U.S. patent application number 11/724957 was filed with the patent office on 2008-08-28 for filter-drier unit for refrigerant circuits.
This patent application is currently assigned to Danfoss A/S. Invention is credited to Sergio Uribe Gutierrez, Nestor E. Cabrera Munoz.
Application Number | 20080202152 11/724957 |
Document ID | / |
Family ID | 39535459 |
Filed Date | 2008-08-28 |
United States Patent
Application |
20080202152 |
Kind Code |
A1 |
Munoz; Nestor E. Cabrera ;
et al. |
August 28, 2008 |
FILTER-DRIER UNIT FOR REFRIGERANT CIRCUITS
Abstract
In known filter-drier cases for refrigerant circuits, the
refrigerant flows through filter and drying means in a serial
manner. During operation of the refrigerant circuit, this causes an
undesirably large pressure drop. It is the task of the invention to
provide an improved filter-drier arrangement (1, 1') with a smaller
pressure drop. For this purpose, it is proposed to design the
filter-drier arrangement so that a part of the refrigerant flows in
parallel through the filter (21, 43) and the drying means (17,
43).
Inventors: |
Munoz; Nestor E. Cabrera;
(Leon Gto, MX) ; Gutierrez; Sergio Uribe;
(Monterrey N.L., MX) |
Correspondence
Address: |
MCCORMICK, PAULDING & HUBER LLP
CITY PLACE II, 185 ASYLUM STREET
HARTFORD
CT
06103
US
|
Assignee: |
Danfoss A/S
Nordborg
DK
|
Family ID: |
39535459 |
Appl. No.: |
11/724957 |
Filed: |
March 16, 2007 |
Current U.S.
Class: |
62/474 |
Current CPC
Class: |
F25B 43/003
20130101 |
Class at
Publication: |
62/474 |
International
Class: |
F25B 43/00 20060101
F25B043/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 27, 2007 |
DE |
10 2007 009 760.5 |
Claims
1. A filter-drier arrangement for refrigerant circuits with at
least one drier arrangement and at least one filter arrangement,
wherein at least one short-circuiting path extending through the
filter arrangement, said path bypassing the drier arrangement and
connecting an inlet connection and an outlet connection of the
filter-drier arrangement.
2. The filter-drier arrangement according to claim 1, wherein the
drier arrangement and the filter arrangement are accommodated in a
common housing.
3. The filter-drier arrangement according to claim 1 wherein the
short-circuiting path extends adjacently to at least one surface of
the drier arrangement.
4. The filter-drier arrangement according to claim 1, wherein the
drier arrangement is made to be cylindrical.
5. The filter-drier arrangement according to claim 1, wherein the
drier arrangement has a through, central recess.
6. The filter-drier arrangement according to claim 5, wherein the
cross-section of the central recess tapers, particularly
conically.
7. The filter-drier arrangement according to claim 1, wherein the
drier arrangement comprises a self-supporting drying material.
8. The filter-drier arrangement according to claim 1, wherein the
filter arrangement is located in the area of the outlet connection
and touches particularly the drier arrangement.
9. The filter-drier arrangement according to claim 1, wherein the
filter arrangement is made as a resilient membrane, and
particularly made of polyester.
10. The filter-drier arrangement according to claim 1, wherein
adjacent to the filter arrangement the housing of the filter
arrangement has a hollow in the downstream direction.
11. The filter-drier arrangement according to claim 1, wherein
size, fixing and resiliency of the filter arrangement have been
chosen so that a flow of refrigerant through the filter arrangement
will cause the filter arrangement to be resiliently deformed in
such a manner that at least one cavity is formed between the filter
arrangement and an adjacent supporting surface.
12. A refrigerant circuit with at least one drier arrangement and
at least one filter arrangement for the refrigerant, wherein at
least a part of the refrigerant flows in parallel through the
filter arrangement and the drier arrangement.
13. The refrigerant circuit according to claim 12, wherein at least
one feature according to claim 1.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] Applicant hereby claims foreign priority benefits under
U.S.C. .sctn. 119 from German Patent Application No. 10 2007 009
760.5 filed on Feb. 27, 2007, the contents of which are
incorporated by reference herein.
FIELD OF THE INVENTION
[0002] The invention concerns a filter-drier system for refrigerant
circuits with at least one drier arrangement and at least one
filter arrangement. Further, the invention concerns a refrigerant
circuit with at least one drier arrangement and at least one filter
arrangement for the refrigerant.
BACKGROUND OF THE INVENTION
[0003] Refrigeration systems, air-conditioning systems and heat
pumps are commonly used for very different applications. The
presently most frequent design of such systems is the so-called
compression refrigeration machine, in which a refrigerant is pumped
in a closed circuit by a compressor. The compressor and an
expansion member divide the circuit into an area with refrigerant
under higher pressure and an area with refrigerant under lower
pressure. In both areas is located a heat exchanger, which
transfers heat from the refrigerant to the environment or heat from
the environment to the refrigerant, respectively.
[0004] The presently most common refrigerants are pentane, ammonia,
R 134a and R 22. At present also the use of CO.sub.2 as refrigerant
(R 744) is tested.
[0005] For a reliable operation of a compression refrigerant
circuit over a long period it is also required that impurities are
removed from the circulating refrigerant. Common impurities in this
case are mechanical impurities, for example swarf, which partly
originate from the manufacturing of the system or the system
components, and partly originate from mechanically moving parts
(for example the compressor) during operation. Such particles have
to be filtered away, as otherwise they could obstruct the circuit
or cause an increased wear of the components. In this connection,
particularly the expansion member or the compressor, respectively,
must be mentioned. To remove such mechanical impurities, filters
are built into the refrigerant circuit.
[0006] A further contamination of the refrigerant occurs by the
releasing of substances, which diffuse into the refrigerant
circuit. As traditional refrigerants are heavily hygroscopic; water
turns out to be particularly problematic in this connection. Water
dissolved in the refrigerant can reduce the performance and
efficiency of the system and additionally cause internal corrosion.
To avoid this, drying means are provided in the circuit, which
absorb the water dissolved in the refrigerant. Usually zeolites and
silicates are used as drying means.
[0007] To ensure a sufficient effect of the filters and the drying
means, filters and drying means are usually looped into the
refrigerant circuit, so that they are passed in series, after each
other, by the refrigerant. In the flow direction of the circulating
refrigerant the filter arrangement is located before the drying
means to avoid that the drying means is obstructed by the
mechanical impurities.
[0008] For space and cost reasons, however, a combined filter-drier
unit has become popular, which is looped into the refrigerant
circuit as a unit. Both the filter and the drying means are
integrated in a common housing, the refrigerant also here flowing
through the filter and the drying means serially.
[0009] Such a filter-drier arrangement is, for example, described
in U.S. Pat. No. 6,106,596. The arrangement shown here has an
additional volume, so that the drier-collector unit also serves as
refrigerant accumulator. The described unit has a housing, in which
a filter-drier cartridge is inserted. It is ensured that both the
inlet and the outlet connection of the housing are provided on the
same side of the housing. To make this possible, the supplied
refrigerant flows through a tube into a lower area of the tank,
where the refrigerant is deflected and changes its flow direction.
The inlet tube extends through a central opening of the circular
filter-drier cartridge. After the deflection, the refrigerant first
flows through a filter and then through a granulated drying means,
both filter and drying means being located in a case arrangement.
Subsequently, a further hollow is provided that serves as
accumulator. The refrigerant flows serially, first through the
filter area and subsequently through the drying area of the
filter-drier cartridge.
[0010] U.S. Pat. No. 5,440,898 describes a further filter-drier
unit. Here, the drying means is adopted in the cylindrical housing
as a cylindrical member. A centrically arranged, through recess is
provided in the centre of the cylindrical drying means member, so
that the drying means member ends up being a hollow cylinder with
increased wall strength. On the inlet side of filter-drier unit a
filter arrangement is fixed on the front side of the drying means
member. Housing, filter arrangement and drying means member are
made to be fluid-tight in relation to each other, so that the
refrigerant is forced to pass through the filter to reach the
central opening of the drying means hollow cylinder. Further, on
the outlet side of the filter-drier unit is located a closing
element that closes the central through-opening of the drying means
member is a likewise fluid-tight manner. With this design of the
filter-drier unit the refrigerant flows serially through firstly
the filter and subsequently the drying means, before the
refrigerant leaves the filter-drier unit again.
[0011] A major problem with such filter-drier units is to combine a
good filtering and drying effect, a small pressure drop of the
circulating refrigerant during operation of the refrigerant
circuit, low costs and the smallest possible dimensions of the
filter-drier unit.
[0012] If, for example, an arrangement with small dimensions is
chosen, the surface, through which the refrigerant can pass the
drier unit, is correspondingly small, so that a high flow
resistance occurs. During operation of the refrigerant circuit this
causes a high pressure drop of the refrigerant in the area of the
filter-drier unit. If, on the other hand, it is endeavored to
minimise the pressure drop, the passage surface for the refrigerant
through the drier unit must be chosen to be correspondingly large.
This causes correspondingly large dimensions of the filter-drier
unit and correspondingly high costs.
SUMMARY OF THE INVENTION
[0013] The invention is based on the task of providing an improved
filter-drier arrangement.
[0014] Further, the task of the invention is to provide an improved
refrigerant circuit.
[0015] With a filter-drier arrangement for refrigerant circuits
having at least one drier arrangement and at least one filter
arrangement, it is proposed to provide at least one
short-circuiting path extending through the filter arrangement,
said path bypassing the drier arrangement and connecting an inlet
connection and an outlet connection of the filter-drier
arrangement. In other words, the flow runs at least partially in
parallel through the filter arrangement and the drier arrangement.
A part of the refrigerant flows through the filter arrangement
without necessarily having to flow through the drier arrangement.
On the other hand, it is also possible that a part of the
refrigerant only flows through the drier arrangement, without
flowing through the filter arrangement. However, it is also
possible that a (further) part of the refrigerant flows through
both the filter arrangement and the drier arrangement. In this
connection, please note that traditional drier arrangements also
have a certain filtering effect. Additionally to the "normal"
filter arrangement, it is also possible to provide an additional
filter arrangement in connection with the drier arrangement. The
provided additional filter arrangement or the drier arrangement,
respectively, can have a filter quality that deviates from that of
the "normal" filter arrangement.
[0016] The proposed design is based on the surprising recognition
that the drying effect of the drier arrangement does usually not,
or at least only to a small extent, depend on whether the total
amount of refrigerant flows through the drier arrangement, whether
only parts of the refrigerant flow through the drier arrangement,
or whether the refrigerant only flows past a surface of the drier
arrangement. It has turned out that with a typical refrigerant
circuit the time constant of the absorption process is in the range
of days, also when the whole refrigerant flow passes through the
drier arrangement. With such time constants, the proposed
arrangement only increases the time constant of the absorption
process to a small extent. To have the smallest possible reduction
of the drying effect, it is of course expedient, depending on the
application concerned, to let a suitably large amount of the
refrigerant flow through the drier arrangement, or to select a
corresponding size of the drier arrangement surface that is passed
by the refrigerant flow.
[0017] On the other hand, the proposed filter-drier arrangement can
under certain circumstances considerably reduce the flow
resistance, to which the passing refrigerant flow is exposed. This
again causes that, compared to the known filter-drier arrangements;
the pressure drop can be considerably reduced. This is possible,
even though the filter-drier arrangement does not, or at least to a
reduced extent, have to be enlarged.
[0018] It is possible for the drier arrangement and the filter
arrangement of the filter-drier arrangement to be at least partly
placed in different housings, if this should, for example, be
required for space reasons.
[0019] It is, however, preferred to place the drier arrangement and
the filter arrangement in a common housing. In this case a
particularly compact design can be realised. Also, fewer connecting
spots with piping components or other components of the refrigerant
circuit will be needed, which can reduce the mounting costs and
improve the tightness of the whole arrangement. Also a replacement
of the filter-drier arrangement will be simpler.
[0020] It is advantageous that the short-circuiting path extends
adjacent to at least one surface of the drier arrangement. In this
case, also the amount of refrigerant only passing through the
filter arrangement can experience a certain drying. The effect can
be increased, if the surface of the drier arrangement that is
passed by the refrigerant, and/or the dwell time of the refrigerant
in the area of this surface are selected to be relatively large in
relation to the fluid flow passing this surface.
[0021] Further, it is advantageous, if the drier arrangement is
made to be cylindrical. As the currently used drier arrangements
are typically cylindrical, a drop-in solution can thus be realised.
Further, a particularly compact design occurs, and under certain
circumstances advantages in manufacturing and during operation of
the drier arrangement may occur.
[0022] It is particularly advantageous, if the drier arrangement
has a through, central recess. The refrigerant can then flow
through the drier arrangement from the inside to the outside (or
vice versa), so that with a relatively simple design a large
surface can be provided, with which the refrigerant can get in
contact or which the refrigerant can penetrate to get into the
drier arrangement. Thus, the resulting pressure drop of the
refrigerant flowing through the filter-drier arrangement can be
reduced again.
[0023] In this connection it may prove to be expedient, if the
cross-section of the central recess tapers, particularly if it
tapers conically. In this connection, a tapering particularly means
a monotonous or strictly monotonous reduction of the cross-section.
The change may be constant or stepwise. For example, a kind of
funnel shaped central recess may be provided in the drier
arrangement. With the tapering of the central recess the parts of
the refrigerant flow passing through the filter arrangement can be
taken into account. Alternatively or additionally, the tapering
recess can also cause that the speed of the refrigerant flow in the
central recess increases in the direction of the tapering. For
example in the case, where a filter arrangement is provided at the
end of the central recess, the larger speed may cause that the
filter arrangement is cleaned of impurities by the incoming fluid
jet. Under certain circumstances, the higher speed can also improve
the passage of the refrigerant through the filter arrangement. It
is also possible that the central recess only tapers in a partial
area.
[0024] If the drier arrangement comprises an inherently stable
material, a particularly simple design of the filter arrangement,
and thus of the complete filter-drier arrangement, can be
supported. In this case, for example, a supporting structure and/or
a structure enclosing the drying material, which would, for
example, be required for a granulate-like drying material, can be
avoided. Of course, it can still be imagined to make at least parts
of the drier arrangement from a granulate-like drying material.
[0025] A particularly favourable design occurs, if the filter
arrangement is located in the area of the outlet connection and
touches particularly the drier arrangement. With such a design a
particularly compact filter-drier arrangement can be realised.
Further, the pressure drop caused by the filter arrangement can be
used to form a pressure difference between the inlet surface and
the outlet surface of a drier arrangement, so that a part of the
refrigerant flowing through the filter-drier arrangement flows
through the drier arrangement.
[0026] A further favourable embodiment occurs, if the filter
arrangement is made as a resilient membrane, and is particularly
made of polyester. When made as a resilient membrane, the filter
arrangement can be deformed during operation because of the
pressure difference occurring at the membrane. The deformation may
cause a slight increase of the pore size of the filter, so that the
pore size of the filter arrangement can increase in connection with
an increased refrigerant flow, meaning that the pressure difference
occurring at the filter arrangement must not increase
excessively.
[0027] It is advantageous if the housing of the filter arrangement
has a hollow in the outlet side next to the filter arrangement. In
this way, the fluid leaving the filter arrangement and, under
certain circumstances, also the refrigerant part having passed the
drier arrangement can be gathered and/or calmed, and subsequently
led to the outlet of the filter-drier arrangement. Particularly in
the case of a resilient filter membrane, the proposed embodiment
can also provide a correspondingly dimensioned chamber, into which
the filter membrane can move. With correspondingly large dimensions
of the hollow, also an accumulator function is possible.
[0028] A particularly advantageous embodiment occurs, if the size,
the fixing and the resiliency of the filter arrangement are chosen
so that, in connection with a flow of refrigerant through the
filter arrangement, the filter arrangement is resiliently deformed
in such a manner that at least one cavity is formed between the
filter arrangement and an adjacent supporting surface. In this way,
the arrangement can be designed so that during the flow through the
filter-drier arrangement a refrigerant flow is generated, of which
a part of the refrigerant flows into the cavity, that is, into a
hollow. The impurities taken along by the refrigerant are thus
forced into the formed cavity. The cavity can thus act as pick-up
for the impurities trapped by the filter arrangement. When, after
turning off the system, the filter arrangement resiliently
reassumes its shape, the impurities gathered in the cavities can be
retained. The exposed area of the filter arrangement can thus be
kept free of impurities, so that a particularly low pressure drop
of the filter-drier arrangement can be supported.
[0029] Further, a refrigerant circuit is proposed, with at least
one drier arrangement and at least one filter arrangement for the
refrigerant circulating in the refrigerant circuit, in which at
least a part of the refrigerant flows in parallel through the
filter arrangement and the drier arrangement. A refrigerant circuit
with this embodiment has the advantages already mentioned in an
analogue form.
[0030] It is particularly advantageous, if for the refrigerant
circuit a filter-drier arrangement is chosen, which has at least
one feature according to the possible designs mentioned above. Also
here, the advantages already described appear in an analogue
form.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] In the following the invention is described in detail on the
basis of a preferred embodiment with reference to the enclosed
drawings, showing:
[0032] FIG. 1 shows a filter-drier unit according to a first
embodiment of the invention,
[0033] FIG. 2 shows a filter-drier unit according to a second
embodiment of the invention,
[0034] FIG. 3 shows the filter area of a filter-drier unit during
operation,
[0035] FIG. 4 shows a flow simulation of a filter-drier unit,
[0036] FIG. 5 shows the speed distribution of a filter-drier
unit,
[0037] FIG. 6a, 6b shows the water absorption capacity and the
water absorption speed of different filter-drier units, and
[0038] FIG. 7a, 7b is a schematic view of refrigerant circuits
according to a third and a fourth embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0039] FIG. 1 shows a first embodiment of a combined filter-drier
case that can, for example, be used for the refrigerant circuit of
vehicle air-conditioning systems or domestic refrigeration or
freezing appliances. In the embodiment shown in FIG. 1, the housing
is made of two identical, cup-shaped housing parts 3, 4. One end of
each of the two housing halves 3, 4 has a projection 5, 6. The
projection 5, 6 enables a simple fluid-tight connection with the
respective other housing part 3, 4.
[0040] At the respective other end of each housing part 3, 4,
facing the projection 5, 6, a tub shaped housing bottom 7, 8 is
provided. In the centre of each housing bottom 7, 8 a circular
recess 15, 16 is provided, into which a connection tube 13, 14 is
inserted and connected in a fluid-tight manner with the housing
bottom 7, 8. Between the housing bottom 7, 8 and the cylindrically
shaped cup area 11, 12 of the respective housing part 3, 4 is
provided a ring-shaped, circumferential support 9, 10. These
supports 9, 10 serve as supports for the inner components of the
filter-drier case 1 adopted in the housing 2.
[0041] Inside the housing 2 of the filter-drier case 1 is located a
drying means 17. The outer contour of the drying means 17 is
adapted to the design of the housing 2 to fill the largest possible
share of the inner volume of the housing 2 with a drying means. The
volume required by the filter-drier case 1 is thus optimally
utilised. In the embodiment concerned the drying means 17 thus have
a cylindrical outer contour. Further, a projecting area 18 of the
drying means 17 can be seen in FIG. 1, said area 18 extending
somewhat into the tub shaped housing bottom 7 of the left housing
part 3 shown in the drawing, so that also this volume area is
utilised. A conically tapering recess 19 is provided in the centre
of the drying means member 17. Merely in an end area 20 of the
recess 19, which is immediately adjacent to the filter membrane 21,
the cross-section of the recess remains the same or increases
slightly. In the present example, the recess 19 and its end area 20
together with the corresponding area of the filter membrane 21 form
the short-circuiting path that connects the fluid inlet 13 and the
fluid outlet 14 by passing the drying means 17.
[0042] At the inlet side front end 22 (shown to the left of FIG. 1)
the drying means member 17 has, between its main area 26 and its
projecting area 18, a support 24. Between the support 24 of the
drying means member 17 and the support 9 of the housing part 3
shown to the left of the drawing is provided a wave spring 25. This
wave spring 25 pushes the drying means member 17 towards the other
housing half 4, where the facing, outlet side front end 23 of the
drying means member 17 is pressed against the annular support 10 of
the outlet side housing part 4. Thus, the drying means member 17 is
firmly supported in the housing 2 of the filter-drier case 1.
Further, the preloading of the drying means member 17 caused by the
wave spring 25 in connection with the filter membrane 21 ensures a
fluid-tight sealing between the drying means member 17 and the
housing 2 at the outlet side front end 23. During operation a
refrigerant pressure difference occurs between the inlet side area
13 and the outlet side area 14, said difference improving the
sealing effect.
[0043] In the present example, the filter membrane 21 is made of a
polyester material with the commercial name of Feltmat. However, it
can also be made of other materials, for example fibre glass or the
like. The filter membrane 21 is resilient, so that it deforms
resiliently on the occurrence of a pressure difference between the
fluid inlet 13 and the fluid outlet 14, as shown in FIG. 3. The
pressure difference between the fluid inlet 13 and the fluid outlet
14 is bound to occur, when during operation of the refrigerant
circuit refrigerant flows through the filter-drier case 1. The
filter membrane 21 surrounds the outlet side front end 23 as well
as a part 27 of the outside of the drying means member 17 in a
bowl-like manner. In this part 27 of the outside of the drying
means member 17 as well as in the area of the support 10 of the
outlet side housing part 4 of the filter-drier case 1 the filter
membrane 21 acts as sealing means for the refrigerant.
[0044] In the present embodiment example the drying means member 17
is made of an aluminium silicate that is reinforced by fibres and a
resin. The composition has been chosen so that the drying means
member 17 is self-supporting, meaning that no separate housing or
support means is required.
[0045] Due to the through, central recess 19 in the drying means
member 17, the drying means member has, compared with other drying
means members having no or a smaller internal recess, with the same
dimensions a smaller drying means volume. Preferably, however, the
outer dimension of the drying means member is increased so that the
resulting drying means volume of the drying means member 17
corresponds to the drying means volume of known filter-drier
units.
[0046] During operation of the filter-drier case 1 shown in FIG. 1,
the picture shown in FIG. 3 occurs. For reasons of clarity, FIG. 3
merely shows an enlarged view of the outlet side 14 area of the
filter-drier case 1. In FIG. 3 the refrigerant flow is shown
schematically by means of arrows. The refrigerant takes along
impurities 28, which have to be removed by the filter 21. Due to
the flow of refrigerant passing the filter-drier case 1, a pressure
difference occurs between the fluid inlet 13 and the fluid outlet
14, as both the drying means member 17 and the filter membrane 21
expose the flowing refrigerant to a flow resistance. Said pressure
difference causes a deformation of the centre of the resilient
fibre membrane 21, typically by about 1 mm, which gives rise to
cavities 29 between the filter membrane 21 and the outlet side
front end 23 of the drying means member 17. The flow resistance of
the filter membrane 21 is usually clearly smaller than the flow
resistance of the drying means member 17. For this reason, the
amount of refrigerant flowing through the central recess 19 of the
drying means member 17 and its end area 20 is clearly larger than
the amount of refrigerant passing through the drying means member
17. This is shown in FIG. 3 by different numbers of arrows.
Further, in the area of the transition edge 30 between the end area
20 of the recess 19 provided in the drying means member 17 and the
cavities 29, a flow component occurs into the cavities 29. For
reasons of space, this flow component is not shown in FIG. 3. The
flow causes a movement of the impurities 28 into the cavities.
Thus, the cavities 29 can serve as collecting area for the
impurities. If, on turning off the refrigerant circuit, the filter
membrane 21 returns to its starting position, the impurities 28 in
the cavity area 29 will be jammed between the filter membrane 21
and the outlet side front end 23 of the drying means member 17.
[0047] As, in the filter-drier case 1 shown in the FIGS. 1 and 3, a
part of the refrigerant flows through the filter 21 without having
to pass through the drying means member 17, a clearly smaller flow
resistance for the refrigerant occurs for the complete filter-drier
case 1. Due to the design with the resilient filter membrane 21, in
which the filter membrane 21 lifts off from the outlet side front
end 23 of the drying means member 17 during operation of the
refrigerant circuit, substantially the whole cross-section of the
housing 2 is available as filter cross-section, which further
reduces the flow resistance of the filter-drier case 1 during
operation.
[0048] The refrigerant flowing through the central recess 19 of the
drying means member 17 still flows past the surface 46 of the
recess 19 and thus experiences a certain degree of drying.
[0049] The flow conditions during operation of the filter-drier
case 1 of FIG. 1 are shown schematically in FIG. 3, and in FIGS. 4
and 5 they are shown again in a quantitative view. FIG. 4 shows a
numerical flow simulation, whereas FIG. 5 shows the speed
distribution of the refrigerant flowing through the filter-drier
case 1.
[0050] Even though, in the filter-drier case 1 shown in FIG. 1 or
3, a large part of the refrigerant does not flow though the drying
means member 17, the drying performance of the filter-drier case 1
is surprisingly approximately as good as that of filter-drier units
according to the state of the art. This is clearly seen from the
FIGS. 6a and 6b. Here, type A is a known filter-drier case, whereas
type B corresponds to a filter-drier case 1 as shown in FIG. 1. To
enable a comparison of data, the same mass of drying means has been
chosen for both types.
[0051] In FIG. 6a the total water absorption capacity of the drying
means (ordinate) in relation to the relative humidity of the
refrigerant (abscissa) is shown in logarithmic units. In the
present case, R22 was used as refrigerant. As can be seen from the
graphic, the difference, if any, between the two curves is
marginal.
[0052] Astonishingly, also the speed, at which the water is
absorbed, is only minimally smaller in the design shown in FIG. 1
than it is with traditional filter-drier cases. This is shown in
FIG. 6b, in which the humidity of the drying means (ordinate) is
shown in relation to the time (abscissa).
[0053] FIG. 2 shows a filter-drier case 1', which is slightly
changed in relation to FIG. 1. The basic design of the filter-drier
case 1' shown in FIG. 2, however, corresponds to the design of the
filter-drier case 1 shown in FIG. 1. Similar components therefore
have the same reference numbers.
[0054] In the filter-drier case 1' shown in FIG. 2, the drying
means member 17 has a large outer dimension. At the same time, the
size of the conically tapering central recess 19 inside the drying
means member 17 has been enlarged. The dimensioning of the drying
means member 17 and the recess 19 therein has been chosen so that
the overall mass of drying means is the same as in the drying means
member 17 shown in FIG. 1. Of course, also the size of the housing
2' has been adapted accordingly.
[0055] A further difference is that the housing 2' of the
filter-drier case 1' shown in FIG. 2 is made of three parts 31, 32,
33. The housing 2' consists of an inlet side, first housing part
31, an outlet side, second housing part 33 and an intermediately
arranged, cylindrical housing sleeve 32. The first housing part 31
and the housing sleeve 32 are in contact with each other in an
overlapping area 34 and, for example, connected to each other by
soldering. The same applies for the overlapping area 35 between the
second housing part 33 and the cylindrical housing sleeve 32.
[0056] Also in the embodiment of a filter-drier case 1 shown in
FIG. 2 the first housing part 31 and the second housing part 33 are
made to be identical. The housing parts 31, 33 substantially
comprise the cup-shaped housing bottoms 7, 8, which form the
collecting chambers 15, 16, as well as the supports 9, 10 for the
drying means member 17. For the main length of the filter-drier
case 1', however, as opposed to the filter-drier case 1 shown in
FIG. 1, a separate housing sleeve 32 is provided. Particularly in
connection with large filter-drier cases 1', the embodiment
according to FIG. 2 may have advantages for the production. Also
different lengths of the filter-drier case 1' can more easily be
realised, as, in spite of different lengths of the filter-drier
case 1', the two outer housing parts 31, 33 can be used in the
identical shape.
[0057] FIG. 7a shows a schematically simplified view of a
refrigerant circuit 36. The refrigerant circuit 36 has a compressor
37. The compressor pumps the refrigerant in the refrigeration
circuit 36 through the refrigerant tubes 38. Further shown is a
condenser 39 (in super critical refrigerant circuits accordingly a
gas cooler), via which the refrigerant compressed in the compressor
37 can emit heat to the environment. Subsequently, the refrigerant
flows through an expansion member 40, which reduces the pressure so
that the refrigerant is cooled. For example, fixed orifice tubes or
expansion valves known from the state of the art can be used as
expansion member 40. Then the refrigerant cooled by the expansion
flows through the evaporator 41, where the refrigerant assumes heat
from the environment, thus cooling the environment. Before the
refrigerant enters the compressor 37 again, it flows through the
filter-drier case 1, for example of the type shown in FIG. 1.
However, in this connection also other embodiments are
possible.
[0058] FIG. 7b shows a refrigerant circuit 36' that is slightly
modified in relation to FIG. 7a. Same components again have the
same reference numbers. Also here the refrigerant is pumped through
the circuit by a compressor 37. After compression in the compressor
37, the refrigerant, like in the refrigerant circuit 36 shown in
FIG. 7a, flows through a condenser (gas cooler) 39, an expansion
member 40 and an evaporator 41. However, in the refrigerant circuit
36' according to FIG. 7b, the refrigerant tube branches off into
two refrigerant branches 42, 44 extending in parallel. The first
refrigerant branch 42 flows through a pure filter case 43, whereas
the second refrigerant branch 44 leads to a pure drying means case
45. Also in the refrigerant circuit 36' shown in FIG. 7b a small
flow of refrigerant through the drying means case 45 is ensured, as
inevitably the filter case 43 generates a flow resistance against
the passing refrigerant, so that a pressure difference occurs
between the inlet and the outlet of the filter case 43, said
pressure difference also ruling between the inlet and the outlet of
the drying means case 45.
[0059] While the present invention has been illustrated and
described with respect to a particular embodiment thereof, it
should be appreciated by those of ordinary skill in the art that
various modifications to this invention may be made without
departing from the spirit and scope of the present invention.
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