FR2875894A1 - COMBINED INTERNAL HEAT EXCHANGER AND ACCUMULATOR DEVICE FOR AIR CONDITIONING CIRCUIT - Google Patents

Abstract

The device has an outer cylindrical wall (20) with channels (22) to vertically circulate refrigerant upwards at high pressure and temperature. An annular space (48) is defined between the wall (20) and a cylindrical wall of a refrigerant container (32) to vertically circulate the refrigerant downwards at low pressure and temperature. Heat is exchanged between the refrigerants. Connections for the refrigerant, and for connection to an evaporator and a compressor, are grouped respectively in an upper flange (26) and a lower flange (24). An independent claim is also included for a gas cooler for an air-conditioning circuit circulated by a refrigerant in gaseous phase.

Description

2875894 VCL1557.FRD.wpd

  The invention relates to the field of air conditioning circuits, in particular for motor vehicles.

  In a conventional air conditioning circuit, the refrigerant fluid, usually a fluorinated compound, is present in two different phases, namely a gas phase and a liquid phase. The gaseous cooling fluid set in motion by a compressor is condensed in the liquid state in a condenser and then expanded in a pressure reducer. From there, he gains an evaporator where he turns into a gaseous state to win the compressor, and so on.

  To avoid the disadvantages due to the use of compounds harmful to the environment, it has been proposed to replace conventional refrigerants with less harmful fluids, in particular with natural compounds, such as carbon dioxide (CO2), the coolant remaining mostly in the gaseous state.

  Air conditioning circuits have therefore been proposed which use such natural fluids, present in the supercritical state, which operate at much higher pressures than in the case of conventional air-conditioning circuits. In such circuits, the refrigerant gas is sent by the compressor to a gas cooler and then in a first part of an internal heat exchanger before gaining an expander and an evaporator. At the exit of the evaporator, the coolant gains an accumulator then crosses a second part of the internal heat exchanger before returning to the compressor inlet.

  In the internal heat exchanger, the high-pressure, high-temperature refrigerant exchanges heat with the same refrigerant at low pressure and low temperature.

  To simplify the construction of such air conditioning circuits, it has already been proposed, as taught by US Pat. No. 6,523,365, to provide an internal heat exchanger integrated in an accumulator. However, this known device has a number of disadvantages. The volume occupied by the internal heat exchanger in the accumulator is relatively high. The diameter of the accumulator is determined by the minimum radius of curvature of the coaxially disposed heat exchanger. The inner wall of the heat exchanger is at low temperature, which causes a large heat exchange with the surrounding environment resulting in a loss of efficiency of the system. In addition, the relatively thick wall of the accumulator has no other function than to contain the coolant.

  It has also been proposed, as taught by US Pat. No. 6,539,746, to incorporate an accumulator and an internal heat exchanger into the gas cooler.

  However, this known device has a number of disadvantages. The accumulator and the internal heat exchanger are two different components mounted together with the gas cooler, which increases the number of parts.

  The thickness of the wall of the accumulator must be relatively large to withstand relatively high burst pressure levels. The accumulator wall is in direct contact with the surrounding environment and placed in a high airflow zone, which increases the heat exchange with the surrounding environment and results in a loss of efficiency. The connections for the coolant are placed at the four corners of the heat exchange module, which leads to complex connections.

  Also known from US Pat. No. 6,189,334, an air conditioning device in which an internal heat exchanger is combined with a condenser and a collector.

  Furthermore, according to US Pat. No. 6,751,983, an air conditioning device is known in which the internal heat exchanger comprises ducts arranged in a spiral.

  The invention aims to provide a combined device for internal heat exchanger and accumulator for an air conditioning circuit traversed by a refrigerant, which overcomes the aforementioned drawbacks.

  It is another object of the invention to provide such a combined device of this type which is of a simple construction and which makes it possible to group the fluid connections.

  The invention proposes for this purpose a combined device of the type defined in the introduction, which comprises an outer cylindrical wall in which are formed a plurality of channels for the circulation of the high-pressure refrigerant at high temperature, a lower flange clean closing a lower end of the cylindrical wall, an upper flange adapted to close an upper end of the cylindrical wall, coolant access ports provided in the lower and upper flanges, a container disposed in the space defined by the cylindrical wall and the lower and upper flanges, a low-pressure, low-temperature refrigerant supply communicating with the container, and a passage for the circulation of the low-pressure, low-temperature refrigerant fluid provided between the cylindrical wall and the container and fed from the container.

  As a result, the internal heat exchanger has a coaxial structure integrated directly into the wall of the accumulator. The wall of the accumulator, which can be made for example in the form of an extruded profile or in the form of a plurality of coaxial tubes, now has a dual function: it allows for a heat exchange between the low temperature and low temperature refrigerant at the outlet of the accumulator and the high temperature and high temperature refrigerant at the outlet of the gas cooler; and it makes it possible to make a container under pressure for the accumulator.

  The connections for the refrigerant, for connection to the evaporator and the compressor, are grouped respectively in the upper flange and in the lower flange, which simplifies the structure.

  The term "container" here means an element which essentially delimits a phase separation zone for the cooling fluid, that is to say for separating the gaseous and liquid phases of this fluid. It is furthermore advantageous that this container also delimits a coolant storage zone in the liquid phase, thus forming a liquid reservoir.

  In the invention, the channels formed in the outer cylindrical wall are preferably parallel.

  The lower and upper flanges are closure members for sealing the outer cylindrical wall at its lower and upper ends. The lower and upper flanges are advantageously respectively provided with a lower groove arranged to receive the lower end of the outer cylindrical wall and an upper groove arranged to receive an upper end of the outer cylindrical wall.

  In one embodiment of the invention, the container comprises an inner cylindrical wall spaced internally from the outer cylindrical wall to define an annular space, forming a passage for the circulation of the refrigerant fluid at low pressure and at low temperature, which communicates in part upper with the container and in the lower part with a low-pressure refrigerant discharge passage at low temperature, which passes through the lower flange.

  In this first embodiment of the invention, the annular space may constitute a passage without obstacles, or direct passage, for the circulation of refrigerant fluid at low pressure and low temperature. Alternatively, said annular space can accommodate a heat exchange means to form a helical channel between the outer cylindrical wall and the inner cylindrical wall. This heat exchange means may be, for example, a helical member or a helical capillary tube which extends into the container.

  In this first embodiment, the inner cylindrical wall is advantageously connected to a domed bottom which rests against the lower flange.

  The outer cylindrical wall is advantageously formed of an extruded profile in which the channels are formed for the circulation of the refrigerant fluid at high pressure and at high temperature.

  In a second embodiment of the invention, the device comprises an extruded profile comprising external channels which constitute the channels for the circulation of the high-pressure refrigerant fluid at high temperature and the internal channels which constitute the fluid circulation passage. refrigerant at low pressure and low temperature.

  The refrigerant supply at low pressure and at low temperature, communicating with the container, advantageously comprises means for forming a vortex in the refrigerant fluid at low pressure and low temperature entering the container to separate the gas phase and the phase liquid refrigerant.

  The means for forming this vortex can be constituted for example by a helical tube housed in the container, or by cyclone means.

  The device of the invention advantageously comprises a return member to ensure the transfer of a lubricating oil conveyed by the refrigerant from the bottom of the container to the passage ensuring the circulation of the coolant at low pressure and low temperature.

  It is advantageous that the lower flange comprises an internal passage forming an inlet adapted to be connected to the outlet of a compressor and an outlet outlet adapted to be connected to the inlet of a gas cooler.

  In the invention, the cooling fluid is advantageously carbon dioxide.

  In another aspect, the invention relates to a gas cooler for an air conditioning circuit traversed by a refrigerant fluid in the gas phase, this cooler being equipped with a combined device of internal heat exchanger and accumulator as defined above.

  The gas cooler preferably comprises a manifold having an inlet adapted to be connected to the outlet of a compressor, through a passageway provided in the lower flange, and an outlet port adapted to be connected to a inlet port of the lower flange.

  In the description which follows, made only by way of example, reference is made to the accompanying drawings, in which: FIG. 1 is a diagrammatic view in axial section of a combined device according to a first embodiment of the invention; , the drawing also showing the elements of the air conditioning circuit to which this device is connected; Figure 2 is a detailed view in axial section of the upper part of a device similar to that of Figure 1; FIG. 3 is an end view of the upper flange of the device of FIG. 2; FIG. 4 is an axial sectional view of the lower part of the device of FIG. 2; - Figure 5 is a sectional view along the line V-V of Figure 4; Figure 6 is a perspective view of the outer wall and the inner wall of the device of Figures 1 to 4; - Figure 7 is a view similar to Figure 6 in an alternative embodiment; - Figure 8 is a sectional view of the device wall, in an alternative embodiment wherein the fluid flows in several passes; - Figure 9 is an axial sectional view of an alternative embodiment in which the coolant from the accumulator flows in a helical tube; FIG. 10 is a front view of a gas cooler incorporating a combined device according to the invention; - Figure 11 is a sectional view similar to Figure 5 in an alternative embodiment; - Figure 12 is a partial sectional view, on an enlarged scale, taken along the line XII-XII of Figure 11; - Figure 13 is a sectional view similar to Figure 5 in another embodiment; and FIG. 14 is a partial sectional view, on an enlarged scale, taken along line XIV-XIV of FIG. 13.

  Referring first to Figure 1 which shows a combined device of internal heat exchanger and accumulator, designated as a whole by the reference 10. The device 10 is part of an air conditioning circuit traversed by a fluid gaseous refrigerant, operating in the supercritical state, for example carbon dioxide (CO2). In addition to the device 10, the circuit comprises a compressor 12, a gas cooler 14, an expander 16 and an evaporator 18.

  The device 10 comprises an outer cylindrical wall 20, in the example of circular section, in which are formed a multiplicity of channels 22, in the example of the parallel channels, for the circulation of the refrigerant fluid at high pressure and at high temperature. from the gas cooler 14. The wall 20 is bounded by an inner surface 20a and an outer surface 20b, both cylindrical. The wall 20 is mounted between a lower flange 24 and an upper flange 26. The lower flange 24 is provided with a lower groove 28, here of circular shape, arranged to receive the lower end of the cylindrical wall 20. Correspondingly , the upper flange 26 is provided with an upper groove 30, here of circular shape, arranged to receive the upper end of the outer cylindrical wall 20.

  A container 32 is disposed in the space (cylindrical volume) defined by the outer cylindrical wall 20 and the flanges 24 and 26. The container 32 delimits at the same time a separation zone of the gaseous and liquid phases of the cooling fluid and a zone of storing the refrigerant fluid in the liquid phase, thus forming a liquid reservoir for the accumulation of refrigerant fluid This container comprises a cylindrical wall 34 arranged coaxially and at a distance from the outer wall 20 and a bulging bottom 36, which rests against one side upper 38 of the lower flange 24. The latter is also limited externally by a lower face 40. The wall 34 may be described as "inner wall" of the device insofar as it is spaced internally from the outer wall 20. The wall 34 is bounded by an inner surface 34a and an outer surface 34b. The domed bottom 36 and the lower flange 24 define an annular channel for the discharge of the refrigerant, as will be seen later.

  The upper flange 26 is limited by a lower face 42 and an upper face 44. The two flanges are advantageously made in the form of machined blocks.

  The cylindrical wall 34 of the container 32 has an open end 46 which is at a small distance d from the lower face 42 of the upper flange. In this way, the interior of the container 32 can communicate with a passage 48 of annular shape between the outer wall 20 and the container, this passage being intended for the circulation of the coolant at low pressure and at low temperature.

  In the embodiment of FIG. 1, the above-mentioned passage 48 coincides with the annular space delimited between the cylindrical wall 34 of the container, which constitutes an inner wall, and the outer cylindrical wall 20. This annular space allows here a passage without obstacles, or direct passage, for the circulation of the coolant at low pressure and at low temperature.

  The annular space thus formed communicates in the lower part with a discharge passage 50 for the refrigerant fluid at low pressure and at low temperature, which passes through the lower flange 24, between its faces 38 and 40, and which thus constitutes an orifice of 52. The passage 50 opens in the upper part in the aforementioned annular channel, formed between the curved bottom 36 and the upper face 38 of the lower flange 24.

  The upper flange 26 has a feed passage 54 for the refrigerant fluid at low pressure and low temperature. This passage 54 is made in the form of a bore passing through the flange 26 and opening on its faces 42 and 44. The passage 54 forms an inlet orifice 56 for the refrigerant fluid at low pressure and at low temperature coming from the evaporator 18.

  In the lower part of the passage 54 is fitted an end 58 of a tube 60 arranged helically inside the container 32 and ending with an end 62. This helical tube 60 constitutes means for forming a vortex in the refrigerant fluid low pressure and low temperature entering the container. This makes it possible to separate the gaseous and liquid phases of the refrigerant fluid. The liquid phase thus separated accumulates in the container 32, the level of the liquid being identified by the N mark in Figure 1, while the gas phase gains the passage 48 to leave the device 10 through the evacuation passage 50.

  Moreover, the coolant conveys an oil that is necessary to ensure the lubrication of the compressor 12. This lubricating oil is discharged from the container 32 by a return member 64, here made in the form of a capillary tube, the lower end 66 reaches the bottom of the container, while the upper end 68, in the form of a stick, opens in the upper part of the passage 48.

  The upper flange 26 further comprises an outlet port 70 communicating with the upper groove 30 and adapted to be connected to the inlet of the expander 16.

  The lower flange. 24 comprises an orifice 72 opening into the lower groove 28 and adapted to be connected to the outlet of the gas cooler 14. Furthermore, the lower flange 24 comprises an internal passage 74 made by two bores at right angles which communicate with each other and which open on the underside 40 of the flange 24 and on a side face 76 of the flange to form an inlet port 78 adapted to be connected to the output of the compressor 12 and an outlet port 80 to be connected to the The orifice of the gas cooler 14. The orifices 72 and 80 of the flange 24 are located close to each other, opening on the lateral face 76, to facilitate connection or soldering of the flange to the gas cooler 14 .

  The circuit thus equipped with the device 10 operates in the following manner. The gaseous cooling fluid coming from the compressor 12 passes through the internal passage 74 of the flange 24 to reach the gas cooler 14. Then, the coolant reaches the lower groove 28 and then flows vertically, from bottom to top, in the channels 22 of the wall 20 as shown by the arrows. Then, the refrigerant reaches the upper groove 30 and then successively passes through the expander and the evaporator 18 to gain the inlet orifice 56. The refrigerant then enters the container 32 via the helical tube 60. Due to the swirling motion thus produced, the liquid and gaseous phases of the coolant separate. The gaseous refrigerant then gains the passage 48 to access the evacuation passage 50 and reach the inlet of the compressor 12. On its side, the lubricating oil is discharged from the bottom of the container by the capillary tube 64 and is then conveyed in the refrigerant to allow lubrication of the compressor.

  With this construction, a heat exchange is obtained between the refrigerant fluid at high pressure and at high temperature which flows vertically upwards in the channels 22 of the wall 20 and the low-temperature refrigerant fluid at low temperature circulating vertically from top to bottom in the annular space 48 defined between the wall 20 and the cylindrical wall 34 of the container. This provides an integrated structure of small footprint and weight with a minimum of connections, the latter being all grouped on the flanges 24 and 26.

  In addition, the thermal performance is increased because the heat exchange between the accumulator (i.e. the container 32) and the ambient is reduced. This also results in a reduction of possible leaks due to the reduced number of connections.

  In the embodiment of FIG. 1, the outer cylindrical wall 20 is advantageously made in the form of an extruded profile, preferably made of metallic material, in which the parallel channels 22 are formed. In this example, the container 32 is realized in the form of a separate component, in this case a convex bottom container, which is received inside this wall 20. However, as will be seen later, other embodiments are possible .

  Figure 2 is a detailed view of an upper part of a device 10 according to Figure 1. The elements common with those of Figure 1 are designated by the same references. In addition, a bore 82 is seen in the form of a blind hole which opens onto the upper face 44 of the upper flange 26. This bore is intended for fixing a counter flange (not shown) via of a screw or the like.

  In FIG. 3, which is an end view of the upper flange 26, the bore 82 and the orifices 56 and 76 are also visible.

  Figure 4 is a detailed view of the lower part of the combined device of Figure 2. The elements common with those of Figure 1 are designated by the same reference numerals. The lower flange 24 also comprises a bore 84 formed in the form of a blind hole which opens on the lower face 40 of the flange 24. This bore is intended to allow the attachment of a counter flange (not shown) by the intermediate of a screw or the like.

  FIG. 5 is a horizontal sectional view of the device of FIG. 4. It shows in detail the structure of the cylindrical wall 20, which is in the form of an extruded profile and which defines the channels 22. It is also seen that the container 32 is made in the form of a separate component which is housed coaxially inside the wall 20.

  Figure 6 is a perspective view showing the coaxial arrangement of the outer wall 20 and the inner wall 34 of the container 32.

  In the embodiment of FIG. 7, the device comprises an extruded profile 86 which comprises, on the one hand, external channels 22 which constitute the parallel channels for the circulation of the refrigerant fluid at high pressure and at high temperature, and internal channels 88 which constitute the circulation passage of the refrigerant fluid at low pressure and at low temperature. The channels 20 and 22 are arranged in a circular configuration which surrounds another circular configuration formed by the channels 88. In this way, the high temperature and high temperature refrigerant circulates countercurrently with the low pressure and low temperature refrigerant. temperature.

  In the preceding embodiments, the refrigerant circulates in a single pass, both in the channels 22 and in the passage 48 or the channels 88. However, it is conceivable to circulate the fluid in several passes. As shown in FIG. 8, the outer wall 20 is divided into two parts, a portion 20A for fluid flow in one direction and a portion 20B for fluid flow in another direction. Correspondingly, the passage 48 is divided into two parts, a portion 48A in correspondence of the portion 20A and a portion 48B in correspondence of the portion 20B. For example, the fluid can flow up and down in the portion 20A and up and down in the portion 20B, from bottom to top in the portion 48A and from top to bottom in the portion 48B. This assumes of course to arrange the grooves flanges to allow each time a return of the fluid.

  Referring now to Figure 9 which shows another alternative embodiment in which the annular space between the outer wall 20 and the wall 34 of the container 32 houses a heat exchange means 90, for example a flat wire wound helically around the wall 34, to form a helical channel 91 between the walls 20 and 34. Alternatively, it may be a helically wound capillary tube which extends into the container to form the tube 64 mentioned upper. The objective is to reduce the passage section in the annular passage 48 to cause an increase in the flow rate of the refrigerant fluid at low pressure and low temperature. This increase in speed has a positive impact on the heat exchange coefficient between the wall 20 and the refrigerant.

  Figure 10 shows a gas cooler 14 equipped with a combined device 10 according to the invention. The gas cooler 14 comprises a beam 92 mounted between two tubular collectors 94 and 96 capable of being arranged vertically. The combined device 10 is substantially vertically and coaxially implanted along the manifold 94. The lower flange 24 comprises, as in Figs. 1 and 4, an inlet port 72 and an outlet port 80. The outlet port 80 is adapted to be connected to an inlet port 98 of the manifold 94 for connection of the manifold to the outlet of the compressor 12 through the passage 74 formed in the lower flange. The collector 94 further comprises an outlet orifice 100 adapted to be connected to the inlet orifice 72 of the lower flange which opens into the lower groove 28. FIG. 10 also shows the orifices 52 and 78 of the lower flange which allow the connection with the compressor 12 as well as the orifices 70 and 56 of the upper flange which allow the connection with the expander 16 and the evaporator 18.

  In the embodiment of FIGS. 11 and 12, the cylindrical wall 34 of the container 32 has an outer surface 34b of very slightly corrugated shape to create corrugations which are pressed against the inner surface 20a of the wall 20 and thus form channels 102 for the circulation of refrigerant fluid at low pressure and at low temperature. These channels 102 together form the passage 48 mentioned above. The container 32 is thus in thermal contact with the profile 20 and the exchange surface in contact with the refrigerant fluid at low pressure and at low temperature is considerably increased. In addition, the inner surface 34a of the wall 34 is provided with an insulating coating 104 to reduce the heat transfer from the wall 20 to the coolant in liquid form which is contained in the container 32.

  FIGS. 13 and 14 illustrate another variant in which a cylinder 106 with a corrugated surface is inserted between the inner surface 20a of the wall 20 and the outer surface 34b of the wall 34. The corrugated cylinder 106 is brazed on the wall 20, the two being made for example of an aluminum-based material. On the other hand, is formed of a material that does not burn aluminum, for example steel, for brazing temperature. In this form of container 32 is not provided with a coating the container 32 easily with resisting achievement, the interior 104.

  The invention is not limited to the embodiments described previously by way of example and extends to other variants.

Claims (19)

claims   Combined device for internal heat exchanger and accumulator for an air-conditioning circuit traversed by a refrigerant, characterized in that it comprises an outer cylindrical wall (20) in which a multiplicity of channels (22) are formed. for the circulation of the refrigerant fluid at high pressure and at high temperature, a lower flange (24) adapted to close a lower end of the outer cylindrical wall (20), an upper flange (26) adapted to close an upper end of the wall outer cylindrical port (20), access ports (52, 78; 56, 70) for the coolant arranged in the lower and upper flanges, a container (32) disposed in the space defined by the outer cylindrical wall (20). ) and the lower and upper flanges, a low-pressure, low-temperature coolant supply (54) communicating with the container (32), and a passage (48; 88; 0) for the circulation of the refrigerant fluid at low pressure and low temperature, arranged between the outer cylindrical wall (20) and the container (32) and fed from the container.   2. Device according to claim 1, characterized in that the container (32) defines a phase separation zone for the refrigerant fluid and a coolant storage zone in the liquid phase.   3. Device according to one of claims 1 and 2, characterized in that the channels (22) formed in the outer cylindrical wall (20) are parallel.   4. Device according to one of claims 1 to 3, characterized in that the lower flanges (24) and upper (26) are respectively provided with a lower groove (28) arranged to receive the lower end of the cylindrical wall an outer groove (30) and an upper groove (30) arranged to receive an upper end of the outer cylindrical wall (20).   5. Device according to one of claims 1 to 4, characterized in that the container (32) comprises an inner cylindrical wall (34) spaced internally from the outer cylindrical wall (20) to define an annular space (48), forming passage for the circulation of the refrigerant fluid at low pressure and at low temperature, which communicates in the upper part with the container (32) and in the lower part with a discharge passage (50) of the coolant at low pressure and at low temperature, which passes through the lower flange (24).   6. Device according to claim 5, characterized in that the annular space (48) is a barrier-free passage for the circulation of refrigerant fluid at low pressure and low temperature.   7. Device according to claim 5, characterized in that the annular space (48) houses a heat exchange means (90; 64) to form a helical channel between the outer cylindrical wall (20) and the inner cylindrical wall. (34).   8. Device according to claim 7, characterized in that the heat exchange means is a helical member (90).   9. Device according to claim 7, characterized in that the heat exchange means is a helical capillary tube (64) which extends into the container (32).   10. Device according to one of claims 5 to 9, characterized in that the inner cylindrical wall (34) of the container is connected to a curved bottom (36) which rests against the lower flange (24).   11. Device according to one of claims 5 to 10, characterized in that the outer cylindrical wall (20) is formed of an extruded profile in which are formed the channels (22) for the circulation of the refrigerant fluid at high pressure and at high temperature.   12. Device according to claim 1, characterized in that it comprises an extruded profile (86) having outer channels (22) which constitute the channels for the circulation of the refrigerant fluid at high pressure and at high temperature and internal channels ( 88) which constitute the circulation passage of the coolant fluid at low pressure and at low temperature.   13. Device according to one of claims 1 to 12, characterized in that the supply (54) of refrigerant fluid at low pressure and low temperature, communicating with the container (32), comprises means (60) for forming a vortex in the refrigerant fluid at low pressure and low temperature entering the container, to separate the gas phase and the liquid phase of the refrigerant.   14. Device according to claim 13, characterized in that the means for forming a vortex comprise a helical tube (60) housed in the container (32).   15. Device according to one of claims 1 to 14, characterized in that it comprises a return member (64) for the transfer of a lubricating oil carried by the refrigerant from the bottom of the container (32). to the passage (48) for the circulation of the refrigerant fluid at low pressure and at low temperature.   16. Device according to one of claims 1 to 15, characterized in that the lower flange (24) comprises an internal passage (74) forming an inlet (78) adapted to be connected to the outlet of a compressor (12) and an outlet (80) adapted to be connected to the inlet of a gas cooler (14).   17. Device according to one of claims 1 to 16, characterized in that the coolant is carbon dioxide.   18. Gas cooler for an air-conditioning circuit carried by a refrigerating fluid in the gas phase, characterized in that it is equipped with a combined device (10) for internal heat exchanger and accumulator according to one of the Claims 1 to 17.   19. Gas cooler according to claim 18, characterized in that it comprises a manifold (94) with an inlet orifice (98) adapted to be connected to the outlet of a compressor (12) through a passage (74) in the lower flange (24), and an outlet (100) adapted to be connected to an inlet of the lower flange (24).