Note: Descriptions are shown in the official language in which they were submitted.
D~.SCR_TION:
METHOD FOR CONVERTING ONE FORM OF
ENERGY INTO ANOTHER FORM OF ENERGY
ac~round of the Invention
While the present invention is not limited to
any particular type of energy converter, it will be
described herein in connection with a unidirectional
energy converter such as that shown in U~S. Patent No.
3,859,789, issued January 14, 1975. In an energy
10 converter of this type, a closed, continuous loop pas-
sageway contains a plurali~y of freely-movable bodies
which travel around the passageway in one direction
only. Force is applied to successive ones of the bodies
in one reglon of the passageway to thereby propel them
15 around the passageway. At points around the passage-
way, at least a portion of the kinetic energy of the
propelled bodies is converted into another form of
energy. Thereafter, successive ones of the bodies are
returned back to the starting region where they are
Zo again propelled in one direction by application of a
~orce thereto. The unidireckional energy converter
shown in the aforesaid patent may be operated in accor-
dance with various well-known thermodynamic cycles such
as the Brayton, Otto and Diesel cycles. Such thermo-
25 dynamic cycles employ adiabatic expansion of a gasduring the power stroke. This is followed by an exhaust
stroke, during which heat is rejected, and adiabatic
compression back to a higher pressure. With isothermal
compression of a gas, however, variations can be visu-
30 alized in thermodynamic cycles which more closely ap-
proximate the Carnot cycle.
ummary of the Invention
In accordance with the present invention, a
i~
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method for operating an energy converter is provided
which employs a thermodynamic cycle of higher effi-
ciency than conventional cycles by virtue of the fact
that approximately isothermal compression of a gas is
5 employed during part of the cycle rather than adiabatic
compression. Such isothermal compression can be ap~
proximated hy injecting into the gas, at the completion
of adiabatic expansion, a fluid such as water at a
temperature that is preferably approximately equal to
10 that of the expanded gas.
In one embodiment:of the invention, the cycle
is comprised of isobaric (i.e., constant pressure)
heating and expansion, adiabatic expansion, and ap-
proximately isothermal compression. The advantage of
15 this cycle is that it can utilize hot air at atmospheric
pressure and thus has important applications in waste-
heat utilization from low-temperature hot air. In
another embodiment of the invention, the cycle is com-
prised of adiabatic compression~ isobaric heating and
20 expansion, adiabatic expansion and finally approxi-
mately isothermal compression. The primary advantage
of this cycle is a thermodynamic efficiency greater
than the Brayton cycle for similar temperature-pressure
ranges and potentially significantly higher than other
25 practical cycles currently in use~
In the case of a unidirectional energy con-
verter such as that shown in U.S. Patent No. 3,859,789,
which employs freely~mova~le bodies within a continuous
loop passageway, hot gas at ambient pressure is intro-
30 duced into the expander region of the passageway and isthen expanded adiabatically below ambient pressure. As
the working body within the passageway nears the end of
the expander section, a liquid such as water at a
tempera~ure that is preferably approximately equal to
35 the temperature of the expanded gas is sprayed into the
expander section. The gas~liquid mixture ahead of the
ensuing piston is then compressed approximately iso-
thermally to ambient pressure and expelled from the
expander section when the expander section exit port is
opened by the passage of the preceding piston. The
5 liquid is then separated from the gas by a centrifugal
separator and the heat is xemoved by a heat exchanger.
The ahove and other objects and features of
the invention will become apparent frvm the following
detailed description taken in connection with the ac-
10 companying drawings which form a part of this specifi-
cation, and in which.
Figure 1 is a schematic illustration of one
embodiment of the invention which employs both adia-
batic compression as well as approximately isothermal
15 compression;
Fig. 2 is a pressure-volume diagram illus-
trating the thermodynamic cycle of the apparatus of
Fig. l;
Figs. 3A-3D schematically illustrate the ac-
20 tion on a unit gas cell between successive pistonC inthe expander section of the unidirectional energy con-
verter shown in Fig. l;
Fig. 4 is an illustration of another embodi-
ment of the invention wherein approximately isothermal
25 compression is employed without being followed by adia-
batic compression;
Fig. 5 is a pressure-volume diagram illus-
trating the thermodynamic cycle of the apparatus of
Fig. 4;
30Fig. 6 is an illustration of a further em-
bodiment of the invention employing dual expander re-
gions and gates; and
Fig. 7 is a perspective view of the gate
device utilized in the embodiment of Fig. 6.
35With reference now to the drawings, and par-
ticularly to Fig. 1, a unidirectional energy converter
is shown comprising a closed-loop, circular passageway
10 having a plurality of freely-movable bodies or pis-
tons 12 therein. The pistons may comprise cylindrical,
curved elements having a radius of curvature corre-
5 sponding to the radius of curvature of the closed~looppassageway 10. Alternatively, the pistons 12 may com-
prise spheres or other geometries conforming to the
geometry of the passageway. The tolerance or clearance
between the surfaces of the pistons 12 and the inside
10 walls of the closed-loop passageway 10 is such as to
permit the pistons to move freel~ through the passage-
way. However, fluid flow past the pistons within the
passageway is substantially prevented. Piston rings
may be used as required. The continuous, closed-loop
15 passageway 10 is provided with four ports 14, 16, 18 and
20 spaced around the passageway at in~ervals of about
90. The region between por~s 14 and 16 includes an
expander section where hot gases entering port 14 cause
successive ones of the pistons 12 to be propelled around
20 the passageway 10 in a counterclockwise direction as
viewed in Fig. 1. That is, the hot gases entering the
port 14 expand adiabatically, imparting kinetic energy
in the form of increased forward velocity to each piston
12. Af~er the hot gases are expanded adiabatically,
25 they are then compressed approximately isothermally as
will be explained hereinafter.
In the region between ports 16 and 18, the
pistons 12 move without acceleration or deceleration
except for deceleration caused by frictional forces.
30 Between ports 18 and 20, the unit gas cells between
successive pistons are compressed. This compressed gas
exits through port 20 and is fed to a gas heater-22 where
it is heated and then fed back into port 14 prior to
adiabatic expansionu Between ports 20 and 14 is a
35 thruster region where the pistons 12 move downwardly
under ~he force of gravity to the port 14 where they are
again propelled in a counterclockw-ise direction~ It should be unclerstood,
however, that other forms of force in the thruster region may be employecl.
Part oE the kinetic energy of the propelled pistons may be
extracted by means oE elec~romagnetic coi]s 24 which surround the passageway
10 assuming, oE course, that the pistons 12 are Eormed from a magnetically-
permeable material such as iron. Other materials and other Eorms of energy
extraction may also be used. Beyond the region of energy extraction, shown
as coil 24, but ahead of the port 16 is a nozzle 26 adapted to spray a liquid,
such as water, into the interior oE the passageway 10. The mixture of the
liquid vapor and gas is exhausted through port 16 to a liquid-gas separator
28. ~le separated liquid is then fed to a heat exchanger 30 where heat is
extracted and then back to the nozzle 26. On the other hand, the separated
gas is applied through conduit 32 to port 18 where it is again compressed in
the region between the ports 18 and 20. It wîll be appreciated, of course,
that the air/liquid mixture from port 16 can simply be exhausted to the
atmosphere and that atmospheric air can be drawn into port 18. Likewise,
instead of recyc]ing the liquid through a heat exchanger 30, a continuous or
new supply of liquid at the proper temperature can be injected into the
passageway lOo The coil 24 can be replaced by oth~r types of power take-offs
such as that shown in United States Patent No. 3,859,789. In this system,
the kinetic energy of the pistons and the spacing (and thus the pressure-
volume relations) are interrelated. Therefore, the useful power must be
removed in the expander section between ports 14 and 15 and optimally between
the liquid spray nozzle 26 and port 16, or an appropriate pressure gate, as
described later, must be used at the expander exit.
_ 5 _
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The operation of the unidirectional energy
converter of Fig. 1 can best be understood by reference
to Figs. 2 and 30 In Fig. 3, positions of s~ccessive
ones of the pistons in the region between ports 14 and
5 16 are shown, the ports in passageway 10 being separated
by an angle less than 90 in Figs. 3A-3D for illustra-
tive purposes only. In the thruster region between
ports 20 and 14, the unit gas cell between successive
pistons is collapsed to essentially zero volume at
10 point 1 shown in the P-V diagram of ~ig 2. The hot,
high pressure gas from gas heater 22 then enters the
inlet port 14 and expands the lead piston (piston A in
Figs. 3A-3D) at constant pressure to point 2 in Fig. 2,
until the trailing piston B (Fig. 3B) seals off the unit
15 cell. The unit cell now undergoes adiabatic expansion
between points 2 and 3 shown in Fig. 2 to subatmospheric
pressure p3 at point 3. At this time (Fig. 3C), the lead
piston A moves against the pressure (assumed to be
atmospheric pressure) at the outlet 16 and tends to slow
20 down. On the other hand, the trailing piston B sees high
pressure behind it and vacuum ahead of it, such that it
still accelerates for a period of time. The result is
compression of the gas in the unit cell However, to
avoid just climbiny back up the adiabatic curve betw~en
25 points 2 and 3 in Fig. 2, a liquid spray from nozzle 26
is injected into the unit cell between pistons A and B.
This liquid absorbs ~he heat of compression, forcing
the compression pxocess to be approximately isothermal
compression up to atmospheric pressure Pa at point 4
30 shown in Fig. 2. At this juncture (Fig. 3D), the unit
cell exhausts its moist gas through the outlet 16. The
liquid is then separated from the gas in separator 28
and the dry gas compressed between ports 18 and 20 where
the gas in a unit cell is adiabatically cGmpressed from
35 point 4 to point 5 in Fig 20 The exhaust gases from
port 20 are then exhausted to the heater 22 and the unit
cell collapses to point 1 in the thruster region between
ports 20 and 14. The gain in the net work of this cycle
over the Brayton cycle is shown as the cross-hatched
area in the P-V diagram of Fig. 2. Thus, very high
5 efficiencies are possible with the cycle of the inven-
tion, approaching the Carnot efficiency. Heat is ab-
sorbed by the liquid during isothermal compression~
Consequently, the temperat:ure of the liq~id entering
the unit cell through nozzle 26 should be approximately
10 that of the àdiabatically-expanded gas in the unit
cell. The tempera~ure of the liquid in the unit cell
increases slightly during the approximately isothermal
compression, but this temperature is again decreased in
the heat exchanger 30 where heat is extracted.
In Fig. 4, another embodiment of the inven-
tion is shown in which adiabatic compression is elimi-
nated and points 1, 2 and 5 in Fig. 2 are, in effect,
reduced to atmospheric pressure Pao In the embodiment
of Fig. 4, the ports 1~ and 20 in the continuous,
20 closed-loop passageway 10 are eliminated and the pis-
tons are permitted to move freely without compression
of a gas between ports 16 and 14. The gas separated in
the separator 28 at atmospheric pressure is simply fed
back to the gas heater 22. The result is the thermo-
25 dynamic cycle shown in Fig. 5 wherein isobaric heatingoccurs between points 2 and 4 in heater 22 followed by
adiabatic expansion and ~hen approximately isothermal
compression between points 3 and 4~ ~eat is again
extracted by the heat exchanger 30 to lower the temper-
30 ature of the entering liquid.
In Fig. 6l a further embodiment of the inven-
tion is shown which employs two expander regions and two
power take-off stations. Ambient air is introduced
into a combustion chamber 40 where it is heated and then
35 fed through conduits 42 and 44 into two expander regions
formed in a continuous, closed-loop passageway 46 As
in the embodiments of Figs. 1 and 4, water is sprayed
into the expander sections via noz~les 48 and 50; while
energy is extracted from the contin~ous loop passageway
by means of a pair of linear generators 52 and 54. ~s
5 the pistons 56 leave the expander sections, they pass
through pressure gates 58 and 60 loca~ed just beyond the
nozzles 48 and 50. The gates 58 and 60l which may take
the form of segmented rubber diaphragms as showrlin Fig.
7, act as check valves. That is, the segments 61 will
10 separate along seams 63 ko permi.t a piston S6 to pass
through in one direction. ~fter the piston passes
through the gate, the segments are forced back into
sealing engagement along seam 63 due to the fact that
the pressure in the unit cell at the point of water
15 injection is below atmospheric pressure existing at
exhaust duct 62. In this respect, the gates assume the
function of the piston A in Fig. 3C, for example, and
prevent atmospheric air from entering the unit cell in
the area adjacent the nozzles 48 and 50. As each piston
2Q leaves the expander, it passes through a pressure gate;
and behind the piston the pressure gate closes and
maintains a pressure below atmospheric in the region of
the nozzles 48 and 50. Water is injected at a rate
appropriate to the heat rejected by the gas ahead of.the
25 piston moving out of the expander to effect approxi-
mately isothermal compression as.in the previous embod-
iments of the inventionO
Although the invention has been shown in
connection with certain specific embodiments, it will
30 be readily apparent to those skilled in the art that
various changes in form and arrangement of parts may be
made to suit requirements without departing from the
spirit and scope of the invention. In this regard, it
will be apparent that instead of extracting energy from
35 the movi.ng pistons with the use of an electromagnetic
coil such as that shown in Figs. 1 and 4, any of the
t)~
methods for extracting energy from a unidirectional
energy converter as shown~ for example, in the afore-
said U.S. Patent No. 3,859,789 can be used equally as
well~
