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(11) | EP 3 812 679 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A HEAT EXCHANGER |
| (57) A condenser (100) includes a first and a second manifold (30a) and (30b) and a receiver
drier (40). The first and the second manifold (30a) and (30b) are connected by tubes
configuring a first and a second pass (10a) and (10b) of a heat exchange fluid. The
receiver drier (40) connected to the second manifold (30b) provides fluid connection
between the first and the second pass (10a) and (10b). The second manifold (30b) is
connected to the receiver drier (40) through a channel (50). The channel (50) receives
fluid from the first pass (10a) through a first hole (32a) and a second hole (32b)
of the second manifold (30b) that are distant from each other. The channel (50) further
supplies the receiver drier (40) with fluid through a first opening (42a) of the receiver
drier (40) which is closer to the first hole (32a) than the second hole (32b).
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[0001] The present invention relates to a heat exchanger, particularly a condenser for an air conditioning unit for a vehicle.
[0002] Conventional air conditioning system for example for a vehicle cabin includes a condenser, an evaporator, an expansion device, a compressor and a heater. The compressor pumps refrigerant gas up to a high pressure and temperature. Thereafter, refrigerant gas enters the condenser, where the refrigerant gas rejects heat energy to external ambient (through ambient air or a specific low temperature coolant circuit), gets cooled, and condenses into liquid phase. Thereafter, the expansion valve regulates refrigerant liquid to flow at proper rate, reducing its pressure due its expansion, and finally, the cooled liquid refrigerant flows to the evaporator, where the cooled liquid refrigerant is evaporated, reducing its temperature. As the liquid refrigerant evaporates, the refrigerant extracts or absorbs heat energy from air inside an enclosure to be conditioned, specifically, a vehicle cabin in case of a vehicle air conditioning system and returns to the compressor, and the above cycle repeats. In the process, the heat is extracted from inside the vehicle cabin and rejected to outside vehicle cabin, resulting in cooling of air inside the vehicle cabin.
[0003] The conventional air conditioning system configured with expansion valves are also configured with a receiver drier that is disposed in the high-pressure section of the air conditioning system, usually located between condenser and expansion valve in the air conditioning loop. Referring to FIG. 1 of the accompanying drawings, a condenser 1 with a receiver drier 3 is illustrated. The condenser 1 includes a first manifold 2a and a second manifold 2b formed at opposite sides of a condenser core 4. Further, the heat exchange tubes of the condenser core 4 connects the first manifold 2a to the second manifold 2b. The first manifold 2a includes an inlet "I" for ingress of refrigerant into the condenser 1 and an outlet "O" for egress of refrigerant from the condenser 1. The second manifold 2b is in fluid communication with the receiver drier 3. The receiver drier 3 is in form of an airtight container of a tubular configuration with extreme ends thereof closed by lids 5. The receiver drier 3 is either mounted along an outlet side of the condenser core 4 or is integrally formed along the outlet side of the condenser core 4. The receiver drier 3 includes an inlet 3a and an outlet 3b. The inlet 3a receives refrigerant that is condensed by passing through heat exchange tubes 4a defining a first pass of the condenser core 4. The receiver drier 3 acts as a temporary storage for refrigerant (and oil) and receives a desiccant material to absorb moisture (water) that may have entered inside an air conditioning system of which the condenser is a part of. The receiver drier 3 also includes a filter to trap debris that may have entered inside fluid lines of the air conditioning system. Accordingly, the receiver drier 3 prevents the moisture and/or debris from reaching critical elements of the air conditioner unit, particularly the compressor, thereby preventing any detrimental impact to performance or damage to the critical elements of the air conditioning system. The outlet 3b delivers condensed refrigerant from which debris and moisture has been removed by passing through the receiver drier 3 to heat exchange tubes 4b defining a second pass of the condenser core 4 for sub-cooling of the condensed refrigerant from which debris and moisture has been removed. The sub-cooled refrigerant egresses through the outlet "O".
[0004] However, with such configuration of the condenser 4 and the receiver drier 3, the distribution and flow of the refrigerant through the heat exchange tubes of the condenser core 4 is non-uniform. Particularly, dead zones 4c are formed at the certain regions of the condenser core 4, thereby detrimentally impacting efficiency and performance of the condenser. Few prior art propose use of external jumper lines to manipulate pressure drop across heat exchanger tubes to achieve uniform flow distribution of refrigerant through the condenser core 4, however, such an arrangement increases overall size of the condenser and cause packaging issues.
[0005] Accordingly, there is a need for a condenser with an arrangement for improving distribution of refrigerant through a core of the condenser for preventing dead zone formation in the core of the condenser and improving efficiency and performance of the condenser. Also, there is a need for an arrangement for achieving uniform distribution of refrigerant through a core of the condenser that is compact in configuration and does not impact overall size of the condenser and as such packaging issues are avoided.
[0006] An object of the present invention is to provide a condenser exhibiting improved distribution of refrigerant through a core of the condenser while still obviating drawbacks associated with conventional arrangement for improving distribution of refrigerant through the core.
[0007] Another object of the present invention is to provide a condenser with an arrangement for improving distribution of refrigerant through a core of the condenser and preventing dead zone formation in the core of the condenser.
[0008] Still another object of the present invention is to provide a condenser with improved distribution of refrigerant through core thereof, thereby exhibiting improved efficiency and performance.
[0009] Yet another object of the present invention is to provide a condenser with improved distribution of refrigerant through core thereof without requiring any external jumper lines, as such the condenser is compact and packaging issues are avoided.
[0010] Another object of the present invention is to provide a condenser that is simple in construction.
[0011] In the present description, some elements or parameters may be indexed, such as a first element and a second element. In this case, unless stated otherwise, this indexation is only meant to differentiate and name elements which are similar but not identical. No idea of priority should be inferred from such indexation, as these terms may be switched without betraying the invention. Additionally, this indexation does not imply any order in mounting or use of the elements of the invention.
[0012] A heat exchanger, particularly, a condenser is disclosed in accordance with an embodiment of the present invention. The heat exchanger includes a first manifold, a second manifold and a receiver drier. The first manifold and the second manifold are connected by tubes configured to provide at least a first pass and a second pass of a heat exchange fluid. The receiver drier is connected to the second manifold and is providing fluid connection between the first pass and the second pass, wherein the second manifold is connected to the receiver drier through a channel. The channel receives fluid from the first pass through a first hole and a second hole configured on the second manifold. The first hole and the second hole are distant from each other. The channel further supplies the receiver drier with fluid through a first opening of the receiver drier which is closer to the first hole than the second hole.
[0013] Further, the channel supplies the fluid received in the receiver drier to the second pass through a second opening that is in fluid connection with third hole but is in fluid isolation from the second hole within the channel.
[0014] Specifically, the channel includes a first aperture which is aligned and in fluid connection with first hole and the first opening, a second aperture which is aligned and in fluid connection with a third hole and the second opening and an intermediate aperture that is in fluid connection with the second hole.
[0015] More specifically, the first aperture and the second aperture are through apertures, whereas the intermediate aperture is a blind aperture.
[0016] Preferably, at least one of the first hole and the second hole is either one of oval shaped and any other oblong shaped hole.
[0017] Generally, the at least one intermediate aperture is comparatively larger than the first aperture.
[0018] Particularly, the at least one intermediate aperture is at least 1.5 times larger than the first aperture.
[0023] Further, the channel includes a first sealing element, a second sealing element and a third sealing element, wherein the first sealing element and the second sealing element close ends of the channel, whereas the third sealing element configures fluid isolation between the second opening of the receiver drier and the second hole of the second manifold.
[0024] A receiver drier configured on a heat exchanger is disclosed in accordance with an embodiment of the present invention. The receiver drier includes a tubular casing and a channel. The tubular casing is connected to a second manifold of the heat exchanger and provides fluid connection between the first pass and the second pass. The channel forms fluid connection between the second manifold and the tubular casing, wherein the channel receives fluid from the first pass through a first hole and a second hole configured on the manifold, the first hole and the second hole being distant from each other. The channel further supplies the tubular casing with fluid through a first opening of the tubular casing which is closer to the first hole than the second hole. The channel still further supplies the fluid received in tubular casing to the second pass through a second opening that is in fluid connection with third hole but is in fluid isolation from the second hole.
[0025] Other characteristics, details and advantages of the invention can be inferred from the description of the invention hereunder. A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying figures, wherein:
FIG. 1 illustrates a conventional heat exchanger, particularly, a condenser configured with a receiver drier in accordance with prior art;
FIG. 2 illustrates a heat exchanger, particularly, a condenser configured with a receiver drier in accordance with an embodiment of the present invention;
FIG. 3a illustrates an isometric view of the receiver drier of the FIG. 2 depicted along with a channel;
FIG.3b illustrates another isometric view of the receiver drier of FIG. 3a.
[0026] It must be noted that the figures disclose the invention in a detailed enough way to be implemented, said figures helping to better define the invention if needs be. The invention should however not be limited to the embodiment disclosed in the description.
[0027] Although the present invention is explained in the forthcoming description with example of a receiver drier for a condenser, wherein the receiver drier is configured with a channel disposed between the receiver drier and a second manifold of the condenser for manipulating pressure difference across different sections of a condenser core for achieving uniform distribution of the refrigerant throughout the condenser core. Such configuration of channel disposed between the condenser and the receiver drier imparts compact configuration to the condenser and is capable of uniformly distributing the refrigerant throughout the condenser core, thereby preventing formation of dead zones in the condenser core and enhancing efficiency and performance of the condenser. However, the present invention is applicable for any heat exchanger, not limited to condenser alone, wherein uniform flow of heat exchange fluid through the heat exchanger is required to enhance efficiency and performance the heat exchanger without requiring any external jumper lines that increases overall size of the heat exchanger.
[0028] Referring to FIG. 2 a heat exchanger, particularly, a condenser 100 in accordance with an embodiment of the present invention is illustrated. The condenser 100 includes a first manifold 30a and a second manifold 30b connected by a plurality of tubes 10 configured to provide at least a first pass 10a and a second pass 10b. Specifically, the pair of manifolds 30a, 30b is connected to respective collector plates 20a, 20b. The first manifold 30a receives refrigerant in vapor phase from an inlet 70. The pair of manifolds 30a, 30b in conjunction with the respective collector plates 20a, 20b either distributes heat exchange fluid, particularly, the refrigerant to or collects heat exchange fluid, particularly, the condensed refrigerant from the tubes 10 of the condenser 100. More specifically, at least a portion of the first manifold 30a of the pair of manifolds 30a, 30b distributes the refrigerant vapor received thereby to the first pass 10a. The refrigerant vapors flows through the first pass 10a in a flow direction depicted by arrows "A". Similarly, at least a portion of the second manifold 30b collects refrigerant condensed by passing the refrigerant vapor through the first pass 10a.
[0029] The condenser 100 includes a receiver drier 40. The receiver drier 40 includes a tubular casing 42. The tubular casing 42 is having a tubular configuration closed and sealed at both ends thereof. The tubular casing 42 receives a filter and a desiccant material therein. The filter trap debris that may have entered inside fluid lines of an air conditioning system of which the condenser 100 is a part of, whereas the desiccant absorbs any incompressible moisture that may have entered inside the air conditioning system. Accordingly, the receiver drier 40 not only acts as a temporary storage for refrigerant (and oil) but also prevents moisture and/or debris from reaching critical elements of the air conditioning system, particularly the compressor, thereby preventing any detrimental impact to performance or damage to the critical elements of the air conditioning system. The receiver drier 40 further includes a channel 50 extending along at least a portion of length of the tubular casing 42 such that the channel 50 is disposed between the second manifold 30b and the receiver drier 40 of the condenser 100.
[0030] The receiver drier 40 is connected to the second manifold 30b and provides fluid connection between the first pass 10a and the second pass 10b. More specifically, the second manifold 30b is in fluid connection with the receiver drier 40 through the channel 50 at two locations, configured with apertures for ingress and egress of the refrigerant from the receiver drier 50. Generally, the channel 50 is integrally formed with the receiver drier 40. Alternatively, the channel 50 is detachably mounted on the receiver drier 40. The channel 50 is connected to the second manifold 30b by crimping operation. However, the present invention is neither limited to any particular configuration of connection between the channel 50 and the receiver drier 40 nor limited to any particular configuration of the connection between the channel 50 and the second manifold 30b.
[0031] The second manifold 30b includes a first hole 32a, a second hole 32b and a third hole 32c. The tubular casing 42 includes a first opening 42a and a second opening 42b. The channel 50 includes a first aperture 50a, a second aperture 50b and an intermediate aperture 50c as illustrated in FIG. 3a and FIG. 3b. At least one of the first hole 32a and the second hole 32b is either one of oval shaped and any other oblong shaped hole. In one example, the first hole 32a and the second hole 32b are oval shaped apertures or any other oblong shaped apertures, such that the oval or oblong shape of the second hole 32b enhances fluid flow rate through the second hole 32b and fluid flow through second hole 32b is more than fluid flow through first hole 32a. In another example, the second hole 32b is oval shaped while the first hole 30a is circular shaped so that the fluid flow through second hole 32b is more than fluid flow through first hole 32a. However, the present invention is not limited to any particular shape or configuration of the first hole 32a and the second hole 32b, as long as fluid flow through second hole 32b is more than fluid flow through first hole 32a. Generally, the first aperture 50a is configured near bottom end of the channel 50, the second aperture 50b is configured near top end of the channel 50, whereas the at least one intermediate aperture 50c is disposed between the first aperture 50a and the second aperture 50b and at proximity to the second aperture 50b. Further, the inlet 70 is configured on the first manifold 30a and is aligned to or close to alignment with the first hole 32a of the second manifold 30b. Such positioning of the inlet 70 with respect to the first hole 32a creates back pressure and also contributes to achieve uniform distribution of the refrigerant in the first pass 10a. Further, such positioning prevents formation of dead zones within the core of the condenser 100 and enhances heat exchange at the first pass 10a of the condenser 100 to improve efficiency and performance of the condenser 100.
[0032] The first aperture 50a is aligned and in fluid connection with the first hole 32a and the first opening 42a, the second aperture 50b is aligned and in fluid connection with the third hole 32c and the second opening 42b and the at least one intermediate aperture 50c is in fluid connection with the second hole 32b only. More specifically, the first aperture 50a and the second aperture 50b are through apertures, whereas the at least one intermediate aperture 50c is a blind aperture that is open towards and in fluid communication with the second manifold 30b but closed at the receiver drier 40 side. The at least one intermediate aperture 50c is comparatively larger than the first aperture 50a. The at least one intermediate aperture 50c is at least 1.5 times larger than the first aperture 50a. Also, the second hole 32b is larger than the first hole 32a. The second hole 32b is at least 1.5 times larger than the first hole 32a. With such configuration, the condensed refrigerant received by the channel 50 through the at least one intermediate aperture 50c from the first pass 10a. The condensed refrigerant is not passed to the receiver drier 40 but is collected at the bottom of the channel 50 to build back pressure. The back pressure so created cause uniform distribution of the refrigerant in the first pass 10a, thereby preventing formation of dead zones within core of the condenser 100 and enhancing heat exchange at the first pass 10a of the condenser 100 to improve efficiency and performance of the condenser 100.
[0033] The channel 50 includes a first sealing element 52a, a second sealing element 52b and a third sealing element 52c. The first sealing element 52a and the second sealing element 52b closes ends of the channel 50. The third sealing element 52c configures fluid isolation between the second opening 42b and the second hole 32b. The sealing elements 52a, 52b, 52c disposed inside the channel 50 divide interior of the channel 50 into a first compartment 50d and a second compartment 50e. The first compartment 50d supplies condensed refrigerant from the receiver drier 40 to the second pass 10b or the tubes configuring sub-cooling section of the condenser 100 via the second aperture 50b and a second portion 30d of the second manifold 30b. The second compartment 50e receives condensed refrigerant from the first pass 10a or the tubes configuring the condensing section of the condenser 100 via a first portion 30c of the second manifold 30b, the at least one intermediate aperture 50c and the first aperture 50a.
[0034] The channel 50 receives fluid, particularly, condensed refrigerant from the first pass 10a through the first hole 32a and the second hole 32b. The first hole 32a and the second hole 32b are distant from each other. The channel 50 further supplies the condensed fluid, particularly, condensed refrigerant to the receiver drier 40 through the first opening 42a which is closer to the first hole 32a than the second hole 32b. Specifically, the first aperture 50a configures fluid communication between the first portion 30c of the second manifold 30b corresponding to the first pass 10a, particularly, the tubes configuring the condensing section of the condenser 100 and the receiver drier 40. More specifically, the refrigerant that is condensed after passing through the first pass 10a or the tubes configuring the condensing section of the condenser 100 along with uncondensed vapor refrigerant, moisture and debris, if any, enters the receiver drier 40 through the first aperture 50a aligned and in fluid connection with the first hole 32a and the first opening 42a. The receiver drier 40 removes moisture, debris, if any from the condensed refrigerant received thereby and the condensed refrigerant flows through the receiver drier 40 along flow direction depicted by arrows "B".
[0035] The channel 50 further supplies the condensed fluid, particularly, condensed refrigerant from which moisture and debris are removed by passing through the receiver drier 40 to the second pass 10b, through the second opening 42b that is in fluid connection with the third hole 32c but is in fluid isolation from the second hole 32b. Specifically, the second aperture 50b configures fluid communication between the receiver drier 40 and the second portion 30d of the second manifold 30b. More specifically, the condensed refrigerant with moisture, debris, if any removed therefrom egresses through the second aperture 50b that is aligned to the third hole 32c and the second opening 42b to enter the second portion 30d of the second manifold 30b. The second manifold 30b distributes the condensed refrigerant to the second pass 10b for sub-cooling of the condensed refrigerant. The condensed refrigerant flows through the second pass 10b along the flow direction depicted by arrow "C" and gets sub-cooled. The sub-cooled refrigerant is received in the first manifold 30a and egresses the first manifold 30a through the outlet 60.
[0036] The at least one intermediate aperture 50c is disposed upstream of the third sealing element 52c. The third sealing element 52c defines the first compartment 50d of the channel 50 that is in fluid communication with the second portion 30d of the second manifold 30b. The second portion 30d receives and distributes condensed refrigerant that had passed through the receiver drier 40 to the second pass 10b or the tubes configuring the sub-cooling section of the condenser 100. Specifically, the at least one intermediate aperture 50c configures fluid communication between the first portion 30c of the second manifold 30b and the channel 50. The refrigerant, that is condensed after passing through the first pass 10a or the tubes configuring the condensing section of the condenser 100 along with uncondensed refrigerant vapor, debris and moisture, if any ingresses the channel 50 via the at least one intermediate aperture 50c, flows through the channel 50 along direction depicted by arrow "D" to be collected to build back-pressure. The at least one intermediate aperture 50c along with back-pressure so created manipulates pressure difference across different sections of the core of the condenser 100 for achieving uniform distribution of the refrigerant throughout the core. Further, such configuration of the channel 50 disposed between the second manifold 30b and the receiver drier 40 imparts compact configuration to the condenser 100 and is capable of uniformly distributing the refrigerant throughout the core of the condenser 100, thereby preventing formation of dead zones in the core of the condenser 100 and enhancing efficiency and performance of the condenser 100.
[0037] Also is disclosed a receiver drier 40 in accordance with an embodiment of the present invention. The receiver drier 40 is part of a heat exchanger, particularly a condenser 100 and includes a tubular casing 42 and a channel 50. The tubular casing 42 is connected to a second manifold 30b of the condenser 100 and provides fluid connection between a first pass 10a and a second pass 10b. The channel 50 forms fluid connection between the second manifold 30b and the tubular casing 42. The channel 50 receives fluid, particularly, condensed refrigerant from the first pass 10a through a first hole 32a and a second hole 32b. The first hole 32a and the second hole 32b are distant from each other. The channel 50 further supplies the condensed fluid, particularly, condensed refrigerant received thereby to the receiver drier 40 through a first opening 42a which is closer to the first hole 32a than the second hole 32b. The channel 50 still further supplies the condensed fluid, particularly, condensed refrigerant from which moisture and debris are removed by passing through the receiver drier 40 to the second pass 10b through a second opening 42b that is in fluid connection with third hole 32c but is in fluid isolation from the second hole 32b.
[0038] Several modifications and improvement might be applied by the person skilled in the art to the heat exchanger 100 as defined above,_and such modifications and improvements will still be considered within the scope and ambit of the present invention, as long as the heat exchanger, heat exchanger comprises a first manifold, a second manifold and a receiver drier. The first manifold and the second manifold are connected by tubes configured to provide at least a first pass and a second pass of a heat exchange fluid. The receiver drier is connected to the second manifold and is providing fluid connection between the first pass and the second pass, wherein the second manifold is connected to the receiver drier through a channel. The channel receives fluid from the first pass through a first hole and a second hole configured on the second manifold. The first hole and the second hole are distant from each other. The channel further supplies the receiver drier with fluid through a first opening of the receiver drier which is closer to the first hole than the second hole.
1. A heat exchanger (100) comprising:
• a first manifold (30a) and a second manifold (30b) connected by a plurality of tubes (10) configured to provide at least a first pass (10a) and a second pass (10b) of a heat exchange fluid;
• a receiver drier (40) connected to the second manifold (30b) and providing fluid connection between the first pass (10a) and the second pass (10b), wherein the second manifold (30b) is connected to the receiver drier (40) through a channel (50);
wherein the channel (50) is adapted to receive fluid from the first pass (10a) through a first hole (32a) and a second hole (32b) configured on the second manifold (30b) which are distant from each other, the channel (50) being further adapted to supply the receiver drier (40) with the fluid through a first opening (42a) of the receiver drier (40) which is closer to the first hole (32a) than the second hole (32b).2. The heat exchanger (100) as claimed in claim 1, wherein the channel (50) is further
adapted to supply the fluid passed through the receiver drier (40) to the second pass
(10b) through a second opening (42b) that is in fluid connection with a third hole
(32c) but is in fluid isolation from the second hole (32b) within the channel (50).
3. The heat exchanger (100) as claimed in any of the previous claim, wherein the channel
(50) comprises a first aperture (50a) which is aligned and in fluid connection with
the first hole (32a) and the first opening (42a), a second aperture (50b) which is
aligned and in fluid connection with the third hole (32c) and the second opening (42b)
and at least one intermediate aperture (50c) that is in fluid connection with the
second hole (32b).
4. The heat exchanger (100) as claimed in the previous claim, wherein the first aperture
(50a) and the second aperture (50b) are through apertures, whereas the at least one
intermediate aperture (50c) is a blind aperture.
5. The heat exchanger (100) as claimed in any one of the preceding claims, wherein at
least one of the first hole (32a) and the second hole (32b) is either one of oval
shaped and any other oblong shaped hole.
6. The heat exchanger (100) as claimed in the claim 3, wherein the at least one intermediate
aperture (50c) is comparatively larger than the first aperture (50a).
7. The heat exchanger (100) as claimed in claim 3, wherein the at least one intermediate
aperture (50c) is at least 1.5 times larger than the first aperture (50a).
8. The heat exchanger (100) as claimed in any of the preceding claims, wherein the channel
(50) is integrally formed with the receiver drier (40).
9. The heat exchanger (100) as claimed in any of the preceding claims, wherein the channel
(50) is detachably mounted on the receiver drier (40).
10. The heat exchanger (100) as claimed in any of the preceding claims, wherein the channel
(50) is connected to the second manifold (30b) by crimping operation.
11. The heat exchanger (100) as claimed in any of the preceding claims, wherein the channel
(50) comprising a first sealing element (52a), a second sealing element (52b) and
a third sealing element (52c), wherein the first sealing element (52a) and the second
sealing element (52b) are adapted to close ends of the channel (50) whereas the third
sealing element (52c) is adapted to configure fluid isolation between the second opening
(42b) of the receiver drier (40) and the second hole (32b) of the second manifold
(30b).
12. A receiver drier (40) configured on a heat exchanger (100), the receiver drier (40)
comprising:
• a tubular casing (42) connected to a second manifold (30b) of the heat exchanger (100) and providing fluid connection between a first pass (10a) and a second pass (10b) of the heat exchanger (100); and
• a channel (50) adapted to form fluid connection between the second manifold (30b) and the tubular casing (42), wherein the channel (50) adapted to receive fluid from the first pass (10a) through a first hole (32a) and a second hole (32b) configured on the manifold (30b), the first hole (32a) and the second hole (32b) being distant from each other, the channel (50) further adapted to supply the tubular casing (42) with fluid through a first opening (42a) of the tubular casing (42) which is closer to the first hole (32a) than the second hole (32b), the channel (50) still further adapted to supply the fluid passed through the receiver drier (40) to the second pass (10b) through a second opening (42b) that is in fluid connection with a third hole (32c) but is in fluid isolation from the second hole (32b).