U.S. patent application number 14/115057 was filed with the patent office on 2014-03-13 for apparatus and method for controlling refrigerant temperature in a heat pump or refrigeration apparatus.
The applicant listed for this patent is Douglas Lloyd Lockhart. Invention is credited to Douglas Lloyd Lockhart.
Application Number | 20140069122 14/115057 |
Document ID | / |
Family ID | 47107700 |
Filed Date | 2014-03-13 |
United States Patent
Application |
20140069122 |
Kind Code |
A1 |
Lockhart; Douglas Lloyd |
March 13, 2014 |
APPARATUS AND METHOD FOR CONTROLLING REFRIGERANT TEMPERATURE IN A
HEAT PUMP OR REFRIGERATION APPARATUS
Abstract
An apparatus includes: a compressor including a pair of ports in
fluid communication with first and second heat exchangers and a
reduced temperature refrigerant inlet for receiving reduced
temperature refrigerant; and an expansion device coupled between
the first and second heat exchangers for reducing a pressure of
refrigerant flowing from one of the first and second heat
exchangers to the other of the first and second heat exchangers;
wherein the compressor, the first heat exchanger, the expansion
device and the second heat exchanger are arranged in a loop to
operate as a refrigeration or heat pump apparatus.
Inventors: |
Lockhart; Douglas Lloyd;
(Cobble Hill, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lockhart; Douglas Lloyd |
Cobble Hill |
|
CA |
|
|
Family ID: |
47107700 |
Appl. No.: |
14/115057 |
Filed: |
March 30, 2012 |
PCT Filed: |
March 30, 2012 |
PCT NO: |
PCT/CA2012/000328 |
371 Date: |
October 31, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61482923 |
May 5, 2011 |
|
|
|
Current U.S.
Class: |
62/56 ;
62/498 |
Current CPC
Class: |
F25B 2313/02741
20130101; F25B 13/00 20130101; F25B 2400/16 20130101; F25B 31/008
20130101; F25B 30/02 20130101 |
Class at
Publication: |
62/56 ;
62/498 |
International
Class: |
F25B 30/02 20060101
F25B030/02 |
Claims
1. An apparatus comprising: a compressor comprising a pair of ports
in fluid communication with first and second heat exchangers and a
reduced temperature refrigerant inlet for receiving reduced
temperature refrigerant; an expansion device coupled between the
first and second heat exchangers for reducing a pressure of
refrigerant flowing from one of the first and second heat
exchangers to the other of the first and second heat exchangers;
wherein the compressor, the first heat exchanger, the expansion
device and the second heat exchanger are arranged in a loop to
operate as a refrigeration or heat pump apparatus.
2. An apparatus as claimed in claim 1, comprising an expansion
device in fluid communication with the reduced temperature
refrigerant port for reducing a pressure of the reduced temperature
refrigerant entering the compressor.
3. An apparatus as claimed in claim 1, comprising a receiver
coupled between the first heat exchanger and the expansion device
when fluid flow is from the first heat exchanger and the second
heat exchanger.
4. An apparatus as claimed in claim 1, comprising a receiver
coupled between the second heat exchanger and the expansion device
when fluid flow is from the second heat exchanger and the first
heat exchanger
5. An apparatus as claimed in claim 1, wherein two expansion
devices are coupled between the first and second heat exchangers
and a receiver is coupled between the pair of expansion devices,
one of the two expansion devices being operable as a check
valve.
6. An apparatus as claimed in claim 5, wherein the reduced
temperature refrigerant port is in fluid communication with the
receiver.
7. An apparatus as claimed in claim 1, wherein a volume of
refrigerant flowing through the apparatus is generally
constant.
8. An apparatus as claimed in claim 1, wherein the reduced
temperature refrigerant is Trifluoroiodomethane.
9. An apparatus as claimed in claim 8, wherein sesquiterpene is
added to the refrigerant.
10. An apparatus as claimed in claim 1, wherein the compressor is a
scroll compressor and the reduced temperature refrigerant inlet is
located in a flank of the scroll compressor.
11. An apparatus as claimed in claim 1, wherein the compressor is
driven by a variable speed motor.
12. A method comprising: compressing a refrigerant during a
compression step of a refrigeration cycle; and injecting a reduced
temperature refrigerant into a compressor part-way through the
compression step.
13. A method as claimed in claim 12, wherein the reduced
temperature refrigerant is received from a receiver located between
the condenser and evaporator.
14. A method as claimed in claim 12, wherein the reduced
temperature refrigerant is Trifluoroiodomethane.
15. A method as claimed in claim 12, comprising measuring a
temperature of the refrigerant at an outlet of the compressor and
in response to the temperature being within a predetermined
temperature range, injecting the reduced temperature refrigerant
into a compressor part-way through the compression step.
Description
FIELD OF TECHNOLOGY
[0001] The present disclosure relates to compressors for heat pump
or refrigeration apparatus.
BACKGROUND
[0002] A typical refrigeration cycle is a closed loop system which
uses a refrigerant having a low boiling point to produce a relative
coldness. A compressor compresses the refrigerant in order to
increase its pressure. As the pressure increases, the refrigerant
gas temperature also rises and subsequently the gas then flows
through a heat exchanger to transfer heat to the adjacent medium in
the heat exchanger. As the heat dissipates, the refrigerant cools
and condenses to a liquid. The liquid then flows through an
expansion valve which causes the refrigerant to expand and change
phases into a gas. The cold gas then circulates into a second heat
exchanger and absorbs heat and then passes into the compressor
where the cycle repeats.
[0003] Lubricant is provided in the compressor 12 to lubricate the
compressor crankcase and other compressor components. Proper
lubrication helps to avoid compressor failures, which can be costly
both in terms of production down time and part replacement. The
lubricant is intended to remain primarily in the compressor
crankcase, however, the lubricant often migrates to other parts of
a refrigeration apparatus.
[0004] In general, the temperature output of a refrigeration
apparatus is limited by the effective temperature range of the
lubricant and the compression process of the compressor. When
operating above the effective temperature range, lubricants may
break down over time in response to the high temperatures in the
compressor. When the lubricant breaks down, the degraded lubricant
may flow throughout the compressor and may cause compressor
failure.
SUMMARY
[0005] In an aspect there is provided, an apparatus including: a
compressor comprising a pair of ports in fluid communication with
first and second heat exchangers and a reduced temperature
refrigerant inlet for receiving reduced temperature refrigerant;
and an expansion device coupled between the first and second heat
exchangers for reducing a pressure of refrigerant flowing from one
of the first and second heat exchangers to the other of the first
and second heat exchangers; wherein the compressor, the first heat
exchanger, the expansion device and the second heat exchanger are
arranged in a loop to operate as a refrigeration or heat pump
apparatus.
[0006] In another aspect there is provided a method including:
compressing a refrigerant during a compression step of a
refrigeration cycle; and injecting a reduced temperature
refrigerant into a compressor part-way through the compression
step.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Embodiments of the present disclosure will now be described,
by way of example only, with reference to the attached figures,
wherein:
[0008] FIG. 1 is a cycle diagram of an apparatus according to an
embodiment; and
[0009] FIG. 2 is a schematic top sectional view of a scroll
compressor.
DETAILED DESCRIPTION
[0010] The following describes an apparatus and method of
compressing a refrigerant during a compression step of a
refrigeration cycle; and injecting a reduced temperature
refrigerant into a compressor part-way through the compression
step.
[0011] For simplicity and clarity of illustration, reference
numerals may be repeated among the figures to indicate
corresponding or analogous elements. Numerous details are set forth
to provide an understanding of the embodiments described herein.
The embodiments may be practiced without these details. In other
instances, well-known methods, procedures, and components have not
been described in detail to avoid obscuring the embodiments
described. The description is not to be considered as limited to
the scope of the embodiments described herein.
[0012] Referring to FIG. 1, an apparatus 10 is schematically shown
by way of a cycle diagram. The apparatus 10 is generally a
refrigeration apparatus, which may also be referred to as a heat
pump. In general, the components of the apparatus 10 are arranged
in a loop and refrigerant flows through the apparatus 10 in a first
direction to generate heat at a first side of the apparatus 10. The
flow may be reversed to switch the side of the apparatus 10 at
which heat is generated.
[0013] The apparatus 10 includes a compressor 12, first heat
exchanger 14 and second heat exchanger 16. A four-way reversing
valve 18 is located between the compressor 12 and the heat
exchangers 14, 16 to reverse the direction of fluid flow. First
heat exchanger 14 and second heat exchanger 16 are both operable as
an evaporator and a condenser depending on the direction of fluid
flow through the apparatus 10. A first heat exchange conduit 28
communicates with the first heat exchanger 14 to transfer heat to
the first heat exchanger 14 when the first heat exchanger 14 is
operating as an evaporator and remove heat from the first heat
exchanger 14 when the first heat exchanger 14 is operating as a
condenser. Similarly, a second heat exchange conduit 30
communicates with the second heat exchanger 16 to transfer heat to
the second heat exchanger 16 when the second heat exchanger 16 is
operating as an evaporator and remove heat from the second heat
exchanger 16 when the second heat exchanger 16 is operating as a
condenser. The apparatus 10 further includes drive mechanisms (not
shown) for pumping fluid through the first and second heat exchange
conduits 28, 30.
[0014] A receiver 20 is located between the heat exchangers 14, 16.
Refrigerant flowing from the first heat exchanger 14 enters the
receiver 20 before flowing into the second heat exchanger 16.
Similarly, when flow is reversed, fluid flowing from the second
heat exchanger 16 enters the receiver 20 before flowing into the
first heat exchanger 18. The receiver 20 is a reservoir for storing
high pressure liquid. A volume of the receiver 20 is sized to
compensate for expansion and contraction of the refrigerant in the
constant volume apparatus 10.
[0015] A first valve 22 is located between the first heat exchanger
14 and the receiver 20 and a second 24 valve is located between the
second heat exchanger 16 and the receiver 20. Both valves 22, 24
are capable of operating as expansion valves or as check valves,
which are also referred to as one-way valves. The mode of operation
of the valves 22, 24 depends on the direction of fluid flow through
the apparatus 10. The valve 22, 24 that is located adjacent to an
inlet of the heat exchanger operating as an evaporator operates as
an expansion valve to reduce a pressure of the fluid entering the
heat exchanger 14, while the valve 22, 24 that is located adjacent
to an exit of the condenser operates as a check valve.
[0016] An accumulator 26 is located between the four-way reversing
valve 18 and the compressor 12. The accumulator 26 is an optional
component of the apparatus 10 and is generally provided to store
excess liquid refrigerant and lubricant that may not have boiled
off during evaporation.
[0017] Conduits, such as pipes, for example, are disposed between
components of the apparatus 10 for conveying refrigerant
therethrough. Conduit 32 is coupled between the compressor 12 and
the four-way reversing valve 18. Conduit 34 is coupled between the
four-way reversing valve 18 and the first heat exchanger 14.
Conduits 36 and 38 are coupled between the first heat exchanger 14
and the valve 22 and the valve 22 and the receiver 20,
respectively. Conduits 40 and 42 are coupled between the receiver
20 and the valve 24 and the valve 24 and the second heat exchanger
16, respectively. Conduit 44 is coupled between the second heat
exchanger 16 and the four-way reversing valve 18. Conduit 46 is
coupled between the four-way reversing valve 18 and the accumulator
26 and conduit 48 is coupled between the accumulator 26 and the
compressor 12.
[0018] Conduits 32 and 48 are coupled to ports 50 and 52,
respectively, of the compressor 12. The port 50 is an outlet port
and the port 52 in an inlet port. The compressor 12 may have more
than one inlet port 52.
[0019] A scroll compressor, which is shown schematically in FIG. 2,
generally includes two inlet ports for receiving refrigerant from
the evaporator. In a scroll compressor, refrigerant is compressed
between two scroll plates that are nested together. One plate may
be stationary while the other plate moves in an orbital path.
Refrigerant is received through inlet ports at the perimeter of the
scroll and as the plate orbits, an enclosed volume containing the
refrigerant is transferred toward a decreased volume region at the
center of the scroll. As the volume decreases, the refrigerant is
compressed and discharged through an outlet port.
[0020] The compressor 12 further includes an injection inlet 54 for
receiving a reduced temperature refrigerant from the receiver 20.
Conduit 56 is coupled between the receiver 20 and an expansion
valve 58 and conduit 60 is coupled between the expansion valve 58
and inlet 54 of the compressor 12 to facilitate delivery of the
refrigerant to the compressor 12. The expansion valve 58 reduces a
pressure of the refrigerant prior to the refrigerant entering the
compressor 12. In a scroll compressor, the injection inlet 54 is
located in interior or middle scrolls of the flanks of the scroll
compressor.
[0021] The injection inlet 54 facilitates injection of refrigerant
into the compressor 12 through the inlet 54 part-way through the
compression step of the refrigeration cycle. In general, compressor
outlet temperature is maintained below 300.degree. F. in order to
avoid damage due to lubricant breakdown. One or more of compressor
outlet temperature, compressor motor temperature and compressor
flank temperature are measured in order to determine when and how
much of the reduced temperature refrigerant may be injected into
the injection inlet 54. Methods for measuring compressor
temperatures are well known in the art and therefore will not be
described further.
[0022] The injection of reduced temperature refrigerant reduces the
temperature of the refrigerant proceeding through the compression
step and exiting the compressor 12. The reduced temperature
refrigerant is less likely to cause the lubricant in the compressor
to break down, which may result in an increased operating life of
the compressor 12.
[0023] The refrigerant used in the apparatus 10 is
Trifluoroiodomethane (CF3I), which may also be referred to as
Iodotrifluoromethane, Monoiodotrifluoromethane, Trifluoromethyl
iodide, Perfluoromethyl iodide or Freon 13T1. The chemical
composition of the Trifluoroiodomethane includes one carbon atom
combined with 3 flourine atoms and one Iodine atom. Sesquiterpene,
which is a stabilizer may be added to the refrigerant
[0024] Alternatively, the refrigerant may be one of other blends
fluorinated carbon compounds to facilitate the higher efficiency
and work well with mid-compression refrigeration injection. The
refrigerants generally have a low GWP (global warming potential)
and are ozone friendly.
[0025] Operation of the apparatus 10 will now be described with
reference to FIG. 1. In this example, heat exchanger 14 is
operating as a condenser and heat exchanger 16 is operating as an
evaporator.
[0026] Low pressure refrigerant enters the compressor 12 through
port 52 and is compressed. Part-way through compression, reduced
temperature refrigerant, which has a lower temperature than the
refrigerant that is in the compressor 12, is injected through inlet
54. The reduced temperature refrigerant flows from the receiver 20,
through the expansion valve 58, to enter the compressor 12 with a
pressure that is lower than the pressure of the refrigerant in the
receiver 20. The refrigerant entering the compressor 12 through the
inlet 54 has an absolute pressure that is approximately mid-way
between the absolute pressure at the inlet port 52 and the absolute
pressure at the outlet port 50. The reduced temperature refrigerant
mixes with the refrigerant in the compressor 12 and exits the
compressor 12 through conduit 32 as a high pressure, high
temperature gas. The refrigerant exiting the compressor 12 is at a
high temperature, however, the temperature is less than the
temperature would have been without the addition of the reduced
temperature refrigerant, which facilitates protection of the
lubricant and the moving mechanical parts of the compressor and
other components of the apparatus 10.
[0027] The gas exiting the compressor 12 flows through the four-way
reversing valve 18, through conduit 34 and enters the first heat
exchanger 14. As the refrigerant flows through the first heat
exchanger 14, the refrigerant is in indirect contact with fluid
flowing through the first heat exchange conduit 28 to remove heat
from the refrigerant. The condensed refrigerant exits the heat
exchanger 14, flows through conduit 36 and travels past valve 22,
which functions as a check valve. The condensed refrigerant then
flows through conduit 38 and into the receiver 20.
[0028] The condensed refrigerant exits the receiver 20, flows
through conduit 40 and travels past the valve 24, which functions
as an expansion valve where the pressure of the refrigerant is
reduced to facilitate expansion and lowering of the refrigerant
temperature. The refrigerant then flows through conduit 42 and into
the second heat exchanger 16. As the refrigerant flows through the
second heat exchanger 16, the refrigerant is in indirect contact
with fluid flowing through the second heat exchange conduit 30 and
heat is absorbed by the refrigerant. As heat is absorbed, the
refrigerant vaporizes and exits the second heat exchanger 16
through conduit 44 and flows into the four-way reversing valve 18.
From the four-way reversing valve 18, the refrigerant flows through
conduit 46 to enter the accumulator 26. The refrigerant then exits
the accumulator 26 through conduit 48 and flows into the compressor
12 to begin the cycle again.
[0029] In general, the refrigerant temperature is maintained below
a breakdown temperature of the lubricant. In one example, the
refrigerant temperature is maintained 25 to 50 degrees Fahrenheit
below the lubricant breakdown temperature. When Polyolester (POE),
which is a common lubricant used with Hydro fluorocarbon (HFC)
refrigerants, is used, the breakdown temperature is approximately
300 degrees Fahrenheit. Therefore, in this example, the temperature
at the outlet port 50 of the compressor 12 may be between 250 and
275 degrees Fahrenheit.
[0030] In one embodiment, the four-way reversing valve 18 is
eliminated from the embodiment of FIG. 1 and the apparatus 10 is
operable in a single direction.
[0031] In another embodiment, a motor of the compressor 12 includes
a frequency drive for controlling the compressor motor speed. There
is a large difference between refrigeration densities at opposite
ends of the operating conditions as determined by the refrigerant
gas specific volumes and resultant density. For example, a
compressor may need to move significantly more pounds of
refrigerant gas for a particular pressure increase, which may
consequently overload the connected refrigerant compressor motor.
By slowing down the motor using a frequency drive, power input may
be reduced. Control over the motor speed may improve the service
life of the compressor 12.
[0032] In another embodiment, the reduced temperature refrigerant
may be injected into the compressor 12 in response to a temperature
at the outlet port 50 of the compressor 12 being within a
predetermined temperature range. In one example, the reduced
temperature refrigerant is injected into the compressor when the
temperature at the outlet port 50 is between 250 and 275 degrees
Fahrenheit.
[0033] The apparatus 10 described herein may include any type of
compressor that is capable of compound and/or inter-stage
compression. A scroll compressor is provided as an example and is
not intended to be limiting.
[0034] By reducing the temperature of the refrigerant exiting the
compressor 12, the operating life of the lubricant and therefore
the operating life of the compressor 12 and other components of the
heat pump/refrigeration apparatus may be extended.
[0035] In addition, by reducing the temperature of the refrigerant
exiting the compressor 12, the efficiency of the refrigeration
apparatus 10 may be increased. By achieving cooling/heating results
more efficiently, the operating time of the refrigeration apparatus
10 may be reduced resulting in less energy consumed.
[0036] The present disclosure may be embodied in other specific
forms without departing from its spirit or essential
characteristics. The described embodiments are to be considered in
all respects only as illustrative and not restrictive. The scope of
the present disclosure is, therefore, indicated by the appended
claims rather than by the foregoing description. All changes that
come within the meaning and range of equivalency of the claims are
to be embraced within their scope.
* * * * *