U.S. patent application number 17/292808 was filed with the patent office on 2022-01-27 for system and method of mechanical compression refrigeration based on two-phase ejector.
The applicant listed for this patent is Her Majesty the Queen in Right of Canada as Represented by the Minister of Natural Resources. Invention is credited to Zine AIDOUN, Khaled AMEUR, Messaoud BADACHE.
Application Number | 20220026114 17/292808 |
Document ID | / |
Family ID | 1000005897966 |
Filed Date | 2022-01-27 |
United States Patent
Application |
20220026114 |
Kind Code |
A1 |
AIDOUN; Zine ; et
al. |
January 27, 2022 |
SYSTEM AND METHOD OF MECHANICAL COMPRESSION REFRIGERATION BASED ON
TWO-PHASE EJECTOR
Abstract
The present invention discloses the use of two-phase ejector(s)
activated by pressurized refrigerant, said two-phase ejector(s) are
strategically located in the cycle of the refrigeration system so
as to provide part of the compression effect required for the
refrigeration load, thereby relieving the conventional mechanical
compressor from part of its duty, hence increasing the overall
cycle efficiency of the refrigeration system.
Inventors: |
AIDOUN; Zine; (Laval,
CA) ; AMEUR; Khaled; (Montreal, CA) ; BADACHE;
Messaoud; (Saint-Leonard, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Her Majesty the Queen in Right of Canada as Represented by the
Minister of Natural Resources |
Ottawa |
|
CA |
|
|
Family ID: |
1000005897966 |
Appl. No.: |
17/292808 |
Filed: |
December 4, 2019 |
PCT Filed: |
December 4, 2019 |
PCT NO: |
PCT/CA2019/051742 |
371 Date: |
May 11, 2021 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
62775068 |
Dec 4, 2018 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F25B 41/40 20210101;
F25B 1/06 20130101 |
International
Class: |
F25B 1/06 20060101
F25B001/06; F25B 41/40 20060101 F25B041/40 |
Claims
1. A refrigeration system, comprising: a metering device for
controlling flow of a refrigerant, an evaporator, means for
supplying the refrigerant from the metering device into the
evaporator wherein the refrigerant evaporates into vapor, a
two-phase ejector comprising means defining a liquid chamber having
a liquid inlet, means defining a vapor chamber having a vapor
inlet, and an outlet discharging a two-phase vapor-liquid
refrigerant stream, means for supplying the vapor from the
evaporator into the vapor inlet of the two-phase ejector, a flash
tank compound separator, means for supplying the refrigerant from
the two-phase ejector into the flash tank compound separator
wherein the refrigerant separates into two phases, a compressor,
means for supplying the refrigerant from the flash tank compound
separator into the compressor wherein the refrigerant compresses, a
condenser, means for supplying the refrigerant from the compressor
into the condenser wherein the refrigerant condenses, a receiver,
means for supplying the refrigerant from the condenser to the
receiver, means for supplying the refrigerant from the receiver to
the liquid inlet of the two-phase ejector, means for supplying the
refrigerant from the receiver to the metering device and then into
the evaporator to start another cycle through the system, means for
supplying the refrigerant from the flash tank compound separator
into a pump where the pressure of the refrigerant is regulated,
means for supplying the refrigerant from the pump into the
receiver, wherein the two-phase ejector then draws vapor from the
evaporator lifting its pressure to an intermediate level when
activated a mixture of condensate from the condenser and subcooled
refrigerant fed by the pump, and wherein the pressure of the liquid
inlet of the two-phase ejector is controlled by the pump in
accordance with the operating conditions of the compressor.
2. A refrigeration system, comprising: a metering device for
controlling flow of a refrigerant, an evaporator, means for
supplying the refrigerant from the metering device into the
evaporator wherein the refrigerant evaporates into vapor, a
two-phase ejector comprising means defining a liquid chamber having
a liquid inlet, means defining a vapor chamber having a vapor
inlet, and an outlet discharging a two-phase vapor-liquid
refrigerant stream, means for supplying the vapor from the
evaporator into the vapor inlet of the two-phase ejector, a flash
tank compound separator, means for supplying the refrigerant from
the two-phase ejector into the flash tank compound separator
wherein the refrigerant separates into two phases, a compressor,
means for supplying the refrigerant from the flash tank compound
separator into the compressor wherein the refrigerant compresses, a
condenser, means for supplying the refrigerant from the compressor
into the condenser wherein the refrigerant condenses, a heat
exchanger, means for supplying the refrigerant from the condenser
to the heat exchanger, means for supplying the refrigerant from the
heat exchanger to the liquid inlet of the two-phase ejector, means
for supplying the refrigerant from the heat exchanger to the
metering device where the pressure and temperature of the
refrigerant decrease and then into the evaporator to start another
cycle through the system, wherein the heat exchanger simultaneously
increases condensate subcooling at the inlet of metering device and
decreases motive liquid subcooling at the liquid inlet of two-phase
ejector, means for supplying the refrigerant from the flash tank
compound separator into a pump where the pressure of the
refrigerant is regulated, means for supplying the refrigerant from
the pump into the heat exchanger, wherein the two-phase ejector
then draws vapor from the evaporator lifting its pressure to an
intermediate level when activated a mixture of condensate from the
condenser and subcooled refrigerant fed by the pump, and wherein
the pressure of the liquid inlet of the two-phase ejector is
controlled by the pump in accordance with the operating conditions
of the compressor.
3. A refrigeration system, comprising: a metering device for
controlling flow of a refrigerant, an evaporator, means for
supplying the refrigerant from the metering device into the
evaporator wherein the refrigerant evaporates into vapor, a
two-phase ejector comprising means defining a liquid chamber having
a liquid inlet, means defining a vapor chamber having a vapor
inlet, and an outlet discharging a two-phase vapor-liquid
refrigerant stream, means for supplying the vapor from the
evaporator into the vapor inlet of the two-phase ejector, a flash
tank compound separator, means for supplying the refrigerant from
the two-phase ejector into the flash tank compound separator
wherein the refrigerant separates into two phases, a compressor,
means for supplying the refrigerant from the flash tank compound
separator into the compressor wherein the refrigerant compresses, a
condenser, means for supplying the refrigerant from the compressor
into the condenser wherein the refrigerant condenses, a mixing
junction, means for supplying the refrigerant from the condenser to
the mixing junction, means for supplying the refrigerant from the
mixing junction to the liquid inlet of the two-phase ejector, means
for supplying the refrigerant from the flash tank compound
separator to the metering device where the pressure and temperature
of the refrigerant decrease and then into the evaporator to start
another cycle through the system, means for supplying the
refrigerant from the flash tank compound separator into a pump,
means for supplying the refrigerant from the pump into the mixing
junction, wherein the two-phase ejector then draws vapor from the
evaporator lifting its pressure to an intermediate level when
activated a mixture of condensate from the condenser and subcooled
refrigerant fed by the pump, and wherein the pressure of the liquid
inlet of the two-phase ejector is controlled by the pump in
accordance with the operating conditions of the compressor.
4. A refrigeration system, comprising: a metering device for
controlling flow of a refrigerant, an evaporator, means for
supplying the refrigerant from the metering device into the
evaporator wherein the refrigerant evaporates into vapor, a
two-phase ejector comprising means defining a liquid chamber having
a liquid inlet, means defining a vapor chamber having a vapor
inlet, and an outlet discharging a two-phase vapor-liquid
refrigerant stream, means for supplying the vapor from the
evaporator into the vapor inlet of the two-phase ejector, a flash
tank compound separator, means for supplying the refrigerant from
the two-phase ejector into the flash tank compound separator
wherein the refrigerant separates into two phases, a compressor,
means for supplying the refrigerant from the flash tank compound
separator into the compressor wherein the refrigerant compresses, a
condenser, means for supplying the refrigerant from the compressor
into the condenser wherein the refrigerant condenses, a heat
exchanger, means for supplying the refrigerant from the condenser
to the heat exchanger, means for supplying the refrigerant from the
compressor to the heat exchanger, a first valve for controlling the
supply of the refrigerant from the compressor to the condenser and
a second valve for controlling the supply of the refrigerant from
the compressor to the heat exchanger; wherein by controlling and
adjusting the first and/or the second valve, the heat exchanger
transfers part of condensation heat of the compressed vapor to
subcooled compressed liquid circulated by pump to the two-phase
ejector, means for supplying the refrigerant from the heat
exchanger to the liquid inlet of the two-phase ejector, means for
supplying the refrigerant from the heat exchanger to the metering
device where the pressure and temperature of the refrigerant
decrease and then into the evaporator to start another cycle
through the system, wherein the heat exchanger simultaneously
increases condensate subcooling at the inlet of metering device and
decreases motive liquid subcooling at the liquid inlet of two-phase
ejector, means for supplying the refrigerant from the flash tank
compound separator into a pump where the pressure of the
refrigerant is regulated, means for supplying the refrigerant from
the pump into the heat exchanger, wherein the two-phase ejector
then draws vapor from the evaporator lifting its pressure to an
intermediate level when activated a mixture of condensate from the
condenser and subcooled refrigerant fed by the pump, and wherein
the pressure of the liquid inlet of the two-phase ejector is
controlled by the pump in accordance with the operating conditions
of the compressor.
5. A refrigeration system, comprising: a metering device for
controlling flow of a refrigerant, an evaporator, means for
supplying the refrigerant from the metering device into the
evaporator wherein the refrigerant evaporates into vapor, a
two-phase ejector comprising means defining a liquid chamber having
a liquid inlet, means defining a vapor chamber having a vapor
inlet, and an outlet discharging a two-phase vapor-liquid
refrigerant stream, means for supplying the vapor from the
evaporator into the vapor inlet of the two-phase ejector, a flash
tank compound separator, means for supplying the refrigerant from
the two-phase ejector into the flash tank compound separator
wherein the refrigerant separates into two phases, a compressor,
means for supplying the refrigerant from the flash tank compound
separator into the compressor wherein the refrigerant compresses, a
condenser, means for supplying the refrigerant from the compressor
into the condenser wherein the refrigerant condenses, a direct
contact condenser, means for supplying the refrigerant from the
condenser to the direct contact condenser, means for supplying the
refrigerant from the compressor to the direct contact condenser, a
first valve for controlling the supply of the refrigerant from the
compressor to the condenser and a second valve for controlling the
supply of the refrigerant from the compressor to the direct contact
condenser; wherein by controlling and adjusting the first and/or
the second valve, the direct contact condenser transfers part of
condensation heat of the compressed vapor to subcooled compressed
liquid circulated by pump to the two-phase ejector, means for
supplying the refrigerant from the direct contact condenser to the
liquid inlet of the two-phase ejector, means for supplying the
refrigerant from the flash tank compound separator to the metering
device where the pressure and temperature of the refrigerant
decrease and then into the evaporator to start another cycle
through the system, means for supplying the refrigerant from the
flash tank compound separator into a pump where the pressure of the
refrigerant is regulated, means for supplying the refrigerant from
the pump into the direct contact condenser, wherein the two-phase
ejector then draws vapor from the evaporator lifting its pressure
to an intermediate level when activated a mixture of condensate
from the condenser and subcooled refrigerant fed by the pump, and
wherein the pressure of the liquid inlet of the two-phase ejector
is controlled by the pump in accordance with the operating
conditions of the compressor.
6. The refrigeration system according to any one of claims 1 to 5,
wherein the metering device is a thermal expansion valve, or a
capillary tube.
7. The refrigeration system according to any one of claims 1 to 6,
wherein the refrigerant is carbon dioxide.
Description
FIELD OF THE INVENTION
[0001] The invention relates to system and method of mechanical
compression refrigeration. In particular, the present invention
discloses the use of a two-phase ejector to improve efficiency and
stability of mechanical compression refrigeration system.
BACKGROUND OF THE INVENTION
[0002] In recent years, technological advancements in the field of
equipment optimization and controls have substantially reduced
energy consumption. At the same time, the demand for increased
comfort (for example, heating and air-conditioning) or production
of goods (for example, Agro-food industry), however, undermines
these achievements by giving rise to demands for additional energy
consumption. As a result, the overall costs relating to energy
consumption increase.
[0003] Estimations by research carried out by Natural Resources
Canada indicate that ten percent of total energy consumption in
commercial, institutional and industrial activities relates to
refrigeration. Refrigeration, or more generally, air conditioning,
are no longer an option but a requirement for daily consumptions,
given the increasing demand from consumers.
[0004] Currently, one of the solutions most investigated in
improving energy efficiency in refrigeration involves the use of an
ejector which may be integrated into conventional refrigeration
systems as internal components in order to form hybrid cycles and
improve performance. A number of these options are being considered
in the current research (for example, cascades, hybrids, subcooling
agents, ejecto-compression or ejecto-absorption).
[0005] Some of these options, such as cascade and hybrid
configurations, have a good potential for performance improvement
and have been studied theoretically and experimentally at
CanmetENERGY. They are typically suitable for low temperatures and
medium to large capacities.
[0006] The refrigeration systems most currently used are based on
mechanical compression. Electrically driven compressors are the
main components in such systems. Decent performance is generally
obtained in such systems, which explains the popularity of this
technology. However, low temperature refrigeration or heat pumping
in cold conditions or air conditioning in a hot environment imposes
a heavy load on the electrical grid so that innovative ways of
increasing efficiency and decreasing energy consumption are
sought.
[0007] Other than ejectors, other technologies based on heat
activation (i.e. absorption, adsorption and chemical heat pumps)
may also be available. However, they are complex, bulky and are not
suitable alternatives to mechanical compression.
[0008] Mechanical based compression refrigeration becomes
increasingly complex and consumes increasingly more electricity
(noble energy) at high and/or low temperature working
conditions.
[0009] Therefore, there is the need for an efficient mechanical
compression refrigeration system.
SUMMARY OF THE INVENTION
[0010] The objective of the present invention is to enhance the
efficiency of the existing refrigeration cycles by assisting the
compressor in a refrigeration system with a two-phase ejector
activated by potential energy and available internal heat
recovery.
[0011] According to one aspect of the invention, there is provided
a refrigeration system, comprising: [0012] a metering device for
controlling flow of a refrigerant, [0013] an evaporator, [0014]
means for supplying the refrigerant from the metering device into
the evaporator wherein the refrigerant evaporates into vapor,
[0015] a two-phase ejector comprising means defining a liquid
chamber having a liquid inlet, means defining a vapor chamber
having a vapor inlet, and an outlet discharging a two-phase
vapor-liquid refrigerant stream, [0016] means for supplying the
vapor from the evaporator into the vapor inlet of the two-phase
ejector, [0017] a flash tank compound separator, [0018] means for
supplying the refrigerant from the two-phase ejector into the flash
tank compound separator wherein the refrigerant separates into two
phases, [0019] a compressor, [0020] means for supplying the
refrigerant from the flash tank compound separator into the
compressor wherein the refrigerant compresses, [0021] a condenser,
[0022] means for supplying the refrigerant from the compressor into
the condenser wherein the refrigerant condenses, [0023] a receiver,
[0024] means for supplying the refrigerant from the condenser to
the receiver, [0025] means for supplying the refrigerant from the
receiver to the liquid inlet of the two-phase ejector, [0026] means
for supplying the refrigerant from the receiver to the metering
device and then into the evaporator to start another cycle through
the system, [0027] means for supplying the refrigerant from the
flash tank compound separator into a pump where the pressure of the
refrigerant is regulated, [0028] means for supplying the
refrigerant from the pump into the receiver, [0029] wherein the
two-phase ejector then draws vapor from the evaporator lifting its
pressure to an intermediate level when activated a mixture of
condensate from the condenser and subcooled refrigerant fed by the
pump, and [0030] wherein the pressure of the liquid inlet of the
two-phase ejector is controlled by the pump in accordance with the
operating conditions of the compressor.
[0031] According to another aspect of the invention, there is
provided a refrigeration system, comprising: [0032] a metering
device for controlling flow of a refrigerant, [0033] an evaporator,
[0034] means for supplying the refrigerant from the metering device
into the evaporator wherein the refrigerant evaporates into vapor,
[0035] a two-phase ejector comprising means defining a liquid
chamber having a liquid inlet, means defining a vapor chamber
having a vapor inlet, and an outlet discharging a two-phase
vapor-liquid refrigerant stream, [0036] means for supplying the
vapor from the evaporator into the vapor inlet of the two-phase
ejector, [0037] a flash tank compound separator, [0038] means for
supplying the refrigerant from the two-phase ejector into the flash
tank compound separator wherein the refrigerant separates into two
phases, [0039] a compressor, [0040] means for supplying the
refrigerant from the flash tank compound separator into the
compressor wherein the refrigerant compresses, [0041] a condenser,
[0042] means for supplying the refrigerant from the compressor into
the condenser wherein the refrigerant condenses, [0043] a heat
exchanger, [0044] means for supplying the refrigerant from the
condenser to the heat exchanger, [0045] means for supplying the
refrigerant from the heat exchanger to the liquid inlet of the
two-phase ejector, [0046] means for supplying the refrigerant from
the heat exchanger to the metering device where the pressure and
temperature of the refrigerant decrease and then into the
evaporator to start another cycle through the system, [0047]
wherein the heat exchanger simultaneously increases condensate
subcooling at the inlet of metering device and decreases motive
liquid subcooling at the liquid inlet of two-phase ejector, [0048]
means for supplying the refrigerant from the flash tank compound
separator into a pump where the pressure of the refrigerant is
regulated, [0049] means for supplying the refrigerant from the pump
into the heat exchanger, [0050] wherein the two-phase ejector then
draws vapor from the evaporator lifting its pressure to an
intermediate level when activated a mixture of condensate from the
condenser and subcooled refrigerant fed by the pump, and [0051]
wherein the pressure of the liquid inlet of the two-phase ejector
is controlled by the pump in accordance with the operating
conditions of the compressor.
[0052] According to a further aspect of the invention, there is
provided a refrigeration system, comprising: [0053] a metering
device for controlling flow of a refrigerant, [0054] an evaporator,
[0055] means for supplying the refrigerant from the metering device
into the evaporator wherein the refrigerant evaporates into vapor,
[0056] a two-phase ejector comprising means defining a liquid
chamber having a liquid inlet, means defining a vapor chamber
having a vapor inlet, and an outlet discharging a two-phase
vapor-liquid refrigerant stream, [0057] means for supplying the
vapor from the evaporator into the vapor inlet of the two-phase
ejector, [0058] a flash tank compound separator, means for
supplying the refrigerant from the two-phase ejector into the flash
tank compound separator wherein the refrigerant separates into two
phases, [0059] a compressor, [0060] means for supplying the
refrigerant from the flash tank compound separator into the
compressor wherein the refrigerant compresses, [0061] a condenser,
[0062] means for supplying the refrigerant from the compressor into
the condenser wherein the refrigerant condenses, [0063] a mixing
junction, [0064] means for supplying the refrigerant from the
condenser to the mixing junction, [0065] means for supplying the
refrigerant from the mixing junction to the liquid inlet of the
two-phase ejector, [0066] means for supplying the refrigerant from
the flash tank compound separator to the metering device where the
pressure and temperature of the refrigerant decrease and then into
the evaporator to start another cycle through the system, [0067]
means for supplying the refrigerant from the flash tank compound
separator into a pump, [0068] means for supplying the refrigerant
from the pump into the mixing junction, [0069] wherein the
two-phase ejector then draws vapor from the evaporator lifting its
pressure to an intermediate level when activated a mixture of
condensate from the condenser and subcooled refrigerant fed by the
pump, and [0070] wherein the pressure of the liquid inlet of the
two-phase ejector is controlled by the pump in accordance with the
operating conditions of the compressor.
[0071] According to one aspect of the invention, there is provided
a refrigeration system, comprising: [0072] a metering device for
controlling flow of a refrigerant, [0073] an evaporator, [0074]
means for supplying the refrigerant from the metering device into
the evaporator wherein the refrigerant evaporates into vapor,
[0075] a two-phase ejector comprising means defining a liquid
chamber having a liquid inlet, means defining a vapor chamber
having a vapor inlet, and an outlet discharging a two-phase
vapor-liquid refrigerant stream, [0076] means for supplying the
vapor from the evaporator into the vapor inlet of the two-phase
ejector, [0077] a flash tank compound separator, [0078] means for
supplying the refrigerant from the two-phase ejector into the flash
tank compound separator wherein the refrigerant separates into two
phases, [0079] a compressor, [0080] means for supplying the
refrigerant from the flash tank compound separator into the
compressor wherein the refrigerant compresses, [0081] a condenser,
[0082] means for supplying the refrigerant from the compressor into
the condenser wherein the refrigerant condenses, [0083] a heat
exchanger, [0084] means for supplying the refrigerant from the
condenser to the heat exchanger, [0085] means for supplying the
refrigerant from the compressor to the heat exchanger, [0086] a
first valve for controlling the supply of the refrigerant from the
compressor to the condenser and a second valve for controlling the
supply of the refrigerant from the compressor to the heat
exchanger; [0087] wherein by controlling and adjusting the first
and/or the second valve, the heat exchanger transfers part of
condensation heat of the compressed vapor to subcooled compressed
liquid circulated by pump to the two-phase ejector, [0088] means
for supplying the refrigerant from the heat exchanger to the liquid
inlet of the two-phase ejector, [0089] means for supplying the
refrigerant from the heat exchanger to the metering device where
the pressure and temperature of the refrigerant decrease and then
into the evaporator to start another cycle through the system,
[0090] wherein the heat exchanger simultaneously increases
condensate subcooling at the inlet of metering device and decreases
motive liquid subcooling at the liquid inlet of two-phase ejector,
[0091] means for supplying the refrigerant from the flash tank
compound separator into a pump where the pressure of the
refrigerant is regulated, [0092] means for supplying the
refrigerant from the pump into the heat exchanger, [0093] wherein
the two-phase ejector then draws vapor from the evaporator lifting
its pressure to an intermediate level when activated a mixture of
condensate from the condenser and subcooled refrigerant fed by the
pump, and [0094] wherein the pressure of the liquid inlet of the
two-phase ejector is controlled by the pump in accordance with the
operating conditions of the compressor.
[0095] According to one aspect of the invention, there is provided
a refrigeration system, comprising: [0096] a metering device for
controlling flow of a refrigerant, [0097] an evaporator, [0098]
means for supplying the refrigerant from the metering device into
the evaporator wherein the refrigerant evaporates into vapor,
[0099] a two-phase ejector comprising means defining a liquid
chamber having a liquid inlet, means defining a vapor chamber
having a vapor inlet, and an outlet discharging a two-phase
vapor-liquid refrigerant stream, [0100] means for supplying the
vapor from the evaporator into the vapor inlet of the two-phase
ejector, [0101] a flash tank compound separator, [0102] means for
supplying the refrigerant from the two-phase ejector into the flash
tank compound separator wherein the refrigerant separates into two
phases, [0103] a compressor, [0104] means for supplying the
refrigerant from the flash tank compound separator into the
compressor wherein the refrigerant compresses, [0105] a condenser,
[0106] means for supplying the refrigerant from the compressor into
the condenser wherein the refrigerant condenses, [0107] a direct
contact condenser, [0108] means for supplying the refrigerant from
the condenser to the direct contact condenser, [0109] means for
supplying the refrigerant from the compressor to the direct contact
condenser, [0110] a first valve for controlling the supply of the
refrigerant from the compressor to the condenser and a second valve
for controlling the supply of the refrigerant from the compressor
to the direct contact condenser; [0111] wherein by controlling and
adjusting the first and/or the second valve, the direct contact
condenser transfers part of condensation heat of the compressed
vapor to subcooled compressed liquid circulated by pump to the
two-phase ejector, [0112] means for supplying the refrigerant from
the direct contact condenser to the liquid inlet of the two-phase
ejector, [0113] means for supplying the refrigerant from the flash
tank compound separator to the metering device where the pressure
and temperature of the refrigerant decrease and then into the
evaporator to start another cycle through the system, [0114] means
for supplying the refrigerant from the flash tank compound
separator into a pump where the pressure of the refrigerant is
regulated, [0115] means for supplying the refrigerant from the pump
into the direct contact condenser, [0116] wherein the two-phase
ejector then draws vapor from the evaporator lifting its pressure
to an intermediate level when activated a mixture of condensate
from the condenser and subcooled refrigerant fed by the pump, and
[0117] wherein the pressure of the liquid inlet of the two-phase
ejector is controlled by the pump in accordance with the operating
conditions of the compressor.
[0118] Preferably, the metering device is a thermal expansion
valve, or a capillary tube.
[0119] Preferably, refrigerant used in the refrigeration system is
carbon dioxide.
[0120] Other features and advantages of the present invention will
become apparent from the following detailed description and the
accompanying drawings, which illustrate, by way of example, the
principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0121] By way of example only, preferred embodiments of the present
invention are described hereinafter with reference to the
accompanying drawings, wherein:
[0122] FIG. 1 is a schematic representation of an embodiment of a
conventional refrigeration cycle (prior art);
[0123] FIG. 2 is a schematic representation of an embodiment of a
two-phase ejector assisted mechanical refrigeration cycle according
to the present invention;
[0124] FIG. 3 is a schematic representation of a second embodiment
of a two-phase ejector assisted mechanical refrigeration cycle
according to the present invention;
[0125] FIG. 4 is a schematic representation of a third embodiment
of a two-phase ejector assisted mechanical refrigeration cycle
according to the present invention;
[0126] FIG. 5 is a schematic representation of a fourth embodiment
of a two-phase ejector assisted mechanical refrigeration cycle
according to the present invention; and
[0127] FIG. 6 is a schematic representation of a fifth embodiment
of a two-phase ejector assisted mechanical refrigeration cycle
according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0128] Mechanical refrigeration is the utilization of mechanical
components arranged in a "refrigeration system" for the purpose of
transferring heat. The refrigeration cycle is based on the
well-known physical principle that a liquid evaporating into a gas
extracts heat from the surrounding area. The refrigeration cycle is
to remove unwanted heat from one place and discharge it into
another. To accomplish this, the refrigerant is pumped through a
closed refrigeration system.
[0129] Refrigerants are chemical compounds that are alternately
compressed and condensed into a liquid and then permitted to expand
and to evaporate into a vapor or gas as they are pumped through the
mechanical refrigeration system to cycle. Refrigerants evaporate at
much lower temperatures than water, which permits them to extract
heat at lower temperature than water.
[0130] Two different pressures exist in the cycle--the evaporating
or low pressure in the "low side," and the condensing, or high
pressure, in the "high side." These pressure areas are separated by
two dividing points: one is the metering device where the
refrigerant flow is controlled, and the other is at the compressor,
where vapor is compressed.
[0131] Referring to FIG. 1, a schematic representation of an
embodiment of an existing conventional refrigeration cycle system
1, a metering device 5 may be a thermal expansion valve, a
capillary tube, or any other device to control the flow of
refrigerant into an evaporator 6, or cooling coil, as a
low-pressure, low-temperature refrigerant. The expanding
refrigerant evaporates as it goes through evaporator 6, where it
removes the heat from the substance or space in which evaporator 6
is located. Heat travels from the warmer substance to evaporator 6
cooled by the evaporation of the refrigerant within the system,
causing the refrigerant to evaporate to a vapor. This low-pressure,
low-temperature vapor is then drawn to a compressor 7 where the
low-temperature vapor is compressed into a high-temperature,
high-pressure vapor. Compressor 7 then discharges the
high-temperature, high-pressure vapor to a condenser 8. The
high-temperature, high-pressure refrigerant vapor is at a higher
temperature than the air or water passing across the condenser,
therefore heat is transferred to the cooler air or water. As heat
is removed from the vapor, the vapor is condensed into a liquid, at
a high-pressure. The liquid refrigerant travels to metering device
5 where it passes through a small opening or orifice where a drop
in pressure and temperature occurs, and then it enters into
evaporator 6. As the refrigerant makes its way into the large
opening of the evaporator tubing or coil, it vaporizes, ready to
start another cycle through the system.
[0132] An ejector is a device in which two streams flow in intimate
contact at relatively high velocity such that the driving stream
transfers momentum to the driven stream, thereby increasing the
stagnation pressure of the driven stream. The two streams are
accelerated in separate nozzles to approximately the same pressure
before being brought together in a mixing section and the mixed
stream is decelerated in a diffuser. An ejector can be used to
generate isentropic condition in the throttling process. Because
the phase of the working fluid in the diffuser is a two phase, an
ejector is usually named as two-phase ejector.
[0133] In the present invention, two-phase ejector(s) activated by
pressurized refrigerant are used and strategically located in the
cycle of the refrigeration system so as to provide part of the
compression effect required for the refrigeration load, thereby
relieving the conventional mechanical compressor from part of its
duty, hence increasing the overall cycle efficiency of the
refrigeration system.
[0134] The two-phase ejectors are pressure-activated. In a
mechanical refrigeration cycle, the two-phase ejectors can recover
internal energy otherwise wasted, in order to produce a modest
compression effect, a pseudo-isentropic expansion and an
appreciable refrigerant circulatory effect. The two-phase ejectors
can be integrated therefore in a mechanical compression system to
produce improved cooling or refrigeration of the conventional
cycle.
[0135] Unlike conventional mechanical compressors, the two-phase
ejectors are static mechanical components; they are compact,
flexible, simple and low cost.
[0136] In its function, the two-phase ejector contributes to the
overall compression so that conventional mechanical compressor's
work is reduced, and its efficiency improved, resulting in overall
improved cycle performance.
[0137] Because two-phase ejectors are static and compact
components, modification to the conventional refrigeration cycle to
incorporate the two-phase ejectors introduces no major and/or
costly changes but results in substantial performance gains.
[0138] According to the present invention, the two-phase ejector
does not completely replace the conventional mechanical compressor
but serves to build a new cycle arrangement in which the
conventional mechanical compressor and the two-phase ejector can
fulfill their respective duties of fluid circulation and
compression without or with minimal interference.
[0139] According to the present invention, the two-phase ejector is
placed in series with the conventional mechanical compressor to the
suction of which it feeds refrigerant drawn from the evaporator,
but it is activated independently from the conventional mechanical
compressor.
[0140] The two-phase ejector and conventional mechanical compressor
assembly forms a hybrid system which uses a common refrigerant to
both components.
[0141] In existing prior art refrigeration systems, either: [0142]
(1) the two-phase ejector completely replaces the conventional
mechanical compressor which is then replaced by a pump; or [0143]
(2) the two-phase ejector and the conventional mechanical
compressor are arranged in series in such a way that the ejector is
activated by the conventional mechanical compressor via the
condensate and in turn the two-phase ejector feeds the conventional
mechanical compressor in vapor via the evaporator.
[0144] In these types of existing setups, it is obvious that both
the two-phase ejector and the conventional mechanical compressor
are strongly coupled, therefore preventing their stable
operation.
[0145] In contrast, the refrigeration cycle options described in
the present invention hybrid the two-phase ejector and conventional
mechanical compressor configurations. Their main features are
summarized below.
[0146] In FIG. 2, an embodiment of a two-phase ejector assisted
mechanical refrigeration system 10 consists of a cycle in which a
two-phase ejector 11 and a flash tank compound separator (or a
second reservoir) 12 are positioned sequentially between a receiver
(or the first fluid distribution reservoir) 9 and a compressor 7.
Part of the liquid in receiver 9 is expanded through metering
device 5 to the conditions of evaporator 6. The two-phase ejector
11 draws vapor from evaporator 6 lifting its pressure to an
intermediate level when activated a mixture of condensate and
subcooled refrigerant fed by a pressure pump 13. Therefore,
adequate subcooling of the two-phase ejector feed and the
evaporator can be adjusted for optimal operation. This combination
minimizes the detrimental coupling of two-phase ejector 11 and
compressor 7 and results in improved cycle stability and
performance. The two-phase ejector 11 and compressor 7 are in
series and are always both in operation. The system uses one
refrigerant and is suitable for a wide range of applications and
capacities.
[0147] FIG. 3 depicts another embodiment of a two-phase ejector
assisted mechanical refrigeration system 20, which is a variant of
system 10 as described in FIG. 2.
[0148] In FIG. 3, receiver (or the first fluid distribution
reservoir) 9 in FIG. 2 is replaced by a compact heat exchanger 21,
which allows for more operational flexibility. This measure
simultaneously increases condensate subcooling at the inlet of
metering device (expansion valve) 5 and decreases motive liquid
subcooling at the primary inlet of two-phase ejector 11, which
improve the overall cycle performance. In addition, the primary
inlet pressure of two-phase ejector 11 is controlled by pump 13
independently of the pressure of condenser 8.
[0149] FIG. 4 depicts another embodiment of a two-phase ejector
assisted mechanical refrigeration system 30, which is a variant of
system 10 and 20 as depicted in FIGS. 2 and 3, respectively.
[0150] In FIG. 4, evaporator 6 is fed by the refrigerant from flash
tank compound separator (or a second reservoir) 12 at intermediate
pressure; and receiver (or the first fluid distribution reservoir)
9 in FIG. 2 is replaced by a mixing junction 31. This configuration
simplifies the cycle of the refrigeration system further by the
removal of a vessel, therefore reducing expansion losses in
evaporator 6.
[0151] FIG. 5 represents an additional embodiment of a two-phase
ejector assisted mechanical refrigeration system 40 wherein the
condenser 8 is partially replaced by a heat exchanger 21, achieved
by controlling valves 42 (valve 42a for controlling the supply of
the refrigerant from compressor 7 to condenser 8 and/or valve 42b
for controlling the supply of the refrigerant from compressor 7 to
heat exchanger 21) and depend on the expansion extent and quality
in the nozzle of two-phase ejector 11; the other components
remaining unchanged.
[0152] In this case, heat exchanger 21 transfers a variable part of
the condensation heat of the compressed vapor to the highly
subcooled compressed liquid circulated by pump 13 to two-phase
ejector 11. This process has, inter alia, the following advantages:
[0153] By condensing part of the compression vapor, the size of
condenser 8 will be substantially reduced; [0154] The two-phase
ejector 11 subcooled inlet conditions can be adjusted to maximize
its efficiency; [0155] The level of heat rejection can be varied to
maximize the efficiency of compressor 7 and maximize overall
performance of the system, particularly when condenser 8 is less
needed; and [0156] Where condenser 8 is fully used, two-stage
compressor and multi-circuit heat exchanger may be contemplated to
divert only minimal stream to condenser 8 in order for the
compressor 7 to operate with minimal consumption.
[0157] FIG. 6 depicts another embodiment of a two-phase ejector
assisted mechanical refrigeration system 50, which is a variant of
system 40 as described in FIG. 5.
[0158] In FIG. 6, the heat exchanger 21 in FIG. 5 is replaced by a
more efficient and direct contact condenser 55 and an evaporator
feed from intermediate pressure flash tank compound separator (or a
second reservoir) 12 to further reduce expansion losses.
[0159] Any of the configurations as described above may use any of
the refrigerants currently available.
[0160] Preferably, carbon dioxide (CO.sub.2) is more suitable for
the intended two-phase ejector refrigeration/heat pump
operation.
[0161] Preferably, the metering device is a thermal expansion
valve, or a capillary tube.
[0162] Although the present invention has been described in
considerable detail with reference to certain preferred embodiments
thereof, other embodiments and modifications are possible.
Therefore, the scope should not be limited by the preferred
embodiments set forth in the afore-mentioned illustrative examples
but should be given the broadest interpretation consistent with the
description as a whole.
* * * * *