BACKGROUND
[0001] This disclosure relates generally to chiller systems used in air conditioning systems,
and more particularly to a purge system for removing contaminants from a refrigeration
system.
[0002] Chiller systems such as those utilizing centrifugal compressors may include sections
that operate below atmospheric pressure. As a result, leaks in the chiller system
may draw air into the system, contaminating the refrigerant. This contamination degrades
the performance of the chiller system. To address this problem, existing low pressure
chillers include a purge unit to remove contamination. Existing purge units use a
vapor compression cycle to separate non-condensable contaminant gas from the refrigerant.
Existing purge units are complicated and lose refrigerant in the process of removing
contamination.
[0003] US 5 062 273 A discloses a refrigeration system according to the preamble of claim 1, and further
shows a process for separating and removing non-condensible gaseous contaminants (e.g.,
nitrogen, oxygen and the like) from a conventional halocarbon vapor compression refrigeration
system by withdrawing a vapor stream above liquified refrigerant exiting the condenser
on the high pressure side of the expansion valve and then processing this vapor by
use of a second compression step, followed by condensation into a receiver. The liquid
halocarbon from the receiver is returned to the evaporator while the vapor phase is
sent to a semipermeable membrane separation unit.
[0004] US 5 044 166 A shows a refrigeration process including a refrigeration cycle, and refrigerant purge
and recovery operations is disclosed. The refrigeration cycle is a vapor compression
cycle or an absorption cycle. A purge stream is withdrawn from the refrigeration cycle
and subjected to treatment by means of a membrane separation unit. The purge-stream
treatment operation produces an essentially pure refrigerant stream, suitable for
return to the refrigeration cycle, and an air stream, clean enough for direct discharge
to the atmosphere.
BRIEF DESCRIPTION
[0005] Disclosed is a refrigeration system including a heat transfer fluid circulation loop
configured to allow a refrigerant to circulate therethrough, a purge outlet from the
heat transfer fluid circulation loop, and at least one gas permeable membrane having
a first side in communication with the purge outlet. The membrane includes a porous
inorganic material with pores of a size to allow passage of contaminants through the
membrane and restrict passage of the refrigerant through the membrane. A retentate
return flow path connects the first side of the membrane to the heat transfer fluid
circulation loop. The present invention provides a refrigeration system having the
features of claim 1.
[0006] In some embodiments, the enclosure includes a vapor compression heat transfer fluid
circulation loop including a compressor, a heat rejection heat exchanger, an expansion
device, and a heat absorption heat exchanger, connected together in order by conduit
and having the refrigerant disposed therein. In an operational state, the refrigerant
is at a pressure less than atmospheric pressure in at least a portion of the fluid
circulation loop.
[0007] In any one or combination of the foregoing embodiments, the retentate return flow
path includes a control device.
[0008] In any one or combination of the foregoing embodiments, the system is configured
for continuous purge operation.
[0009] In any one or combination of the foregoing embodiments, the system further includes
a prime mover configured to move gas from a second side of the membrane to an exhaust
port leading outside the refrigeration system, and a controller configured to operate
the refrigeration system in response to a cooling demand signal, and to operate the
prime mover in response to a purge signal.
[0010] In any one or combination of the foregoing embodiments including a control device,
the controller is further configured to operate the control device in response to
the purge signal.
[0011] In some embodiments, the prime mover includes a vacuum pump in communication with
the second side of the membrane.
[0012] In any one or combination of the foregoing embodiments, the system further includes
a purge gas collector between the purge outlet and the membrane.
[0013] In any one or combination of the foregoing embodiments, the retentate return flow
path includes an expansion device and returns retentate to the fluid circulation loop
to the heat absorption heat exchanger or to the compressor inlet.
[0014] In any one or combination of the foregoing embodiments, the at least one gas permeable
membrane includes a plurality of gas permeable membranes in serial or parallel communication
between the purge outlet and the exhaust port. In some embodiments, the system includes
a retentate return flow path operably coupling the first side of each of plurality
of membranes to the fluid circulation loop
[0015] In any one or combination of the foregoing embodiments, the contaminants includes
nitrogen, oxygen, or water.
[0016] In any one or combination of the foregoing embodiments, the system further includes
a pressure sensor operably coupled to the fluid circulation loop, and the controller
generates the purge signal in response to output from the pressure sensor.
[0017] In any one or combination of the foregoing embodiments, the pressure sensor is operably
coupled to the condenser or to the outlet of the compressor.
[0018] In any one or combination of the foregoing embodiments, the system further includes
a temperature sensor operably coupled to the fluid circulation loop, and the controller
generates the purge signal in response to output from the temperature sensor.
[0019] In any one or combination of the foregoing embodiments, the temperature sensor is
operably coupled to the condenser or evaporator.
[0020] In any one or combination of the foregoing embodiments, the system further includes
a refrigerant gas detection sensor operably coupled to second side of the membrane,
and the controller generates the purge signal in response to output from the refrigerant
gas detection sensor.
[0021] In any one or combination of the foregoing embodiments, the controller is configured
to generate the purge signal based at least in part on a timer setting.
[0022] In any one or combination of the foregoing embodiments, the controller is configured
to, in response to the purge signal, operate the control device to provide a varying
flow rate or pressure drop through the control device.
[0023] In any one or combination of the foregoing embodiments, the controller is configured
to, in response to the purge signal, vary prime mover pressure in coordination with
varying control device setting. In some embodiments, the control device includes a
control valve, and the controller is configured to, in response to the purge signal,
alternately operate the prime mover with the control valve closed and suspend operation
of the prime mover with the control valve open.
[0024] In any one or combination of the foregoing embodiments, the controller is configured,
in response to the purge signal, to operate the prime mover at a constant pressure.
[0025] In any one or combination of the foregoing embodiments, the controller is configured,
in response to the purge signal, to operate the prime mover at a varying pressure.
[0026] In any one or combination of the foregoing embodiments, the purge outlet is operably
coupled to the condenser.
[0027] Also disclosed is a method of operating the refrigeration system of any one or combination
of the foregoing embodiments, including circulating the refrigerant through the vapor
compression heat transfer fluid circulation loop in response to the cooling demand
signal under conditions in which the refrigerant is at a pressure less than atmospheric
pressure in at least a portion of the fluid circulation loop, and operating the prime
mover and the control device with the controller as configured.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The following descriptions should not be considered limiting in any way. With reference
to the accompanying drawings, like elements are numbered alike:
FIG. 1 is a schematic depiction of a vapor compression heat transfer refrigerant fluid
circulation loop;
FIG. 2 is schematic depiction of an example embodiment of a purge system and relevant
components of a vapor compression heat transfer refrigerant fluid circulation loop,
with membrane unit retentate directed to the system evaporator;
FIG. 3 is schematic depiction of another example embodiment of a purge system and
relevant components of a vapor compression heat transfer refrigerant fluid circulation
loop, with membrane retentate directed to the condenser;
FIG. 4 is a schematic depiction of another example embodiment of a purge system and
relevant components of a vapor compression heat transfer refrigerant fluid circulation
loop, with membrane units in a cascade configuration; and
FIG. 5 is a schematic depiction of another example embodiment of a purge system and
relevant components of a vapor compression heat transfer refrigerant fluid circulation
loop, with condenser pressure-based control.
DETAILED DESCRIPTION
[0029] A detailed description of one or more embodiments of the disclosed apparatus and
method are presented herein by way of exemplification and not limitation with reference
to the Figures.
[0030] With reference to FIG. 1, a refrigerant enclosure in the form of a heat transfer
fluid circulation loop is shown in block diagram form in FIG. 1. As shown in FIG.
1, a compressor 10 pressurizes heat transfer fluid in its gaseous state, which both
heats the fluid and provides pressure to circulate it throughout the system. In some
embodiments, the heat transfer fluid, or refrigerant, comprises an organic compound.
In some embodiments, the refrigerant comprises a hydrocarbon or substituted hydrocarbon.
In some embodiments, the refrigerant comprises a halogen-substituted hydrocarbon.
In some embodiments, the refrigerant comprises a fluoro-substituted or chloro-fluoro-substituted
hydrocarbon. The hot pressurized gaseous heat transfer fluid exiting from the compressor
10 flows through conduit 15 to heat exchanger condenser 20, which functions as a heat
exchanger to transfer heat from the heat transfer fluid to the surrounding environment,
resulting in condensation of the hot gaseous heat transfer fluid to a pressurized
moderate temperature liquid. The liquid heat transfer fluid exiting from the condenser
20 flows through conduit 25 to expansion valve 30, where the pressure is reduced.
The reduced pressure liquid heat transfer fluid exiting the expansion valve 30 flows
through conduit 35 to heat exchanger evaporator 40, which functions as a heat exchanger
to absorb heat from the surrounding environment and boil the heat transfer fluid.
Gaseous heat transfer fluid exiting the evaporator 40 flows through conduit 45 to
the compressor 10, thus completing the heat transfer fluid loop. The heat transfer
system has the effect of transferring heat from the environment surrounding the evaporator
40 to the environment surrounding the condenser 20. The thermodynamic properties of
the heat transfer fluid must allow it to reach a high enough temperature when compressed
so that it is greater than the environment surrounding the condenser 20, allowing
heat to be transferred to the surrounding environment. The thermodynamic properties
of the heat transfer fluid must also have a boiling point at its post-expansion pressure
that allows the temperature surrounding the evaporator 40 to provide heat to vaporize
the liquid heat transfer fluid.
[0031] With reference now to FIG. 2, there is shown an example embodiment of a purge system
connected to a vapor compression heat transfer fluid circulation loop such as FIG.
1 (not all components of FIG. 1 shown). As shown in FIG. 2, a purge collector 66 receives
purge gas comprising refrigerant gas and contaminants (e.g., nitrogen, oxygen) from
a purge connection 52 connected to the condenser 20. The purge gas is directed from
the purge collector 66 to a first side of a membrane 56 in a membrane separator 54.
A prime mover such as a vacuum pump 58 connected to the membrane separator 54 provides
a driving force to pass the contaminant molecules through the membrane 56 and exit
the system from a second side of the membrane 56 through an outlet. In some embodiments,
the prime mover can be in the fluid loop, e.g., a refrigerant pump or compressor.
Retentate comprising refrigerant gas (and optionally other components including but
not limited to oil(s) or other contaminants that did (e.g., nitrogen, gas remains
on the first side of the membrane 56 and returns to the fluid circulation loop through
a connection 67 that bypasses the condenser 20. A controller 50 receives system data
(e.g., pressure, temperature, mass flow rates) and system or operator control (e.g.,
on/of, receipt of cooling demand signal), and utilizes electronic control components
(e.g., a microprocessor) to control system components such as various pumps, valves,
switches.
[0032] In some embodiments, the connection of the purge connection 52 to the condenser can
be made at a high point of the condenser structure. In some embodiments, the purge
collector 66 can provide a technical effect of promoting higher concentrations of
contaminants at the membrane separator 54, which can promote more effective mass transfer
and separation. This effect can occur through a stratification of gas in the purge
collector 66 in which lighter contaminants concentrate toward the top of the purge
collector 66 and heavier refrigerant gas concentrates toward the bottom of the purge
collector 66. In some embodiments, the purge collector 66 can be any kind of vessel
or chamber with a volume or cross-sectional open space to provide for collection of
purge gas and for a low gas velocity during operation of the purge system vacuum pump
58 to promote stratification. Stratification can also occur at any time when the purge
system is not operating (including during operation of the refrigeration system fluid
circulation loop), as the purge collector 66 remains in fluid communication with the
purge connection 52 with essentially stagnant gas in the purge collector 66. Other
embodiments can also be employed to promote higher concentrations of contaminants
at the membrane separator 54, as discussed in more detail below.
[0033] With reference again to FIG. 2, the connection 67 returns retentate gas from the
first side of membrane 56 to the refrigerant fluid circulation loop at the evaporator
40, through a control device such as expansion valve 68 utilized to accommodate the
pressure differential between the first side of the membrane 56 (which is close to
the pressure at the condenser 20) and pressure at the evaporator 40. It should be
noted that the control device can control either or both flow through or pressure
drop across the control device, and expansion valve 68 is shown as an integrated control
device unit that performs both functions for ease of illustration, but could be separate
components such as a control valve and an expansion orifice. Other types of expansion
devices can also be used, including but not limited to capillaries, solenoids, thermostatic,
or electronic expansion devices. In some embodiments, utilization of a bypass refrigerant
return can provide a technical effect of promoting greater concentrations of contaminants
at the first side of membrane 56 by removing gas at the membrane 56 that is concentrated
with refrigerant after removal of contaminant molecules through the membrane 56, so
that refrigerant-concentrated gas can be displaced with gas from the purge collector
66 that has a higher concentration of contaminants. In alternative embodiments as
shown in FIG. 3, the connection 67 can return retentate gas to the colder side of
the condenser 20 or the inlet of the compressor 10, in which case an expansion device
may not be needed due to lower pressure differential compared to that of a bypass
return to the evaporator 40. In such as case, the connection 67 can utilize a control
device such as a control or shut-off valve 69 that does not provide gas expansion.
[0034] The membrane 56 comprises a porous inorganic material. Examples of porous inorganic
materials can include ceramics such as metal oxides or metal silicates, more specifically
aluminosilicates (e.g., Chabazite Framework (CHA) zeolite, Linde type A (LTA) zeolite,
porous carbon, porous glass, clays (e.g., Montmorillonite, Halloysite). Porous inorganic
materials can also include porous metals such as platinum and nickel. Hybrid inorganic-organic
materials such as a metal organic framework (MOF) can also be used. Other materials
can be present in the membrane such as a carrier in which a microporous material can
be dispersed, which can be included for structural or process considerations.
[0035] Metal organic framework materials are well-known in the art, and comprise metal ions
or clusters of metal ions coordinated to organic ligands to form one-, two- or three-dimensional
structures. A metal-organic framework can be characterized as a coordination network
with organic ligands containing voids. The coordination network can be characterized
as a coordination compound extending, through repeating coordination entities, in
one dimension, but with cross-links between two or more individual chains, loops,
or spiro-links, or a coordination compound extending through repeating coordination
entities in two or three dimensions. Coordination compounds can include coordination
polymers with repeating coordination entities extending in one, two, or three dimensions.
Examples of organic ligands include but are not limited to bidentate carboxylates
(e.g., oxalic acid, succinic acid, phthalic acid isomers, etc.), tridentate carboxylates
(e.g., citric acid, trimesic acid), azoles (e.g., 1,2,3-triazole), as well as other
known organic ligands. A wide variety of metals can be included in a metal organic
framework. Examples of specific metal organic framework materials include but are
not limited to zeolitic imidazole framework (ZIF), HKUST-1.
[0036] In some embodiments, pore sizes can be characterized by a pore size distribution
with an average pore size from 2.5 Å to 10.0 Å, and a pore size distribution of at
least 0.1 Å. In some embodiments, the average pore size for the porous material can
be in a range with a lower end of 2.5 Å to 4.0 Å and an upper end of 2.6 Å to 10.0
Å. Å. In some embodiments, the average pore size can be in a range having a lower
end of 2.5 Å, 3.0 Å, 3.5 Å, and an upper end of 3.5 Å, 5.0 Å, or 6.0 Å. These range
endpoints can be independently combined to form a number of different ranges, and
all ranges for each possible combination of range endpoints are hereby disclosed.
Porosity of the material can be in a range having a lower end of 5 %, 10 %, or 15
%, and an upper end of 85 %, 90 %, or 95 % (percentages by volume). These range endpoints
can be independently combined to form a number of different ranges, and all ranges
for each possible combination of range endpoints are hereby disclosed.
[0037] The above microporous materials can be can be synthesized by hydrothermal or solvothermal
techniques (e.g., sol-gel) where crystals are slowly grown from a solution. Templating
for the microstructure can be provided by a secondary building unit (SBU) and the
organic ligands. Alternate synthesis techniques are also available, such as physical
vapor deposition or chemical vapor deposition, in which metal oxide precursor layers
are deposited, either as a primary microporous material, or as a precursor to an MOF
structure formed by exposure of the precursor layers to sublimed ligand molecules
to impart a phase transformation to an MOF crystal lattice.
[0038] In some embodiments, the above-described inorganic or MOF membrane materials can
provide a technical effect of promoting separation of contaminants (e.g., nitrogen,
oxygen, water) from refrigerant gas, which is condensable. Other microporous materials,
such as porous polymers can be subject to solvent interaction with the matrix material,
which can interfere with effective separation. In some embodiments, the capabilities
of the materials described herein can provide a technical effect of promoting the
implementation of a various example embodiments of refrigeration systems with purge,
as described in more detail with reference to the example embodiments below.
[0039] The membrane material can be self-supporting or it can be supported, for example,
as a layer on a porous support or integrated with a matrix support material. In some
embodiments, thickness of a support for a supported membrane can range from 50 nm
to 1000 nm, more specifically from 100 nm to 750 nm, and even more specifically from
250 nm to 500 nm. In the case of tubular membranes, fiber diameters can range from
100 nm to 2000 nm, and fiber lengths can range from 0.2 m to 2 m.
[0040] In some embodiments, the microporous material can be deposited on a support as particles
in a powder or dispersed in a liquid carrier using various techniques such as spray
coating, dip coating, solution casting, etc. The dispersion can contain various additives,
such as dispersing aids, rheology modifiers, etc. Polymeric additives can be used;
however, a polymer binder is not needed, although a polymer binder can be included
and in some embodiments is included such as with a mixed matrix membrane comprising
a microporous inorganic material (e.g., microporous ceramic particles) in an organic
(e.g., organic polymer) matrix. However, a polymer binder present in an amount sufficient
to form a contiguous polymer phase can provide passageways in the membrane for larger
molecules to bypass the molecular sieve particles. Accordingly, in some embodiments
a polymer binder is excluded. In other embodiments, a polymer binder can be present
in an amount below that needed to form a contiguous polymer phase, such as embodiments
in which the membrane is in series with other membranes that may be more restrictive.
In some embodiments, particles of the microporous material (e.g., particles with sizes
of 0.01 µm to 10 mm, or in some embodiments from 0.5 µm to 10 µm, can be applied as
a powder or dispersed in a liquid carrier (e.g., an organic solvent or aqueous liquid
carrier) and coated onto the support followed by removal of the liquid. In some embodiments,
the application of solid particles of microporous material from a liquid composition
to the support surface can be assisted by application of a pressure differential across
the support. For example a vacuum can be applied from the opposite side of the support
as the liquid composition comprising the solid microporous particles to assist in
application of the solid particles to the surface of the support. A coated layer of
microporous material can be dried to remove residual solvent and optionally heated
to fuse the microporous particles together into a contiguous layer. Various membrane
structure configurations can be utilized, including but not limited to flat or planar
configurations, tubular configurations, or spiral configurations.
[0041] In some embodiments, the microporous material can be configured as nanoplatelets
such as zeolite nanosheets. Zeolite nanosheet particles can have thicknesses ranging
from 2 to 50 nm, more specifically 2 to 20 nm, and even more specifically from 2 nm
to 10 nm. The mean diameter of the nanosheets can range from 50 nm to 5000 nm, more
specifically from 100 nm to 2500 nm, and even more specifically from 100 nm to 1000
nm. Mean diameter of an irregularly-shaped tabular particle can be determined by calculating
the diameter of a circular-shaped tabular particle having the same surface area in
the x-y direction (i.e., along the tabular planar surface) as the irregularly-shaped
particle. Zeolite such as zeolite nanosheets can be formed from any of various zeolite
structures, including but not limited to framework type MFI, MWW, FER, LTA, FAU, and
mixtures of the preceding with each other or with other zeolite structures. In a more
specific group of exemplary embodiments, the zeolite such as zeolite nanosheets can
comprise zeolite structures selected from MFI, MWW, FER, LTA framework type. Zeolite
nanosheets can be prepared using known techniques such as exfoliation of zeolite crystal
structure precursors. For example, MFI and MWW zeolite nanosheets can be prepared
by sonicating the layered precursors (multilamellar silicalite-1 and ITQ-1, respectively)
in solvent. Prior to sonication, the zeolite layers can optionally be swollen, for
example with a combination of base and surfactant, and/or melt-blending with polystyrene.
The zeolite layered precursors are typically prepared using conventional techniques
for preparation of microporous materials such as sol-gel methods.
[0042] The above embodiments are examples of specific embodiments, and other variations
and modifications may be made. For example, a single membrane is depicted for ease
of illustration in the above-discussed Figures. However, multiple membranes (or membrane
separation units) can be utilized, either in cascaded or parallel configurations.
An example embodiment of a cascaded configuration is schematically depicted in FIG.
4. As shown in FIG. 4, membrane separation units 54a and 54b (with membranes 56a and
56b) are disposed in a cascaded configuration in which permeate from the separation
unit 54a is fed to the first side of the second separation unit 54b. Retentate from
the first side of the membranes 56a and 56b is routed through connections 67a and
67b to the refrigerant fluid circulation loop at the evaporator 40, with expansion
valves 68a and 68b utilized to accommodate the pressure differential between the first
side of the membrane 56 (which is close to the pressure at the condenser 20) and pressure
at the evaporator 40. Other system variations such as centrifugal separators or chilling
coils integrated with a purge chamber, pumped recycle of permeate back to the retentate
(upstream) side of the membrane, cascaded multiple membranes, heated membranes, or
alternative prime movers such as a thermal prime mover or a pump or compressor in
the fluid circulation loop, are described in more detail in US patent application
Serial No. / , entitled "Low Pressure Refrigeration System", filed on even date herewith
under attorney docket number 98251US01 (U301399US), the disclosure of which is incorporated
herein by reference in its entirety.
[0043] As mentioned above, the system includes a controller such as controller 50 for controlling
the operation of the heat transfer refrigerant flow loop and the purge system. As
mentioned above, a refrigeration or chiller system controller can operate the refrigerant
heat transfer flow loop in response to a cooling demand signal, which can be generated
externally to the system by a master controller or can be entered by a human operator.
Some systems can be configured to operate the flow loop continuously for extended
periods. The controller can also be configured to also operate the control device
in the retentate return flow path, or the prime mover, or both the control device
and the prime mover, in response to a purge signal. The purge signal can be generated
from various criteria. In some embodiments, the purge signal can be in response to
elapse of a predetermined amount of time (e.g., simple passage of time, or tracked
operating hours) tracked by the controller circuitry. In some embodiments, the purge
signal can be in response to human operator input. In some embodiments, the purge
signal can be in response to measured parameters of the refrigerant fluid flow loop.
For example, as shown in FIG. 5, a pressure sensor 80 at the condenser 20 (e.g., a
condenser discharge pressure sensor) can provide a pressure signal to the controller
50, based on which the controller can generate a purge signal control the expansion
valve 68 and/or the vacuum pump 58.
[0044] Various control schemes can be utilized for operating the vacuum pump 58 (or other
prime mover) and the expansion valve 68 (or other control device). For example, in
some embodiments, the controller 50 can be configured to operate the control device
to provide a varying flow rate through the connection 67 during purge. In some embodiments,
the controller 50 can be configured to operate a vacuum pump 58 or other prime mover
at a constant pressure during purge. In some embodiments, the controller 50 can be
configured to operate the vacuum pump 58 or other prime mover at varying pressure
during purge. In some embodiments, the controller 50 can be configured to vary vacuum
pressure or on/off status (with "off" including a vacuum shut-off valve (not shown))
during purge in coordination with varying settings of the control valve 68 or other
control device. For example, in some embodiments, the controller 50 can be configured
to alternately operate the vacuum pump 58 or other prime mover with the expansion
valve 68 or other control device closed and suspend operation of the vacuum pump 58
or other prime mover with the expansion valve 68 or other control device open. In
some embodiments, the expansion valve 68 or other control device can be left open
while the vacuum pump 58 or other prime mover is cycled on or off or with varying
output. In some embodiments, the vacuum pump 58 or other prime mover can be operated
continuously or at constant pressure while the expansion valve 68 or other control
device is cycled open and closed or to vary the flow rate or pressure drop across
the control device.
[0045] The term "about", if used, is intended to include the degree of error associated
with measurement of the particular quantity based upon the equipment available at
the time of filing the application. For example, "about" can include a range of ±
8% or 5%, or 2% of a given value.
1. A refrigeration system comprising
a heat transfer fluid circulation loop configured to allow a refrigerant to circulate
therethrough;
a purge outlet from the heat transfer fluid circulation loop;
at least one gas permeable membrane (56) comprising a porous inorganic material with
pores of a size to allow passage of contaminants through the membrane (56) and restrict
passage of the refrigerant through the membrane, said membrane (56) having a first
side in communication with the purge outlet; and
a retentate return flow path from the first side of the membrane (56) to the heat
transfer fluid circulation loop,
characterized in that:
the retentate flow path includes a control device, and/or
the system includes a prime mover configured to move gas from a second side of the
membrane (56) to an exhaust port leading outside the refrigeration system, and a controller
(50) configured to operate the refrigeration system in response to a cooling demand
signal, and to operate the prime mover in response to a purge signal.
2. The refrigeration system of claim 1, wherein the heat transfer fluid circulation loop
comprises a compressor (10), a heat rejection heat exchanger, an expansion device,
and a heat absorption heat exchanger, connected together in order by conduit (15,
25, 35, 45).
3. The refrigeration system of any preceding claim, wherein the controller (50) is further
configured to operate the control device in response to the purge signal.
4. The refrigeration system of any preceding claim,
wherein the prime mover comprises a vacuum pump (58) in communication with the second
side of the membrane (56) and/or.
further comprising a purge gas collector (66) between the purge outlet and the membrane
(56).
5. The refrigeration system of any preceding claim, wherein the control device comprises
an expansion device and returns retentate to the fluid circulation loop to the heat
absorption heat exchanger or to the compressor inlet.
6. The refrigeration system of any preceding claim,
wherein the at least one gas permeable membrane (56) comprises a plurality of gas
permeable membranes (56) in serial or parallel communication between the purge outlet
and the exhaust port; and/or
comprising a retentate return flow path operably coupling the first side of each of
plurality of membranes (56) to the fluid circulation loop.
7. The refrigeration system of any preceding claim, wherein the contaminant comprises
nitrogen, oxygen, or water.
8. The refrigeration system of any preceding claim,
wherein the system further comprises a pressure sensor (80) operably coupled to the
fluid circulation loop, and the controller (50) generates the purge signal in response
to output from the pressure sensor; and
wherein the pressure sensor (80) is optionally operably coupled to the condenser or
to the outlet of the compressor.
9. The refrigeration system of any preceding claim,
wherein the system further comprises a temperature sensor operably coupled to the
fluid circulation loop, and the controller (50) generates the purge signal in response
to output from the temperature sensor; and
wherein the temperature sensor is optionally operably coupled to the condenser or
evaporator.
10. The refrigeration system of any preceding claim, wherein the system further comprises
a refrigerant gas detection sensor operably coupled to second side of the membrane
(56), and the controller (50) generates the purge signal in response to output from
the refrigerant gas detection sensor; and/or
wherein the controller (50) is configured to generate the purge signal based at least
in part on a timer setting; and/or
wherein the controller (50) is configured, in response to the purge signal, to operate
the control device to provide a varying flow rate or pressure drop through the control
device.
11. The refrigeration system of any preceding claim,
wherein the controller (50) is configured, in response to the purge signal, to vary
prime mover pressure in coordination with varying the control device setting; and,
particularly,
wherein the control device includes a control valve, and the controller (50) is configured,
in response to the purge signal, to alternately operate the prime mover with the control
valve closed and suspend operation of the prime mover with the control valve open;
and/or
wherein the controller (50) is configured, in response to the purge signal, to operate
the prime mover at a constant pressure, or to operate the prime mover at a varying
pressure.
12. The refrigeration system of any preceding claim, wherein the purge outlet is operably
coupled to the condenser.
13. A method of operating the refrigeration system of any preceding claim, comprising
circulating the refrigerant through the vapor compression heat transfer fluid circulation
loop in response to the cooling demand signal under conditions in which the refrigerant
is at a pressure less than atmospheric pressure in at least a portion of the fluid
circulation loop; and
operating the prime mover and the control device with the controller (50) as configured.
1. Kühlsystem, das Folgendes umfasst:
eine Wärmeübertragungsfluid-Zirkulationsschleife, die dazu konfiguriert ist, einem
Kältemittel das Zirkulieren durch sie hindurch zu ermöglichen;
einen Spülauslass von der Wärmeübertragungsfluid-Zirkulationsschleife;
mindestens eine gasdurchlässige Membran (56), die ein poröses, anorganisches Material
mit Poren einer Größe umfasst, die den Durchgang von Verunreinigungen durch die Membran
(56) ermöglichen und den Durchgang des Kältemittels durch die Membran einschränken,
wobei die Membran (56) eine erste Seite in Verbindung mit dem Spülauslass aufweist;
und
einen Retentat-Rückströmungsweg von der ersten Seite der Membran (56) zu der Wärmeübertragungsfluid-Zirkulationsschleife,
dadurch gekennzeichnet, dass:
der Retentat-Strömungsweg eine Steuereinrichtung umfasst und/oder
das System eine Antriebsmaschine, die dazu konfiguriert ist, Gas von einer zweiten
Seite der Membran (56) an eine Abgasöffnung aus dem Kühlsystem heraus zu bewegen,
und eine Steuerung (50) beinhaltet, die dazu konfiguriert ist, das Kühlsystem als
Reaktion auf ein Kältebedarfssignal zu betreiben und die Antriebsmaschine als Reaktion
auf ein Spülsignal zu betreiben.
2. Kühlsystem nach Anspruch 1, wobei die Wärmeübertragungsfluid-Zirkulationsschleife
einen Verdichter (10), einen Wärmeabgabewärmetauscher, eine Expansionseinrichtung
und einen Wärmeaufnahmewärmetauscher umfasst, die durch eine Leitung (15, 25, 35,
45) in Reihe verbunden sind.
3. Kühlsystem nach einem der vorhergehenden Ansprüche, wobei die Steuerung (50) ferner
dazu konfiguriert ist, die Steuereinrichtung als Reaktion auf das Spülsignal zu betreiben.
4. Kühlsystem nach einem der vorhergehenden Ansprüche,
wobei die Antriebsmaschine eine Vakuumpumpe (58) in Verbindung mit der zweiten Seite
der Membran (56) umfasst und/ oder
ferner einen Spülgassammler (66) zwischen dem Spülauslass und der Membran (56) umfasst.
5. Kühlsystem nach einem der vorhergehenden Ansprüche, wobei die Steuereinrichtung eine
Expansionseinrichtung umfasst und Retentat an die Fluidzirkulationsschleife, an den
Wärmeabgabewärmetauscher oder an den Verdichtereinlass zurückführt.
6. Kühlsystem nach einem der vorhergehenden Ansprüche,
wobei die mindestens eine gasdurchlässige Membran (56) eine Vielzahl an gasdurchlässigen
Membranen (56) in serieller oder paralleler Verbindung zwischen dem Spülauslass und
der Abgasöffnung umfasst; und/oder
einen Retentat-Rückströmungsweg umfasst, der die erste Seite jeder der Vielzahl an
Membranen (56) betriebsmäßig an die Fluidzirkulationsschleife koppelt.
7. Kühlsystem nach einem der vorhergehenden Ansprüche, wobei die Verunreinigung Stickstoff,
Sauerstoff oder Wasser umfasst.
8. Kühlsystem nach einem der vorhergehenden Ansprüche,
wobei das System ferner einen Drucksensor (80) umfasst, der betriebsmäßig an die Fluidzirkulationsschleife
gekoppelt ist und wobei die Steuerung (50) das Spülsignal als Reaktion auf die Ausgabe
des Drucksensors generiert; und
wobei der Drucksensor (80) optional betriebsmäßig an den Kondensator oder den Auslass
des Verdichters gekoppelt ist.
9. Kühlsystem nach einem der vorhergehenden Ansprüche,
wobei das System ferner einen Temperatursensor umfasst, der betriebsmäßig an die Fluidzirkulationsschleife
gekoppelt ist und wobei die Steuerung (50) das Spülsignal als Reaktion auf die Ausgabe
des Temperatursensors generiert; und
wobei der Temperatursensor optional betriebsmäßig an den Kondensator oder den Verdampfer
gekoppelt ist.
10. Kühlsystem nach einem der vorhergehenden Ansprüche, wobei das System ferner einen
Kältemittelgaserkennungssensor umfasst, der betriebsmäßig an die zweite Seite der
Membran (56) gekoppelt ist und wobei die Steuerung (50) das Spülsignal als Reaktion
auf die Ausgabe des Kältemittelgaserkennungssensors generiert; und/oder
wobei die Steuerung (50) dazu konfiguriert ist, das Spülsignal mindestens teilweise
auf Grundlage einer Timer-Einstellung zu generieren; und/oder
wobei die Steuerung (50) als Reaktion auf das Spülsignal dazu konfiguriert ist, die
Steuereinrichtung zu betreiben, um eine variable Strömungsgeschwindigkeit oder einen
Druckabfall über die Steuereinrichtung bereitzustellen.
11. Kühlsystem nach einem der vorhergehenden Ansprüche,
wobei die Steuerung (50) als Reaktion auf das Spülsignal dazu konfiguriert ist, den
Antriebsmaschinendruck in Koordination mit variablen Steuereinheitseinstellungen zu
variieren; und insbesondere
wobei die Steuereinheit ein Steuerventil umfasst und wobei die Steuerung (50) als
Reaktion auf das Spülsignal dazu konfiguriert ist, abwechselnd die Antriebsmaschine
mit geschlossenem Steuerventil zu betreiben und den Betrieb der Antriebsmaschine mit
geöffnetem Steuerventil einzustellen; und/oder
wobei die Steuerung (50) als Reaktion auf das Spülsignal dazu konfiguriert ist, die
Antriebsmaschine mit einem konstanten Druck zu betreiben oder die Antriebsmaschine
mit einem variablen Druck zu betreiben.
12. Kühlsystem nach einem der vorhergehenden Ansprüche, wobei der Spülauslass betriebsmäßig
an den Kondensator gekoppelt ist.
13. Verfahren zum Betreiben des Kühlsystems nach einem der vorhergehenden Ansprüche, das
Folgendes umfasst:
Zirkulieren des Kältemittels durch die Dampfkompressionswärmeübertragungsfluid-Zirkulationsschleife
als Reaktion auf das Kältebedarfssignal unter Bedingungen, in denen das Kältemittel
mindestens in einem Abschnitt der Fluidzirkulationsschleife einen geringeren Druck
als den Umgebungsdruck aufweist; und
Betreiben der Antriebsmaschine und der Steuereinrichtung mit der Steuerung (50) gemäß
der Konfiguration.
1. Système de réfrigération comprenant :
une boucle de circulation de fluide de transfert de chaleur conçue pour permettre
à un réfrigérant de circuler à travers celle-ci ;
une sortie de purge provenant de la boucle de circulation du fluide de transfert de
chaleur ;
au moins une membrane perméable au gaz (56) comprenant un matériau inorganique poreux
avec des pores d'une taille pour permettre le passage de contaminants à travers la
membrane (56) et restreindre le passage du réfrigérant à travers la membrane, ladite
membrane (56) ayant un premier côté en communication avec la sortie de purge ; et
un trajet d'écoulement de retour de rétentat depuis le premier côté de la membrane
(56) vers la boucle de circulation de fluide de transfert de chaleur, caractérisé en ce que :
le trajet d'écoulement de rétentat comporte un dispositif de commande, et/ou
le système comporte un moteur principal conçu pour déplacer du gaz depuis un second
côté de la membrane (56) vers un orifice d'échappement menant à l'extérieur du système
de réfrigération, et un régulateur (50) conçu pour faire fonctionner le système de
réfrigération en réponse à un signal de demande de refroidissement, et pour faire
fonctionner le moteur principal en réponse à un signal de purge.
2. Système de réfrigération selon la revendication 1, dans lequel la boucle de circulation
de fluide de transfert de chaleur comprend un compresseur (10), un échangeur de chaleur
à rejet de chaleur, un dispositif de détente et un échangeur de chaleur à absorption
de chaleur, reliés ensemble dans l'ordre par un conduit (15, 25, 35, 45).
3. Système de réfrigération selon une quelconque revendication précédente, dans lequel
le régulateur (50) est en outre conçu pour faire fonctionner le dispositif de commande
en réponse au signal de purge.
4. Système de réfrigération selon une quelconque revendication précédente,
dans lequel le moteur principal comprend une pompe à vide (58) en communication avec
le second côté de la membrane (56) et/ou
comprenant en outre un collecteur de gaz de purge (66) entre la sortie de purge et
la membrane (56).
5. Système de réfrigération selon une quelconque revendication précédente, dans lequel
le dispositif de commande comprend un dispositif de détente et renvoie le rétentat
à la boucle de circulation de fluide vers l'échangeur de chaleur à absorption de chaleur
ou à l'entrée de compresseur.
6. Système de réfrigération selon une quelconque revendication précédente,
dans lequel l'au moins une membrane perméable au gaz (56) comprend une pluralité de
membranes perméables au gaz (56) en communication en série ou parallèle entre la sortie
de purge et l'orifice d'échappement ; et/ou
comprenant un trajet d'écoulement de retour de rétentat couplant de manière fonctionnelle
le premier côté de chacune d'une pluralité de membranes (56) à la boucle de circulation
de fluide.
7. Système de réfrigération selon une quelconque revendication précédente, dans lequel
le contaminant comprend de l'azote, de l'oxygène ou de l'eau.
8. Système de réfrigération selon une quelconque revendication précédente,
dans lequel le système comprend en outre un capteur de pression (80) couplé de manière
fonctionnelle à la boucle de circulation de fluide, et le régulateur (50) émet le
signal de purge en réponse à la sortie du capteur de pression ; et
dans lequel le capteur de pression (80) est éventuellement couplé de manière fonctionnelle
au condenseur ou à la sortie du compresseur.
9. Système de réfrigération selon une quelconque revendication précédente,
dans lequel le système comprend en outre un capteur de température couplé de manière
fonctionnelle à la boucle de circulation de fluide, et le régulateur (50) émet le
signal de purge en réponse à la sortie du capteur de température ; et
dans lequel le capteur de température est éventuellement couplé de manière fonctionnelle
au condenseur ou à l'évaporateur.
10. Système de réfrigération selon une quelconque revendication précédente, dans lequel
le système comprend en outre un capteur de détection de gaz réfrigérant couplé de
manière fonctionnelle au second côté de la membrane (56), et le régulateur (50) émet
le signal de purge en réponse à la sortie du capteur de détection de gaz réfrigérant
; et/ou
dans lequel le régulateur (50) est conçu pour émettre le signal de purge sur la base
au moins en partie d'un réglage de minuterie ; et/ou
dans lequel le régulateur (50) est conçu, en réponse au signal de purge, pour faire
fonctionner le dispositif de commande afin de fournir un débit ou une chute de pression
variable à travers le dispositif de commande.
11. Système de réfrigération selon une quelconque revendication précédente,
dans lequel le régulateur (50) est conçu, en réponse au signal de purge, pour faire
varier la pression du moteur principal en coordination avec la variation du réglage
du dispositif de commande ; et en particulier,
dans lequel le dispositif de commande comporte une soupape de commande, et le régulateur
(50) est conçu, en réponse au signal de purge, pour faire fonctionner alternativement
le moteur principal avec la soupape de commande fermée et suspendre le fonctionnement
du moteur principal avec la soupape de commande ouverte ; et/ou
dans lequel le régulateur (50) est conçu, en réponse au signal de purge, pour faire
fonctionner le moteur principal à une pression constante, ou pour faire fonctionner
le moteur principal à une pression variable.
12. Système de réfrigération selon une quelconque revendication précédente, dans lequel
la sortie de purge est couplée de manière fonctionnelle au condenseur.
13. Procédé de fonctionnement du système de réfrigération selon une quelconque revendication
précédente, comprenant
la circulation du réfrigérant à travers la boucle de circulation de fluide de transfert
de chaleur par compression de vapeur en réponse au signal de demande de refroidissement
dans des conditions dans lesquelles le réfrigérant est à une pression inférieure à
la pression atmosphérique dans au moins une partie de la boucle de circulation de
fluide ; et
le fait de faire fonctionner le moteur principal et le dispositif de commande avec
le régulateur (50) tel que configuré.