DE102015121594A1 - Device for separating oil of a refrigerant-oil mixture in a refrigerant circuit and arrangement with the device and a heat exchanger for cooling the oil - Google Patents

Abstract

The invention relates to a device (1) for separating and returning oil of a refrigerant-oil mixture in a refrigerant circuit. The refrigerant circuit is formed in the flow direction of the refrigerant with a compressor and a heat exchanger for cooling and / or liquefying the refrigerant. The refrigerant circuit also has a pressure pulsation damper, which is arranged in the flow direction of the refrigerant between the compressor and the heat exchanger for cooling and / or liquefying the refrigerant. The device (1) for separating the oil is formed integrated within the pressure pulsation damper.
The invention also relates to an arrangement for separating, returning and cooling oil of a refrigerant-oil mixture in a refrigerant circuit. The arrangement comprises a device (1) for separating and returning oil and a heat exchanger (11, 11 ', 11'') for cooling the oil deposited with the device (1). The heat exchanger (11, 11 ', 11'') is arranged between the device (1) and the compressor.

Description

The invention relates to a device for separating and returning oil of a refrigerant-oil mixture in a refrigerant circuit. The refrigerant circuit has in the flow direction of the refrigerant to a compressor and a heat exchanger for cooling and / or liquefying the refrigerant. The invention also relates to an arrangement for separating, for returning and for cooling oil of a refrigerant-oil mixture in a refrigerant circuit. The arrangement comprises the apparatus for separating and returning the oil and a heat exchanger for cooling the oil separated with the device.

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

Although the oil is essentially only needed within the compressor, it is inevitable that the oil will circulate within the refrigerant circuit. The amount of circulating and circulating oil depends on several factors. Factors include, but are not limited to, the design and construction and configuration of the compressor and peripherals, particularly the refrigeration cycle, the age and condition of compressor deterioration, operating conditions and system conditions, and the miscibility of the oil with the refrigerant.

In prior art refrigerant circuits, 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 together with the refrigerant through the refrigerant circuit, has various effects. For example, it changes the quality and the physical and thermodynamic properties of the refrigerant-oil mixture. The presence of the oil reduces the effectiveness of the heat exchangers of the refrigerant circuit, since the heat transfer and thus the heat transfer are affected when the heat transfer surfaces are covered inside the heat exchanger with an oil film, since the oil film acts as an additional insulating layer. Under certain circumstances, the oil can be retained in so-called oil traps of the refrigerant circuit, which form particularly in areas with low velocities of the refrigerant. The accumulated in the oil traps oil can, like a liquid vibrating column, suddenly overflow and flow back to the compressor. In this case, a pressure wave can be generated, which in turn causes liquid shocks. In low temperature applications, the possibility of movement of the oil within the refrigerant circuit is severely limited due to the higher viscosity at low temperatures. The drop in oil level within the compressor can lead to mechanical irreversible damage to the compressor. Moreover, the substantially incompressible oil does not cool down during a process of negligible expansion. The oil is mixed with the refrigerant, whereby the refrigerant partially evaporates. In this case, a part of the cooling capacity of the refrigerant, that is about 8% to 10%, spent for the cooling of the compressor oil.

In the US 6,058,727 A a refrigerant circuit for cooling air with a compressor, a condenser, an expansion element and an evaporator will be described. The refrigerant circuit also has a flow path for returning the oil from the outlet of the compressor to the inlet of the compressor with an oil separator and an oil cooler. The heated in the compression of the gaseous refrigerant oil is cooled before the inlet to the compressor. The heat from the oil is transferred to the refrigerant sucked in by the compressor. The oil cooler is formed with an internal heat exchanger as a heat exchanger unit, wherein the heat exchanger unit may be disposed within an accumulator of the refrigerant.

The US 2010/0251756 A1 also discloses a refrigerant circuit for cooling air with a compressor, a condenser, an expansion device and an evaporator and a flow path for returning the oil from the outlet of the compressor to the inlet of the compressor with an oil separator and an oil cooler. The oil cooler is designed as an air-oil heat exchanger and arranged in the flow direction of the air after the evaporator. The heat is transferred from the oil to the cooled air flowing through the evaporator.

From the US 6,579,335 B2 is a device for compressing a gaseous fluid with components for separating oil from the compressed gas, for cooling the oil after the Compressing the gas and storing the oil out. The oil is fed back to the compressor with the gaseous fluid to be compressed. To cool the oil, the oil is passed through a heat exchanger. The heat is transferred from the oil to the gaseous fluid to be compressed. Subsequently, the gaseous fluid is compressed. The oil separator, the oil cooler and the oil reservoir are arranged integrated in a common housing. The oil is directed via a connecting line from the oil reservoir to the compressor.

In conventional refrigerant circuits, the refrigerant-oil mixture is passed through the arranged after the compressor heat exchanger. In addition, it is known from the prior art to separate the refrigerant-oil mixture after exiting the compressor when flowing through an oil separator into a proportion of refrigerant and a proportion of oil. The separated oil is subsequently cooled, for example in heat transfer with the refrigerant circulating in the refrigerant circuit or with the air conditioned in the evaporator, which reduces the efficiency of the refrigerant circuit.

The object of the invention is now to provide a device for separating oil of a refrigerant-oil mixture and an arrangement for cooling the oil in a refrigerant circuit. The device and the arrangement should be space-saving and allow efficient and safe operation of the refrigerant circuit. In addition, the cost of manufacturing, maintenance and assembly of the device and the arrangement should be minimal.

The object is achieved by the subject matters with the features of the independent claims. Further developments are specified in the dependent claims.

The object is achieved by a device according to the invention for separating and returning oil of a refrigerant-oil mixture in a refrigerant circuit. The refrigerant circuit is formed in the flow direction of the refrigerant with a compressor and a heat exchanger for cooling and / or liquefying the refrigerant.

According to the concept of the invention, the refrigerant circuit has a pressure pulsation damper, which is arranged in the flow direction of the refrigerant between the compressor and the heat exchanger for cooling and / or liquefying the refrigerant. The device for separating the oil is designed according to the invention integrated within the Druckpulsationsdämpfers.

According to a development of the invention, the pressure pulsation damper has an inlet for the inflow of the refrigerant-oil mixture and in each case an outlet for the refrigerant and an outlet for the oil. Within the pressure pulsation damper, a baffle plate for flowing the refrigerant-oil mixture and a collecting region for the separated oil are advantageously formed. The inlet and the baffle plate are in an upper region of the volume enclosed by the device and the collecting region is arranged in a lower region of the volume enclosed by the device below the baffle plate.

According to a preferred embodiment of the invention, the baffle plate is aligned perpendicular to the flow direction of the refrigerant-oil mixture after the inlet to cause the largest possible change in the flow direction and flow rate of the refrigerant-oil mixture and a maximum separation of refrigerant and oil, because the separation is based on different inertial forces of the shares. Alternatively, the baffle plate can be arranged inclined to the flow direction of the refrigerant-oil mixture after the inlet and at an angle deviating from 90 °.

According to an advantageous embodiment of the invention, a closure element for closing the outlet is arranged within the collecting region of the device in the direction of the outlet of the oil. With the closure element, a connecting line between the device for separating and for returning oil to the compressor is closed, so that the mass flow of the separated oil to the compressor can be controlled. The adjustable and closable connection to the compressor prevents any potential unwanted bypass between the high pressure side refrigerant at the compressor outlet and the low side refrigerant at the inlet of the compressor within the oil return. The closure element for closing the outlet and thus the connecting line to the compressor is preferably designed as a float.

With the device according to the invention, the oil separated from the refrigerant-oil mixture and the refrigerant can be cooled separately in different mass flows. As a driving potential for cooling the two parts and thus as heat-absorbing fluids can advantageously the ambient air and / or a coolant of a coolant circuit can be used.

The object is also achieved by an inventive arrangement for separating, for returning and for cooling oil of a refrigerant-oil mixture in a refrigerant circuit. The Arrangement conceptually includes a device for separating and returning oil with the above features and a heat exchanger for cooling the oil deposited with the device. The heat exchanger is arranged between the device for separating the oil and the compressor.

According to a first alternative embodiment of the invention, the heat exchanger is designed to cool the deposited with the device oil from at least one coaxial tube of concentrically arranged tubes. The heat from the oil is preferably transferred to a coolant as a heat-absorbing fluid. For example, when using the refrigerant cycle in an air conditioning system of a motor vehicle, the refrigerant may circulate within a low-temperature refrigerant circuit or within a high-temperature refrigerant circuit.

The heat exchanger is advantageously configured as a countercurrent heat exchanger, wherein the oil flows through the inner tube and the coolant through the formed between the outside of the inner tube and the inside of the outer tube gap.

According to a second alternative embodiment of the invention, the heat exchanger is formed from at least one finned tube. The heat is transferred from the oil to air as a heat-absorbing fluid. The air is passed over the finned outside of the finned tube.

According to a third alternative embodiment of the invention, the heat exchanger is designed as a refrigerant circulating internal heat exchanger. The heat is transferred from the oil to the refrigerant as a heat-absorbing fluid. The heat exchanger is advantageously arranged on the refrigerant side between an outlet of an evaporator and the compressor.

It should be noted that the refrigerant circuit can be operated both as a component of a compression refrigeration system and a heat pump, so that the inventive device can be used both as part of a refrigerant circuit of a compression refrigeration system and a heat pump system, in particular an air conditioning system of a motor vehicle.

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

• – Reduzieren des Druckverlustes des Kältemittels beim Durchströmen der Wärmeübertrager, da das Kältemittel und das Öl getrennt voneinander und kein Kältemittel-Öl-Gemisch durch die Wärmeübertrager strömt, dadurch auch
• – Erhöhen der Effizienz und der Sicherheit beim Betrieb des Systems, insbesondere des Kältemittelkreislaufs, da das Öl beim Durchströmen der Kältemittel-Wärmeübertrager nicht mehr abgekühlt oder erwärmt werden muss,
• – Reduzieren der Kosten für die Herstellung, Wartung und den Betrieb des Kältemittelkreislaufs, da die Menge an Öl optimiert und damit minimiert wird,
• – Reduzieren des Platzbedarfs des gesamten Kältemittelkreislaufs und
• – Reduzieren akustischer Druckpulsationen in Kältemittelkreisläufen, insbesondere von Klimaanlagen und Wärmepumpensystemen.

The device according to the invention has in summary the following further advantages:

• - Reduce the pressure loss of the refrigerant when flowing through the heat exchanger, as the refrigerant and the oil separated from each other and no refrigerant-oil mixture flows through the heat exchanger, thereby also
• Increasing the efficiency and safety of the operation of the system, in particular of the refrigerant circuit, since the oil does not have to be cooled or heated as it flows through the refrigerant heat exchangers,
• - Reduce the cost of manufacturing, maintaining and operating the refrigerant circuit by optimizing and minimizing the amount of oil
• - Reducing the space requirement of the entire refrigerant circuit and
• - Reduce acoustic pressure pulsations in refrigerant circuits, in particular of air conditioning and heat pump systems.

Further details, features and advantages of embodiments of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. Show it:

1 a device integrated in a pressure pulsation damper for mechanically separating oil of a refrigerant-oil mixture of a refrigerant circuit having a baffle plate and a collecting region for the separated oil, and
an arrangement of the device for the mechanical separation of the oil 1 With

2 a heat exchanger formed of a coaxial tube for cooling the oil,

3 a formed of a finned tube heat exchanger for cooling the oil and

4 : a refrigerant circulation internal heat exchanger for cooling the oil.

1 shows a device 1 for separating oil of a refrigerant-oil mixture G of a refrigerant circuit. The device 1 is designed to be integrated in a pressure pulsation damper for the refrigerant.

The two components of refrigerant and oil of the refrigerant-oil mixture G are by means of the device 1 mechanically separated from each other for separating the oil. The oil is separated from the refrigerant-oil mixture, so that after the separation, a refrigerant-rich portion and an oil-rich fraction or low-refrigerant fraction are present. The refrigerant-rich portion is in Short form also as refrigerant KM and the oil-rich portion is referred to in short form as oil. The mechanical separation is based on the inertial force as a driving force, which requires a sufficiently large density difference between the components to be separated. A sufficiently large density difference between the components to be separated refrigerant and oil is present within a refrigerant circuit at the outlet of the compressor or at the inlet of a heat exchanger operated as a condenser / gas cooler. If the liquefaction of the refrigerant occurs in subcritical operation, such as with the refrigerant R134a or under certain ambient conditions with carbon dioxide, the heat exchanger is called a condenser. Part of the heat transfer takes place at a constant temperature. In supercritical operation or supercritical heat in the heat exchanger, the temperature of the refrigerant steadily decreases. In this case, the heat exchanger is also referred to as a gas cooler. Supercritical operation may occur under certain environmental conditions or operations of the refrigerant cycle with, for example, the refrigerant carbon dioxide.

The device 1 for separating the oil, also referred to as Druckpulsationsdämpfer with Ölabscheidefunktion or as a combination of Druckpulsationsdämpfer and oil separator, due to the training integrated in the pressure pulsation damper, has an inlet 2 for the refrigerant-oil mixture G, and in each case an outlet 3 for the refrigerant KM and an outlet 4 for the oil. The inlet 2 is connected via a connecting line with an outlet of the compressor, not shown, of the refrigerant circuit. The connection line 2 thus corresponds to the pressure line of the compressor. The device 1 is therefore as a modified pressure pulsation damper with Ölabscheidefunktion within the outlet line of the compressor or the connecting line 2 arranged between the compressor and operated as a condenser / gas cooler heat exchanger and separates the refrigerant-oil mixture G in the refrigerant-rich portion and the oil-rich share.

The oil gets through one in the device 1 or the pressure pulsation damper integrated baffle plate 5 in conjunction with one below the baffle plate 5 arranged collection area 6 for the separated oil mechanically separated from the refrigerant-oil mixture and stored. The refrigerant-oil mixture G flows through the inlet 2 into the device 1 a, hits the baffle plate 5 on and drips into the below the flapper 5 arranged collection area 6 from. The inlet 2 is as an inlet for the refrigerant-oil mixture G as perpendicular to the baffle plate 5 aligned. After flowing into the device 1 bounces the refrigerant-oil mixture G on the front of the baffle plate 5 , Due to the abrupt changes in the flow velocity and the flow direction, the refrigerant-rich portion and the oil-rich portion are separated from each other due to the different inertial forces of the refrigerant-rich portion and the oil-rich portion with which the two portions of the change in direction follow differently. The oil-rich portion is at the flapper 5 down to the collection area 6 passed the oil separation. The refrigerant-rich portion flows in the upper region of the device 1 enclosed volume around the baffle plate 5 around to the outlet 3 of the refrigerant KM. At the outlet 3 of the refrigerant KM from the device 1 is a filter element 8th , For example, in the form of a sieve, arranged so that the refrigerant-rich portion through the filter element 8th flowing. The refrigerant KM passes through the outlet 3 and those with the outlet 3 coupled connection line from the device 1 out. The down to the collection area 6 Guided separated oil-rich proportion is also by a, in particular designed as a sieve filter element 7 passed.

The oil or the oil-rich portion is in the lower part of the device 1 within the collection area 6 collected and then passes through the outlet 4 as well as with the outlet 4 coupled connection line from the device 1 off and is directed to the pressure side of the compressor of the refrigerant circuit. Within the collection area 6 of the oil is a float 9 as a closure element of the collection area 6 or the device 1 for separating the oil in the direction of the outlet 4 formed of the oil. The swimmer 9 is about a guide element 10 held arranged. The guide element 10 Advantageously, a spring element, wherein the spring force of the device 1 closing on the float 9 acts. The swimmer 9 closes the outlet 4 the oil to the compressor, especially at too low a level of oil within the collection area 6 to make a refrigerant bypass through the device 1 From the high pressure side of the refrigerant circuit to the low pressure side of the refrigerant circuit to prevent. At a corresponding level of stored oil, the oil raises in the collection area 6 trained swimmer 9 to which the outlet 4 of the oil from the device 1 releases. The device 1 can also do without the float 9 be formed, the refrigerant bypass then, for example, on the choice of the inner diameter of the outlet 4 the oil arranged connecting line to the compressor is controlled.

After flowing out of the device 1 For example, the separated oil is outside the pressure pulsation damper in various ways cooled. In this case, the oil-rich fraction flows through a heat exchanger, which is also referred to as an oil cooler, through. The heat is transferred from the oil to a heat-absorbing fluid.

Out 2 an arrangement goes out of the device 1 for mechanically separating the oil from the refrigerant-oil mixture G according to 1 with a formed of at least one coaxial heat exchanger 11 to cool the oil.

That from the device 1 derived oil is formed by means of concentrically arranged tubes heat exchanger 11 , also referred to as coaxial tube heat exchanger, cooled. The heat is transferred from the oil to a coolant, in particular water or a water-glycol mixture, which flows in countercurrent to the oil. The oil flows through the centrally located tube while passing the coolant through the gap between the coaxially disposed tubes. After flowing out of the heat exchanger 11 the oil is returned to the refrigerant on the suction side of the compressor.

When using the device 1 and the heat exchanger 11 In a refrigerant circuit of a motor vehicle, the coolant circulates advantageously within a low-temperature coolant circuit.

The 3 shows an arrangement of the device 1 for mechanically separating the oil from the refrigerant-oil mixture G according to 1 with a heat exchanger formed of at least one finned tube 11 ' to cool the oil.

That from the device 1 derived oil is cooled by means of the pipe formed on the outside to increase the heat transfer area and to improve the heat transfer with ribs. The heat is transferred from the oil to the surrounding air. The oil flows inside the tube while the air passes over the ribbed outside. After flowing out of the heat exchanger 11 ' the oil is returned to the refrigerant on the suction side of the compressor.

When using the device 1 and the heat exchanger 11 ' in a refrigerant circuit of a motor vehicle, the oil is cooled in particular by means of wind.

In 4 is an arrangement of the device 1 for mechanically separating the oil from the refrigerant-oil mixture G according to 1 with a refrigerant circuit internal heat exchanger 11 '' to cool the oil.

That from the device 1 derived oil is by means of the refrigerant circuit internal heat exchanger 11 '' cooled. The heat is transferred from the oil to the refrigerant. The refrigerant is in front of the inlet into the heat exchanger 11 '' Evaporates in the evaporator and enters in a state in the heat exchanger 11 '' which is at least near the saturation state. With the heat transferred from the oil to the refrigerant, the refrigerant overheats before entering the compressor, so that no liquid drops can occur. In front of the outlet from the heat exchanger 11 '' For example, the superheated refrigerant and the cooled oil can be mixed and used as a refrigerant-oil mixture in the connection line 4 flow to the compressor and be fed back to the compressor on the suction side. In an alternative embodiment, not shown, the superheated refrigerant and the cooled oil are separately directed to the suction side of the compressor.

The refrigerant circuit internal heat exchanger 11 '' may also be formed as an internal heat exchanger, wherein the flow path for the oil to be cooled as the third flow path of the heat exchanger 11 '' is trained. Under the internal heat exchanger is an internal circulation heat exchanger to understand, which serves the heat transfer between the refrigerant at high pressure and the refrigerant at low pressure. In this case, for example, on the one hand, the liquid refrigerant after condensation further cooled and on the other hand, the suction gas overheated before the compressor.

LIST OF REFERENCE NUMBERS

1

 Device for separating oil

2

 Inlet, connecting line refrigerant-oil mixture

3

 Outlet refrigerant

4

 Outlet oil, connecting line oil to the compressor

5

 flapper

6

 Collection area oil

7

 Filter element oil

8th

 Filter element refrigerant

9

 swimmer

10

Guide element float 8th

11, 11 ', 11' '

 Heat exchanger

KM

 Refrigerant, refrigerant-rich fraction

oil

 Oil, oil-rich fraction

G

 Refrigerant-oil mixture

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 6058727A [0005]
• US 2010/0251756 A1 [0006]
• US 6579335 B2 [0007]

Claims (10)

Contraption ( 1 ) for separating and returning oil of a refrigerant-oil mixture in a refrigerant circuit, wherein the refrigerant circuit in the flow direction of the refrigerant comprises a compressor and a heat exchanger for cooling and / or liquefying the refrigerant, characterized in that - the refrigerant circuit comprises a pressure pulsation damper, which is arranged in the flow direction of the refrigerant between the compressor and the heat exchanger for cooling and / or liquefying the refrigerant, and that - the device ( 1 ) is formed integrated for the separation of the oil within the Druckpulsationsdämpfers. Contraption ( 1 ) according to claim 1, characterized in that the pressure pulsation damper is provided with an inlet ( 2 ) to the inflow of the refrigerant-oil mixture and in each case an outlet ( 3 ) for the refrigerant and an outlet ( 4 ) is formed for the oil and that within the Druckpulsationsdämpfers a baffle plate ( 5 ) for the flow for the refrigerant-oil mixture and a collecting area ( 6 ) are formed for the separated oil, wherein the inlet ( 2 ) and the baffle plate ( 5 ) in an upper region of the device ( 1 ) enclosed volume and the collecting area ( 6 ) in a lower region of the device ( 1 ) enclosed volume below the baffle plate ( 5 ) is arranged. Contraption ( 1 ) according to claim 2, characterized in that the baffle plate ( 5 ) perpendicular to the flow direction of the refrigerant-oil mixture after the inlet ( 2 ) is aligned. Contraption ( 1 ) according to claim 2 or 3, characterized in that within the collecting area ( 6 ) in the direction of the outlet ( 4 ) of the oil, a closure element for closing the outlet ( 4 ) is arranged. Contraption ( 1 ) according to claim 4, characterized in that the closure element for closing the outlet ( 4 ) as a swimmer ( 9 ) is trained. Arrangement for separating, returning and cooling oil of a refrigerant-oil mixture in a refrigerant circuit, comprising a device ( 1 ) for separating and returning oil according to any one of claims 1 to 5 and a heat exchanger ( 11 . 11 ' . 11 '' ) for cooling the device ( 1 ) separated oil, wherein the heat exchanger ( 11 . 11 ' . 11 '' ) between the device ( 1 ) and the compressor is arranged. Arrangement according to claim 6, characterized in that the heat exchanger ( 11 ) is formed of at least one coaxial tube of concentrically arranged tubes, wherein the heat is transferred from the oil to a coolant as a heat-absorbing fluid. Arrangement according to claim 6, characterized in that the heat exchanger ( 11 ' ) is formed of at least one finned tube, wherein the heat is transferred from the oil to air as heat-absorbing fluid, and wherein the air is passed over the finned outside of the finned tube. Arrangement according to claim 6, characterized in that the heat exchanger ( 11 '' ) is formed as a refrigerant circuit internal heat exchanger, wherein the heat is transferred from the oil to the refrigerant as heat-receiving fluid. Contraption ( 1 ) according to claim 9, characterized in that the heat exchanger ( 11 '' ) is disposed on the refrigerant side between an outlet of an evaporator and the compressor.

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