U.S. patent application number 11/465096 was filed with the patent office on 2008-02-21 for external heat engine of the rotary vane type and compressor/expander.
Invention is credited to Eric Scott Carnahan.
Application Number | 20080041056 11/465096 |
Document ID | / |
Family ID | 39082434 |
Filed Date | 2008-02-21 |
United States Patent
Application |
20080041056 |
Kind Code |
A1 |
Carnahan; Eric Scott |
February 21, 2008 |
EXTERNAL HEAT ENGINE OF THE ROTARY VANE TYPE AND
COMPRESSOR/EXPANDER
Abstract
A heat engine of the rotary vane type and thermodynamic cycle is
disclosed. The engine converts thermal energy contained within
relatively low temperature hot gasses into mechanical energy. The
engine operates by expanding a hot gas to a sub-atmospheric
pressure, cooling the gas at a roughly constant volume and then
cooling the gas further while compressing it back to atmospheric
pressure. Possible sources of hot gasses for powering the engine
include exhaust gasses from other engines and air heated by solar
collectors. A novel compressor and expander comprised of the
primary components of the engine is also disclosed.
Inventors: |
Carnahan; Eric Scott;
(Smyrna, GA) |
Correspondence
Address: |
Eric Scott Carnahan
2615 Carolyn Dr
Smyrna
GA
30080
US
|
Family ID: |
39082434 |
Appl. No.: |
11/465096 |
Filed: |
August 16, 2006 |
Current U.S.
Class: |
60/670 ; 418/112;
418/145 |
Current CPC
Class: |
F01C 1/3442 20130101;
F01C 21/0836 20130101; F01C 21/04 20130101; F01C 21/06 20130101;
F01C 21/0881 20130101 |
Class at
Publication: |
60/670 ; 418/112;
418/145 |
International
Class: |
F01C 19/02 20060101
F01C019/02; F01C 19/00 20060101 F01C019/00; F01K 23/06 20060101
F01K023/06 |
Claims
1. A heat engine comprising: a housing enclosing a cavity, said
housing having an inner and outer wall surface; a rotatable rotor
mounted within the cavity of said housing; a plurality of slots
contained within said rotor; a plurality of sliding vanes mounted
within said slots extending outwards towards the inner surface of
said housing; a plurality of variable volume gas chambers defined
by the regions between said rotor, said sliding vanes and said
housing; an inlet port wherein a high temperature working gas
enters said variable volume gas chambers moving past said inlet
port; an expansion section in fluid communication with said inlet
port wherein said vanes moving through said expansion section slide
outwards away from said rotor increasing the volume and decreasing
the pressure of the gas within said section; a compression section
in fluid communication with said expansion section wherein said
vanes moving through said compression section slide inwards toward
said rotor decreasing the volume and increasing the pressure of the
gas within said section; a means for injecting a cooling liquid
into said working gas moving through said compression section of
said engine; an outlet port in fluid communication with said
compression section wherein said working gas and said cooling
liquid injected into said working are expelled from said engine; a
means for transferring mechanical energy from the spinning rotor to
an external apparatus.
2. An engine according to claim 1 having cooling liquid passageways
within the walls of said housing wherein cooling liquid is injected
in said engine.
3. An engine according to claim 1 having cooling liquid pumped
through said rotor and into said engine through nozzles located on
said rotor.
4. An engine according to claim 1 wherein each vane is connected to
another vane on the opposite side of said rotor by a connecting
linkage wherein each connecting linkage is offset from the other
connecting linkages through a distance parallel to said rotors axis
of rotation.
5. An engine according to claim 1 having a means to change the size
of the inlet port.
6. An engine according to claim 1 having a means to change the size
of the outlet port.
7. An engine according to claim 1 wherein a lubricant is injected
into said engine along with said cooling liquid.
8. An engine according to claim 1 wherein the cooling liquid
contains a solution capable of absorbing pollutants from said
working gas.
9. An engine according to claim 1 having a section in between said
expansion and said compression sections wherein said variable
volume gas chambers moving through said section maintain a
generally constant volume.
10. An engine according to claim 1 having a plurality of friction
reducing roller means at the tips of said engine vanes in contact
with the inner wall of said housing.
11. An engine according to claim 1 having a plurality of floating
seals at the tips of said engine vanes making contact with the
inner wall of said housing.
12. A machine for changing the volume of a gas comprising: a
housing enclosing a cavity, said housing having an inner and outer
wall surface; a rotatable rotor eccentrically mounted within the
cavity of said housing; a plurality of slots contained within said
rotor; at least four sliding vanes mounted within said slots
extending outwards towards the inner surface of said housing
wherein each of said vanes is connected to another vane on the
opposite side of said rotor by a connecting linkage wherein each
connecting linkage is offset from the other connecting linkages by
a distance parallel to the axis of rotation of said rotor; a
plurality of variable volume gas chambers defined by the regions
between said rotor, said sliding vanes and said housing; a
relatively large port wherein a gas enters said variable volume gas
chambers moving past said relatively large port when said machine
is being used to decrease the volume of a gas and wherein a gas
leaves said variable volume gas chambers moving past said
relatively large port when said machine is being used to increase
the volume of a gas; a relatively small port wherein a gas enters
said variable volume gas chambers moving past said relatively small
port when said machine is being used to increase the volume of a
gas and wherein a gas leaves said variable volume gas chambers
moving past said relatively small port when said machine is being
used to decrease the volume of a gas; a volume changing section in
fluid communication with each of said ports wherein said vanes
moving through said section slide outwards away from said rotor
increasing the volume of the gas within said section when said
machine is used to increase the volume of a gas and wherein said
vanes moving through said section slide inwards toward said rotor
decreasing the volume of the gas within said section when said
machine is being used to decrease the volume of a gas; a means for
transferring rotational mechanical energy between the spinning
rotor and an external apparatus.
Description
BACKGROUND OF THE INVENTION
[0001] Heat engines that convert thermal energy into mechanical
energy by cycling a working fluid through a suitable thermodynamic
cycle have been around for a very long time and come in countless
varieties. To maximize efficiency heat engines are typically
designed to heat their working fluid to a high temperature. The
higher the temperature reached by the working fluid the more
efficient the engine can become.
[0002] However, heat engines that are designed to operate at high
temperatures and high efficiencies typically cannot effectively or
economically convert thermal energy from low temperature heat
sources into other usable forms of energy.
[0003] Given the rising cost of fuel and a relative abundance of
low cost and environmentally friendly low temperature heat sources,
the economic viability of an engine that can effectively harness
the energy of low temperature heat sources is greater than
ever.
[0004] The Ranking Vapor Compression cycle if often used to harness
power from low temperature heat sources. However the ranking cycle
does not efficiently harness thermal energy from gasses at
temperatures above or below the boiling point of its working
fluid.
[0005] Gas turbines that follow the Inverted Brayton cycle have
been proposed to harness waste heat from exhaust gasses. However
the high cost of manufacturing gas turbines has prevented such
engines from being used on a large scale.
SUMMARY OF THE INVENTION
[0006] Accordingly, it is an object of this invention to provide an
engine capable of effectively converting thermal energy contained
within relatively low temperature hot gasses into mechanical energy
at the lowest possible cost. The invention can be used in addition
to or as a replacement for the ranking vapor compression cycle
commonly used for such purposes.
[0007] Briefly described in a preferred embodiment, the invention
is a heat engine of the rotary vane type. The engine requires a
source of hot gas and a source of cool liquid to operate. The
thermodynamic cycle of the engine begins as a gas is heated by a
heat source external to the engine. Possible sources of hot gasses
to power the engine include exhaust gasses from gas turbine or
diesel engines, and air heated by solar collectors. It is even
possible that warm atmospheric air located near a cold body of
water could be used to power the engine. Although the efficiency of
the engine decreases as the temperature difference between the gas
and the water decreases.
[0008] After the gas is heated it enters the engine through the
inlet port into the spaces between the engines vanes, rotor and
housing. As the gas moves past the inlet port it enters the
expansion section of the engine where the gas expands adiabatically
to a sub-atmospheric pressure. Just before the gas leaves the
expansion section a cooling liquid is injected into the gas through
holes in the walls of the engine housing further reducing its
temperature and pressure.
[0009] Next the gas leaves the expansion section of the engine it
enters the compression section. Here more cooling liquid is
injected into the gas, which absorbs heat generated by the
compression process. This reduces the amount of work required to
compress the gas back to atmospheric pressure. Finally, the working
gas and the cooling liquid leave the engine through the outlet port
at the bottom of the engine.
[0010] Because the expansion process occurs at a higher temperature
than the compression process, more work is created by expanding the
gas than is consumed by compressing it and a net work output is
produced by the engine.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present invention will be better understood by reading
the Detailed Description of the Preferred and Alternate Embodiments
with reference to the accompanying drawing figures, in which like
reference numerals denote similar structure and refer to like
elements throughout, and in which:
[0012] FIG. 1 is a cross section schematic illustration of the
present engine;
[0013] FIG. 2 is a side view schematic illustration of the engine
showing a preferred power transfer means;
[0014] FIG. 3 is a schematic illustration of two of the engines
sliding vanes connected by four connecting linkages;
[0015] FIG. 4 is a schematic illustration of another pair of the
engines sliding vanes connected by four connecting linkages offset
from the connecting linkages in FIG. 3;
[0016] FIG. 5. is a side view schematic illustration of the tip of
an engine vane;
[0017] FIG. 6. is a schematic illustration of an alternative
embodiment of the engine inlet port.
[0018] FIG. 7. is a pressure-volume diagram of the thermodynamic
cycle of the present engine;
[0019] FIG. 8. is a schematic illustration of a novel
compressor/expander comprised of the primary components of the
present engine.
DETAILED DESCRIPTION
[0020] In describing the preferred and alternate embodiments of the
present invention, as illustrated in FIGS. 1-8, specific
terminology is employed for the sake of clarity. The invention,
however, is not intended to be limited to the specific terminology
so selected, and it is to be understood that each specific element
includes all technical equivalents that operate in a similar manner
to accomplish similar functions.
[0021] Referring now to FIG. 1, illustrated therein is heat engine
100, having an outer housing 2 and a rotor 1 that rotates within
the housing. Contained within the rotor 1 are a plurality of slots
12 and a plurality of sliding vanes 3 residing within the slots 12.
The vanes 3 extend outwards to make contact with the inner walls of
the housing 2.
[0022] Each vane 3 is connected to another vane 3 on the opposite
side of the rotor 1 by one or more connecting linkages 13. The
connecting linkages 13 that connect a pair of vanes 3 are
horizontally offset from other connecting linkages 13 that connect
other pairs of vanes 3. This allows the linkages to slide past each
other through the rotor's axis of rotation. The shape of the
housing 2 is such that the distance from one point on the surface
of the inner wall of the housing 2 to another point on the opposite
side of the housing through the axis of rotation of the rotor is
always the same. This allows the vanes 3 to be connected by
connection linkages 13 of fixed length.
[0023] The space between the engine vanes 3, the rotor 1 and the
housing 2 define variable volume gas chambers 16. The volume of the
gas chambers 16 change as the rotor 1 rotates within the housing 2
and the distance between the rotor 1 and the inner wall of the
housing 2 changes.
[0024] A heat source external to the engine 100 heats a gas, which
is supplied to the engine 100. This hot gas is both the energy
source and working fluid of the engine. The thermodynamic cycle
begins as the engine 100 draws in the hot gas through the inlet
port 4 into the space between the rotating vanes 3. A guide rail 17
traverses the inlet port 4 keeping the vanes 3 in the proper
position as they move past the inlet port 4 while allowing the hot
gas to flow around it.
[0025] As the vanes 3 move past the inlet port 4 they enter the
expansion section of the engine. In this section the vanes 3 slide
outwards from the rotor 1 and the volume of the gas chambers 16
increases. The expansion section of the engine extends from the
point where a trailing vane 3 of a gas chamber 16 passes the inlet
port until the center of the gas chamber 16 reaches the midpoint of
the engine 18. This expansion lowers the pressure and temperature
of the working gas.
[0026] Just before the gas chamber 16 reaches the end of the
expansion section, a cooling liquid, such as water, is injected
into the gas chambers 16 through a plurality of nozzles 7 in the
wall of the housing 2. This further reduces the temperature and
pressure of the working gas. A plurality of valve means 9 can be
utilized to control the timing of the injection of the cooling
liquid into the gas chambers.
[0027] When the center of a gas chamber passes the midpoint of the
engine 18 it leaves the expansion section of the engine and enters
the compression section of the engine. Cooling liquid is
continuously injected into the lower portion of the compression
section of the engine through nozzles 7. A lubricant could be
injected into the engine along with the cooling liquid to lubricate
the engine. Additionally a chemical solution capable of absorbing
pollutants within the working gas could be injected into the engine
along with the cooling liquid.
[0028] When the leading vane 3 of a gas chamber 16 reaches the
outlet port 5 the compression process is complete and the working
gas and cooling liquid are expelled from the engine through the
outlet port 5. The outlet port 5 is positioned at the bottom of the
engine 100 allowing gravity to assist in expelling the cooling
liquid from the engine 100.
[0029] A catch basin 8 is positioned beneath the outlet port 5 to
collect the cooling liquid expelled from the engine 100. A metal
grate 15 covers the catch basin. A pump means 10 pumps water
through a pipe 14 from the catch basin 8 through an evaporative
heat exchanger 11 then back to the engine 100. The heat exchanger
11 expels heat from the cooling liquid before it returns to the
engine 100.
[0030] Referring now to FIG. 2 illustrated therein is a side view
of engine 100 illustrating the power transfer means of a preferred
embodiment. The rotor 1 extends outward through a circular hole 19
in the sidewall of the housing 2. A shaft 20 is attached to the
sidewall 25 of the rotor 1 and extends away from the rotor 1. A
bearing means 26 mounted on a supporting structure 27 supports the
rotor 1 and allows it rotate about its axis of rotation.
[0031] A pulley 21 is coupled to the shaft 20 on the opposite side
of the supporting structure 27 from the rotor 1. A belt 22
transfers mechanical power from the pulley 21 to another pulley 23
coupled to a generator 24.
[0032] Referring now to FIG. 3 illustrated therein is a front view
of a pair of engine vanes 3 connected by four connecting linkages
13.
[0033] Referring now to FIG. 4 illustrated therein is a front view
of another pair of engine vanes 3 connected by four connecting
linkages 13. The connecting linkages 13 illustrated in FIG.4 are
horizontally offset from the connecting linkages 13 illustrated in
FIG. 3. This allows the connecting linkages 13 to slide past each
other through the axis of rotation of the rotor 1. The connection
linkages 13 connecting other pairs of engine vanes 3 would also be
horizontally offset from the connecting linkages illustrated in
FIG. 3 and FIG. 4.
[0034] Referring now to FIG. 5 illustrated therein is a side view
schematic of the tip of an engine vane. Attached to the tip of the
vane 3 is a rolling element 50. This rolling element 50 reduces
friction as the vane moves along the inner surface of the housing
2. A floating seal 51 is housed within the tip of a vane. A spring
52 exerts a force on the floating seal 51 keeping it on contact
with the inner wall of the housing 2. The floating seal 51 is
designed to minimize gas leakage from one gas chamber to
another.
[0035] Referring now to FIG. 6 illustrated therein is a cross
section schematic of an alternate embodiment of the engine inlet
port 4. This alternative embodiment has a movable member 30 and an
actuator 31 connected to the movable member. The actuator can move
the movable member into a position along the guide rail 17. This
decreases the size of the inlet port and changes the pressure ratio
of the engine. A similar configuration can be used to change the
size of the engine outlet port providing an additional means to
alter the pressure ratio of the engine.
[0036] Referring now to FIG. 7 illustrated therein is a
pressure-volume diagram of the thermodynamic cycle of the present
engine 100. The pressure of the working gas is plotted on the
vertical axis and the volume is plotted on the horizontal axis.
Line a-b is a constant pressure heat addition line representing the
working gas of the engine being heated and expanded by some process
external to the engine. Line b-c is an adiabatic expansion line
representing the working gas being expanded adiabatically in the
expansion section of the engine. Line c-d is a constant volume heat
rejection line representing the working gas being cooled at a
roughly constant volume while cooling liquid is being injected into
the working gas as the working gas begins to leave the expansion
section and enter the compression section. Line d-a is an
isothermal compression line representing the working gas being
simultaneously compressed and cooled in the compression section of
the engine.
[0037] Referring now to FIG. 8, illustrated therein is a novel
machine 200 of the rotary vane type that can be used as either a
compressor or an expander. The machine 200 is comprised of the main
components of engine 100. It has an outer housing 2 and a rotor 1
that rotates within the housing. Contained within the rotor 1 are a
plurality of slots 12 and a plurality of sliding vanes 3 residing
within the slots 12. The vanes 3 extend outwards to make contact
with the inner walls of the housing 2.
[0038] Each vane 3 is connected to another vane 3 on the opposite
side of the rotor 1 by one of more connecting linkages 13. The
connecting linkages 13 that connect a pair of vanes 3 are
horizontally offset from other connecting linkages 13 that connect
other pairs of vanes 3. This allows the linkages to slide past each
other through the rotor's axis of rotation. The shape of the
housing 2 is such that the distance from one point on the surface
of the inner wall of the housing 2 to another point on the opposite
side of the housing through the axis of rotation of the rotor is
always the same. This allows the vanes 3 to be connected by
connection linkages 13 of constant length. Utilizing the connecting
linkages 13 to connect the vanes reduces the centrifugal force
exerted by the vanes on the wall of the housing, improving the
efficiency and durability of the machine 200 over existing
compressors and expanders of the rotary vane type.
[0039] The rotor 1 rotates clockwise when the machine 200 is
operating as a compressor and counterclockwise when it is operating
as an expander. A large port 40 is used as the inlet port when the
machine 200 is operating as a compressor and as the outlet port
when it is operating as an expander. A small port 41 is used as the
inlet port when the machine 200 is operating as an expander and as
the outlet port when it is operating as a compressor.
[0040] A cooling liquid could be injected into machine 200 like it
is in engine 100 when it is operating as a compressor to cool the
gas while it is being compressed. Alternatively a hot liquid could
be injected into the machine 200 like it is in engine 100 when it
is operating as an expander to increase the power output of the
expander. However in this arrangement the locations of the large
port 40 and the small port 41 should be reversed to allow gravity
to assist in expelling the heating liquid from the machine 200.
[0041] Having thus described exemplary embodiments of the present
invention, it should be noted by those skilled in the art that the
within disclosures are exemplary only, and that various other
alternatives, adaptations, and modifications may be made within the
scope of the present invention. Accordingly, the present invention
is not limited to the specific embodiments illustrated herein, but
is limited only by the following claims.
* * * * *