most of the heat received from the source is transferred to the sink, with a small portion (about 30%) being inefficiently converted to mechanical energy in a typical, good heat engine.
An exemplary reference Stirling cycle engine
50
is shown in
FIG. 1
as a power piston and displacer system, with piston motion controlled by cam surfaces on the flywheel, but alternative methods of piston motion control may be incorporated by the Stirling cycle engine. As shown in
FIG. 1
, a volume contains the fluid (e.g. air) within a vessel
52
having thermal insulation there around. Typically, a displacer comprises a form of a baffle which divides the volume within the vessel
52
into two regions or portions of complementary varying size, specifically, a “cold” end 52 C cooled to temperature T
2
as provided by a heat sink
54
to the ambient temperature, and a “warm” (or heated) end 52W heated by source
56
to temperature T
1
. The displacer is fitted within the vessel sufficiently completely so that fluid moves between the warm and cold regions substantially entirely via a regenerator
58
which is disposed in and moved with the displacer
60
within the volume
52
by the displacer
60
and rod
62
. For simplicity, the piston and displacer rods in the exemplary embodiment of
FIG. 1
are coaxial. That is, the displacer rod goes through the piston rod and the displacer rod goes over the flywheel axle (
71
in FIG.
1
.), which can be stationary and have a bearing interfacing with the flywheel
70
. In this case, the axle or its assembly may be penetrated by the displacer rod. Alternate flywheel arrangements are possible in which the cam tracks do not cross and can be placed on opposite sides of the flywheel.
Mechanical energy output is provided by ‘power’ piston
64
which in this embodiment, also incorporates a heat conductive material and the heat sink
54
attached thereto. The mechanical energy from the power piston is transferred to a flywheel
70
via connecting rod
74
and cam track
68
, connected to or part of (together with the displacer cam track
72
) the flywheel
70
.
Stirling Cycle engines include constant volume processes (e.g.
84
A and
88
A) and constant temperature processes (e.g.
82
B and
86
B) cycles, as illustrated by the graphs
80
A and
80
B of
FIGS. 2A and 2B
, respectively. Also typically, as in other embodiments of the Stirling ling Cycle engine, the cyclical power piston and displacer motions of the embodiment of
FIG. 1
are generally identical in sinusoidal motion, but offset by 90°. The typical piston and displacer positions-versus-time over the cycle reference points A-D (also in graphs
80
A and
80
B) are illustrated by respective segments
92
P,
94
P,
96
P,
98
P and
92
D,
94
D,
96
D,
98
D in the graph
90
of FIG.
2
C.
SUMMARY OF THE INVENTION
The novel thermodynamic heat engines according to the present invention provide efficiencies higher than Carnot efficiency. In the present inventions, generally referred to as “Superclassical Cycle” engines, constant volume cooling with displacement and regeneration, and aspects of the “Proell Effect” (relative to cooling) are utilized. Moreover, the gas temperature on the cold side of a fluid displacer is below the lowest regenerator temperature due to “self-refrigeration.”
The “Proell Effect” (as described in The Thermodynamic Theory and Engineering Design of Supercarnot Heat Engines, by Wayne Proell, Cloud Hill Press, Las Vegas, N.Mex., 1984) incorporated by reference, refers to thermodynamic heat engine cycles and includes previous behavior of all gases in constant volume conditions with regeneration. The Proell Effect, by itself, conforms to the most rigorous definition of the Second Law of Thermodynamics which calls for zero or greater than zero entropy increases in isolated energy systems. However, the Proell Effect is unrecognized, unpredicted and not fully explored for traditional analyses of constant volume processes, such as in the Stirling cycle engines. The Proell Effect is not seem in the Stirling cycle because of the summetry created by two constant volume processes of opposite direction of fluid flow which cancels the Proell Effect.
Conventional thermodynamics identifies only one behavior of gases in a constant volume process, that is a change in internal energy directly proportional to its temperature, which equates to the heat added or removed, as its heat capacity at constant volume, C
V
, times the temperature change experienced,
Q=C
V
(&Dgr;
T
) (1)
In addition to a description of gas behavior at constant volume as described by Equation 1, above, the constant volume environment and its energy flows become more complex when the constant volume is not at a uniform temperature and is divided by a displacer and the subdivided volumes are connected via a regenerator as illustrated by the engine
50
of FIG.
1
.
Further understanding may be provided by the Proell Effect, wherein the fluid is exemplified by a gas. In a constant volume process with regeneration, the change in volume of a gas displaced through a regenerator as a result of its change in temperature going from the hot side (T
1
) of a constant volume to the cold side (T
2
) of a constant volume, or vice-versa, the gas being separated in the constant volume and displaced from said hot and cold sides through a regenerator by a displacer, must be compensated by an equal and opposite volume change in the remainder of the gas not in the regenerator, in the hot and cold sides of said constant volume. The corresponding pressure-volume work energies involved with all localized volume changes within the constant volume transfer thermal energy between said regenerator and the gas of the hot and cold sides of the constant volume. This results in a temperature change experienced by the gas under adiabatic conditions in the hot and cold sides of the constant volume which will be greater than the temperature difference of said regenerator, up to a limit proportional to said gas' heat capacity ratio, gamma. The pressure-volume work transfers heat inside the regenerator by heat capacity at constant pressure C
P
and transfers heat by heat capacity at constant volume, C
V
, in said hot and cold sides of the constant volume.
The Proell effect may occur for fluid (gas) flow in either direction through the regenerator. When the gas going through the regenerator is heated, it expands, causing a compensatory compression in the remainder of the gas in the constant volume chamber. When the gas going through the regenerator is cooled, it compresses, causing a compensatory expansion in the remainder of the gas in the constant volume chamber. By normal gas behavior under adiabatic conditions, expansion is accompanied by a drop in temperature and compression is accompanied by a rise in temperature. These temperature changes are in addition to the temperature changes caused by intimate thermal contact with the regenerator while passing through the regenerator.
In the present invention, the final gas temperature on the cold side of the displacer in constant volume cooling is below the lowest regenerator temperature. The magnitude of how far below the conventional constant volume cooling temperature the gas goes depends upon the temperatur
Cool Engines, Inc.
Matzuk Stephen G.
Nguyen Hoang
LandOfFree
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