U.S. patent application number 13/284776 was filed with the patent office on 2013-05-02 for integrated absorption-cycle refrigeration and power generation system.
This patent application is currently assigned to Lockheed Martin Corporation. The applicant listed for this patent is Frank Mills. Invention is credited to Frank Mills.
Application Number | 20130105110 13/284776 |
Document ID | / |
Family ID | 48171210 |
Filed Date | 2013-05-02 |
United States Patent
Application |
20130105110 |
Kind Code |
A1 |
Mills; Frank |
May 2, 2013 |
INTEGRATED ABSORPTION-CYCLE REFRIGERATION AND POWER GENERATION
SYSTEM
Abstract
An integrated power and refrigeration system is disclosed. The
integrated system includes a solution comprising an absorber fluid
and a working fluid that can be selectively dissolved into the
absorber fluid. The integrated system also includes a first
subsystem configured to extract heat from an external cooling load
by pumping the solution through a vapor absorption cycle and a
second subsystem configured to provide power by accepting a first
portion of the solution from the first subsystem, extracting at
least a portion of the working fluid from the accepted solution,
heating the extracted working fluid, using the heated extracted
working fluid to drive a turbine that is coupled to a power
generator, and then returning the extracted working fluid and the
remaining accepted solution to the first subsystem.
Inventors: |
Mills; Frank; (Altadena,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mills; Frank |
Altadena |
CA |
US |
|
|
Assignee: |
Lockheed Martin Corporation
Bethesda
MD
|
Family ID: |
48171210 |
Appl. No.: |
13/284776 |
Filed: |
October 28, 2011 |
Current U.S.
Class: |
165/62 |
Current CPC
Class: |
F25B 27/02 20130101;
Y02A 30/274 20180101; F01K 23/10 20130101; F01K 25/065 20130101;
F01K 13/00 20130101 |
Class at
Publication: |
165/62 |
International
Class: |
F25B 13/00 20060101
F25B013/00 |
Claims
1. An integrated power and refrigeration system comprising: a
solution comprising an absorber fluid and a working fluid that can
be selectively dissolved into the absorber fluid; a first subsystem
configured to extract heat from an external cooling load by pumping
the solution through a vapor absorption cycle; and a second
subsystem configured to provide power by accepting a first portion
of the solution from the first subsystem, extracting at least a
portion of the working fluid from the accepted solution, heating
the extracted working fluid, expanding the heated extracted working
fluid to extract work thereby driving a turbine that is coupled to
a power generator, and then returning the expanded working fluid
and the remaining accepted solution to the first subsystem.
2. The system of claim 1, wherein: the solution is characterized as
a strong solution when the amount of the working fluid that is
dissolved in the absorber fluid is greater than a determined
percentage and characterized as a weak solution when the amount of
the working fluid that is dissolved in the absorber fluid is less
than or equal to the determined percentage; and the first subsystem
comprises: a first pump configured to accept a strong solution,
increase the pressure of the accepted strong solution, and provide
a pressurized strong solution; and a first generator thermally
coupled to an engine, the first generator configured to accept a
second portion of the pressurized strong solution, extract a
portion of the working fluid from the accepted pressurized strong
solution using heat extracted from the engine, and provide both a
pressurized working fluid and a weak solution.
3. The system of claim 2, wherein the second subsystem comprises: a
second generator thermally coupled to the engine, the second
generator configured to accept the first portion of the pressurized
strong solution received from the first subsystem, extract a
portion of the working fluid from the pressurized strong solution
using heat extracted from the propulsive engine, and provide both a
pressurized working fluid and a weak solution; a superheater
thermally coupled to the engine, the superheater configured to
accept the pressurized working fluid, heat the pressurized working
fluid using heat extracted from the engine, and provide a hot
pressurized working fluid; a power generator configured to provide
power; and a turbine coupled to the power generator, the turbine
configured to accept the hot pressurized working fluid from the
superheater, expand and extract work from the hot pressurized
working fluid thereby driving the power generator, and provide a
working fluid.
4. The system of claim 3, wherein the turbine is further coupled to
the first pump and a portion of the work extracted from the hot
pressurized working fluid drives the first pump.
5. The system of claim 4, wherein: the second subsystem further
comprises a second pump configured to accept the first portion of
pressurized strong solution received from the first subsystem,
increase the pressure of the accepted pressurized strong solution,
and provide a highly pressurized strong solution; the second
generator is configured to accept the highly pressurized strong
solution from the second pump in place of the pressurized strong
solution from the first subsystem and to provide a highly
pressurized working fluid in place of the pressurized working
fluid; the superheater is configured to accept the highly
pressurized working fluid in place of the pressurized working fluid
and to provide a hot highly pressurized working fluid in place of
the hot pressurized working fluid; the turbine is further coupled
to the second pump; and the turbine is configured to accept the hot
highly pressurized working fluid in place of the hot pressurized
working fluid and expand and extract work from the hot highly
pressurized working fluid thereby driving the power generator and
the first and second pumps.
6. The system of claim 4, wherein: the first subsystem further
comprises an absorber configured to accept the working fluid from
both the evaporator and the turbine and the weak solution from both
the first and second generators, dissolve the accepted working
fluid in the accepted weak solution, and provide a strong solution
to the first pump.
7. The system of claim 2, wherein the engine is a Brayton-cycle
engine.
8. The system of claim 2, wherein the engine is a Otto-cycle
engine.
9. The system of claim 2, wherein the engine is a Diesel-cycle
engine.
10. An integrated power and refrigeration system comprising: a
solution comprising an absorber fluid and a working fluid selected
such that the working fluid can be at least partially absorbed into
the absorber fluid, wherein the solution is characterized as a
strong solution when the percentage of working fluid is greater
than a determined value and characterized as a weak solution when
the percentage of working fluid is less than or equal to the
determined value; a first pump configured to accept a flow of
strong solution, increase the pressure of the accepted strong
solution, and provide a flow of pressurized strong solution; a
low-pressure generator coupled to a heat source, the low-pressure
generator configured to accept a first portion of the pressurized
strong solution flow from the first pump, extract at least a
portion of the working fluid from the strong solution using heat
extracted from the heat source, and provide both a flow of
pressurized working fluid and a flow of weak solution; a condenser
coupled to a cooling medium, the condenser configured to accept the
pressurized working fluid from the low-pressure generator, decrease
the temperature of the accepted pressurized working fluid by
rejecting heat to the cooling medium, and provide a flow of cool
pressurized working fluid; a throttle configured to accept the flow
of cool pressurized working fluid from the condenser and reduce the
pressure of the cool pressurized working fluid so as to vaporize a
portion of the cool pressurized working fluid thereby reducing the
temperature of the fluid, and provide a flow of cold working fluid;
an evaporator coupled to an external cooling load, the evaporator
configured to accept the flow of cold working fluid from the
throttle, vaporize at least a further portion of the cold working
fluid using heat extracted from the external cooling load, and
provide a flow of working fluid; a second pump configured to accept
a second portion of the pressurized strong solution flow from the
first pump, increase the pressure of the accepted pressurized
strong solution, and provide a flow of highly pressurized strong
solution; a high-pressure generator coupled to the heat source, the
high-pressure generator configured to accept the highly pressurized
strong solution flow from the second pump, extract at least a
portion of the working fluid from the strong solution using heat
extracted from the heat source, and provide both a flow of highly
pressurized working fluid and a flow of weak solution; a
superheater coupled to the heat source, the superheater configured
to accept the highly pressurized working fluid from the
high-pressure generator, increase the temperature of the accepted
highly pressurized working fluid using heat extracted from the heat
source, and provide a flow of hot highly pressurized working fluid;
a power generator configured to provide power; a power turbine
coupled to the power generator and the first and second pumps, the
power turbine configured to accept the hot highly pressurized
working fluid, expand and extract work from the hot highly
pressurized working fluid thereby driving the power generator and
the first and second pumps, and provide a flow of working fluid; a
first cooler coupled to the cooling medium, the first cooler
configured to accept the flows of working fluid from both the
evaporator and the turbine, reject heat from the accepted working
fluid to the cooling medium, and provide a flow of working fluid; a
second cooler coupled to the cooling medium, the second cooler
configured to accept the flows of weak solution from both the
low-pressure generator and the high-pressure generator, reject heat
from the accepted weak solution to the cooling medium, and provide
a flow of weak solution; and an absorber configured to accept the
flow of weak solution from the second cooler and the flow of
working fluid from the first cooler, dissolve the working fluid in
the weak solution to create a strong solution, and provide a flow
of the strong solution to the first pump.
11. The system of claim 10, wherein the heat source is waste heat
from an engine.
12. The system of claim 10, wherein the cooling medium is ambient
air.
13. A method of providing power and refrigeration on a vehicle
having an engine, the method comprising the steps of: pressurizing
a strong solution wherein the percentage of a working fluid
dissolved in an absorber fluid is greater than a determined value;
extracting at least a portion of the working fluid from the
pressurized strong solution using heat extracted from the engine;
condensing a first portion of the extracted working fluid by
rejecting heat to a cooling medium; providing refrigeration to an
external cooling load by evaporating the condensed working fluid
using heat extracted from the external cooling load; heating a
second portion of the extracted working fluid using heat extracted
from the engine; and providing power by expanding and extracting
work from the heated second portion of the extracted working fluid
in a turbine that is coupled to a power generator.
14. The method of claim 13, wherein the step of providing power
comprises driving a first pump to perform the step of pressurizing
the strong solution.
15. The method of claim 13, further comprising the steps of:
further pressurizing a portion of the pressurized strong solution
to form a highly pressurized strong solution; and extracting a
highly pressurized working fluid from the highly pressurized strong
solution using heat extracted from the engine; wherein: the step of
heating a second portion of the extracted working fluid comprises
heating the highly pressurized working fluid; and the step of
providing power comprises expanding and extracting work from the
heated highly pressurized working fluid.
16. The method of claim 15, wherein the step of providing power
comprises driving a second pump to perform the step of further
pressurizing a portion of the pressurized strong solution.
17. The method of claim 13, further comprising the step of:
dissolving the evaporated working fluid that was used to provide
cooling and the expanded working fluid that was used to provide
power in a weak solution wherein the percentage of the working
fluid dissolved in the absorber fluid is less than or equal to the
determined value that was formed from the strong solution when the
working fluid was extracted.
18. A power system comprising: a solution comprising an absorber
fluid and a working fluid selected such that the working fluid can
be at least partially absorbed into the absorber fluid, wherein the
solution is characterized as a strong solution when the percentage
of working fluid is greater than a determined value and
characterized as a weak solution when the percentage of working
fluid is less than or equal to the determined value; a pump
configured to accept a flow of strong solution, increase the
pressure of the accepted strong solution, and provide a flow of
pressurized strong solution; a generator coupled to a heat source,
the generator configured to accept the pressurized strong solution
flow from the pump, extract at least a portion of the working fluid
from the strong solution using heat extracted from the heat source,
and provide both a flow of pressurized working fluid and a flow of
weak solution; a superheater coupled to the heat source, the
superheater configured to accept the pressurized working fluid flow
from the generator, increase the temperature of the accepted
pressurized working fluid using heat extracted from the heat
source, and provide a flow of hot pressurized working fluid; a
power generator configured to provide power; a power turbine
coupled to the power generator and the pump, the power turbine
configured to accept the hot pressurized working fluid from the
superheater, expand and extract work from the hot pressurized
working fluid thereby driving the power generator and the pump, and
provide a flow of expanded working fluid; and an absorber
configured to accept the flow of weak solution and the flow of
expanded working fluid, dissolve the working fluid into the weak
solution to create a strong solution, and provide a flow of the
strong solution to the pump.
19. The power system of claim 18, wherein the heat source is waste
heat from an engine.
20. A refrigeration system comprising: a solution comprising an
absorber fluid and a working fluid selected such that the working
fluid can be at least partially absorbed into the absorber fluid,
wherein the solution is characterized as a strong solution when the
percentage of working fluid is greater than a determined value and
characterized as a weak solution when the percentage of working
fluid is less than or equal to the determined value; a pump
configured to accept a flow of strong solution, increase the
pressure of the accepted strong solution, and provide a flow of
pressurized strong solution; a generator coupled to a heat source,
the generator configured to accept a first portion of the
pressurized strong solution flow from the pump, extract at least a
portion of the working fluid from the strong solution using heat
extracted from the heat source, and provide both a flow of
pressurized working fluid and a flow of weak solution; a condenser
coupled to a cooling medium, the condenser configured to accept the
pressurized working fluid from the generator, decrease the
temperature of the accepted pressurized working fluid by rejecting
heat to the cooling medium, and provide a flow of cool pressurized
working fluid; a throttle configured to accept the flow of cool
pressurized working fluid from the condenser and reduce the
pressure of the cool pressurized working fluid so as to vaporize a
portion of the cool pressurized working fluid thereby reducing the
temperature of the fluid, and provide a flow of cold working fluid;
an evaporator coupled to an external cooling load, the evaporator
configured to accept the flow of cold working fluid from the
throttle, vaporize at least a further portion of the cold working
fluid using heat extracted from the external cooling load, and
provide a flow of working fluid; an absorber configured to accept
the flow of working fluid from the evaporator and the flow of weak
solution from the generator, dissolve the working fluid in the weak
solution to create a strong solution, and provide a flow of the
strong solution to the pump.
21. The power system of claim 20, wherein the heat source is waste
heat from an engine.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Not applicable.
Statement Regarding Federally Sponsored Research or Development
[0002] Not applicable.
BACKGROUND
[0003] 1. Field
[0004] The present disclosure generally relates to systems and
methods of generating refrigeration and power and, in particular,
mobile systems that use waste heat to improve the performance of
refrigeration and power generation systems.
[0005] 2. Description of the Related Art
[0006] A traditional passive absorption-cycle refrigerator uses
ammonia and water as ammonia will dissolve in water at certain
temperatures and pressures. The ammonia can be extracted from the
ammonia-water solution using heat while maintaining a constant
pressure, as ammonia boils at -33 degrees C. at a pressure of 1
atmosphere. In a ground-based system, such as the propane-powered
refrigerators used in recreational vehicles, there is no pump in
the absorption-cycle system. The cooling cycle starts with
liquefied ammonia entering an evaporator at room temperature
wherein the ammonia boils from the heat extracted from the external
cooling load. The gaseous ammonia is introduced at the bottom of an
uphill series of tubes into which water is added at the top. The
ammonia dissolves in the water, producing a ammonia/water solution
that collects at the bottom and passes to a generator. In the
generator, the ammonia/water solution is heated in a vertical
column which releases the ammonia as bubbles in the liquid
solution, which is now mainly water. The buoyancy of the ammonia
bubbles force the remaining water up the column. At the top of the
column, the water spills over into a tube that provides a pressure
head to drive the water back to the top of the uphill series of
tubes while the gaseous ammonia is carried off to a condenser that
cools the ammonia to a liquid, thereby completing the vapor
absorption cycle. Operation of this type of system depends on the
partial pressure of ammonia to drive part of the cycle and hydrogen
gas is provided in part of the system to maintain a constant total
pressure while allowing the partial pressure of the ammonia to
vary.
[0007] A traditional vapor-compression refrigerator uses a single
refrigerant, such as Freon.RTM. or other haloalkane refrigerant, in
a closed-loop system. Liquid refrigerant is provided to an
expansion valve where it undergoes a reduction in pressure, causing
part of the liquid refrigerant to evaporate and cool the remaining
liquid. This cold liquid/gas fluid is carried to an evaporator
coupled to the heat load wherein heat is extracted from the heat
load by warming the liquid/gas fluid and evaporating the liquid to
form a gas. This fluid is compressed to a higher pressure and
temperature in a compressor and provided to the condenser which
cools the fluid and provides it to the expansion valve, thereby
completing the cycle.
SUMMARY
[0008] Traditional vapor-compression refrigeration system are
driven by electrical power that is a significant load on an
aircraft power generation system. It is desirable to provide
refrigeration for equipment and personnel on aircraft using a
reduced amount of electrical power. While it may be easier to
compress a liquid, such as the ammonia-water solution used in a
traditional vapor absorption cycle refrigeration system, to a
specified pressure rather than to compress a gas to this same
pressure, a traditional absorption-cycle refrigeration system will
not operate in a variable-orientation and/or variable acceleration
environment such as on-board an aircraft. As such, neither of the
traditional vapor-compression or vapor absorption systems met this
need.
[0009] There is growing interest in converting aircraft waste heat
(e.g., engine heat dissipations, exhaust gas) into useable power or
refrigeration. Conversion of such "low-grade" heat into electrical
power or directly into refrigeration can be inherently inefficient
if the size and weight of the conversion equipment is low.
[0010] The goal of this invention is to convert waste heat into
useful power and/or refrigeration. The invention uses a working
fluid that can be dissolved into an absorber fluid to reduce the
amount of work required to pressurize the solution, and then
extract the working fluid at the higher pressure to drive either a
power turbine or provide cooling.
[0011] In certain embodiments, an integrated power and
refrigeration system is disclosed. The integrated system includes a
solution comprising an absorber fluid and a working fluid that can
be selectively dissolved into the absorber fluid. The integrated
system also includes a first subsystem configured to extract heat
from an external cooling load by pumping the solution through a
vapor absorption cycle and a second subsystem configured to provide
power by accepting a first portion of the solution from the first
subsystem, extracting at least a portion of the working fluid from
the accepted solution, heating the extracted working fluid, using
the heated extracted working fluid to drive a turbine that is
coupled to a power generator, and then returning the extracted
working fluid and the remaining accepted solution to the first
subsystem.
[0012] In certain embodiments, an integrated power and
refrigeration system is disclosed. The integrated system includes a
solution comprising an absorber fluid and a working fluid selected
such that the working fluid can be at least partially absorbed into
the absorber fluid. The solution is characterized as a strong
solution when the percentage of working fluid is greater than a
determined value and characterized as a weak solution when the
percentage of working fluid is less than or equal to the determined
value. The integrated system includes a first pump configured to
accept a flow of strong solution, increase the pressure of the
accepted strong solution, and provide a flow of pressurized strong
solution. The integrated system also includes a low-pressure
generator coupled to a heat source. The low-pressure generator is
configured to accept a first portion of the pressurized strong
solution flow from the first pump, extract at least a portion of
the working fluid from the strong solution using heat extracted
from the heat source, and provide both a flow of pressurized
working fluid and a flow of weak solution. The integrated system
also includes a condenser coupled to a cooling medium. The
condenser is configured to accept the pressurized working fluid
from the low-pressure generator, decrease the temperature of the
accepted pressurized working fluid by rejecting heat to the cooling
medium, and provide a flow of cool pressurized working fluid. The
integrated system also includes a throttle configured to accept the
flow of cool pressurized working fluid from the condenser and
reduce the pressure of the cool pressurized working fluid so as to
vaporize a portion of the cool pressurized working fluid thereby
reducing the temperature of the fluid, and provide a flow of cold
working fluid. The integrated system also includes an evaporator
coupled to an external cooling load. The evaporator is configured
to accept the flow of cold working fluid from the throttle,
vaporize at least a further portion of the cold working fluid using
heat extracted from the external cooling load, and provide a flow
of working fluid. The integrated system also includes a second pump
configured to accept a second portion of the pressurized strong
solution flow from the first pump, increase the pressure of the
accepted pressurized strong solution, and provide a flow of highly
pressurized strong solution. The integrated system also includes a
high-pressure generator coupled to the heat source. The
high-pressure generator is configured to accept the highly
pressurized strong solution flow from the second pump, extract at
least a portion of the working fluid from the strong solution using
heat extracted from the heat source, and provide both a flow of
highly pressurized working fluid and a flow of weak solution. The
integrated system also includes a superheater coupled to the heat
source. The superheater is configured to accept the highly
pressurized working fluid from the high-pressure generator,
increase the temperature of the accepted highly pressurized working
fluid using heat extracted from the heat source, and provide a flow
of hot highly pressurized working fluid. The integrated system also
includes a power generator configured to provide power and a power
turbine coupled to the power generator and the first and second
pumps. The power turbine is configured to accept the hot highly
pressurized working fluid, expand and extract work from the hot
highly pressurized working fluid thereby driving the power
generator and the first and second pumps, and provide a flow of
working fluid. The integrated system also includes a first cooler
coupled to the cooling medium. The first cooler is configured to
accept the flows of working fluid from both the evaporator and the
turbine, reject heat from the accepted working fluid to the cooling
medium, and provide a flow of working fluid. The integrated system
also includes a second cooler coupled to the cooling medium. The
second cooler is configured to accept the flows of weak solution
from both the low-pressure generator and the high-pressure
generator, reject heat from the accepted weak solution to the
cooling medium, and provide a flow of weak solution. The integrated
system also includes an absorber configured to accept the flow of
weak solution from the second cooler and the flow of working fluid
from the first cooler, dissolve the working fluid in the weak
solution to create a strong solution, and provide a flow of the
strong solution to the first pump.
[0013] In certain embodiments, a method of providing power and
refrigeration on a vehicle having an engine is disclosed. The
method includes the steps of pressurizing a strong solution wherein
the percentage of a working fluid dissolved in an absorber fluid is
greater than a determined value, extracting at least a portion of
the working fluid from the pressurized strong solution using heat
extracted from the engine, condensing a first portion of the
extracted working fluid by rejecting heat to a cooling medium,
providing refrigeration to an external cooling load by evaporating
the condensed working fluid using heat extracted from the external
cooling load, heating a second portion of the extracted working
fluid using heat extracted from the engine, and providing power by
expanding and extracting work from the heated second portion of the
extracted working fluid in a turbine that is coupled to a power
generator.
[0014] In certain embodiments, a power system is disclosed that
includes a solution comprising an absorber fluid and a working
fluid selected such that the working fluid can be at least
partially absorbed into the absorber fluid. The solution is
characterized as a strong solution when the percentage of working
fluid is greater than a determined value and characterized as a
weak solution when the percentage of working fluid is less than or
equal to the determined value. The power system also includes a
pump configured to accept a flow of strong solution, increase the
pressure of the accepted strong solution, and provide a flow of
pressurized strong solution. The power system also includes a
generator coupled to a heat source. The generator is configured to
accept the pressurized strong solution flow from the pump, extract
at least a portion of the working fluid from the strong solution
using heat extracted from the heat source, and provide both a flow
of pressurized working fluid and a flow of weak solution. The power
system also includes a superheater coupled to the heat source. The
superheater is configured to accept the pressurized working fluid
flow from the generator, increase the temperature of the accepted
pressurized working fluid using heat extracted from the heat
source, and provide a flow of hot pressurized working fluid. The
power system also includes a power generator configured to provide
power and a power turbine coupled to the power generator and the
pump. The power turbine is configured to accept the hot pressurized
working fluid from the superheater, expand and extract work from
the hot pressurized working fluid thereby driving the power
generator and the pump, and provide a flow of expanded working
fluid. The power system also includes an absorber configured to
accept the flow of weak solution and the flow of expanded working
fluid, dissolve the working fluid into the weak solution to create
a strong solution, and provide a flow of the strong solution to the
pump.
[0015] In certain embodiments, a refrigeration system is disclosed
that includes a solution comprising an absorber fluid and a working
fluid selected such that the working fluid can be at least
partially absorbed into the absorber fluid. The solution is
characterized as a strong solution when the percentage of working
fluid is greater than a determined value and characterized as a
weak solution when the percentage of working fluid is less than or
equal to the determined value. The refrigeration system also
includes a pump configured to accept a flow of strong solution,
increase the pressure of the accepted strong solution, and provide
a flow of pressurized strong solution. The refrigeration system
also includes a generator coupled to a heat source. The generator
is configured to accept a first portion of the pressurized strong
solution flow from the pump, extract at least a portion of the
working fluid from the strong solution using heat extracted from
the heat source, and provide both a flow of pressurized working
fluid and a flow of weak solution. The refrigeration system also
includes a condenser coupled to a cooling medium. The condenser is
configured to accept the pressurized working fluid from the
generator, decrease the temperature of the accepted pressurized
working fluid by rejecting heat to the cooling medium, and provide
a flow of cool pressurized working fluid. The refrigeration system
also includes a throttle configured to accept the flow of cool
pressurized working fluid from the condenser and reduce the
pressure of the cool pressurized working fluid so as to vaporize a
portion of the cool pressurized working fluid thereby reducing the
temperature of the fluid, and provide a flow of cold working fluid.
The refrigeration system also includes an evaporator coupled to an
external cooling load. The evaporator is configured to accept the
flow of cold working fluid from the throttle, vaporize at least a
further portion of the cold working fluid using heat extracted from
the external cooling load, and provide a flow of working fluid. The
refrigeration system also includes an absorber configured to accept
the flow of working fluid from the evaporator and the flow of weak
solution from the generator, dissolve the working fluid in the weak
solution to create a strong solution, and provide a flow of the
strong solution to the pump.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The accompanying drawings, which are included to provide
further understanding and are incorporated in and constitute a part
of this specification, illustrate disclosed embodiments and
together with the description serve to explain the principles of
the disclosed embodiments. In the drawings:
[0017] FIG. 1 is a schematic diagram of an exemplary integrated
power and refrigeration system according to certain aspects of this
disclosure.
[0018] FIG. 2 is another embodiment of the integrated power and
refrigeration system according to certain aspects of this
disclosure.
[0019] FIG. 3 is a schematic diagram of an another embodiment of
the integrated power and refrigeration system according to certain
aspects of this disclosure.
[0020] FIG. 4 is a schematic diagram of another embodiment of an
integrated power and refrigeration system according to certain
aspects of this disclosure.
[0021] FIG. 5 is a schematic diagram of another embodiment of an
integrated power and refrigeration system according to certain
aspects of this disclosure.
[0022] FIG. 6 is a schematic diagram of a power system in
accordance with certain aspects of this disclosure.
[0023] FIG. 7 is a schematic diagram of a refrigeration system
=according to certain aspects of this disclosure.
DETAILED DESCRIPTION
[0024] The following description discloses embodiments of an
integrated power generation and refrigeration system driven by a
heat source and a cooling medium. In certain embodiments, the heat
source is waste heat from a device such as a propulsion engine. In
certain embodiments, the cooling medium is ambient air.
[0025] The disclosed systems use a pair of fluids wherein one of
the fluids, referred to herein as a "working fluid," will dissolve
into the other fluid, referred to as an "absorber fluid," under
certain conditions of temperature and pressure to form a solution.
The working fluid can be extracted from a solution of the two
fluids under certain other conditions of temperature and pressure.
An exemplary pair of fluids is ammonia as the working fluid and
water as the absorber fluid. Another pair of fluids uses water as
the working fluid and lithium bromide as the absorber fluid.
[0026] The amount of working fluid dissolved into the absorber
fluid is different at various points in the disclosed processes.
The solution is characterized herein as a "strong solution" when
the amount of the working fluid that is dissolved in the absorber
fluid is greater than a determined percentage, and characterized
herein as a "weak solution" when the amount of the working fluid
that is dissolved in the absorber fluid is less than or equal to
the determined percentage. The percentage of working fluid in the
absorber fluid for the strong solution is a design choice for a
particular system and the percentage of working fluid in the weak
solution, and therefore the determined percentage that separates a
weak solution from a strong solution, are related to other design
choices, such as the mass flow rate of the strong solution and the
energy input in the generator, that are made for that particular
system.
[0027] In certain embodiments of an ammonia/water system, a strong
solution comprises approximately 30% ammonia by weight and a weak
solution comprises less than 25% ammonia by weight. In certain
embodiments, the weak solution comprises less than 20% by weight.
The amount of ammonia extracted as a "working fluid" from the
strong solution, and therefore the composition of the weak
solution, is a function of the mass flow rate of the strong
solution and the energy input rate. In addition, the working fluid
that is extracted from the strong solution may include some amount
of the absorber fluid. For example, the flow of the working fluid
extracted from a working solution of 30% ammonia may be 90% ammonia
and 10% water. The water vapor will tend to condense into liquid in
the condenser, resulting in a flow of gaseous working fluid from
the condenser that is primarily ammonia and flow of liquid that is
primarily water, which is directed into the weak solution.
[0028] Within this disclosure, the phrase "a highly pressurized
solution" or fluid indicates only that the pressure of the solution
is greater than that of the solution in "a pressurized solution"
that is itself an indication that the pressure is greater than that
of "a solution." There is no implication of the amount of the
difference in pressure between "highly pressurized" and
"pressurized," only that "highly pressurized" is greater than
"pressurized."
[0029] Within this disclosure, the phrase "a hot working fluid" or
other fluid indicates only that the temperature of the "hot working
fluid" solution is greater than that of "a working fluid." There is
no implication of the amount of the difference in temperature
between a "hot" material and a material that lacks the adjective
"hot," only that the temperature of the "hot" material is greater
than the temperature of the material that lacks the adjective
"hot."
[0030] Similarly, within this disclosure the phrase "a cold
solution" indicates only that the temperature of the "cold"
solution is less than that of "a cool solution" that is itself an
indication that the temperature is less than that of "a solution."
There is no implication of the amount of the difference in
temperature between a "cold" material and a "cool" material, only
that the temperature of the "cold" material is less than the
temperature of the "cool" material, and likewise for a "cool"
material compared to a material lacking a temperature-related
adjective. In certain embodiments of the present disclosure, a
"cold" fluid may have a larger fraction of liquid than a "cool"
fluid.
[0031] In the following schematic diagrams, lines carrying certain
types of fluids are indicated by the type of line drawn in the
schematic. For example, a thin black line indicates a line carrying
a working fluid where a thick black line indicates a line carrying
a weak solution. Each figure using these types of line includes a
legend that depicts sample line types.
[0032] Within the scope of this disclosure, reference to a
particular line in a schematic is considered equivalent and
interchangeable with a reference to the type of fluid carried in
that line. For example, the phrase "pressurized strong solution 42"
is equivalent and interchangeable with "line 42." In certain
instances, the composition of the fluid in two lines may be
identical but carry different reference indicators to indicate a
difference in the pressure, temperature, or other physical
characteristic of the fluids in the two lines.
[0033] In the following detailed description, numerous specific
details are set forth to provide a full understanding of the
present disclosure. It will be apparent, however, to one ordinarily
skilled in the art that embodiments of the present disclosure may
be practiced without some of the specific details. In other
instances, well-known structures and techniques have not been shown
in detail so as not to obscure the disclosure.
[0034] The method and system disclosed herein are presented in
terms of systems in use on an aircraft propelled by a turbojet
engine. This exemplary utilization of the disclosed system is
sufficient to describe the attributes and use of the components of
a variety of embodiments of the system. Utilization of the
disclosed system is not limited to aircraft, however, and
advantageous application may be found in other environments where
waste heat is readily available, such as a diesel-engine train or
ground-based locations having available heat but restricted in
electrical power. Nothing in this disclosure shall be interpreted
to limit the application of the disclosed systems and processes to
an aircraft unless explicitly stated as such.
[0035] FIG. 1 is a schematic diagram of an exemplary integrated
power and refrigeration system 10 according to certain aspects of
this disclosure. In the diagram, beginning at the lower right, a
pump 12 pressurizes a strong solution 40 of a working fluid
dissolved in an absorber fluid, such as ammonia dissolved in water,
and provides this pressurized strong solution 30 to a low-pressure
generator 14. The low-pressure generator 14 is coupled to a heat
source 6A, such as the waste heat from an on-board engine (not
shown in FIG. 1), and uses this heat to extract the working fluid
from the strong solution 30. The remaining weak solution 33 is
returned to an absorber 22 as is discussed in greater detail below.
The extracted pressurized working fluid 32 is provided to a
condenser 16 that is coupled to a cooling medium 4. The working
fluid 32 is cooled by rejecting heat from the working fluid 32 to
the cooling medium 4 within the condenser 16, thereby converting at
least a portion of the working fluid 32 to a liquid. The cool
pressurized working fluid 34 passes to a flow control throttle 18
that reduces the pressure of the cool pressurized working fluid 34
so as to vaporize a portion of the cool pressurized working fluid
34 thereby reducing the temperature of the fluid, and provide a
flow of cold working fluid 36. In the evaporator 20, heat is
extracted from the cooling load 2 by evaporation of the liquid
portion of the cold working fluid 36. This evaporated working fluid
38 passes to an absorber 22 that, as stated above, also receives
the weak solution 33 from the low-pressure generator 14. In the
absorber 22, the evaporated working fluid 38 and the weak solution
33 are combined and the evaporated working fluid 38 dissolves into
the weak solution 33, thereby creating a strong solution 40. The
strong solution 40 is provided by the absorber 22 back to the pump
12, thereby completing the vapor absorption cycle.
[0036] In certain embodiments, the portion of the circulation path
from the pump 12 through the generator 14 to the throttle 18 is at
a generally uniform first pressure while the portion of the path
from the throttle 18 through the evaporator 20 to the pump 12 is at
a generally uniform second pressure. The work required within pump
12 to increase the pressure of the liquid strong solution 40 that
is at the second pressure to the first pressure of the pressurized
strong solution 30 may be less than the work required to compress
an amount of gas of the same thermal capacity from the second
pressure to the first pressure.
[0037] In the system of FIG. 1, a power subsystem 50 provides power
in addition to the refrigeration provided by the portion of the
main system 10 that is not within the dashed-line box 50 in FIG. 1.
A second pump 52 accepts a portion of the pressurized strong
solution 30B and further pressurizes this liquid to form a highly
pressurized strong solution 42 while the remaining pressurized
strong solution 30A is directed to the low-pressure generator 14 as
described above. The highly pressurized strong solution 42 is
provided to a high-pressure generator 54. The high-pressure
generator 54 is coupled to a heat source 6B and uses heat extracted
from the heat source 6B to extract the highly pressurized working
fluid 44 from the strong solution 42. The remaining weak solution
43 is returned to absorber 22. The extracted highly pressurized
working fluid 44 travels to a superheater 56 that is coupled to a
heat source 6C wherein the highly pressurized working fluid 44 is
heated to form a hot highly pressurized working fluid 46. This hot
highly pressurized working fluid 46 is provided to a turbine 58
wherein the hot highly pressurized working fluid 46 is expanded and
work extracted from it so as to drive shaft 62 that is coupled to
power generator 60 and, in certain embodiments, pumps 12 and 52.
The expanded working fluid 48 is returned to the absorber 22 along
with the evaporated working fluid 38 from the evaporator 20.
[0038] In certain embodiments, the heat sources 6A, 6B, and 6C are
a common heat source. In certain embodiments, the heat sources 6A,
6B, and 6C are waste heat from an on-board engine (not shown in
FIG. 1). In certain embodiments, the heat sources 6A, 6B, and 6C
are waste heat from a propulsive engine (not shown in FIG. 1). In
certain embodiments, the heat sources 6A, 6B, and 6C are exhaust
gas from a turbojet or turbofan engine (not shown in FIG. 1). In
certain embodiments, the heat sources 6A, 6B, and 6C are exhaust
gas from a reciprocating-piston engine (not shown in FIG. 1).
[0039] As discussed above, the portion of the integrated system 100
that is not included in the power subsystem 50 forms a
refrigeration subsystem 11. The refrigeration subsystem 11 extracts
heat from an external cooling load using a vapor absorption cycle
that comprises a pressurizing pump 12 to allow operation in a
variable orientation and/or variable acceleration environment. The
power subsystem 50 provides power by accepting a portion of the
strong solution 30 from the refrigeration subsystem 11, extracting
at least a portion of the working fluid from the accepted strong
solution 30B, heating the extracted working fluid 44, expanding the
heated extracted working fluid 46 to extract work thereby driving a
turbine 58 that is coupled to a power generator 60, and then
returning the expanded working fluid 48 and the remaining accepted
solution 43 to the refrigeration subsystem 11 where the expanded
working fluid 48 is combined with the vaporized working fluid 38
and the remaining accepted solution 43 is combined with the weak
solution 33.
[0040] FIG. 2 is another embodiment 10A of the integrated power and
refrigeration system according to certain aspects of this
disclosure. In the system 10A, a pair of coolers 23A and 23B have
been added to the system. Each cooler 23A and 23B are coupled to a
cooling medium 4B and 4C, respectively, and pre-cool the returning
evaporated working fluid 38 and the weak solution 33, respectively.
The cooled working fluid 39 and the cold weak solution 35 coming
out of the coolers 23A and 23B are then provided to the absorber
22, wherein the cooled working fluid 39 and weak solution 35 are
mixed as described in FIG. 1.
[0041] In certain embodiments, the cooling media 4A, 4B, and 4C are
a common cooling medium. In certain embodiments, the cooling media
4A, 4B, and 4C are all stream of ambient air drawn from the ambient
environment (not shown in FIG. 2), for example a ram air duct
mounted on an exterior of an aircraft.
[0042] FIG. 3 is a schematic diagram of an another embodiment 10B
of the integrated power and refrigeration system according to
certain aspects of this disclosure. In this embodiment, the heat
source is a stream of exhaust gas 106 from a propulsion engine 20.
In this embodiment, the exhaust gas 106 is split into three
portions. A portion 106A is coupled to the low-pressure generator
14 and provides the heat therein to separate the working fluid 32
from the strong solution 30A. A second portion 106B is coupled to
the high-pressure generator 54 and provides the heat therein to
extract the working fluid 44 from the strong solution 42. A third
portion 106C is coupled to the superheater 56 and therein heats the
highly-pressurized working fluid 44 to become a hot,
highly-pressurized working fluid 46 that is then provided to
turbine 58. A flow of cooling media 104 is air drawn from the
ambient airflow 80A and, after passing through condenser 16, is
exhausted to the ambient airflow 80B that is, in certain
embodiments, downstream of the ambient airflow 80A.
[0043] FIG. 4 is a schematic diagram of another embodiment 10C of
an integrated power and refrigeration system according to certain
aspects of this disclosure. In this embodiment, heat exchangers
210, 220 are used in place of direct heating and cooling of the
generators 14 and 54, condenser 16, and superheater 56 so as to
decouple the exhaust gas 106 from the components that require a
heat source and ambient airflow 80 from the components that require
a cooling medium. In this embodiment 10C, the heat exchanger 210
has three circulating paths 206A, 206B, and 206C coupled to the
low-pressure generator 14, the high-pressure generator 54 and the
superheater 56, respectively. A heat transfer fluid 206 circulates
through these three lines 206A, 206B, and 206 thereby providing
heat extracted from the exhaust gas 106 to each of the three
components 14, 54, and 56. Similarly, a heat exchanger 220 is
coupled to the ambient airflow 80. In this embodiment, cooling
medium 204 is also provided to absorber 22 to assist in the
absorption of the cooled working fluid 39 by the weak solution 35
in the absorber 22. The heat exchanger 220 is coupled to four
re-circulating lines 204A-204D that provide a cooling medium 204 to
the four components 16, 23A, 23B, and 22 that require cooling
herein. As the cooling medium 204 circulates through these four
paths 204A-204D, each of the components 16, 23A, 23B, and 22
rejects heat to the cooling medium 204 that is then returned to the
heat exchanger 220. In certain embodiments, the cooling medium is
provided to the components 16, 23A, 23B, and 22 via other
configurations of paths 204A-204D.
[0044] In certain embodiments, the heat exchanger 210 is
incorporated into the body of an engine and the heat transfer fluid
206 circulated through cooling channels (not shown in FIG. 4) in
the body of engine 20 and thereby extracts heat from the engine 20.
In certain embodiments, the heat transfer fluid 206 is ambient air
that is passed through cooling channels of the body of engine 20
and then passed through the low-pressure generator 14,
high-pressure generator 54, and superheater 56 and then exhausted
to the ambient airflow 80B.
[0045] In certain embodiments, a flow of fuel (not shown in FIG. 4)
replaces the ambient airflow 80 as the heat sink coupled to heat
exchanger 220. In certain embodiments, fuel is received from a fuel
reservoir, passes through the heat exchanger 220 wherein heat is
rejected from the cooling medium 204 to the fuel, and then the fuel
is directed back to the fuel reservoir. In certain embodiments, a
portion of the fuel exiting the heat exchanger 220 is directed to
engine 20 or to another engine (not shown in FIG. 4).
[0046] FIG. 5 is a schematic diagram of another embodiment 10D of
an integrated power and refrigeration system according to certain
aspects of this disclosure. In system 10D, regenerative heat
exchangers 300 and 302 have been added to the subsystems 11 and
50B. Regenerative heat exchanger 300 has been added in conjunction
with low-pressure generator 14, such that the weak solution 33 that
is expelled from the low-pressure generator 14 warms the incoming
strong solution 30A thereby improving the efficiency of the
refrigeration subsystem 11. Similarly, a regenerative heat
exchanger 302 has been added in association with high-pressure
generator 54 wherein the weak solution 43 exiting the high-pressure
generator 54 is warming the highly-pressurized strong solution 42
thereby improving the efficiency of the power subsystem 50B. The
weak solutions 33, 43 exiting from the regenerative heat exchangers
300, 302 are combined in the refrigeration subsystem 11 and
directed to absorber 22.
[0047] In the embodiment of FIG. 5, streams 104A, 104B of ambient
air are directed from a source of ambient airflow 80A, such as an
inlet of a ram air scoop (not shown in FIG. 5) through the absorber
22 and the condenser 16 and then exhausted to the ambient airflow
80B, such as an outlet of a ram air scoop.
[0048] FIG. 6 is a schematic diagram of a power system 400 in
accordance with certain aspects of this disclosure. In this system,
the pump 52 accepts a strong solution 40 from absorber 22 and
provides a highly-pressurized strong solution 42 directly to
generator 54 which provides highly pressurized working fluid 44 to
superheater 56. Hot, highly pressurized working fluid 46 from the
superheater 56 passes to the turbine 58 and, after being expanded
and work extracted therefrom, the expanded working fluid 48 is
directed back to absorber 22, which combines the working fluid 48
and weak solution 43 to create the strong solution 40 provided to
pump 52. In this embodiment, the heat source used by the generator
54 and super heater 56 is provided as exhaust gas 106 from engine
20 and exhausted after use to the ambient airflow 80B. In certain
embodiments, a cooling medium (not shown in FIG. 6) is provided to
the absorber 22 similar to that shown in FIG. 5.
[0049] FIG. 7 is a schematic diagram of a refrigeration system 500
according to certain aspects of this disclosure. The refrigerator
system 500 consists of a pump 12 that provides pressurized strong
solution 30 to generator 14 which in turn provides pressurized
working fluid 32 to condenser 16 and cool pressurized working fluid
34 to throttle 18 and liquid working fluid 36 to evaporator 20 as
before. The weak solution 33 leaving generator 14 is provided to
absorber 22 as is the evaporated working fluid 38 from the
evaporator 20. In the absorber 22, the working fluid 38 and weak
solution 33 are combined to produce the strong solution 40 that is
provided back to pump 12. In this embodiment, the heat source used
by generator 14 is a stream of exhaust gas 106 from engine 20 and
the cooling media used by condenser 16 is a stream of ambient air
104 coupled to the condenser 16. In both cases, the hot exhaust gas
leaving generator 14 and the warmed air flow 104 leaving condenser
16 are both exhausted into the ambient airflow 80B.
[0050] The concepts disclosed herein provide a system and method of
providing one or both of refrigeration and power using an
absorption cycle system. In certain embodiments, the power and
refrigeration systems are integrated and share one or more
components, thus simplifying the system design as well as
potentially reducing the size, weight, and cost of the integrated
system. In certain embodiments, waste heat from an engine or other
existing heat source may be used to operate either or both of the
power and refrigeration systems. In certain embodiments, a portion
of the exhaust gas is passed through the various components that
require a heat source.
[0051] It will be obvious to those of skill in the art that the
various elements of the disclosed embodiments of the present
disclosure may be combined in other configurations to provide
either or both of power and refrigeration. In addition, it will be
apparent that various types of power generators, for example an
electrical generator, an electrical alternator, or a hydraulic
pump, may be used alone or together in the disclosed system.
[0052] The previous description is provided to enable a person of
ordinary skill in the art to practice the various aspects described
herein. While the foregoing has described what are considered to be
the best mode and/or other examples, it is understood that various
modifications to these aspects will be readily apparent to those
skilled in the art, and the generic principles defined herein may
be applied to other aspects. Thus, the claims are not intended to
be limited to the aspects shown herein, but are to be accorded the
full scope consistent with the language claims, wherein reference
to an element in the singular is not intended to mean "one and only
one" unless specifically so stated, but rather "one or more."
Unless specifically stated otherwise, the terms "a set" and "some"
refer to one or more. Pronouns in the masculine (e.g., his) include
the feminine and neuter gender (e.g., her and its) and vice versa.
Headings and subheadings, if any, are used for convenience only and
do not limit the invention.
[0053] It is understood that the specific order or hierarchy of
steps in the processes disclosed is an illustration of exemplary
approaches. Based upon design preferences, it is understood that
the specific order or hierarchy of steps in the processes may be
rearranged. Some of the steps may be performed simultaneously. The
accompanying method claims present elements of the various steps in
a sample order, and are not meant to be limited to the specific
order or hierarchy presented.
[0054] Terms such as "top," "bottom," "front," "rear" and the like
as used in this disclosure should be understood as referring to an
arbitrary frame of reference, rather than to the ordinary
gravitational frame of reference. Thus, a top surface, a bottom
surface, a front surface, and a rear surface may extend upwardly,
downwardly, diagonally, or horizontally in a gravitational frame of
reference.
[0055] A phrase such as an "aspect" does not imply that such aspect
is essential to the subject technology or that such aspect applies
to all configurations of the subject technology. A disclosure
relating to an aspect may apply to all configurations, or one or
more configurations. A phrase such as an aspect may refer to one or
more aspects and vice versa. A phrase such as an "embodiment" does
not imply that such embodiment is essential to the subject
technology or that such embodiment applies to all configurations of
the subject technology. A disclosure relating to an embodiment may
apply to all embodiments, or one or more embodiments. A phrase such
an embodiment may refer to one or more embodiments and vice
versa.
[0056] The word "exemplary" is used herein to mean "serving as an
example or illustration." Any aspect or design described herein as
"exemplary" is not necessarily to be construed as preferred or
advantageous over other aspects or designs.
[0057] All structural and functional equivalents to the elements of
the various aspects described throughout this disclosure that are
known or later come to be known to those of ordinary skill in the
art are expressly incorporated herein by reference and are intended
to be encompassed by the claims. Moreover, nothing disclosed herein
is intended to be dedicated to the public regardless of whether
such disclosure is explicitly recited in the claims. No claim
element is to be construed under the provisions of 35 U.S.C.
.sctn.112, sixth paragraph, unless the element is expressly recited
using the phrase "means for" or, in the case of a method claim, the
element is recited using the phrase "step for." Furthermore, to the
extent that the term "include," "have," or the like is used in the
description or the claims, such term is intended to be inclusive in
a manner similar to the term "comprise" as "comprise" is
interpreted when employed as a transitional word in a claim.
* * * * *