U.S. patent application number 12/367230 was filed with the patent office on 2009-12-03 for method and apparatus for heating or cooling.
This patent application is currently assigned to Rini Technologies, Inc.. Invention is credited to James R. Hughes, Jose Mauricio Recio, Daniel P. Rini, Benjamin A. Saarloos.
Application Number | 20090294097 12/367230 |
Document ID | / |
Family ID | 41378333 |
Filed Date | 2009-12-03 |
United States Patent
Application |
20090294097 |
Kind Code |
A1 |
Rini; Daniel P. ; et
al. |
December 3, 2009 |
Method and Apparatus for Heating or Cooling
Abstract
Embodiments of the subject invention pertain to a method and
apparatus for heating or cooling. Embodiments relate to a method
and apparatus utilizing a vapor compression cycle to accomplish
active heating or cooling. In a specific embodiment, the subject
invention relates to a lightweight, compact, reliable, and
efficient heating or cooling system for underwater applications.
The subject system can provide heating or cooling stress relief to
individuals operating under, for example, hazardous conditions, or
in low temperature underwater environments where passive protective
clothing provides insufficient mitigation of cooling stress.
Further embodiments can be utilized to provide heat stress relief
to users who are working in thermally encapsulated ensembles that
hinder the body's natural ability to expel heat. The subject system
can be utilized in other applications that can benefit from this
type of heating or cooling system. The performance of this system
cannot be matched simply by using smaller versions of currently
available designs or technologies.
Inventors: |
Rini; Daniel P.; (Orlando,
FL) ; Saarloos; Benjamin A.; (Orlando, FL) ;
Recio; Jose Mauricio; (Oviedo, FL) ; Hughes; James
R.; (Winter Park, FL) |
Correspondence
Address: |
SALIWANCHIK LLOYD & SALIWANCHIK;A PROFESSIONAL ASSOCIATION
PO Box 142950
GAINESVILLE
FL
32614
US
|
Assignee: |
Rini Technologies, Inc.
Oviedo
FL
|
Family ID: |
41378333 |
Appl. No.: |
12/367230 |
Filed: |
February 6, 2009 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61056357 |
May 27, 2008 |
|
|
|
Current U.S.
Class: |
165/63 ; 62/113;
62/238.7 |
Current CPC
Class: |
F25D 23/006 20130101;
F25B 2500/01 20130101; F25B 30/06 20130101 |
Class at
Publication: |
165/63 ;
62/238.7; 62/113 |
International
Class: |
F25B 29/00 20060101
F25B029/00; F25B 27/00 20060101 F25B027/00; F25B 41/00 20060101
F25B041/00 |
Claims
1. An apparatus for heating, comprising: an evaporator; a
compressor, wherein the compressor receives refrigerant vapor
exiting from the evaporator, wherein the compressor compresses the
refrigerant vapor received from the evaporator; a condenser,
wherein compressed refrigerant exits the compressor and flows into
the condenser, wherein the condenser acts as a heat exchanger so
that heat is removed from the compressed refrigerant by a first
external fluid; an expansion device, wherein the expansion device
receives refrigerant from the condenser, wherein the refrigerant
received from the condenser is expanded through the expansion
device; wherein the refrigerant exiting the expansion device flows
through the evaporator, wherein the refrigerant absorbs heat from a
second external fluid as the refrigerant passes through the
evaporator; and a housing, wherein the condenser and the evaporator
are within the housing.
2. The apparatus according to claim 1, wherein the condenser
comprises a pair of channels, wherein the refrigerant flows through
one of the channels of the pair of channels and the first external
fluid flows through the other channel of the pair of channels such
that the refrigerant and the first external fluid flowing in the
pair of channels are in thermal contact with each other.
3. The apparatus according to claim 1, wherein the evaporator
comprises a second pair of channels, wherein the refrigerant flows
through one of the channels of the second pair of channels and the
second external fluid flows through the other channel of the second
pair of channels such that the refrigerant and the second external
fluid flowing in the second pair of channels are in thermal contact
with each other.
4. The apparatus according to claim 2, wherein the evaporator
comprises a second pair of channels, wherein the refrigerant flows
through one of the channels of the second pair of channels and the
second external fluid flows through the other channel of the second
pair of channels such that the refrigerant and the second external
fluid flowing in the second pair of channels are in thermal contact
with each other.
5. The apparatus according to claim 1, wherein the compressor and
the expansion device are within the housing.
6. The apparatus according to claim 1, wherein the housing is
substantially tubular.
7. The apparatus according to claim 6, wherein the housing is
substantially cylindrical, wherein the condenser is substantially
cylindrical in shape, wherein the pair of channels spiral from a
center of the condenser to an outer portion of the condenser,
wherein the evaporator is substantially cylindrical in shape, where
the second pair of channels spiral from a center of the evaporator
to an outer portion of the evaporator.
8. The apparatus according to claim 4, wherein the pair of channels
are parallel, wherein the second pair of channels are parallel.
9. The apparatus according to claim 1, further comprising: a power
source, wherein the power source powers the compressor wherein the
power source is proximate the housing.
10. The apparatus according to claim 1, wherein the second external
fluid is air.
11. The apparatus according to claim 9, wherein the second external
fluid is water.
12. The apparatus according to claim 1, wherein the first external
fluid is water.
13. The apparatus according to claim 1, wherein the temperature of
the compressed refrigerant vapor flowing through the condenser
decreases below the saturation temperature of the refrigerant and
the refrigerant vapor condenses to liquid refrigerant, wherein the
liquid refrigerant exits the condenser and is expanded through the
expansion device, wherein the pressure and temperature of the
liquid refrigerant are reduced upon exiting the expansion device,
wherein the liquid refrigerant exiting the expansion device flows
through the evaporator, wherein the liquid refrigerant and the
second external fluid are in thermal contact, wherein the liquid
refrigerant absorbs heat from the second external fluid as the
liquid refrigerant passes through the evaporator such that the
liquid refrigerant boils to produce vapor, wherein the vapor exits
the evaporator, and wherein the compressor receives the refrigerant
vapor exiting from the evaporator, wherein the compressor
compresses the refrigerant vapor to a pressure at which the vapor
temperature is above the ambient temperature of the condenser,
wherein the compressed refrigerant vapor exits the compressor and
flows into the condenser.
14. The apparatus according to claim 1, further comprising a pump,
wherein the pump causes the first external fluid to flow through
the condenser.
15. The apparatus according to claim 7, wherein the compressor is
substantially cylindrical in shape.
16. The apparatus according to claim 15, further comprising: a
motor, wherein the motor is substantially cylindrical in shape, and
wherein the motor drives the compressor wherein the motor is within
the housing.
17. The apparatus according to claim 1, wherein the housing seals
the condenser, the evaporator, the compressor, and the expansion
device from a surrounding environment outside the housing, wherein
the first external fluid entering the housing through a first input
port and exits the housing through a first output port, wherein the
second external fluid enters the housing through a second input
port and exits the housing through a second output port.
18. The apparatus according to claim 1, wherein heat from the first
external fluid is transferred to a user.
19. The apparatus according to claim 1, wherein the first external
fluid is circulated from an output of the condenser to the user,
from the user to an input of the condenser, and from the input of
the condenser through the condenser to the output of the
condenser.
20. An apparatus for heating, comprising: an evaporator; a
compressor, wherein the compressor receives refrigerant vapor
exiting from the evaporator, wherein the compressor compresses the
refrigerant vapor received from the evaporator; a condenser,
wherein compressed refrigerant exits the compressor and flows into
the condenser, wherein the condenser acts as a heat exchanger so
that heat is removed from the compressed refrigerant by a first
external fluid; and an expansion device, wherein the expansion
device receives refrigerant from the condenser, wherein the
refrigerant received from the condenser is expanded through the
expansion device, wherein the refrigerant exiting the expansion
device flows through the evaporator, wherein the refrigerant
absorbs heat from a second external fluid as the refrigerant passes
through the evaporator; wherein the evaporator comprises a heat
transfer surface in contact with a surrounding environment, wherein
the surrounding environment is the second external fluid.
21. The apparatus according to claim 20, wherein the second
external fluid is a liquid.
22. The apparatus according to claim 21, wherein the first external
fluid is water.
23. The apparatus according to claim 20, wherein the second
external fluid is water.
24. The apparatus according to claim 20, wherein the second
external fluid is air.
25. The apparatus according to claim 24, further comprising a fan,
wherein the fan moves air across the heat transfer surface.
26. The apparatus according to claim 20, wherein the evaporator
comprises a dividing wall having an interior surface and an
exterior surface, wherein the interior surface is in thermal
contact with the refrigerant exiting the expansion device and the
exterior surface is the heat transfer surface.
27. The apparatus according to claim 20, wherein the evaporator
comprises a second surface, wherein the heat transfer surface is on
the exterior side of the evaporator and the second surface is on
the interior side of the evaporator, and wherein a volume is formed
by the second surface of the evaporator.
28. The apparatus according to claim 27, wherein the evaporator has
a substantially tubular shape having a first end and a second
end.
29. The apparatus according to claim 27, wherein the second surface
is substantially parallel to the heat transfer surface.
30. The apparatus according to claim 28, wherein the compressor is
positioned within the volume created by the second surface of the
evaporator.
31. The apparatus according to claim 30, wherein the condenser is
positioned within the volume created by the second surface of the
evaporator.
32. The apparatus according to claim 31, wherein the expansion
device is positioned within the volume created by the second
surface of the evaporator.
33. The apparatus according to claim 20, wherein the surrounding
environment is water, wherein the surrounding water flows across
the heat transfer surface of the evaporator.
34. The apparatus according to claim 20, further comprising
switching valves, wherein the switching valves allow the apparatus
to remove heat from the first external fluid by driving the
evaporator as a second condenser and driving the condenser as a
second evaporator.
35. The apparatus according to claim 20, wherein the first external
fluid flows through the condenser such that the refrigerant and the
first external fluid are in thermal contact, wherein the first
external fluid absorbs heat from the refrigerant as the refrigerant
flows through the condenser.
36. The apparatus according to claim 35, wherein the temperature of
the compressed refrigerant vapor flowing through the condenser
decreases below the saturation temperature of the refrigerant and
the refrigerant vapor condenses to liquid refrigerant, wherein the
liquid refrigerant exits the condenser and is expanded through the
expansion device, wherein the pressure and temperature of the
liquid refrigerant are reduced upon exiting the expansion device,
wherein the liquid refrigerant exiting the expansion device flows
through the evaporator, wherein the liquid refrigerant and the
second external fluid are in thermal contact, wherein the liquid
refrigerant absorbs heat from the second external fluid as the
liquid refrigerant passes through the evaporator such that the
liquid refrigerant boils to produce vapor, wherein the vapor exits
the evaporator, and wherein the compressor receives the refrigerant
vapor exiting from the evaporator, wherein the compressor
compresses the refrigerant vapor to a pressure at which the vapor
temperature is above the ambient temperature of the condenser,
wherein the compressed refrigerant vapor exits the compressor and
flows into the condenser.
37. The apparatus according to claim 20, wherein the refrigerant
that absorbs heat from the surrounding environment in thermal
contact with the heat transfer surface flows through the evaporator
such that the flow of the refrigerant is substantially parallel to
the heat transfer surface.
38. The apparatus according to claim 28, wherein the evaporator has
a cross-sectional shape selected from a group consisting of:
rectangular, polygonal, square, hexagonal, peanut, and oval.
39. The apparatus according to claim 28, wherein the evaporator has
a substantially circular cross-sectional shape.
40. The apparatus according to claim 20, further comprising a pump,
wherein the pump causes the first external fluid to flow through
the condenser.
41. The apparatus according to claim 39, wherein the compressor is
substantially cylindrical in shape.
42. The apparatus according to claim 41, further comprising: a
motor, wherein the motor is substantially cylindrical in shape, and
wherein the motor drives the compressor.
43. The apparatus according to claim 42, wherein the motor is
positioned substantially within the volume formed by the second
surface of the evaporator.
44. The apparatus according to claim 27, wherein the condenser
comprises a pair of channels wherein the refrigerant flows through
one of the channels of the pair of channels and the first external
fluid flows through the other channel of the pair of channels such
that the refrigerant and the first external fluid flowing in the
pair of channels are in thermal contact with each other.
45. The apparatus according to claim 44, wherein the condenser is
substantially cylindrical in shape.
46. The apparatus according to claim 44, wherein the pair of
channels spiral from the center of the condenser to the outer
portion of the condenser.
47. The apparatus according to claim 44, where the pair of channels
are parallel.
48. The apparatus according to claim 47, wherein each channel of
the pair of parallel channels substantially follows the path of a
corresponding archemidian spiral.
49. The apparatus according to claim 20, wherein heat from the
first external fluid is transferred to a user positioned in the
surrounding environment.
50. The apparatus according to claim 49, wherein the first external
fluid is circulated from an output of the condenser to the user,
from the user to an input of the condenser, and from the input of
the condenser through the condenser to the output of the
condenser.
51. A method for heating, comprising: attaching an apparatus to a
user positioned in a second external fluid, wherein the apparatus
comprises: an evaporator; a compressor, wherein the compressor
receives refrigerant vapor exiting from the evaporator, wherein the
compressor compresses the refrigerant vapor received from the
evaporator; a condenser, wherein compressed refrigerant exits the
compressor and flows into the condenser, wherein the condenser acts
as a heat exchanger so that heat is removed from the compressed
refrigerant by a first external fluid; and an expansion device,
wherein the expansion device receives refrigerant from the
condenser, wherein the refrigerant received from the condenser is
expanded through the expansion device; wherein the refrigerant
exiting the expansion device flows through the evaporator, wherein
the refrigerant absorbs heat from a second external fluid as the
refrigerant passes through the evaporator; wherein the evaporator
comprises a heat transfer surface in contact with a surrounding
environment, wherein the surrounding environment is the second
external fluid; and bringing the first external fluid in thermal
contact with the user such that heat from the first external fluid
is transferred to the user.
52. The method according to claim 51, wherein the apparatus further
comprises: a power source, wherein the power source powers the
compressor.
53. The method according to claim 51, further comprising: attaching
a power source to the user, wherein the power source powers the
compressor.
54. The method according to claim 51, wherein the first external
fluid is circulated from an output of the condenser to the user,
from the user to an input of the condenser, and from the input of
the condenser through the condenser to the output of the
condenser.
55. A method for heating, comprising: attaching an apparatus to a
user positioned in a second external fluid, wherein the apparatus
comprises: an evaporator; a compressor, wherein the compressor
receives refrigerant vapor exiting from the evaporator, wherein the
compressor compresses the refrigerant vapor received from the
evaporator; a condenser, wherein compressed refrigerant exits the
compressor and flows into the condenser, wherein the condenser acts
as a heat exchanger so that heat is removed from the compressed
refrigerant by a first external fluid; an expansion device, wherein
the expansion device receives refrigerant from the condenser,
wherein the refrigerant received from the condenser is expanded
through the expansion device, wherein the refrigerant exiting the
expansion device flows through the evaporator, wherein the
refrigerant absorbs heat from a second external fluid as the
refrigerant passes through the evaporator; and bringing the first
external fluid in thermal contact with the user such that heat from
the first external fluid is transferred to the user.
56. The method according to claim 55, wherein the condenser
comprises a pair of channels, wherein the refrigerant flows through
one of the channels of the pair of channels and the first external
fluid flows through the other channel of the pair of channels such
that the refrigerant and the first external fluid flowing in the
pair of channels are in thermal contact with each other.
57. The method according to claim 55, wherein the evaporator
comprises a second pair of channels, wherein the refrigerant flows
through one of the channels of the second pair of channels and the
second external fluid flows through the other channel of the second
pair of channels such that the refrigerant and the second external
fluid flowing in the second pair of channels are in thermal contact
with each other.
58. The method according to claim 55, wherein the apparatus further
comprises: a housing, wherein the condenser and the evaporator are
within the housing.
59. The method according to claim 58, wherein the compressor and
the expansion device are within the housing.
60. The method according to claim 55, wherein the first external
fluid is circulated from an output of the condenser to the user,
from the user to an input of the condenser, and from the input of
the condenser through the condenser to the output of the
condenser.
61. The method according to claim 55, wherein the apparatus is
attached to a back of the user.
62. The method according to claim 55, wherein the apparatus further
comprises: a power source, wherein the power source powers the
compressor.
63. The method according to claim 55, further comprising: attaching
a power source to the user, wherein the power source powers the
compressor.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims the benefit of U.S.
Provisional Application Ser. No. 61/056,357, filed May 27, 2008,
which is hereby incorporated by reference herein in its entirety,
including any figures, tables, or drawings.
FIELD OF INVENTION
[0002] The subject invention relates to microclimate heating or
cooling, and a miniature heating or cooling system, that can be
used for any purpose that requires a compact heating or cooling
system. Such applications include, but are not limited to, personal
and portable heating or cooling systems.
BACKGROUND OF THE INVENTION
[0003] Deep submersion operations performed by free-swimming
divers, such as Navy divers, often expose them to extremely cold
conditions. Currently, there is no effective and/or efficient
method of heating divers during exposure to such conditions. This
deficiency can induce cold stress, which in turn impairs diver
performance, shortens dive duration, and creates an unnecessary
health risk to divers. The issue usually arises during cold water
dives, and the affects of the cold typically manifest first in the
diver's extremities, such as hands and feet.
[0004] Currently available solutions, such as electrical resistor
type systems, which at maximum can only supply as much heat as the
electrical power expended for unit operation, are inefficient and
require large amounts of portable power supplies. Other alternative
solutions, such as umbilical chord attachments to the diver that
can supply warm water and electrical power, are also too bulky and
significantly restrict the user's freedom of movement.
[0005] Accordingly, there is need for a heating system having a
high coefficient of performance and a light compact design. The
solution should heat effectively to maintain core body
temperatures. The solution should preferably be low profile, small
volume, power efficient, resistant to corrosive saltwater, and
operate for the duration of a typical dive.
BRIEF SUMMARY
[0006] Embodiments of the subject invention pertain to a method and
apparatus for heating or cooling. Embodiments relate to a method
and apparatus utilizing a vapor compression cycle to accomplish
active heating or cooling. In a specific embodiment, the subject
invention relates to a lightweight, compact, reliable, and
efficient heating or cooling system for underwater applications.
The subject system can provide heating or cooling stress relief to
individuals operating under, for example, hazardous conditions, or
in low temperature underwater environments where passive protective
clothing provides insufficient mitigation of cooling stress.
Further embodiments can be utilized to provide heat stress relief
to users who are working in thermally encapsulated ensembles that
hinder the body's natural ability to expel heat. The subject system
can be utilized in other applications that can benefit from this
type of heating or cooling system. The performance of this system
cannot be matched simply by using smaller versions of currently
available designs or technologies.
[0007] Embodiments of the subject invention relate to an underwater
diver heating system that utilizes two-phase heat pump cycle
technology. This vapor compression heat pump process can be
efficient, such that for a given amount of electrical power
supplied to the system at least 2 times that amount of heat,
removed from the sea water, is delivered to the diver's body.
[0008] In a specific embodiment, the subject invention pertains to
a heating system having a total weight of less than about 4.0
pounds, a coefficient of performance of at least 2.4, and a volume
of less than about 1200 cc with a heating capacity between about
100 and about 500 watts. In a further embodiment, the subject
invention pertains to a heating system having a total weight of
less than about 6.0 pounds, a coefficient of performance of at
least 1.5, and a volume of less than about 2000 cc with a heating
capacity between about 100 and about 500 watts. The subject heating
system can provide between 22 and 40 watts of heating per pound and
occupy between 2.4 and 12 cc of volume per watt of cooling. In
comparison, conventional technology units for heating in this range
would between two and three times the amount of battery volume and
weight in order to provide the same heating level for a given
operation time. Resistive heating devices can only provide a
maximum of 1 watt of cooling for every watt of provided electrical
energy, thus requiring significantly larger amounts of batteries to
provide heat rates similar to the subject invention. Similarly,
heating technologies that rely on chemical processes would require
a significant amount of large and bulky support equipment
[0009] The subject system can be scaled to larger or smaller sizes
for different applications. The subject system can incorporate a
compressor and heat exchanger design so as to achieve a high
coefficient of performance and a light and compact design.
Incorporation of a compressor can enhance the overall performance
of the vapor compression system, and incorporation of the heat
exchanger can reduce the overall weight and size of the subject
apparatus. Embodiments of the subject cooling system can utilize a
miniaturized, high efficiency motor, along with the integration of
compact heat exchangers for refrigerant evaporation and liquid
pumps.
[0010] Specific embodiments of the subject cooling system can
involve the use of one or more of the following: micro-fabrication
techniques, an innovative rotary lobed compressor, a miniature high
efficiency permanent magnet motor, compact heat exchanger for
refrigerant evaporation and condensation, and liquid pumps. In a
specific embodiment, the subject system can provide approximately
300 watts of heating or 200 watts of cooling for microclimate and
other temperature control environments.
BRIEF DESCRIPTION OF DRAWINGS
[0011] FIG. 1 shows an internal view of the interior of an
embodiment of the subject invention, illustrating components such
as pumps, heat exchangers, compressor, and motors.
[0012] FIG. 2 shows an expanded view of a compressor incorporated
with the embodiment shown in FIG. 1.
[0013] FIG. 3 shows an embodiment of the subject invention,
illustrating connections between various parts that allow liquids
and/or gases to enter and/or exit the various parts.
[0014] FIG. 4 shows an embodiment of an evaporator or condenser in
accordance with an embodiment of the subject invention.
[0015] FIG. 5 shows the channel design within a condenser or
evaporator in accordance with an embodiment of the subject
invention.
[0016] FIG. 6 shows an Archimedean spiral corresponding to a fluid
path within an evaporator in accordance with a specific embodiment
of the subject invention.
[0017] FIG. 7 shows a schematic of a cooling system in accordance
with the subject invention, incorporating a condenser, an expansion
valve, an evaporator, and a compressor.
[0018] FIG. 8 shows a basic temperature/entropy diagram in
accordance with an embodiment of the subject invention.
[0019] FIG. 9 shows an embodiment of a heating or cooling system,
in the heating configuration, in accordance with the invention
incorporating a heat exchanger in an outer shell of the system.
[0020] FIG. 10 shows the embodiment of the heating or cooling
system of the system of FIG. 9 in the cooling configuration.
DETAILED DISCLOSURE
[0021] Embodiments of the subject invention pertain to a method and
apparatus for heating or cooling. Embodiments relate to a method
and apparatus utilizing a vapor compression cycle to accomplish
active heating or cooling. In a specific embodiment, the subject
invention relates to a lightweight, compact, reliable, and
efficient heating or cooling system for underwater applications.
The subject system can provide supplemental heating or cooling to
individuals operating in, for example, underwater environments
where the loss of control of body temperature or personal comfort
can not be mitigated through passive devices such as wetsuits or
dry-suits. The subject system can be utilized in other applications
that can benefit from this type of heating or cooling system. The
performance of this system cannot be matched simply by using
smaller versions of currently available designs or
technologies.
[0022] In a specific embodiment, the subject microclimate system
can provide at least about 300 watts of heat while consuming less
than about 125 watts of power, and weigh less than about 4.5 pounds
(not including the water jacket or the power source) while having
less than about a 1200 cubic centimeter volume. In a specific
embodiment, the subject system can run for at least about 1.5 hours
or more with the use of batteries. In a specific embodiment, a
heating power to weight ratio of more than 66 W/lb and/or a volume
to heating power ratio of less than 4 cc/W can be achieved
utilizing a vapor compression cycle with heating capacities of
approximately 300 W.
[0023] The same subject microclimate system can provide at least
about 200 watts of cooling while consuming less than about 90 watts
of power. In a specific embodiment, the subject system can run for
at least about 2.0 hours or more with the use of batteries. In a
specific embodiment, a cooling power to weight ratio of more than
44 W/lb and/or a volume to heating power ratio of less than 6 cc/W
can be achieved utilizing a vapor compression cycle with cooling
capacities lower than 200 W.
[0024] A heat pump cycle for an embodiment of a microclimate
heating and cooling system in accordance with the subject invention
can incorporate a vapor compression cycle intended for use with
compressible refrigerants. There are four basic features to such a
vapor compression cycle, including vapor compression, condensation
within a heat exchanger, sub-cooled liquid expansion, and
vaporization within an evaporative heat exchanger. The cycle begins
with a compressor that compresses refrigerant vapor to a pressure
at which the corresponding vapor temperature is above the desired
operating fluid temperature of the condenser. This heated fluid can
in turn be utilized to provide warmth to the user via, for example,
a tube suit or water jacket. The compressed hot refrigerant vapor
flows to a condensing heat exchanger, which is typically a gas to
vapor or liquid to vapor heat exchanger, where the vapor is hotter
than the gas or liquid. Heat is removed from the compressed
refrigerant vapor by the entering fluid on the other side of the
heat exchanger. This causes the temperature of the compressed,
vaporized refrigerant to decrease below the saturation temperature
of the refrigerant and the vapor condenses to liquid. The high
pressure liquid can then be expanded through an expansion device,
such as a throttling valve, capillary tube or pin-hole orifice,
which can cause a rapid decrease in refrigerant pressure after the
valve. The lower pressure can cause the temperature of the liquid
coolant to drop to, for example, the corresponding lower saturation
temperature.
[0025] In a specific embodiment the expanded, cool liquid
refrigerant can then flow through an evaporator that allows the
liquid refrigerant to absorb the heat from a fluid that is desired
to be cooled. The evaporator can act as another heat exchanger with
cool refrigerant on one side and the fluid, either liquid or gas,
that is desired to be cooled on the other side of the heat
exchanger. The absorption of heat in the evaporator from the
entering coolant liquid causes the liquid refrigerant to boil. The
vaporized refrigerant then flows back into the compressor to begin
the cycle again. The exiting coolant can then be either ejected to
the ambient or re-circulated to cool an individual wearing a
cooling jacket or to cool surfaces. In the heating mode of
operation the evaporator transfers heat from the ambient water to
the refrigerant and the condenser transfers heat from the
refrigerant to the liquid used to deliver heat. This liquid can
deliver heat via, for example, a warming garment. In the cooling
mode of operation the condenser transfers heat from the refrigerant
to the ambient water and the evaporator transfers heat from the
liquid in used to remove heat to the refrigerant.
[0026] In a specific embodiment, the subject invention can allow
the use of the standard vapor compression cycle in a compact and
lightweight design by utilizing specialized components that have
been developed specifically for the subject system. FIG. 1 shows a
schematic of a heat pump system in accordance with the subject
invention, incorporating water pumps 1, an evaporator 2, a
compressor 3, a condenser 4, and an expansion device 5. While the
subject invention utilizes two similar heat exchangers for the
evaporator 2 and the condenser 4, the refrigeration cycle processes
of evaporation and condensation can be accomplished with the use of
two significantly different custom heat exchangers.
[0027] FIG. 7 shows a schematic of a heating system, and FIG. 8
shows a basic vapor compression cycle temperature/entropy diagram.
The points 1, 2, 3, and 4 in the heat pump cycle of the heating
system of FIG. 7 and the points 1, 2, 3, and 4 in the
temperature/entropy diagram of FIG. 8 correspond with each other.
Referring to FIG. 8 a compressor intakes cool low pressure vapor
refrigerant at point 1. An isentropic compression would discharge
hot high pressure refrigerant vapor at point 2s. However,
compressors are not 100% efficient and, therefore, typically
exhaust superheated vapor at point 2. The hot, high pressure
refrigerant vapor transfers its heat via a heat exchanger, also
known as a condenser, to an external fluid. As the hot, high
pressure vapor refrigerant cools from point 2 to point 3, it
condenses to warm high pressure liquid refrigerant. The warm
external fluid side is also further heated by means of conduction,
since the heat exchanger is directly in contact with the hot
compressor generating additional heat due to the less than 100%
efficient compression process. An expansion device located between
points 3 and 4 allows the warm high pressure liquid coolant to
become a cold low pressure mixture of refrigerant vapor and liquid.
The cold low pressure refrigerant then flows to another heat
exchanger, typically called an evaporator, to acquire heat from,
for example, another external fluid. Alternatively, the evaporator
can be in thermal contact with a heat source such that heat is
transferred from the heat source to the refrigerant without the use
of a second external fluid. This heat transfer causes the low
pressure liquid coolant to vaporize, shown in FIG. 8 between points
4 and 1, and becomes cool low pressure refrigerant vapor. Each of
the cycle component designs can take size and weight into
account.
[0028] In an alternative operation mode, where the user desires to
circulate cooled liquid in a warm ambient, the re-circulation tubes
of a cooling garment or similar device can be attached to the
evaporative heat exchange portion of the subject invention. In this
mode of operation the compressor, evaporator, condenser, and
expansion device may operate in a similar manner while removing
heat from the tube suit loop and ejecting heat at an elevated
ambient on the condensation side. The liquid side of the condenser
can incorporate a liquid pump flowing ambient water through the
condensing heat exchanger, which warms the fluid and in turn
condenses the refrigerant vapor in point 2 to point 3 of FIG.
8.
[0029] In a specific embodiment, one of the two heat exchangers in
the system can be located to form at least a portion of an outer
shell of the system. A specific embodiment is shown in FIGS. 9 and
10. In the heating system configuration, as shown in FIG. 9, this
heat exchanger can function as the evaporator and in the cooling
system configuration, as shown in FIG. 10, this heat exchanger can
function as the condenser. FIG. 9 shows the heating system
configuration with a compressor 3, condenser 4, expansion device 5,
evaporator 2, and evaporator outlet port 99. FIG. 10 shows the
cooling system configuration with compressor 3, condenser 4,
expansion device 5, evaporator 2 and condenser inlet port 98. In a
specific embodiment, valving can be provided to allow a single
system to both heat and cool by switching the valving depending on
the situation.
[0030] In a specific embodiment, the subject invention can
incorporate compressor 3 shown in FIG. 1. FIG. 2 shows an exploded
view of certain portions of compressor 3 shown in FIG. 1.
Compressor 3 can utilize a positive displacement means to compress
the refrigerant vapor entering the compressor. A positive
displacement means can start with a certain volume of refrigerant
vapor and reduce the volume by a set amount resulting in compressed
refrigerant vapor. The amount of volume change can be a function of
the geometry of the positive displacement means. Valves and
upstream conditions typically govern the pressure at which the
vapor leaves the compressor. The positive displacement means can
be, for example, a piston style, a sliding vane, a screw, a scroll,
or a rotary lobed type. In a specific embodiment, compressor 3 can
incorporate a rotary lobed type positive displacement means. An
example of this type of compressor is shown in FIG. 2, and can be
referred to as a rotary lobed compressor. The purpose of the
compressor is to intake low pressure, low temperature refrigerant
vapor and discharge high temperature high pressure vapor to the
condenser.
[0031] Referring to FIG. 2, the configuration shown can be referred
to as a Wankel compressor. The compressor can incorporate a
substantially triangular shaped rotor 6 which spins on an eccentric
shaft 7. In a specific embodiment, the compressor can use a 3/2
gear ratio for positioning (Ogura, Ichiro, "The Ogura-Wankel
Compressor--Application of a Wankel Rotary Concept as Automotive
Air Conditioning Compressor," SAE Technical Paper 820159, SAE
1982). The gears 8 are used to position the rotation of the rotor
through its eccentric path. The rotor rotates inside of a peanut
shaped epitrochoid chamber 9. Such a rotor positioning results in
the compressor exhibiting two complete compressions per
revolution.
[0032] The shape of an epiterchoid chamber is determined by the
following equations:
x ( t ) = 3 7 M A cos ( t ) - 1 14 M A cos ( 3 M A t ) ##EQU00001##
y ( t ) = 3 7 M A sin ( t ) - 1 14 M A sin ( 3 M A t )
##EQU00001.2##
where MA is the major axis.
[0033] In a specific embodiment, a length of 49 mm can be utilized
for the major axis of the epitrochoid with a height of 6 mm. The
values of the major axis and height can be modified based on the
cooling capacity requirements of the vapor compression cycle and
the desired angular velocity of the compressor. Once these two
constraints are set, the basic designs of the main components of
the compressor can be determined as a function of the geometry. The
major axis determines the size of the rotor and the shape of the
epitrochoid, as well as the gears that are used in the
compressor.
[0034] Using the equations relating to the shape of the epitrochoid
chamber provided above, the rotor size and shape can also be
chosen. Finally, the geometric height of the epitrochoid and rotor
can be determined by the amount of fluid that is desired to be
displaced on each revolution. After having calculated these
dimensions, the compressor's speed can be chosen to determine the
displacement per unit time or volumetric flow rate. In a specific
embodiment, incorporating an epitrochoidal chamber with a major
axis of 49 mm and a height of 6 mm, a speed of 2000 rpm is chosen
to provide a mass flow rate of approximately 1.5 g/s of vapor
refrigerant 134a at an inlet pressure of 50 psi.
[0035] The flow through the compressor can be controlled by inlet
port 10 (shown in FIG. 2) and valved exhaust ports 11 (shown in
FIG. 2). Although a round shaped port is shown here, other shapes
such as oval, triangular, and square can also be used. This design
can allow the cool refrigerant vapor into the compressor. Rotor 6
can then travel over the top of the intake port so as to close the
intake port as rotor 6 begins to compress the refrigerant vapor.
This feature can eliminate the need for an intake check valve,
typically used by positive displacement compressors. Exhaust valve
12 and valve stop 13 can be placed on the top face of the
compressor and positioned on top of the exhaust port 13 to allow
for the maximum compression to occur. The exhaust valve is a check
valve that can prevent hot high pressure refrigerant vapor from
flowing backwards into the compressor. In a specific embodiment,
cantilevered flapper valves can be used to reduce the amount of
space required for the outlet port 11.
[0036] Shaft seals and bearings can be used along the shaft to
assist in sealing and to absorb the loads caused by the rotating
parts. External sealing can be achieved by the shaft seals and
gaskets or by encapsulating the entire compressor and driving motor
unit in a hermetic casing, while internal sealing of the
compression chambers can be accomplished using, for example, a
sealing gasket 14 or o-ring.
[0037] To increase the efficiency and life of the compressor,
referring to FIG. 2, spring loaded tip seals 15 can be installed on
the rotor. The tip seals 15, as shown in FIG. 2, can be designed to
minimize leakage between the chambers during the rotary motion of
the rotor. In a specific embodiment, the seals or entire rotor can
be made of a low friction material to minimize wear and friction
losses. In a further specific embodiment, an engineered plastic
material such as PEEK, TEFLON, NYLON, or DELRIN can be used. Other
materials with similar characteristics can also be used. The tip
seals and face seals are spring loaded to insure that the plastic
seals stay in contact with the metal surfaces of the compressor
housing. In a specific embodiment, the springs used are 2.4 mm in
diameter, 6.2 mm long, have a spring stiffness constant of 2.2 lbs
per inch, and a pitch of 35 coils per inch. Preferably, at least
one spring is used on each of the tip seals. Multiple springs can
be used on the face seal in order to provide an even spring loading
force or additional spring force. In further embodiments, the
spring force can be produced by other means such as wave springs,
elastic rubbers, or gas filled balls. Preferably, the tip and face
seals are fabricated so that a slip fit into the rotor can be
maintained. In a specific embodiment, a slip fit dimensional
tolerance of less than or equal to 8 microns is used.
[0038] Additional methods of sealing may be considered for the
compressor as well. Rather than face sealing with gaskets and
spring loaded plastics, sufficient sealing can be created by
machining the parts with very high precision. In a specific
embodiment, the gaps between the rotor and the upper or lower walls
are machined to fit to within a range of between 0.0001 and 0.002
inches so that the fluid being pressurized has significant
difficulty in leaking past the two surfaces.
[0039] The subject compressor can incorporate low friction, low
corrosion materials. In addition, wear parts other than the seals
can be coated with low friction, high hardness coating, such as
diamond like carbon, TiN, and MoSi.sub.2. In a specific embodiment,
the subject compressor can operate without coolant oil. Compressor
oil can reduce the heat transfer performance of the condenser and
evaporators, requiring a larger heat exchanger to properly transfer
heat. Accordingly, the use of a specific embodiment of the subject
compressor that can operate without oil can allow the use of a
smaller heat exchanger.
[0040] The motor 16 as shown in FIG. 3, can be used to power the
drive shaft 17. In a specific embodiment, the motor 16 can be a
permanent magnetic synchronous motor. Other mechanical devices
capable of producing shaft power can also be used to power the
subject compressor, including, for example, combustion engines,
wind, or paddlewheels. In a specific embodiment, the motor can be
designed for long service life and can operate at much higher
efficiencies than standard motors. The motor design can be a
compact unit specially suited for this type of application. The
motor can deliver a high power density and operate at variable
speeds through a motor controller. The incorporation of a motor
controller can allow the motor to change the amount of compression,
depending on the cooling load. Standard vapor compression cycles
typically turn the compressor on and off in order to adjust to the
net cooling requirements of the cooling load. The turning of the
compressor on and off can reduce the efficiency of the cooling
system, as the start up interval of a motor can be extremely
inefficient. Accordingly, the use of a control feature, in a
specific embodiment of the subject invention, can allow the
variation of the speed of the motor, rather than intermittent
operation of the motor, to adjust the cooling system to the net
heating requirement of the heating load so as to significantly
improve the energy efficiency of the cycle. In a specific
embodiment, the motor can provide 90 Watts of shaft power, provide
60 oz-in torque, weigh approximately 16 ounces, have a diameter of
1.9 inches, and have a maximum efficiency of 78%.
[0041] The subject cooling system can be powered by, for example,
by batteries, AC power, or DC power. An embodiment powered by
batteries can connect to external battery packs or can utilize a
central power unit.
[0042] The compressed vapor refrigerant exiting outlets 18 of the
compressor can flow into a condenser inlet port 19, shown in FIG. 2
and FIG. 3, via connection passageway 20, shown in FIG. 3. The
condenser can be, for example, a general purpose heat exchanger. On
a first side of the heat exchanger the compressed hot refrigerant
gas can flow and on a second side of the heat exchanger an external
fluid can flow. Typically, water can be used on the second side of
the heat exchanger, thus providing heated water to the user if it
is connected to the condensation side, or cooled water to the user
if it is connected to the evaporation side. The heat is transferred
between the two fluids via dividing wall 21 (shown in FIG. 3, FIG.
4 and FIG. 5) such that an external fluid flowing on the outer
surface, or heat transfer surface 22, of dividing wall 21 will
remove heat from the dividing wall which has absorbed heat from the
refrigerant flowing through the condenser. The design of the
subject condenser can involve optimizing the heat transfer between
the two fluids flowing on either side of dividing wall 21.
[0043] A specific embodiment of a condenser 4 in accordance with
the subject invention is shown in FIG. 1, FIG. 3, and FIG. 4. The
compressed vapor refrigerant enters the refrigerant condensation
path 22 after passing through the exiting outlets 18. The
refrigerant can exit the condenser via port 23 and enter an
expansion device. Sub-cooled high pressure liquid refrigerant can
flow from the condenser 4 via connection tube 24 (shown in FIG. 3)
or expansion device into evaporator 2 (shown in FIG. 2 and FIG. 4).
An embodiment of evaporator 2 can have a similar design to
condenser 4, where two channels of two different fluids are in
indirect contact by dividing wall 21 and exchange heat via dividing
wall 21. These fluids can travel in their respective channels in
co-planar, multi-planar, counter rotating, or co-rotating fashion,
while exchanging heat with the opposite fluid via the heat transfer
surface 22 and the dividing wall 21. The cooled, compressed liquid
refrigerant can travel through connector tube 24 and enter
evaporator 2 via, for example, a throttling device. The device can
be a simple port design that causes a long restriction to the flow
via the port diameter, a capillary tube type, or a commercially
available expansion valve that is preset, manually adjustable,
electrically controlled, thermally controlled, or controlled by
system pressure.
[0044] The liquid that is to be heated can enter the condenser via
liquid connection tube 24 and travel to liquid port 25. A pump 1
can pump the heated liquid through the heating path 26. In a
specific embodiment, pump 1 is built into the condenser.
Alternatively, a pump external to the condenser or external to the
entire heat pump system can be utilized. The heated liquid can exit
the condenser via fluid exit port 27 and flow out of connection
tube 28. The heated liquid type can vary depending on the
application and can be, for example, a liquid, gas, or two-phase
mixture. The geometry of the heat exchanging condenser can vary
depending on the type of fluid and required performance. In a
specific embodiment, the liquid is water. Although the embodiment
shown in FIGS. 1, 3, 4, and 5 incorporates counter rotating fluids
that are co-planar, the subject invention can also incorporate
co-rotating fluids in the condenser or fluids that are not
co-planar.
[0045] The subject condenser can exchange heat between a liquid and
the refrigerant. While the refrigerant passes through the
condensing heat exchanger, it can experience a phase change from
vapor to liquid as it loses heat to the heated liquid on the
opposing side. With respect to this atypical heat exchanger,
non-traditional methods can be utilized for predicting the
performance of and designing of the heat exchanger. The liquid side
can adhere to well established heat transfer correlations, which
suggest that the total heat transfer between two substances at
different temperatures is equal to a heat transfer coefficient
constant times the total area that it is acting on and the
temperature gradient.
[0046] Heat transfer characterization and prediction on the
refrigerant side, however, is more complicated due to the phase
change process that occurs while the refrigerant is passing through
the heat exchanger. Approximate correlations, which include
experimental correction factors, have been recently determined and
are discussed in detail in Carey, Van P., Liquid-Vapor Phase Change
Phenomena, Taylor and Francis, New York (1992), which is hereby
incorporated by reference. A specific embodiment of the subject
invention can utilize a heat exchanger geometry that is based on
correlation approximations from Carey (1992) that maximize the
amount of heat transfer on the refrigerant side from the heated
liquid on the other side.
[0047] Similar to the heated liquid side, however, the two phase
heat transfer phenomenon is highly dependent upon the amount of
area available for heat transfer to take place. In a specific
embodiment, the design of the subject condensing heat exchanger
can, in general, maximize heat transfer area, while minimizing
overall weight and dimensions and minimizing the liquid pressure
drop through the heat exchanger. Preferably, the two fluids pass as
close to each other as possible in order to minimize conduction
heat transfer resistance through the separating medium. In a
specific embodiment, a parallel channel construction configuration
can be utilized. In a further specific embodiment, the parallel
channel configuration can have a separation wall of 0.5 mm and can
follow the path of an Archemedian spiral. An archemidian spiral is
defined in a parametric coordinate system as:
x(t)=Atcos(Bt)
y(t)=Atsin(Bt)
where the constants A and B govern the number of spiral revolutions
and the overall diameter of the geometry. One example yields a
spiral path as is seen in FIG. 6. The path shown in FIG. 6 can be
used for one fluid, while rotating the path by 180 degrees can
provide a path to be used by the second fluid. In other
embodiments, other interdigitated spiral paths can also be
utilized.
[0048] In a specific embodiment, the path for both fluids can begin
on the outer edge of the cylinder and terminate in the center,
where both fluids can exit perpendicular to the plane that they are
flowing parallel on. Such a design can eliminate abrupt fluid
turning points, thus minimizing pressure drop. Thin separation
walls can be used to provide a sufficient length of, for example,
approximately 26 inches within the limited area of the condenser
having a diameter of 2.2 inches. The channel depth can be chosen,
using two-phase heat transfer correlations as a guide, to maximize
the heat transfer area available for both fluids and meet the heat
exchange rate requirements of the condenser.
[0049] Condensed high pressure liquid refrigerant can flow from the
condenser 4 via exit port 23 (shown in FIG. 3 and FIG. 5) into
evaporator 2 (shown in FIG. 1 and FIG. 3). This heat exchange
device is similar in design to the condenser component (4), but is
applied as an evaporator at this point of the refrigeration cycle.
The cooled, compressed liquid refrigerant can travel through
connector tube 5 and enter evaporator 2 via, for example, a
throttle device. The device can be a simple port design that causes
a large restriction to the flow via the port diameter, a capillary
tube type, or an expansion valve that is preset, manually
adjustable, electrically controlled, thermally controlled, or
controlled by system pressure. The coolant that is to be cooled can
enter the evaporator via coolant connection tube 36 and travel to
coolant port 37. A pump 1 can pump the coolant through the cooling
path 29. The expanding liquid cools and enters refrigerant
evaporation path 29. The refrigerant can exit the evaporator via
port 30 and enter a connection tube 31 that terminates at the
compressor motor housing chamber 32. From one extreme location of
the motor chamber (point 32) the fluid can traverse the motor
components (16 and 33) and enter the compressor via inlet ports
(34) and populate in inlet manifold distribution area (35).
[0050] A specific embodiment of the subject compact vapor
compression cooling system, shown in FIG. 1 and FIG. 3, can employ
a compact assembly that reduces empty space. A cylindrical shape
enhances the surface area of several of the components of the vapor
compression cycle such as the heat exchangers so as to reduce the
volume of the system. In a specific embodiment, the cylindrical
shape can allow for ease of assembling of the components, along
with enhanced surface area to volume ratios of the heat exchanger
components. Each of the components can be designed into cylindrical
shapes, with similar diameters. The components can then be stacked
together and inserted inside a container (38). This design can
provide an efficient, low mass, low volume vapor compression
cycle.
[0051] All patents, patent applications, provisional applications,
and publications referred to or cited herein are incorporated by
reference in their entirety, including all figures and tables, to
the extent they are not inconsistent with the explicit teachings of
this specification.
[0052] It should be understood that the examples and embodiments
described herein are for illustrative purposes only and that
various modifications or changes in light thereof will be suggested
to persons skilled in the art and are to be included within the
spirit and purview of this application.
* * * * *