DE102018113333B4 - Device for heat transfer in a refrigerant circuit - Google Patents

Abstract

Device (1b) for heat transfer in a refrigerant circuit with a fluid circulating in the refrigerant circuit, having at least two collector tubes (2, 3) which are spaced apart from one another in a vertical direction and which are connected to one another via flow channels for conducting the fluid, the device (1b) has at least two flows (6-1, 6-2, 6-3) and within a first collector pipe (2) at least one inner volume of the first collector pipe (2) into a first chamber (2-1) and a second chamber ( 2-2) dividing separating element (9) is formed, characterized in that within the first, in the vertical direction lower header pipe (2) between the first chamber (2-1) and the second chamber (2-2) for the oil The system (11b) permeable to the refrigerant-oil mixture has a through-opening (12) formed on the vertically aligned separating element (9) and a closure element (13, 13b) for opening and closing the through-opening (12), the closing element (13) is designed as a ball element (13b) with a housing (17), the ball element (13b) being located within a volume which is defined by the housing (17) in connection with an area of the partition wall (9) and an area of the wall of the first collector tube (2), is arranged to be freely movable, and the housing (17) is firmly connected to the partition (9) and the wall of the first collector tube (2) and is designed with openings for oil or a refrigerant-oil mixture to flow through is.

Description

The invention relates to a device for heat transfer in a refrigerant circuit with a fluid circulating in the refrigerant circuit, in particular a refrigerant-oil mixture. The device has at least two collector tubes which are spaced apart from one another in the vertical direction and are connected to one another via flow channels for conducting the fluid, and at least two flows for the fluid to flow through the flow channels.
In addition, the invention relates to a method for operating the device when operating as an evaporator and the use of the device in an air conditioning system of a motor vehicle.

The oil has several functions within a refrigerant circuit. On the one hand, the oil serves to lubricate movable components arranged inside the compressor and thus reduces the friction between the components, which are in particular designed as metal parts. This reduces wear on the compressor. On the other hand, the sealing of the compressor against the environment is improved by means of the oil. Another function of the oil within a refrigerant circuit is to absorb and dissipate the heat generated within the compressor, for example due to the friction between the moving components of the compressor.

Although the oil is essentially only needed inside the compressor, it is inevitable that the oil also circulates inside the refrigerant circuit. The amount of circulating and circulating oil depends on several factors. The factors include the design or the construction and configuration of the compressor and the periphery, i.e. in particular the refrigerant circuit, the age and the state of wear of the compressor, the operating conditions and system conditions and the miscibility of the oil with the refrigerant.

In refrigerant circuits known from the prior art, the circulation rate of the oil varies between 1% and 15% of the mass flow of the refrigerant. The oil of the compressor, which circulates through the refrigerant circuit together with the refrigerant, causes not only a change in the quality and the physical and thermodynamic properties of the refrigerant-oil mixture, but also a reduction in the effectiveness of the heat exchangers in the refrigerant circuit, since the heat transfer and thus the heat passage affected if the heat transfer surfaces inside the heat exchanger are covered with a film of oil.

Refrigerant circuits of conventional air conditioning systems that can be operated both in a refrigeration system mode and in a heat pump mode, in particular with the refrigerant carbon dioxide, also referred to as R744 for short, are designed, for example, with heat exchangers that can be operated as a condenser/gas cooler, which have two or three passages or so-called flows. Since no oil management system is provided inside the condensers/gas coolers known from the prior art, the entire mass flow of refrigerant and oil, ie the refrigerant-oil mixture, is conducted through the heat exchanger. In addition to the heat transfer properties mentioned above and the physical and thermodynamic properties of the refrigerant-oil mixture, the pressure loss of the refrigerant-oil mixture as it flows through the condenser/gas cooler is also influenced by the oil rate in the refrigerant circuit, particularly in the heat exchanger.
Especially when the heat exchanger of the refrigerant circuit, which is operated as a condenser/gas cooler during the refrigeration system mode, is operated as an evaporator in the heat pump mode, less heat is transferred to the refrigerant due to the oil film deposited on the heat transfer surface, so that the refrigeration capacity or the overall capacity of the air conditioning system is reduced. In addition, the pressure loss of the refrigerant as it flows through the heat exchanger leads to a reduction in heat absorption if the suction pressure is limited or to a lower suction density and thus a reduced maximum cooling capacity if the suction pressure is not limited. Furthermore, the oil present in the heat exchanger causes a reduction in the free flow cross section of the flow area and/or a constriction and/or a blockage of the flow paths of the refrigerant, in particular the tubes, especially the multi-channel flat tubes, of the heat exchanger. In connection with high volume flows of the refrigerant when operating the air conditioning system and thus the refrigerant circuit in heat pump mode, a reduced free flow cross section and consequently increased pressure loss has a particularly critical effect on the performance of the system.

In the U.S. 2002/0 084 063 A1 a heat exchanger designed as a downdraft condenser of a refrigerant circuit is described. The heat exchanger has an upper header pipe and a lower header pipe, which are aligned horizontally and whose internal volumes are divided into sections by partition walls. The collector tubes are connected to one another via tubes aligned vertically and parallel to one another. The dividing walls serve to form several flows for the refrigerant, with the dividing walls of the upper header pipe being impermeable. The dividing walls of the lower header pipe are each designed to allow liquid to flow through, so that an inflow of liquid into subsequent pipes in the direction of flow is minimized.

The U.S. 2003/0140647 A1 discloses a condenser having an upper header tube with a first interior volume and a lower header tube disposed below the upper header tube and having a second interior volume. The sizes of the inner volumes of the first and second header pipes are different from each other. The upper and lower collector tubes are connected to one another via tubes which are aligned vertically and parallel to one another. The inner volume of the upper collector tube is divided into two sections by an impermeable partition wall, with a first section having an inlet and a second section having an outlet, and the refrigerant flowing through the heat exchanger in two flows.

In the WO 2013 / 162 222 A1 , the DE 44 18 285 A1 , the DE 10 2013 205 083 A1 and the US 2017 / 0 160 016 A1 each discloses a heat exchanger having a plurality of refrigerant tubes in which a refrigerant flows, cooling fins connected to the plurality of refrigerant tubes, a header tube arranged on at least one side of the plurality of refrigerant tubes for defining a flow space of the refrigerant, and a guide device.

The guide device arranged for dividing the flow space within the collector tube and for guiding the refrigerant from the collector tube to the refrigerant tubes WO 2013/ 162 222 A1 is formed with a movable cover member. The guiding device US 2017 / 0 160 016 A1 has a holder with an opening and a movable element within the liquid refrigerant for opening and closing the opening.

From the DE 44 18 285 A1 a heat exchanger with a water box is produced, which is divided by a partition into two chambers connected by pipes. A passage opening closed by a flap is formed in the partition wall.

The DE 10 2013 205 083 A1 relates to a multi-zone vehicle radiator with a housing, each having a first and second zone formed within the housing, a baffle arranged between the first and the second zone, which is provided within an outlet manifold of the housing, and a zone modifier which is used to regulate a coolant distribution between the first and the second zone is configured according to predetermined conditions.

The object of the invention is now to provide a device for heat transfer in a refrigerant circuit, which is provided for operation in a refrigeration system mode and a heat pump mode, and a method for operating the device as an evaporator. The device should be operable with a minimum pressure loss and designed for operation in both modes in such a way, in particular when the refrigerant circuit is operated in heat pump mode, with a minimum pressure loss to transfer maximum heat to the refrigerant in order to achieve maximum performance of the overall system. The device should be space-saving and enable efficient and safe operation of the refrigerant circuit. In addition, the costs for the production, maintenance and assembly of the device should be minimal.

The object is achieved with a device having the features of claim 1 and its use according to claim 14 and with a method having the features of claim 12. Further developments are specified in the dependent patent claims.

The object is achieved by a device according to the invention for heat transfer in a refrigerant circuit with a fluid circulating in the refrigerant circuit, in particular a mixture. The device is designed with at least two collector tubes which are spaced apart from one another in a vertical direction and are connected to one another via flow channels for conducting the fluid, around which another fluid flows on the outside. The device has at least two streams for flowing the fluid through the flow channels and is formed within a first header tube with at least one partition dividing an inner volume of the first header tube into a first chamber and a second chamber.

According to the conception of the invention, a system that is permeable to the oil of the refrigerant-oil mixture is formed within the first header pipe, which is lower in the vertical direction, between the first chamber and the second chamber.

According to a further development of the invention, at least one separating element dividing an inner volume of the second collector tube into a first chamber and a second chamber is provided within a second collector tube.
The first collector tube and the second collector tube are advantageously each aligned in a horizontal direction and parallel to one another and are connected to one another via tubes aligned vertically and parallel to one another as flow channels. The tubes are preferably designed as flat tubes, in particular as multi-channel flat tubes.

The system according to the invention has a through-opening formed on the vertically aligned separating element of the first header pipe and a closing element for opening and closing the through-opening. The passage opening is preferably formed in the area of a connection of the separating element to a base of the collector tube and preferably has a circular cross section. Alternatively, the cross-sectional area of the through-opening can also be rectangular, in particular square.

A particular advantage of the invention is that the closure element is arranged within the second chamber of the first collector tube.

According to the concept, the closure element is designed as a spherical element with a housing. In this case, the ball element is arranged so that it can move freely within a volume which is delimited by the housing in connection with a region of the partition wall and a region of the wall of the first collector pipe.

The housing is firmly connected to the partition wall and the wall of the first collector pipe and is designed with openings for oil or a mixture of refrigerant and oil to flow through. Another advantage of the invention is that the openings are sized and shaped such that the ball member cannot pass through any of the openings formed in the housing.

The ball element is advantageously made of a material with a lower density than the density of the oil or the refrigerant or the refrigerant-oil mixture.

In a closed state of the through-opening, the ball element is preferably arranged on the edge of the through-opening, lying against the partition wall, sealing the through-opening over its entire circumference.

A further advantageous embodiment of the invention is that the device is designed so that it can be flowed through in both directions, with the direction of flow through the device being dependent on operation as an evaporator or as a condenser/gas cooler.

The device can be used advantageously for various refrigerants, such as R134a, R1234yf, R744, R404a, R600a, R290, R152a, R32 and mixtures thereof, and can be adjusted to the refrigerants.

• - Einströmen eines Kältemittel-Öl-Gemisches in ein zweites, in vertikaler Richtung oberes Sammlerrohr sowie Leiten in einer Strömungsrichtung durch Strömungskanäle einer ersten in der vertikalen Richtung nach unten in eine erste Kammer eines ersten, unteren Sammlerrohres,
• - Trennen des Kältemittel-Öl-Gemisches innerhalb der ersten Kammer des ersten Sammlerrohres in zwei Anteile aus Kältemittel und Öl,
• - Sammeln des abgeschiedenen Öls innerhalb der ersten Kammer im Bereich eines Bodens des ersten Sammlerrohres,
• - Leiten von Kältemittel in einer Strömungsrichtung durch Strömungskanäle einer zweiten Flut in vertikaler Richtung nach oben in eine zweite Kammer des zweiten Sammlerrohres sowie
• - Leiten des Kältemittels in einer Strömungsrichtung durch Strömungskanäle einer dritten Flut in vertikaler Richtung nach unten in eine zweite Kammer des ersten Sammlerrohres,
• - Überströmen des Öls in einer Strömungsrichtung durch eine geöffnete Durchgangsöffnung eines Systems zum Überströmen von Öl von der ersten Kammer in die zweite Kammer des ersten Sammlerrohres,
• - Vermischen des in die zweite Kammer des ersten Sammlerrohres einströmenden Kältemittels und Öls sowie Ableiten des Kältemittel-Öl-Gemisches durch einen im Bereich der zweiten Kammer des ersten Sammlerrohres ausgebildeten Auslass aus der Vorrichtung.

The object is also achieved by a method according to the invention for operating the device for heat transfer in a refrigerant circuit with a fluid circulating in the refrigerant circuit, in particular a refrigerant-oil mixture. The method, when operating as a vaporizer, has the following steps:

• - Inflow of a refrigerant-oil mixture into a second, in the vertical direction upper collector tube and conduction in a flow direction through flow channels of a first in the vertical direction downwards into a first chamber of a first, lower collector tube,
• - Separating the refrigerant-oil mixture within the first chamber of the first collector tube into two portions of refrigerant and oil,
• - Collecting the separated oil within the first chamber in the area of a bottom of the first collector tube,
• - conducting refrigerant in a flow direction through flow channels of a second flood in a vertical direction upwards into a second chamber of the second header tube and
• - conducting the refrigerant in a flow direction through flow channels of a third flow in a vertical direction downwards into a second chamber of the first header pipe,
• - Overflow of the oil in a direction of flow through an open passage opening of a system for overflowing oil from the first chamber into the second chamber of the first collector pipe,
• - Mixing of the refrigerant and oil flowing into the second chamber of the first collector pipe and draining of the refrigerant-oil mixture through an outlet formed in the region of the second chamber of the first collector pipe from the device.

According to a development of the invention, the passage opening of the system for overflowing oil is opened and closed due to pressure differences of the fluid within the first chamber and the second chamber of the first collector pipe.

The advantageous embodiment of the invention allows the use of the device for heat transfer in a refrigerant circuit in an air conditioning system of a motor vehicle.

• - Reduzieren des Druckverlustes des Kältemittels beim Durchströmen der Vorrichtung beim Betrieb als Verdampfer im Wärmepumpenmodus, da das Kältemittel und das Öl getrennt voneinander und kein Kältemittel-Öl-Gemisch durch die Fluten strömt, dadurch auch
• - Erhöhen der Effizienz und der Leistung beim Betrieb der Vorrichtung, insbesondere durch Verringern des Druckverlustes und Verbessern der Wärmeübertragung,
• - Reduzieren der Kosten für die Herstellung, Wartung und den Betrieb des Kältemittelkreislaufs, da beispielsweise die Menge an Öl optimiert und damit minimiert sowie der Platzbedarf und das Gewicht minimiert werden.

In summary, the device according to the invention has the following additional advantages:

• - Reducing the pressure loss of the refrigerant when flowing through the device when operating as an evaporator in heat pump mode, since the refrigerant and the oil flows separately from each other and no refrigerant-oil mixture through the floods, thereby also
• - increasing the efficiency and performance in the operation of the device, in particular by reducing the pressure drop and improving heat transfer,
• - Reducing the cost of manufacturing, maintaining and operating the refrigerant circuit, for example by optimizing and thus minimizing the amount of oil, and minimizing space and weight.

• 1a: in zweiflutiger Ausführungsform und einer undurchlässigen Trennwand im ersten Sammlerrohr aus dem Stand der Technik,
• 1b: in dreiflutiger Ausführungsform und jeweils einer undurchlässigen Trennwand im ersten und im zweiten Sammlerrohr aus dem Stand der Technik,
• 2a: in dreiflutiger Ausführungsform und einer undurchlässigen Trennwand im zweiten Sammlerrohr sowie einem nicht zu Erfindung gehörenden System zum Überströmen von Öl eines Kältemittel-Öl-Gemisches im ersten Sammlerrohr beim Betrieb als Verdampfer in einer ersten Durchströmrichtung des Kältemittel-Öl-Gemisches,
• 2b: System zum Überströmen von Öl des Kältemittel-Öl-Gemisches im ersten Sammlerrohr nach 2a in einer Detailansicht,
• 2c: nach 2a beim Betrieb als Kondensator/Gaskühler in einer zweiten Durchströmrichtung des Kältemittel-Öl-Gemisches,
• 3a: in dreiflutiger Ausführungsform und einer undurchlässigen Trennwand im zweiten Sammlerrohr sowie einem erfindungsgemäßen System zum Überströmen von Öl eines Kältemittel-Öl-Gemisches im ersten Sammlerrohr beim Betrieb als Verdampfer in der ersten Durchströmrichtung des Kältemittel-Öl-Gemisches sowie
• 3b: System zum Überströmen von Öl des Kältemittel-Öl-Gemisches im ersten Sammlerrohr nach 3a in einer Detailansicht.

Further details, features and advantages of embodiments of the invention result from the following description of an exemplary embodiment with reference to the associated drawings. They each show a device through which refrigerant flows for heat transfer of a refrigerant circuit with a first collector pipe and a second collector pipe, which are connected to one another via pipes:

• 1a : in a double-flow embodiment and an impermeable partition in the first header pipe from the prior art,
• 1b : in a three-flow embodiment and in each case an impermeable partition wall in the first and in the second header pipe from the prior art,
• 2a : in a three-flow embodiment and an impermeable partition wall in the second header pipe and a system for overflowing oil of a refrigerant-oil mixture in the first header pipe when operating as an evaporator in a first flow direction of the refrigerant-oil mixture, which does not belong to the invention,
• 2 B : System for overflowing oil of the refrigerant-oil mixture in the first header pipe 2a in a detail view,
• 2c : after 2a when operating as a condenser/gas cooler in a second flow direction of the refrigerant-oil mixture,
• 3a : in a three-flow embodiment and an impermeable partition in the second header pipe and a system according to the invention for overflowing oil of a refrigerant-oil mixture in the first header pipe when operating as an evaporator in the first flow direction of the refrigerant-oil mixture and
• 3b : System for overflowing oil of the refrigerant-oil mixture in the first header pipe 3a in a detailed view.

1a shows a device 1' through which refrigerant flows for heat transfer of a refrigerant circuit with a first collector pipe 2 and a second collector pipe 3, which are connected to one another via pipes 4, in a double-flow embodiment and an impermeable separating element 9', in particular a partition, in the first collector pipe 2 from the state of the art. The inner volumes of the collector tubes 2, 3 and the tubes 4 connecting the collector tubes 2, 3 to one another represent a common volume. The impermeable partition 9' divides the inner volume of the first collector tube 2 into a first chamber 2-1 and a second chamber 2 -2.

The refrigerant-oil mixture flows in the direction of flow 5 through an inlet (not shown) into the device 1'. The inlet is formed in the area of the first chamber 2 - 1 of the first collector pipe 2 . The refrigerant-oil mixture that has flowed into the first chamber 2-1 is divided between the tubes 4 of a first flow 6-1, which are arranged to open into the first chamber 2-1, and in the direction of flow 7-1 through the tubes 4 to the second collector tube 3 passed.

The refrigerant-oil mixture flowing from the tubes 4 of the first flow 6-1 into the second collector pipe 3 is mixed and guided within the second collector pipe 3 to the pipes 4 of a second flow 6-2 and to the pipes 4 of the second flow 6 -2 split. The refrigerant-oil mixture then flows back in the direction of flow 7-2 through the tubes 4 of the second flow 6-2, which open into the second chamber 2-2, to the first collector tube 2.

The coolant-oil mixture flowing from the tubes 4 of the second flow 6-2 into the second chamber 2-2 of the first collector tube 2 is mixed and discharged through an outlet (not shown) in the flow direction 8 from the device 1'. The outlet is formed in the area of the second chamber 2 - 2 of the first collector pipe 2 .
The refrigerant-oil mixture flows in its entirety through the first chamber 2-1 of the first collector tube 2, the tubes 4, the second collector tube 3 and the second chamber 2-2 of the first collector tube 2.

In 1b is a device 1" through which refrigerant flows for heat transfer of a refrigerant circuit with a first collector pipe 2 and a second collector pipe 3, which are connected to one another via pipes 4, in a three-flow embodiment and each with an impermeable separating element 9', 10, in particular separating walls, shown in the first header tube 2 and the second header tube 3 of the prior art. The inner volumes of the collector tubes 2, 3 and the tubes 4 connecting the collector tubes 2, 3 to one another again represent a common volume. The impermeable partitions 9', 10 divide the inner volumes of the first collector tube 2 and the second collector tube 3 into a first Chamber 2-1, 3-1 and a second chamber 2-2, 3-2.

The refrigerant-oil mixture flows in the direction of flow 5 through an inlet (not shown) into the device 1". The inlet is formed in the area of the first chamber 3-1 of the second collector tube 3. The first chamber 3-1 of the second collector tube 3 refrigerant-oil mixture that has flowed in is divided between the tubes 4 of a first flow 6-1, which are arranged opening into the first chamber 3-1, and in the direction of flow 7-1 through the tubes 4 to the first chamber 2-1 of the first collector tube 2. The refrigerant-oil mixture flowing from the tubes 4 of the first flow 6-1 into the first chamber 2-1 of the first collector tube 2 is mixed and within the first chamber 2-1 to the tubes 4 of a second flow 6 -2 and divided between the tubes 4 of the second flow 6-2. The refrigerant-oil mixture then flows in the flow direction 7-2 through the tubes 4 opening into the second chamber 3-2 of the second collector tube 3 back to the second collector tube 3 .

The refrigerant-oil mixture flowing from the tubes 4 of the second flow 6-2 into the second chamber 3-2 of the second collector tube 3 is mixed again and conducted within the second chamber 3-2 to the tubes 4 of a third flow 6-3 and divided between the tubes 4 of the third flood 6-3. The refrigerant-oil mixture then flows back to the first collector pipe 2 in the direction of flow 7 - 3 through the pipes 4 opening into the second chamber 2 - 2 of the first collector pipe 2 .

The refrigerant-oil mixture flowing from the tubes 4 of the third flow 6-3 into the second chamber 2-2 of the first collector tube 2 is mixed and discharged through an outlet, not shown, in the direction of flow 8 from the device 1". The outlet is in the Area of the second chamber 2-2 of the first collector tube 2 is formed.

The refrigerant-oil mixture flows in its entirety through the first chamber 3-1 of the second header tube 3, the tubes 4, the first chamber 2-1 of the first header tube 2, the second chamber 3-2 of the second header tube 3 and the second Chamber 2-2 of the first collector tube 2.

A part of the oil as a portion of the refrigerant-oil mixture circulating through the refrigeration cycle may be separated from the mixture and cover the heat transfer surfaces inside the heat exchanger in the form of a film. The oil film affects, among other things, the effectiveness of the heat transfer, in particular the passage of heat, and causes an additional pressure loss when flowing through the device 1', 1", in particular by reducing the free flow cross section of the tubes 4.

Out of 2a a device 1a, through which refrigerant flows and which does not belong to the invention, for heat transfer of a refrigerant circuit with a first, lower collector pipe 2 and a second, upper collector pipe 3, which are connected to one another via pipes 4, in a three-flow embodiment and with an impermeable separating element 10, in particular a partition, in the second header pipe 3 and a system 11a for overflowing oil of a refrigerant-oil mixture in the first header pipe 2 during operation of the device 1a as an evaporator with a first flow direction of the refrigerant-oil mixture. The lower header pipe 2 is arranged in the vertical direction below the upper header pipe 3, the header pipes 2, 3 being aligned parallel to one another in the horizontal direction. The refrigerant circuit is preferably operated in a heat pump mode.

The inner volumes of the collector tubes 2, 3 and the tubes 4 connecting the collector tubes 2, 3 to one another, which are preferably designed as flat tubes, in particular as multi-channel flat tubes, in turn represent a common volume. The impermeable partition wall 10 divides the inner volume of the second collector tube 3 into a first chamber 3-1 and a second chamber 3-2.

The essential difference of the embodiments of the device 1a from 2a and the device 1". 1b lies in the design of the first, lower collector tube 2 with a system 11a that is permeable, in particular for the oil.

The system 11a, also referred to as an oil supply system or bypass system, has a closure element 13, in particular a flap 13a, for closing the through-opening 12 in addition to the dividing wall 9 aligned in a vertical plane with a through-opening 12. The system 11a designed as a non-return valve with a non-return flap 13a is arranged with the partition 9 between the first chamber 2 - 1 and the second chamber 2 - 2 of the first collector pipe 2 .

The refrigerant-oil mixture flows in the direction of flow 5 through the inlet, not shown, which is formed in the area of the first chamber 3 - 1 of the second, upper header pipe 3 , into the device 1a. The refrigerant-oil mixture that has flowed into the first chamber 3-1 of the second collector pipe 3 is divided between the pipes 4 of the first flow 6-1, which are arranged such that they open into the first chamber 3-1, and through in the direction of flow 7-1 the tubes 4 in the vertical direction downwards to the first chamber 2-1 of the first lower header tube 2.

The refrigerant-oil mixture flowing from the tubes 4 of the first flow 6-1 into the first chamber 2-1 of the first collector tube 2 is mixed. Within the first chamber 2-1 of the first collector tube 2, the two components of refrigerant and oil of the refrigerant-oil mixture are at least partially mechanically separated from one another. In the process, oil is separated from the refrigerant-oil mixture, so that after the separation there is a refrigerant-rich part and an oil-rich part. The refrigerant-rich portion is also referred to as refrigerant and the oil-rich portion is also referred to as oil. The mechanical separation is based in particular on the inertial force as the driving force, which requires a sufficiently large difference in density between the components to be separated.

The oil separated from the refrigerant-oil mixture is collected within the first chamber 2-1 of the first header pipe 2 in the area 14 of the floor.

The refrigerant or the refrigerant-rich portion is within the first chamber 2-1, in particular in the vertical direction above the oil collected in the area 14, out to the tubes 4 of the second flood 6-2 and divided between the tubes 4 of the second flood 6-2 . The refrigerant then flows in the direction of flow 7 - 2 through the tubes 4 opening into the second chamber 3 - 2 of the second collector tube 3 in the vertical direction upwards back to the second collector tube 3 .

The refrigerant flowing from the tubes 4 of the second flow 6-2 into the second chamber 3-2 of the second collector tube 3 is mixed again and guided within the second chamber 3-2 to the tubes 4 of the third flow 6-3 and onto the tubes 4 of the third tide split 6-3. The refrigerant then flows in the direction of flow 7 - 3 through the tubes 4 opening into the second chamber 2 - 2 of the first collector tube 2 in the vertical direction downwards back to the first collector tube 2 .

The refrigerant flowing from the tubes 4 of the third flow 6-3 into the second chamber 2-2 of the first collector tube 2 is mixed with one another and with the oil flowing from the first chamber 2-1 into the second chamber 2-2 of the first collector tube 2 and through an outlet (not shown) formed in the region of the second chamber 2-2 of the first collector pipe 2 in the direction of flow 8 from the device 1a.

The dividing wall 9 of the oil supply system 11a, which is aligned in a vertical plane, is formed with the through-opening 12 in the region of a connection with the bottom of the collector pipe 2, which also consists of 2 B in a detailed view of the system 11a. The through-opening 12 connecting the first chamber 2-1 to the second chamber 2-2 of the first collector tube 2 can be closed by means of the closure element 13, which is designed as a flap 13a pivotable about a rotation axis 15 aligned in the horizontal direction. According to an alternative embodiment that is not shown, the axis of rotation of the closure element designed as a flap can also be aligned in the vertical direction.

The flap 13a designed as an end bearing, that is to say with a rotation axis 15 arranged at a first end, is arranged inside the second chamber 2-2 on the partition wall 9. The axis of rotation 15 is aligned outside the flow cross section of the through-opening 12 and in the vertical direction above the through-opening 12 as a bypass flow path for the oil. Alternatively, the axis of rotation can also be formed below the through-opening in the vertical direction.

When the passage opening 12 is open, the flap 13a is pivoted about the axis of rotation 15 such that an angle in the range greater than 0° to 90° is formed between the partition 9 and the flap 13a in the region of the passage opening 12 . The flap 13a protrudes into the second chamber 2-2 with a second end that is distal to the first end.

Due to the flow direction 7-1, 7-2, 7-3 of the fluid through the flows 6-1, 6-2, 6-3 and the pressure loss occurring when flowing through the device 1a, the pressure of the fluid within the first chamber 2- 1 is greater than the pressure of the fluid within the second chamber 2-2 of the first collector tube 2, so that the surface pressure and the compressive force acting on the flap 13a on the side of the flap 13a facing the first chamber 2-1 are greater than the surface pressure and the compressive force acting on the flap 13a at the direction of the second chamber 2-2 Side of the flap 13a and thus the flap 13a is pivoted in the direction of the second chamber 2-2.

When the flap 13a is open, the oil collected in the area 14 flows in the direction of flow 16 through the passage opening 12 from the first chamber 2-1 into the second chamber 2-2 and within the second chamber 2-2 with the inflowing in the direction of flow 7-3 mixed refrigerant.

Thus, when the device 1a is operated as an evaporator, the fluid flows as a refrigerant-oil mixture only through the first chamber 3-1 of the second collector pipe 3 and the pipes 4 of the first flow 6-1 to the first chamber 2-1 of the first collector pipe 2. The tubes 4 of the second flow 6-2, the second chamber 3-2 of the second collector tube 3 and the tubes 4 of the third flow 6-3 are flowed through exclusively by refrigerant or the refrigerant-rich portion.

The oil conduction system 11a of the device 1a serves in particular to reduce the pressure loss during the operation of the device 1a as an evaporator in the heat pump mode of the refrigerant circuit due to the oil otherwise accumulated on the heat transfer surface during the operation of the device 1a. The amount of oil accumulated on the heat transfer surface is minimized with the oil conduction system 11a.

In addition, the heat that can be transferred to the refrigerant when the device 1a is operating as an evaporator is maximized, since no oil is blocking the flow paths of the tubes 4, specifically the multi-channel flat tubes, and the size of the free cross-sectional area is at a maximum. It also maximizes the performance and efficiency of the climate system when operating in heat pump mode.

In contrast to this, when the device 1a is operated as a condenser/gas cooler in the refrigeration system mode of the refrigerant circuit, the oil must be cooled with the refrigerant in order subsequently to be able to provide sufficient refrigeration capacity. In order to cool the oil sufficiently, especially when the refrigerant circuit is operating under high loads, and to transfer heat from the oil to the environment, the oil, like the refrigerant, must have all three flows 6-1, 6-2, 6-3 happen. The oil supply system 11a of the device 1a, specifically the passage opening 12, is to be closed.

In the closed state of the through-opening 12, the flap 13a rests against the partition wall 9 with the second end, which is formed distal to the first end, which is also shown in FIG 2c is shown. The flap 13a is then arranged parallel to the partition wall 9 in a vertically oriented plane. Due to the preferably planar design of the flap 13a with a surface which is larger than the cross section of the through-opening 12, the flap 13a rests on the partition wall 9 over its entire circumference, closing the through-opening 12.

In 2c The device 1a for heat transfer through which refrigerant flows is shown with the system 11a for overflowing oil of a refrigerant-oil mixture in the first header pipe 2 when the device 1a is operated as a condenser/gas cooler in a second flow direction of the refrigerant-oil mixture 2a shown. The refrigerant circuit is preferably operated in a refrigeration system mode.

If the refrigerant is liquefied during subcritical operation, for example with the refrigerant R134a or with carbon dioxide under certain ambient conditions, the device 1a or the heat exchanger is referred to as a condenser. Part of the heat transfer takes place at constant temperature. In supercritical operation or in the case of supercritical heat emission in the heat exchanger, the temperature of the refrigerant decreases steadily. In this case, the heat exchanger is also referred to as a gas cooler. Supercritical operation can occur under certain environmental conditions or modes of operation of the refrigerant circuit, for example with the refrigerant carbon dioxide.

The difference to the representation of the device 1a from 2a lies in the mode of operation of the refrigerant circuit, for example in the refrigeration system mode or in the heat pump mode, or of the device 1a and associated with the direction of flow of the refrigerant-oil mixture through the device 1a, which is designed to allow bidirectional flow.
When operating in the refrigeration system mode, the device 1a is used as a condenser/gas cooler of the refrigerant circuit 2c for transferring heat from the refrigerant-oil mixture to the environment and when operating in heat pump mode, the device 1a is used as an evaporator of the refrigerant circuit 2a operated to transfer heat to the refrigerant-oil mixture, specifically the refrigerant.

The refrigerant-oil mixture flows in the direction of flow 5 through the inlet, not shown, which is formed in the area of the second chamber 2 - 2 of the first, lower header pipe 2 , into the device 1a. The inlet of the device 1a when operating as a condenser/gas cooler in the refrigeration system mode of the refrigerant circuit corresponds to the outlet of the device 1a when operating as an evaporator in the heat pump mode of the refrigerant circuit.

The refrigerant-oil mixture that has flowed into the second chamber 2-2 of the first collector pipe 2 is divided between the pipes 4 of the first flow 6-1, which are arranged such that they open into the second chamber 2-2, and through in the direction of flow 7-1 the tubes 4 in the vertical direction upwards to the second chamber 3-2 of the second upper header tube 3. The floods 6-1, 6-2, 6-3, like the inlet and outlet of the device 1a, are each referred to according to the flow direction of the refrigerant-oil mixture, so that the refrigerant-oil mixture within the device 1a respectively is introduced into the first flow 6-1 and flows out of the third flow 6-3. Depending on the operating mode of the refrigerant circuit and thus of the device 1a, the flows 6-1, 6-2, 6-3 are also flowed through by the refrigerant-oil mixture in the opposite flow direction 7-1, 7-2, 7-3.

The refrigerant-oil mixture flowing from the tubes 4 of the first flow 6-1 into the second chamber 3-2 of the second collector tube 3 is mixed. Within the second chamber 3-2, the refrigerant-oil mixture is guided to the tubes 4 of the second flow 6-2 and divided between the tubes 4 of the second flow 6-2. The refrigerant then flows in the direction of flow 7 - 2 through the tubes 4 opening into the first chamber 2 - 1 of the first collector tube 2 in the vertical direction downwards back to the first collector tube 2 . The refrigerant flowing from the tubes 4 of the second flow 6-2 into the first chamber 2-1 of the first header tube 2 is mixed again and guided within the first chamber 2-1 to the tubes 4 of the third flow 6-3 and onto the tubes 4 of the third tide split 6-3. The refrigerant then flows in the direction of flow 7 - 3 through the tubes 4 opening into the first chamber 3 - 1 of the second collector tube 3 in the vertical direction upwards back to the second collector tube 3 .

The refrigerant flowing from the tubes 4 of the third flow 6-3 into the first chamber 3-1 of the second collector tube 3 is mixed and exits in the direction of flow 8 through the outlet (not shown) formed in the region of the first chamber 3-1 of the second collector tube 3 derived from the device 1a.

The flap 13a of the oil supply system 11a, which is arranged in the second chamber 2-2 of the first header pipe 2 with the axis of rotation 15 outside the flow cross section of the through-opening 12, in particular in the vertical direction above the through-opening 12, on the partition 9 and is designed to be end-mounted, is the through-opening 12 arranged to be closed. The flap 13a is arranged at an angle of 0° to the partition wall 9. The flap 13a, designed as a check element, in particular as a check flap, of the system 11a designed as a check valve is designed, for example, as a flat sheet metal. By closing the passage opening 12, the system 11a prevents a possible undesired bypass between the second chamber 2-2 and the first chamber 2-1 of the first collector pipe 2.

Due to the direction of flow 7-1, 7-2, 7-3 of the refrigerant-oil mixture through the flows 6-1, 6-2, 6-3, specifically through the first flow 6-1 and the second flow 6-2 , and the pressure loss occurring when flowing through the device 1a, the pressure of the refrigerant-oil mixture within the second chamber 2-2 is greater than the pressure of the refrigerant-oil mixture within the first chamber 2-1 of the first collector tube 2, so that also the surface pressure on the side of the flap 13a facing the second chamber 2-2 is greater than the surface pressure on the side of the flap 13a facing the first chamber 2-1 and the flap 13a is pressed against the partition wall 9. Since part of the surface of the side of the flap 13a facing the partition wall 9 or the first chamber 2-1 rests against the partition wall 9, the surface area for the pressure to act on the side of the flap 13a facing the second chamber 2-2 is also larger than on the side facing the first chamber 2-1, so that the pressing force for abutting the lid 13a on the partition wall 9 is larger than that for opening the lid 13a.

The 3a and 3b show a device 1b according to the invention, through which refrigerant flows, for heat transfer of a refrigerant circuit with the first, lower collector pipe 2 and the second, upper collector pipe 3, which are connected to one another via pipes 4, in a three-flow embodiment and with the impermeable separating element 10, in particular the partition, in the second header pipe 3 and a system 11b according to the invention for overflowing oil of a refrigerant-oil mixture in the first header pipe 2 when the device 1b is operated as an evaporator with the first flow direction of the refrigerant-oil mixture. The refrigerant circuit is preferably operated in a heat pump mode. In 3b is the system 11b after 3a shown in detail.

The device 1a from the 2a until 2c differs from the device 1b of FIGS 3a and 3b only in the design of the systems 11a, 11b designed as oil supply systems or bypass systems for overflowing oil of a refrigerant-oil mixture within the first collector tube 2. Identical components and features of the devices 1a, 1b are provided with the same reference symbols. It will depend on the execution gene to the device 1a in the 2a until 2c referred.

The system 11b has a closure element 13, in particular a ball element 13b with a cage-shaped housing 17, for closing the passage opening 12, in addition to the partition 9 aligned in a vertical plane with the passage opening 12. The system 11b designed as a check valve with the ball element 13b is arranged with the partition wall 9 between the first chamber 2-1 and the second chamber 2-2 of the first collector pipe 2.

The dividing wall 9 of the oil supply system 11b, which is aligned in the vertical plane, is formed with the through opening 12 in the region of a connection to the bottom of the collector pipe 2. The passage opening 12 connecting the first chamber 2-1 to the second chamber 2-2 of the first header pipe 2 can be closed by means of the closure element 13, which is designed as a spherical element 13b. The ball element 13b is arranged within a volume which is delimited by the housing 17 in connection with a region of the partition wall 9 and a region of the wall of the first header pipe 2 around the ball element 13b. The ball element 13b can move freely within the volume. The housing 17, which is firmly connected on the one hand to the partition wall 9 and on the other hand to the wall of the first collector tube 2, is designed with openings for the oil or the refrigerant-oil mixture to flow through, in the form of a cage. The flow cross sections of the openings are designed in size and shape such that the cross-sectional area of the ball element 13b in the area of the circumference is larger than the openings of the housing 17 and the ball element 13b is securely surrounded by the housing 17 . The ball member 13b cannot pass through any of the openings formed in the housing 17.

In the open state of the through hole 12 after 3a and 3b the ball element 13b is arranged within the volume enclosed by the cage 17 in such a way that the flow cross section of the through-opening 12 is open. The ball element 13b can bear against the cage 17 on an inner side.
Due to the flow direction 7-1, 7-2, 7-3 of the refrigerant-oil mixture through the flows 6-1, 6-2, 6-3 and the pressure loss occurring when flowing through the device 1a is the pressure of the refrigerant-oil -Mixture within the first chamber 2-1 greater than the pressure of the refrigerant-oil mixture within the second chamber 2-2 of the first collector tube 2, so that within the oil or the refrigerant-oil mixture or on the surface of the oil respectively of the refrigerant-oil mixture floating ball element 13b is pushed away from the through-opening 12. The ball element 13b is preferably made of a material with a lower density than the density of the oil, the refrigerant or the refrigerant-oil mixture.

When the through-opening 12 is open, the oil collected in the area 14 flows in the direction of flow 16 through the through-opening 12 from the first chamber 2-1 into the second chamber 2-2 and within the second chamber 2-2 with the inflowing in the direction of flow 7-3 mixed refrigerant. Thus, when the device 1b is operated as an evaporator, the fluid flows as a refrigerant-oil mixture only through the first chamber 3-1 of the second collector pipe 3 and the pipes 4 of the first flow 6-1 to the first chamber 2-1 of the first collector pipe 2. The tubes 4 of the second flow 6-2, the second chamber 3-2 of the second collector tube 3 and the tubes 4 of the third flow 6-3 are flowed through exclusively by refrigerant or the refrigerant-rich portion.

In the closed state of the through-opening 12 (not shown), the ball element 13b designed as a non-return element bears against the partition wall 9 in the region of the through-opening 12 . Since the cross-sectional area of the spherical element 13b in the region of the circumference is larger than the circular flow cross-section of the through-opening 12, the spherical element 13b is arranged at the edge of the through-opening 12, completely closing the through-opening 12.
Due to the direction of flow 7-1, 7-2, 7-3 of the refrigerant-oil mixture through the flows 6-1, 6-2, 6-3, specifically through the first flow 6-1 and the second flow 6-2 , and the pressure loss occurring when flowing through the device 1b, the pressure of the refrigerant-oil mixture within the second chamber 2-2 is greater than the pressure of the refrigerant-oil mixture within the first chamber 2-1 of the first collector tube 2, so that the Ball element 13b is sucked or pressed against the partition wall 9 in the area of the through-opening 12 .

With the setting and switching of the direction of flow 5, 7-1, 7-2, 7-3, 8 of the refrigerant and the oil through the device 1a, 1b depending on the operating mode of the refrigerant circuit, the passage opening 12 of the system 11a, 11b without the Automatically opened or closed when exposed to external forces.

The principle on the one hand of separating the oil from the refrigerant-oil mixture within the device 1a, 1b, the separate passage of the refrigerant and the oil through the device 1a, 1b and the mixing of refrigerant and oil within the device operated as an evaporator Device 1a, 1b and, on the other hand, the passage of the refrigerant-oil mixture through the device 1a, 1b operated as a condenser/gas cooler is suitable for devices for heat transfer, regardless of the number of flows.

Instead of the closure elements 13 designed as a flap 13a or ball element 13b, other types and shapes of non-return elements for automatically opening and closing the passage opening 12 are also conceivable.

Reference List

1a, 1b, 1', 1"

contraption

2

first collector pipe

2-1

first chamber first collector tube 2

2-2

second chamber first collector tube 2

3

second collector tube

3-1

first chamber second collector pipe 3

3-2

second chamber second collector tube 3

4

Tube

5

Direction of flow of refrigerant-oil mixture inlet

6-1

first flood

6-2

second flood

6-3

third flood

7-1

Flow direction refrigerant-oil mixture first flow 6-1

7-2

Direction of flow fluid second flood 6-2

7-3

Direction of flow fluid third flood 6-3

8th

Direction of flow of refrigerant-oil mixture Outlet

9, 9'

Separating element, dividing wall of the first header pipe 2

10

Separating element, partition wall of the second header pipe 3

11a, 11b

system, oil control system

12

passage opening

13

closure element

13a

Closing element, flap, non-return valve

13b

Closing element, ball element

14

Oil separation area

15

Axis of rotation flap 13a

16

flow direction of oil

17

Housing, cage ball element 13b

Claims (14)

Device (1b) for heat transfer in a refrigerant circuit with a fluid circulating in the refrigerant circuit, having at least two collector tubes (2, 3) which are spaced apart from one another in a vertical direction and which are connected to one another via flow channels for conducting the fluid, the device (1b) has at least two flows (6-1, 6-2, 6-3) and within a first collector pipe (2) at least one inner volume of the first collector pipe (2) into a first chamber (2-1) and a second chamber ( 2-2) dividing separating element (9) is formed, characterized in that within the first, in the vertical direction lower header pipe (2) between the first chamber (2-1) and the second chamber (2-2) for the oil The system (11b) permeable to the refrigerant-oil mixture has a through-opening (12) formed on the vertically aligned separating element (9) and a closure element (13, 13b) for opening and closing the through-opening (12), the closing element (13) is designed as a ball element (13b) with a housing (17), the ball element (13b) being located within a volume which is defined by the housing (17) in connection with an area of the partition wall (9) and an area of the wall of the first collector tube (2), is arranged to be freely movable, and the housing (17) is firmly connected to the partition (9) and the wall of the first collector tube (2) and is designed with openings for oil or a refrigerant-oil mixture to flow through is. Device (1b) after claim 1 , characterized in that at least one dividing element (10) dividing an inner volume of the second collector tube (3) into a first chamber (3-1) and a second chamber (3-2) is formed within a second collector tube (3). Device (1b) after claim 1 or 2 , characterized in that the first collector tube (2) and a second collector tube (3) are each aligned in a horizontal direction and parallel to one another and are connected to one another as flow channels via tubes (4) aligned vertically and parallel to one another. Device (1b) after claim 3 , characterized in that the tubes (4) are designed as flat tubes. Device (1b) according to one of Claims 1 until 4 , characterized in that the through-opening (12) is formed in the region of a connection of the separating element (9) to a bottom of the collector pipe (2). Device (1b) according to one of Claims 1 until 5 , characterized in that the through-opening (12) has a circular cross-section. Device (1b) according to one of Claims 1 until 6 , characterized in that the closure element (13, 13b) is arranged within the second chamber (2-2) of the first header pipe (2). Device (1b) according to one of Claims 1 until 7 , characterized in that the openings are formed in size and shape such that the ball member (13b) can not pass any of the openings formed in the housing (17). Device (1b) according to one of Claims 1 until 8th , characterized in that the ball element (13b) is formed from a material with a lower density than the density of the oil or the refrigerant or the refrigerant-oil mixture. Device (1b) according to one of Claims 1 until 9 , characterized in that in a closed state of the through-opening (12), the ball element (13b) is arranged on the edge of the through-opening (12), the through-opening (12) completely closing the partition wall (9). Device (1b) according to one of Claims 1 until 10 , characterized in that the device (1b) is designed so that it can be flowed through in both directions, the flow direction being dependent on operation as an evaporator or as a condenser/gas cooler. Method for operating a device (1b) for heat transfer in a refrigerant circuit with a fluid circulating in the refrigerant circuit according to one of claims 2 until 11 when operating as an evaporator, comprising the following steps: - inflow of a refrigerant-oil mixture into a second, upper header pipe (3) and conducting in a flow direction (7-1) through flow channels of a first flood (6-1) in a vertical one downwards into a first chamber (2-1) of a first, lower header pipe (2), - separating the refrigerant-oil mixture within the first chamber (2-1) into two portions of refrigerant and oil, - collecting the separated Oil within the first chamber (2-1) in the area (14) of a bottom of the first header pipe (2), - conducting refrigerant in a flow direction (7-2) through the flow channels of a second flood (6-2) in the vertical direction upwards into a second chamber (3-2) of the second header pipe (3) and - conducting the refrigerant in a flow direction (7-3) through the flow channels of a third bank (6-3) vertically downwards into a second chamber (2-2) of the first collector pipe (2), - the oil overflows in a flow direction (16) through an opened passage opening (12) of a system (11b) for overflowing oil from the first chamber (2-1) into the second Chamber (2-2) of the first header pipe (2), - Mixing of the refrigerant and oil flowing into the second chamber (2-2) of the first header pipe (2) and draining of the refrigerant-oil mixture through a one in the area of the second chamber (2-2) of the first collector tube (2) formed outlet from the device (1b). procedure after claim 12 , characterized in that opening and closing of the through-opening (12) due to pressure differences of the fluid within the first chamber (2-1) and the second chamber (2-2). Use of a device (1b) for heat transfer in a refrigerant circuit according to one of Claims 1 until 11 in an air conditioning system of a motor vehicle.

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