U.S. patent application number 12/450099 was filed with the patent office on 2010-11-11 for device and method for drying fluids conducted in closed circuits.
Invention is credited to Peter Behrends, Alexander Brodel.
Application Number | 20100281891 12/450099 |
Document ID | / |
Family ID | 39522003 |
Filed Date | 2010-11-11 |
United States Patent
Application |
20100281891 |
Kind Code |
A1 |
Behrends; Peter ; et
al. |
November 11, 2010 |
DEVICE AND METHOD FOR DRYING FLUIDS CONDUCTED IN CLOSED
CIRCUITS
Abstract
A device for drying fluids conducted in a closed circuit
provides a bypass line which can be switched in parallel to a pipe
of the closed circuit that conducts a fluid via a first valve and a
second valve. A first demoisturizer may be disposed in the bypass
line. A method for drying fluids conducted in closed circuits is
also provided. Part of the fluid may be directed from the pipe of
the closed circuit into the bypass line connected in parallel to
the pipe of the closed circuit and dried using the device according
to the system described herein.
Inventors: |
Behrends; Peter; (Bobbau,
DE) ; Brodel; Alexander; (Lenzkirch-Kappel,
DE) |
Correspondence
Address: |
MUIRHEAD AND SATURNELLI, LLC
200 FRIBERG PARKWAY, SUITE 1001
WESTBOROUGH
MA
01581
US
|
Family ID: |
39522003 |
Appl. No.: |
12/450099 |
Filed: |
March 13, 2008 |
PCT Filed: |
March 13, 2008 |
PCT NO: |
PCT/EP2008/002007 |
371 Date: |
January 4, 2010 |
Current U.S.
Class: |
62/85 ;
62/474 |
Current CPC
Class: |
F25B 2700/02 20130101;
B01D 53/26 20130101; F25B 41/20 20210101; F25B 2500/14 20130101;
F24F 3/1417 20130101; F25B 43/003 20130101 |
Class at
Publication: |
62/85 ;
62/474 |
International
Class: |
F25B 47/00 20060101
F25B047/00; F25B 43/00 20060101 F25B043/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 14, 2007 |
DE |
10 2007 013 092.0 |
Claims
1. A device for drying fluids circulating in closed circuits,
comprising: a bypass line which is switchable via a first valve and
a second valve parallel to a pipe of a closed circuit conducting a
fluid; and a first demoisturizer situated in the bypass line.
2. The device as recited in claim 1, further comprising: a second
demoisturizer situated in the bypass line downstream from the first
demoisturizer.
3. The device as recited in claim 2, further comprising: a third
valve situated between the first valve and the first demoisturizer;
and a fourth valve situated between the second demoisturizer and
the second valve, either the first demoisturizer or the second
demoisturizer being switchable downstream from the first valve via
the third valve in the direction of flow, and either the second
demoisturizer or the first demoisturizer being switchable upstream
from the second valve via the fourth valve, so that when the fluid
flows from the third valve to the fourth valve, the fluid flows
either first through the first demoisturizer and then through the
second demoisturizer or first through the second demoisturizer and
then through the first demoisturizer.
4. The device as recited in claim 1, wherein the first
demoisturizer includes at least one of: a moisture exchanger and a
moisture filter.
5. The device as recited in claim 2, wherein the second
demoisturizer includes at least one of: a moisture exchanger and a
moisture filter.
6. The device as recited in claim 2, wherein at least one of: the
first demoisturizer and the second demoisturizer includes a
moisture filter having an integrated moisture exchanger.
7. The device as recited in claim 2, wherein the first
demoisturizer includes a moisture filter and the second
demoisturizer includes a moisture exchanger.
8. The device as recited in claim 2, wherein the first
demoisturizer and the second demoisturizer include moisture
filters, and the device further comprising: an additional
demoisturizer situated between the first demoisturizer and the
second demoisturizer, wherein the additional demoisturizer includes
a moisture exchanger.
9. The device as recited in claim 1, wherein at least one of: the
first demoisturizer and the second demoisturizer includes a
moisture exchanger, and the device further comprising: a moisture
gradient device for generating a moisture gradient, wherein the
moisture gradient device is situated on a side of the moisture
exchanger facing away from the closed circuit.
10. The device as recited in claim 9, wherein the moisture gradient
device includes a vacuum device for generating a vacuum.
11. The device as recited in claim 9, the moisture gradient device
includes a drying agent supply device which directs a drying agent
past a moisture exchanger into a drying agent discharge device.
12. The device as recited in claim 11, further comprising: a third
demoisturizer situated between the drying agent supply device and
the moisture exchanger.
13. The device as recited in claim 12, further comprising: a fourth
demoisturizer situated between the moisture exchanger and the
drying agent discharge device.
14. The device as recited in claim 13, further comprising: a fifth
valve situated between the drying agent supply device and the third
demoisturizer; and a sixth valve is situated between the fourth
demoisturizer and the drying agent discharge device, either the
third demoisturizer or the fourth demoisturizer being switchable
downstream from the drying agent supply device via the fifth valve
in the direction of flow, and either the fourth demoisturizer or
the third demoisturizer being switchable upstream from the drying
agent discharge device via the sixth valve, so that when the fluid
flows from the drying agent supply device to the drying agent
discharge device, the fluid flows either first through the third
demoisturizer and then through the fourth demoisturizer or first
through the fourth demoisturizer and then through the third
demoisturizer.
15. The device as recited in claim 13, wherein at least one of: the
third demoisturizer and the fourth demoisturizer includes a
moisture filter.
16. The device as recited in claim 4, wherein the moisture filter
is a zeolith filter.
17. The device as recited in claim 1, wherein the first
demoisturizer is heatable.
18. The device as recited in claim 4, wherein the moisture
exchanger is heatable.
19. The device as recited in claim 4, wherein the moisture
exchanger is a moisture-permeable diaphragm.
20. The device as recited in claim 4, wherein the moisture
exchanger includes a porous ceramic tube having a zeolith
coating.
21. The device as recited in claim 20, wherein the ceramic tube is
filled with a zeolith granulate.
22. The device as recited in claim 21, wherein the ceramic tube is
made of a PTC ceramic.
23. The device as recited in claim 1, further comprising: a
compressor situated in the pipe of the closed circuit conducting
the fluid.
24. The device as recited in claim 1, further comprising: a
moisture sensor situated in the bypass line.
25. The device as recited in claim 1, wherein, at least one of the
following: the fluid is a refrigerant, and the closed circuit is a
refrigeration system.
26. A method for drying fluids circulating in closed circuits,
comprising: directing at least part of a fluid from a pipe of a
closed circuit conducting the fluid into a bypass line connected in
parallel to the pipe of the closed circuit conducting the fluid;
and drying the at least part of the fluid using a drying device
disposed in the bypass line, the drying device including at least
one demoisturizer.
27. A method for drying fluids circulating in closed circuits,
comprising: directing at least part of a fluid from a pipe of a
closed circuit conducting the fluid into a bypass line, connected
in parallel to the pipe of the closed circuit, via a first valve
and a second valve; and drying the at least part of the fluid using
a drying device disposed in the bypass line, the drying device
including: a first demoisturizer that includes a first moisture
filter; and a second demoisturizer that includes a moisture
exchanger, wherein the moisture filter is heated when reaching a
defined moisture threshold value to drive out moisture accumulated
in the moisture filter and discharge the moisture via the moisture
exchanger.
28. The method as recited in claim 27, wherein the drying device
further includes a third demoisturizer disposed in the bypass line,
the third moisturizer including a second moisture filter.
29. The method as recited in claim 27, wherein a third valve is
situated between the first valve and the first demoisturizer, and a
fourth valve is situated between the second demoisturizer and the
second valve, either the first demoisturizer or the second
demoisturizer being switchable downstream from the first valve via
the third valve in the direction of flow, and either the second
demoisturizer or the first demoisturizer is switchable upstream
from the second valve via the fourth valve, so that when the fluid
flows from the third valve to the fourth valve, the fluid flows
either first through the first demoisturizer and then through the
second demoisturizer or first through the second demoisturizer and
then through the first demoisturizer.
30. The method as recited in claim 29, wherein, after heating the
first demoisturizer for driving out the accumulated moisture, the
direction of flow is reversed.
31. The method as recited in claim 27, wherein the drying device
further includes a device for generating a moisture gradient that
is situated on a side of the moisture exchanger facing away from
the closed circuit.
32. The device as recited in claim 13, wherein at least one of: the
first demoisturizer, the second demoisturizer, the third
demoisturizer, and the fourth demoisturizer is heatable.
33. The device as recited in claim 19, wherein the
moisture-permeable diaphragm is at least one of: a Nafion diaphragm
and a zeolith molecular sieve.
34. The device as recited in claim 24, wherein the moisture sensor
is disposed downstream from the first demoisturizer.
Description
[0001] The present invention relates to a device for drying fluids
circulating in closed circuits and a method for drying fluids
circulating in closed circuits.
[0002] Fluids are circulated in closed circuits in various
applications, it being essential that the fluids are dry.
[0003] Moisture, in particular water in refrigerants in
refrigeration systems, represents a serious problem for the
operational capability of the refrigeration system. On the one
hand, important components may become iced and frozen, which
prevents the refrigerant from flowing. On the other hand, water in
conjunction with refrigerant oil results in the formation of acids,
which may cause acid corrosion and occasionally burnout of the
compressor present in the refrigeration system. Therefore, it is
necessary to reduce the moisture content in the refrigeration
circuit and to keep it as low as possible during the operation of
the system.
[0004] It is known to shut down the entire refrigeration system and
then to remove and dispose of all the refrigerant present in the
refrigeration system, to dry the system using nitrogen, and to fill
it again using dry refrigerant. A procedure of this type results in
the refrigeration system being entirely down for a longer time and,
on the other hand, high costs being incurred because the
refrigerant must be fully replaced and, in addition, disposed
of.
[0005] It is furthermore known to install a demoisturizer in the
form of a moisture filter in a line of the refrigeration system
conducting the refrigerant, in particular upstream from a
compressor. The refrigerant thus flows through the moisture filter,
which filters out the moisture, which is thus enriched in the
moisture filter. The moisture filter must be monitored to prevent
the moisture filter from becoming fully saturated, which may result
in water breakthrough. The moisture filter must therefore be
replaced regularly, which also results in downtime of the
refrigeration system and is associated with high labor costs.
[0006] The object of the present invention is therefore to provide
a device and a method for drying fluids circulating in closed
circuits which makes it possible to continuously dry the fluid
during ongoing operation of the closed circuit and thus avoids high
expenditures in terms of time and costs.
[0007] The object is achieved according to the present invention by
using a device for drying fluids circulating in closed circuits
having the features of Patent Claim 1, and a method for drying
fluids circulating in closed circuits having the features of Patent
Claims 26 or 27.
[0008] The subclaims provide advantageous embodiments and
refinements of the present invention.
[0009] The device according to the present invention for drying
fluids circulating in closed circuits is based on providing a
bypass line which is switchable via a first valve and a second
valve parallel to a fluid-conducting line of the closed circuit. A
portion of the fluid flowing through the closed circuit is thus
deviated into the bypass line. According to the present invention,
a first demoisturizer, which removes the moisture from the fluid,
is situated in the bypass line. Since the demoisturizer is no
longer situated directly in the closed circuit, if the
demoisturizer has to be replaced, the bypass line may be closed to
the closed circuit via the first and second valves, whereupon the
demoisturizer may be removed from the bypass line and replaced with
a new or cleaned demoisturizer.
[0010] In an advantageous refinement of the present invention, a
second demoisturizer is situated in the bypass line downstream from
the first demoisturizer, the second demoisturizer being able to
take up the moisture not taken up by the first demoisturizer, to
improve the effectiveness of the fluid drying.
[0011] In a particularly preferred specific embodiment of the
present invention, a third valve is situated between the first
valve and the first demoisturizer, and a fourth valve is situated
between the second demoisturizer and the second valve, either the
first demoisturizer or the second demoisturizer being switchable
downstream from the valve via the third valve in the direction of
flow, and either the second demoisturizer or the first
demoisturizer being switchable upstream from the second valve via
the fourth valve, so that when the fluid flows from the third valve
to the fourth valve, it flows either first through the first
demoisturizer and then through the second demoisturizer or,
alternatively, first through the second demoisturizer and then
through the first demoisturizer.
[0012] The first and/or second demoisturizer(s) may be designed as
moisture exchanger(s), moisture filter(s), or also as moisture
filter(s) having integrated moisture exchanger(s). In one specific
embodiment, the first demoisturizer is designed as a moisture
filter and the second demoisturizer is designed as a moisture
exchanger, or the first and/or second demoisturizer(s) is/are
designed as moisture filter(s) having integrated moisture
exchanger(s), to first enrich the moisture in the moisture filter
during the operation of the closed circuit and subsequently, when a
certain degree of saturation has been reached in the moisture
filter, to be able to heat the moisture filter, for example, and
discharge the moisture out of the closed circuit and the bypass
line to the outside via the moisture exchanger without affecting,
in particular shutting off, the closed circuit or opening the
bypass circuit. The moisture exchanger thus has the advantage that
moisture may be discharged from the closed circuit without downtime
of the circuit, the moisture exchanger needing a certain moisture
gradient for effective water discharge. This is achieved by
combining the moisture exchanger with a moisture filter, which
first enriches the moisture and then releases a large quantity of
it in a controlled manner, so that a high moisture gradient is
obtained across the moisture exchanger and the moisture exchanger
effectively discharges the moisture.
[0013] In a particularly preferred specific embodiment of the
present invention, the first and second demoisturizers are designed
as moisture filters, while another demoisturizer in the form of an
additional moisture exchanger is situated between the two moisture
filters. In particular with the possibility of modifying the
direction of flow via the bypass line, this construction makes it
possible to first accumulate most of the moisture in one of the two
demoisturizers, which are designed as moisture filters, for
example, in the first demoisturizer, while the other, for example,
the second demoisturizer, filters out the residual moisture from
the fluid and subsequently, when the degree of saturation in the
first demoisturizer has been reached, makes the first demoisturizer
release water in a controlled manner, for example, via heating, to
then discharge the moisture via the moisture exchanger situated
downstream from the first demoisturizer, the second demoisturizer
being able to continue to filter out the residual moisture that is
not discharged via the moisture exchanger. The direction of flow
may be subsequently modified, so that the second demoisturizer
removes most of the moisture from the fluid, which makes it
possible to achieve maximally effective drying and maximum moisture
discharge.
[0014] If the fluid only flows past the moisture exchanger, this
means a very low water content, so that the moisture gradient is
relatively small and the moisture exchanger cannot operate in an
optimum or effective manner. Therefore a device for generating a
moisture gradient is situated preferably on the side of the
moisture exchanger facing away from the closed circuit. In one
specific embodiment, this device may be designed as a device for
generating a vacuum. Alternatively, the device for generating a
moisture gradient is designed as a drying agent supply device,
which conducts a drying agent past the moisture exchanger into a
drying agent discharge device. The drying agent may be air or
nitrogen, for example. The drying agent is preferably further
demoisturized via another device.
[0015] For this purpose, in a preferred specific embodiment, a
third demoisturizer, which removes moisture from the drying agent,
is situated between the drying agent supply device and the moisture
exchanger, so that the moisture gradient across the moisture
exchanger is increased.
[0016] A fourth demoisturizer may be preferably situated between
the moisture exchanger and the drying agent discharge device, which
also removes the moisture again from the drying agent which has
been taken up by the drying agent at the moisture exchanger and
removed from the closed circuit, in particular if the drying agent
is directed past the moisture exchanger again.
[0017] In a particularly preferred specific embodiment of the
present invention, a fifth valve is situated between the drying
agent supply device and the third demoisturizer, and a sixth valve
is situated between the fourth demoisturizer and the drying agent
discharge device, either the third demoisturizer or the fourth
demoisturizer being switchable downstream from the drying agent
supply device via the fifth valve in the direction of flow, and
alternatively either the fourth demoisturizer or the third
demoisturizer being switchable upstream from the drying agent
discharge device via the sixth valve, so that when the fluid flows
from the drying agent supply device to the drying agent discharge
device, it flows either first through the third demoisturizer and
then through the fourth demoisturizer or, alternatively, first
through the fourth demoisturizer and then through the third
demoisturizer. A particularly effective drying of the drying agent
is thus possible also in the drying agent circuit as described
previously. However, even if the drying agent is not circulated,
this design ensures that a demoisturizer is basically situated
upstream from the moisture exchanger in both directions of flow to
thus ensure that dry drying agent is conducted to the moisture
exchanger and thus the moisture gradient is increased and that, on
the other hand, each demoisturizer may be switched upstream from
the drying agent discharge device to dry the demoisturizer, so that
when the demoisturizer is heated, the moisture may be conducted
directly into the drying agent discharge device without being
directed past the moisture exchanger to there reduce the moisture
gradient or even introduce moisture into the closed fluid
circuit.
[0018] In a preferred specific embodiment in particular, the third
and/or fourth demoisturizer(s) is/are designed as moisture
filters.
[0019] The moisture filters are preferably designed as zeolith
filters to ensure effective enrichment of the moisture in the
filter.
[0020] To drive out the moisture from the demoisturizers without
replacing the demoisturizers, the different demoisturizers are
preferably heatable. For the same reason, the additional moisture
exchanger, if present, is also heatable.
[0021] The moisture exchanger is preferably designed as a
moisture-permeable diaphragm, in particular as a Nafion diaphragm
or as a zeolith molecular sieve to ensure that water, but not the
fluid or the drying agent, may pass through the diaphragm. In an
alternative specific embodiment, the moisture exchanger is designed
as a porous ceramic tube having a zeolith coating. On the one hand,
the zeolith coating absorbs the moisture, but it also allows the
moisture to pass through. In a preferred specific embodiment, the
ceramic tube is filled with a zeolith granulate to enhance the
storage capacity for moisture and thus to form a combined moisture
filter having an integrated moisture exchanger. The ceramic is a
PTC ceramic, for example, which has the advantage that it may also
be used for heating, in addition to its support function.
[0022] To maintain the continuous flow of fluid through the bypass
line, the bypass line is preferably switched to a pipe of the
closed circuit conducting fluid, which has a compressor. This
generates the appropriate pressure gradient, which maintains the
necessary fluid flow.
[0023] To check how effectively the particular demoisturizers have
demoisturized the fluid, a moisture sensor is placed in the bypass
line, preferably downstream from the first demoisturizer, in
particular upstream from the point where the fluid is returned into
the closed circuit.
[0024] Particularly preferably, the fluid is a refrigerant and/or
the closed circuit is designed as a refrigeration system, since
refrigerants should contain no moisture in order to ensure reliable
operation of the refrigeration system.
[0025] The method according to the present invention for drying
fluids circulating in closed circuits is based on diverting a part
of the fluid from a fluid-conducting pipe of the closed circuit
into a bypass line connected in parallel to the pipe conducting the
fluid. A device for drying a fluid according to the present
invention, using which moisture is removed from the fluid, is
situated in the bypass line. By situating the device in a bypass
line it is possible, on the one hand, to dry the fluid during the
operation of the closed circuit, and, on the other hand, to service
and replace a defective device for drying a fluid or a device for
drying a fluid in which a demoisturizer is saturated.
[0026] In the method according to the present invention a device
for drying a fluid having at least one first demoisturizer, which
is designed as a moisture filter, and at least one other
demoisturizer, which is designed as a moisture exchanger, is
preferably situated in the bypass line; of course, the moisture
filter and the moisture exchanger may also be situated integrated
in a demoisturizer. When a defined moisture threshold value is
reached, the moisture filter is heated to drive out the moisture
accumulated in the moisture filter and to discharge it via the
moisture exchanger. This makes it possible that the bypass line
does not have to be opened for removing the moisture, which has
accumulated in a demoisturizer in the bypass line, from the bypass
line. In particular, no fluid escapes from the bypass line to the
environment, so that no costs arise for disposing of the fluid.
[0027] A second demoisturizer, which is designed as a moisture
filter and is capable of taking up the moisture not filtered out by
the first moisture filter, thus increasing the degree of drying, is
preferably situated in the bypass line.
[0028] A third valve is preferably situated between the first valve
and the first demoisturizer, and a fourth valve is situated between
the second demoisturizer and the second valve, either the first
demoisturizer or the second demoisturizer being switchable
downstream from the first valve via the third valve in the
direction of flow, and either the second demoisturizer or the first
demoisturizer being switchable upstream from the second valve via
the fourth valve, so that when the fluid flows from the third valve
to the fourth valve, it flows either first through the first
demoisturizer and then through the second demoisturizer or,
alternatively, first through the second demoisturizer and then
through the first demoisturizer. This makes it possible to reverse
the direction of flow. A change in the direction of flow is
preferably provided after the moisture filter has been heated to
drive out the accumulated moisture to ensure maximum exchange and
the most effective possible drying both of the drying agents and of
the demoisturizers.
[0029] In a preferred specific embodiment of the method, the
moisture gradient is increased for optimum operation of the
moisture exchanger by placing a device for generating a moisture
gradient on the side of the moisture exchanger facing away from the
closed circuit.
[0030] The present invention is described in greater detail with
reference to the figures below.
[0031] FIG. 1 shows a schematic view of a first exemplary
embodiment of the present invention;
[0032] FIG. 2 shows a schematic view of a second exemplary
embodiment of the present invention;
[0033] FIG. 3 shows a schematic view of a third exemplary
embodiment of the present invention;
[0034] FIG. 4 shows a schematic view of a fourth exemplary
embodiment of the present invention; and
[0035] FIG. 5 shows a schematic view of a fifth exemplary
embodiment of the present invention.
[0036] FIGS. 1 through 5 show different exemplary embodiments of
the present invention, the same reference numerals identifying the
same components.
[0037] FIG. 1 shows a first exemplary embodiment of a device for
drying a fluid circulating in a closed circuit. The closed circuit
is designed, for example, as a refrigeration system in which a
refrigerant is circulated as the fluid. In FIG. 1, a pipe 10, which
conducts a refrigerant, is illustrated as a component of a
refrigeration system. A compressor 15, which maintains and, if
necessary, regulates, the velocity of the flow is situated in pipe
10 conducting the refrigerant. Situated parallel to pipe 10 is a
bypass line 20, which is connected to pipe 10 via a first valve V1
and a second valve V2 and may also be completely isolated from pipe
10 via these two valves V1, V2. A portion of the refrigerant
circulating in pipe 10 flows through first valve V1 into bypass
line 20 when this valve V1 is open. The refrigerant flow in bypass
line 20 should possibly amount to less than 5% of the total flow of
refrigerant and, in particular, should not exceed 10% of the total
mass flow in order to disturb the refrigerant flow in the
refrigeration system as little as possible. A throttle valve 24,
which is used for regulating the mass flow through bypass line 20,
is situated downstream from first valve V1. The direction of flow
of the refrigerant is indicated by the outlined arrows in FIG.
1.
[0038] A first demoisturizer E1, through which the refrigerant
flows, is situated in bypass line 20. The first demoisturizer may
be, in principle, a moisture exchanger or, as illustrated in FIG.
1, a moisture filter, in particular a zeolith filter 50. This
moisture filter has a housing E1a, which is sealed to the outside.
Neither refrigerant nor moisture may thus escape from housing E1a
of first demoisturizer E1. The refrigerant is dried in first
demoisturizer E1, the moisture being enriched in zeolith filter 50.
The refrigerant thus dried flows on through bypass line 20 toward
second valve V2, to enter pipe 10 of the refrigeration system again
downstream from second valve V2. Before the refrigerant enters pipe
10, in particular upstream from second valve V2, there is a
moisture sensor 22, which checks the degree of drying reached by
the refrigerant. In particular, the operation of first
demoisturizer E1 may also be checked using moisture sensor 22.
Since the moisture accumulates in first demoisturizer E1, in
particular in zeolith filter 50, the moisture content of zeolith
filter 50 increases. In the event of high water content in zeolith
filter 50, there is the risk of a water breakthrough. The water
content of zeolith filter 50 must therefore be monitored,
preferably via an appropriately integrated sensor. Zeolith filter
50 must be replaced in regular intervals to prevent a water
breakthrough. For that purpose, valves V1, V2 are closed, so that
bypass line 20 may be opened without disturbing the operation of
the refrigeration system. Subsequently first demoisturizer E1 may
be removed and replaced by a new demoisturizer or reinstalled after
cleaning and drying. By monitoring the water content using a
moisture sensor 22 or similar means for detecting the saturation
state of zeolith filter 50, a stop of the flow through bypass line
20 may also be triggered automatically by activating valves V1, V2.
Closing valve V2 is sufficient in this case
[0039] Since in this specific embodiment a refrigerant in bypass
line 20 must be disposed of at an additional cost, in a second
specific embodiment of the invention, which is illustrated in FIG.
2, another demoisturizer E5 is installed in bypass line 20.
Demoisturizer E5 is designed as a moisture exchanger 30. Moisture
may be removed from the system facing the refrigeration system and
bypass line 20 using a moisture exchanger 30 via a
moisture-permeable layer, in particular a moisture-permeable
diaphragm 32, without having to open bypass line 20 to the outside.
Refrigerant, however, cannot pass through moisture-permeable
diaphragm 32, so that there is no risk that the refrigerant may
escape from bypass line 20. Moisture exchanger 30 operates in such
a way that in the event of a sufficiently high moisture gradient
between the two sides of moisture-permeable diaphragm 32, moisture
diffuses through the diaphragm and may be discharged on the other
side. Moisture-permeable diaphragm 32 may be made of Nafion or
zeolith.
[0040] In the present second exemplary embodiment, most of the
moisture contained in the refrigerant may be collected in zeolith
filter 50 via first demoisturizer E1. Further residual moisture may
be removed via the additional demoisturizer E5, in particular if
the gradient is sufficiently high, for example, because first
demoisturizer E1 has reached its degree of saturation. If first
demoisturizer E1 has reached its degree of saturation, the flow
rate is strongly throttled via throttle valve 24, and first
demoisturizer E1 is heated via a heating terminal E1b, so that the
moisture is driven out of zeolith filter 50 again. A high amount of
water is thus released within a short period, which reaches the
additional demoisturizer E5, i.e., moisture exchanger 30, connected
downstream from first demoisturizer E1. This creates a high
gradient across the diaphragm of additional demoisturizer E5, so
that the moisture may be effectively discharged from bypass line 20
via moisture exchanger 30. After complete removal of moisture by
heating zeolith filter 50, zeolith filter 50 is suitable again for
removing moisture from the refrigerant, so that throttle valve 24
may be opened again to increase the flow again, and more
refrigerant from the refrigeration system may be dried. The
operation of the refrigeration system does not need to be stopped
at any time.
[0041] It is important, however, that in this specific embodiment
attention must be paid that no concentrated water is returned to
the refrigeration system. This may occur if water is driven out by
heating zeolith filter 50, but moisture exchanger 30 does not
discharge all the water. This is prevented by completely closing
valve V2 and preferably also valve V1 during the moisture removal
by heating. Since a higher pressure builds up in bypass line 20
during moisture removal by heating if valves V1, V2 are closed, it
may be necessary to provide a pressure equalizing valve.
Alternatively a second demoisturizer, which is designed as a
moisture filter like first demoisturizer E1 and removes the
moisture from the refrigerant that is not discharged via moisture
exchanger 30, may be connected downstream from moisture exchanger
30.
[0042] Particularly preferably, moisture exchanger 30 is integrated
into first demoisturizer E1 to remove the moisture from the
refrigerant even more effectively.
[0043] FIG. 3 shows a third exemplary embodiment of a device for
drying refrigeration systems, the same components as in the
exemplary embodiments of FIGS. 1 and 2 being labeled with the same
reference numerals.
[0044] First demoisturizer E1, a second demoisturizer E2, and,
between the two demoisturizers E1, E2, additional demoisturizer E5,
which is designed as moisture exchanger 30, are situated in bypass
line 20. First demoisturizer E1 and second demoisturizer E2 are
designed as moisture filters, in particular as zeolith filters 50.
In particular, second demoisturizer E1 also has a housing E1a and a
heating terminal E1b. In the case of a flow direction along the
outlined arrows, the fluid flows from first valve V1 first through
first demoisturizer E1, then through moisture exchanger 30 and then
through second demoisturizer E2 before the refrigerant is
transferred again into pipe 10 of the refrigeration system through
second valve V2. In this specific embodiment, however, a third
valve V3 is additionally situated between first valve V1 and first
demoisturizer E1 and a fourth valve V4 is situated between second
demoisturizer E2 and second valve V2. Third valve V3 and fourth
valve V4 are three-way valves, so that either first demoisturizer
E1 or second demoisturizer E2 may be switched downstream from first
valve V1 via third valve V3 and alternatively second demoisturizer
E2 or first demoisturizer E1 may be switched upstream from second
valve V2 via fourth valve V4. This makes it possible to reverse the
direction of flow between third valve V3 and fourth valve V4
through bypass line 20, so that either the refrigerant flows
initially through first demoisturizer E2 and then second
demoisturizer E2 along the outlined arrows of FIG. 3, or,
alternatively, the flow initially passes through second
demoisturizer E2 and then through first demoisturizer E1 along the
solid arrows in FIG. 3. In particular in combination with the
additional moisture exchanger 30 situated between the two
demoisturizers E1, E2, the following preferred mode of operation
results. Initially, the refrigerant flows along the outlined arrows
first through first demoisturizer E1, in which most of the moisture
contained in the refrigerant is removed from the refrigerant by
zeolith filter 50. This moisture is stored in zeolith filter 50.
The residual moisture may then be effectively removed from the
refrigerant via additional moisture exchanger 30 if the moisture
gradient is sufficiently high, or via second demoisturizer E2, so
that an increased degree of drying of the refrigerant is achieved.
The moisture in the refrigerant is checked via moisture sensor 22.
With the aid of additional sensors on demoisturizers E1, E2, the
degree of saturation already reached by first demoisturizer E1 may
be checked. If the corresponding degree of saturation of
demoisturizer E1 has been reached, the refrigerant flow rate may be
reduced by throttling or stopped via throttle valve 24; first valve
V1 and second valve V2 may also be closed, if necessary, for
greater safety. Demoisturizer E1 is then heated up via heating
terminal E1b, for example, to approximately 200.degree. C. The
heating drives the accumulated water out of zeolith filter 50 of
first demoisturizer E1, transporting it to moisture exchanger 30,
where there is a sufficiently high moisture gradient for
effectively discharging the water via moisture exchanger 30. If
necessary, the residual moisture remaining in the refrigerant is
taken up via second demoisturizer E2. After first demoisturizer E1
has thus been dried, third valves V3 and fourth valve V4 are
switched in such a way that subsequently the fluid flows through
the bypass line along the solid arrows and thus in the opposite
direction through the section of bypass line 20 between third valve
V3 and fourth valve V4, so that the refrigerant may flow initially
through second demoisturizer E2 and then through the additional
moisture exchanger 30 and finally through first demoisturizer E1.
This now loads second demoisturizer E2 predominantly with water
from the refrigerant, while the additional moisture exchanger 30
assumes barely any function and first demoisturizer E1 takes up the
residual moisture from the refrigerant. In this way, maximum
exchange and the most effective possible degree of drying of the
refrigerant, as well as a high degree of drying of demoisturizers
E1, E2 are achieved without having to open bypass line 20 or even
the refrigeration system. In particular, the operation of the
refrigeration system does not have to be stopped.
[0045] In the exemplary embodiments illustrated in FIG. 3, the
water is discharged via moisture exchanger 30 in such a way that it
drips from moisture-permeable diaphragm 32 to the outside, for
example, or fumigates. Diaphragm 32 is designed in such a way that
it is permeable to water only, but not for the refrigerant flowing
through the refrigeration system, and may be manufactured from
Nafion, for example, or designed as a zeolith molecular sieve.
[0046] To increase the moisture gradient across diaphragm 32, a
device for generating a vacuum may be situated on the side of
diaphragm 32 facing away from the refrigeration system, so that the
moisture gradient is increased and more water passes through
diaphragm 32 to the outside. Alternatively, a drying agent may also
be directed past the side of diaphragm 32 facing away from the
refrigeration system to increase the moisture gradient. This may be
achieved, for example, by using a fifth specific embodiment of the
present invention, as illustrated in FIG. 5. In this exemplary
embodiment, a drying agent supply device is situated on the side of
diaphragm 32 facing away from the refrigeration system, which may
be, for example, a device for providing a compressed gas such as
nitrogen or air via a gas supply 41 or an ambient air supply 42
with the aid of a suitable compressor. Drying agent supply device
40 directs the appropriate drying agent, for example, a gas such as
nitrogen or air, past the side of diaphragm 32 of additional
moisture exchanger 30 facing away from the refrigeration system
into a drying agent discharge device 44. To keep the drying agent
in circulation, the drying agent having reached drying agent
discharge device 44 may be returned to the drying agent supply
device. However, the drying agent may also be discharged after a
single use.
[0047] A third demoisturizer E3, which is preferably also designed
as a moisture filter, in particular as a zeolith filter 50, is
situated between drying agent supply device 40 and diaphragm 32.
Third demoisturizer E3 also has a housing E3a and a heating
terminal E3b. The drying agent supplied is additionally
demoisturized in zeolith filter 50 before it is conducted to
diaphragm 32 to further increase the moisture gradient across
diaphragm 32.
[0048] A fourth demoisturizer E4, which is preferably also designed
as a moisture filter, in particular as a zeolith filter 50, is
situated between diaphragm 32 and drying agent discharge device 44.
Fourth demoisturizer E4 also has a housing E4a and a heating
terminal E4b.
[0049] A fifth valve V5 is situated between drying agent supply
device 40 and third demoisturizer E3, while a sixth valve V6 is
situated between fourth demoisturizer E4 and drying agent discharge
device 44. Fifth valve V5 and sixth valve V6 are also designed as
three-way valves, so that third demoisturizer E3 or fourth
demoisturizer E4 may be switched downstream from drying agent
supply device 40 via fifth valve V5, while alternatively fourth
demoisturizer E4 or third demoisturizer E3 may be switched upstream
from drying agent discharge device 44 via sixth valve V6. This
makes it possible, also in this configuration, as indicated by the
outlined and solid arrows, to reverse the direction of flow through
the drying agent circuit. Furthermore, third demoisturizer E3 and
fourth demoisturizer E4 are designed to be heatable. This makes the
following procedure possible for drying the drying agent and for
drying third demoisturizer E3 and fourth demoisturizer E4.
Initially, the drying agent is conducted into first demoisturizer
E3 via drying agent supply device 40 along the outlined arrows,
where the drying agent is demoisturized, so that third
demoisturizer E3 is loaded with moisture. At diaphragm 32, the
drying agent takes up moisture again, which may be filtered out in
fourth demoisturizer E4 if the drying agent is to be returned to
diaphragm 32. Alternatively, demoisturizer E4 connected downstream
from diaphragm 32 may be additionally heated to pass the moisture
absorbed by the drying agent through and drive out the already
absorbed moisture. Demoisturizers E3, E4 connected downstream from
diaphragm 32 may also be completely removed from the drying agent
stream using an additional valve in order to thus save heating
costs. In principle, it is thus also possible to situate only one
demoisturizer in the drying agent circuit.
[0050] If one of the two demoisturizers E3, E4 reaches its degree
of saturation, valves V5, V6 are switched in such a way that the
corresponding demoisturizer E3, E4 is switched upstream from drying
agent discharge device 44. The corresponding demoisturizer E3, E4
is then heated up, so that moisture may be discharged toward drying
agent discharge device 44 without being directed past diaphragm 32
and there possibly causing moisture to be introduced into bypass
line 20.
[0051] FIG. 4 shows a fourth exemplary embodiment of the present
invention. In this exemplary embodiment, a first demoisturizer E1'
and a second demoisturizer E2' are situated in bypass line 20. In
the case of a flow direction along the outlined arrows, the
refrigerant flows from first valve V1 first through first
demoisturizer E1' and then through second demoisturizer E2', before
being supplied again via second valve V2 into pipe 10 of the
refrigeration system conducting the refrigerant. Third valve V3 is
designed again as a three-way valve and situated between first
demoisturizer E1' and first valve V1, via which alternatively first
demoisturizer E1' or second demoisturizer E2' may be switched
downstream from first valve V1. Fourth valve V4 is also designed as
a three-way valve and situated between second demoisturizer E2' and
second valve V2', via which alternatively first demoisturizer E1'
or second demoisturizer E2' may be switched upstream from second
valve V2, so that if the two valves V3, V4 are appropriately
switched, the direction of flow may be reversed in such a way that
between the two valves V3, V4 the flow may also take place along
the solid arrows in the reverse direction first through second
demoisturizer E2' and then through first demoisturizer E1'.
[0052] The two demoisturizers E1', E2' are equipped as porous
ceramic tube 52 having a zeolith coating 54 on the inside of
ceramic tube 52. The zeolith coating ensures that only water may
pass through ceramic tube 52, but the refrigerant will flow inside
zeolith coating 54 through ceramic tube 52 and thus may not escape
from bypass line 20. The ceramic tube is thus used essentially as a
support ceramic for zeolith coating 54. If, for example, a PTC
ceramic is used as the support ceramic, it may be additionally used
for heating. Zeolith coating 54 essentially functions as a moisture
exchanger.
[0053] First demoisturizer E1' and second demoisturizer E2' are
located in a chamber 70, in which the moisture having passed
through zeolith coating 54 accumulates and which is preferably
emptied via a pump 60 during heating to provide a sufficiently high
moisture gradient across zeolith coating 54. In particular, the
moisture may drip out into a container 62 and be removed via pump
60. In normal operation, pump 60 does not necessarily have to run
permanently. However, to prevent moisture from getting from
container 62 back into the refrigerant through the zeolith coating,
a valve, which is closed during operation and is opened only during
moisture removal by heating, is preferably located between chamber
70 and container 62. Since a vacuum is generated by pump 60 in
chamber 70 prior to closing the valve, only a very small amount of
air is in chamber 70, which causes no significant moisture input
back into the refrigerant during operation.
[0054] Alternatively, chamber 70 may also be purged using air or
another drying agent during normal operation to keep the moisture
gradient across zeolith coating 54 sufficiently high. In particular
air may be dried again using a device comparable to the device on
the side of diaphragm 32 of moisture exchanger 30 facing away from
the refrigeration system in the exemplary embodiment illustrated in
FIG. 5.
[0055] Chamber 70 may have, on the one hand, a water-permeable
diaphragm which, on the side facing away from demoisturizers E1',
E2', may be equipped with an appropriate device for increasing the
moisture gradient, so that chamber 70 represents an additional
protection wall if refrigerant should escape through zeolith
coating 54. Should pores in zeolith coating 54 result in passage of
refrigerant, this may be recognized by a pressure increase in
chamber 70 during the drying phase, so that the exiting refrigerant
may be aspirated dry and collected via another demoisturizer (not
depicted) situated in chamber 70.
[0056] To further increase the degree of drying of demoisturizers
E1', E2', a zeolith granulate 56, wetted by the refrigerant flow
which thus removes moisture from the refrigerant, is situated in
ceramic tube 52. Since zeolith granulate 56 thus functions as a
moisture filter, in this specific embodiment demoisturizers E1',
E2' represent moisture filters having integrated moisture
exchangers. When zeolith granulate 56 reaches saturation, first
demoisturizer E1' and second demoisturizer E2' may be designed to
be reheatable to release moisture to the outside via zeolith
coating 54 in a controlled manner.
LIST OF REFERENCE NUMERALS
[0057] 10 pipe [0058] 15 compressor [0059] 20 bypass line [0060] 22
moisture sensor [0061] 24 throttle valve [0062] V1 first valve
[0063] V2 second valve [0064] V3 third valve [0065] V4 fourth valve
[0066] V5 fifth valve [0067] V6 sixth valve [0068] E1 first
demoisturizer [0069] E1' first demoisturizer [0070] E1a housing
[0071] E1b heating terminal [0072] E2 second demoisturizer [0073]
E2' second demoisturizer [0074] E2a housing [0075] E2b heating
terminal [0076] E3 third demoisturizer [0077] E3a housing [0078]
E3b heating terminal [0079] E4 fourth demoisturizer [0080] E4a
housing [0081] E4b heating terminal [0082] E5 fifth demoisturizer
[0083] 30 moisture exchanger [0084] 32 diaphragm [0085] 40 drying
agent supply device [0086] 41 gas supply [0087] 42 ambient air
supply [0088] 44 drying agent discharge device [0089] 50 zeolith
filter [0090] 52 ceramic tube [0091] 54 zeolith coating [0092] 56
zeolith granulate [0093] 60 pump [0094] 62 container [0095] 70
chamber
* * * * *