HEAT EXCHANGER AND AIR CONDITIONING

Abstract

A heat exchanger of the present disclosure comprises a plurality of heat transfer tubes arranged parallel to one another in a first direction, and a refrigerant distributor to which the plurality of heat transfer tubes are connected, the refrigerant distributor extending in the first direction and having a connection opening to which a refrigerant tube is connected, the refrigerant distributor comprising an outer tube to which the plurality of heat transfer tubes are connected, the outer tube extending in the first direction, an inner tube enclosed within the outer tube and extending in the first direction, and a partition plate configured to divide a first space formed between the inner tube and the outer tube into a plurality of compartments in the first direction, the inner tube having a through-hole configured to form a second space.which is formed within the inner tube, to communicate with the first space, wherein the second space is configured to communicate with the connection opening at an end section in the first direction of the inner tube, and wherein two adjacent areas in the first direction of the plurality of areas are configured to communicate with each other via the opening.

Description

Technical field

[0001] The present disclosure relates to a heat exchanger and an air conditioning system with a refrigerant distributor having a double-pipe structure, comprising an inner pipe and an outer pipe. Technical background

[0002] A known heat exchanger used in a known air conditioning system has a refrigerant distributor with a double-pipe structure, comprising an inner and an outer pipe to distribute the refrigerant. In such a double-pipe refrigerant distributor, a refrigerant outlet hole is provided at the bottom of the inner pipe. The refrigerant exiting the outlet hole is expelled into the space between the inner and outer pipes, then flows from the outer pipe into the heat transfer pipe, where heat exchange with the air takes place.

[0003] A heat exchanger with such a refrigerant distributor allows the two-phase gas-liquid refrigerant, which has flowed into the distributor, to be expelled through the refrigerant outlet hole from the inner tube into the space between the inner and outer tubes. As the two-phase gas-liquid refrigerant inside the inner tube flows out through the outlet hole into the space between the inner and outer tubes, it is swirled, making the refrigerant nearly homogeneous. This results in a uniform distribution of the refrigerant across multiple heat transfer tubes, thereby improving the heat transfer efficiency of the heat exchanger.Furthermore, by providing a plurality of outer pipes on an inner pipe, the refrigerant distributor is configured in such a way that a plurality of spaces are formed between the inner pipe and the outer pipes, thereby enabling a reduction in volume (see, for example, patent literature 1). [Patent literature]

[0004] Patent literature 1: WO2019 / 239445 Brief description of the invention: Technical problem

[0005] However, a heat exchanger with a refrigerant manifold featuring a double-pipe structure had the problem that it was difficult to drain oil from the space between the majority of the inner and outer pipes. This oil had accumulated there during the return flow of the gaseous refrigerant from the heat transfer pipe into the double-pipe manifold. This stagnant oil led to an uneven distribution of the refrigerant in the spaces between the majority of the inner and outer pipes within the manifold.

[0006] The present disclosure was made in view of the aforementioned problems and aims to provide a heat exchanger and an air conditioning system in which oil stagnation is suppressed in a plurality of areas formed between the inner tube and the outer tube of the refrigerant distributor. Solution to Problem

[0007] An embodiment of a heat exchanger of the present disclosure comprises a plurality of heat transfer tubes arranged parallel to one another in a first direction, and a refrigerant distributor to which the plurality of heat transfer tubes are connected, the refrigerant distributor extending in the first direction and having a connection opening to which a refrigerant tube is connected, the refrigerant distributor comprising an outer tube to which the plurality of heat transfer tubes are connected, the outer tube extending in the first direction, an inner tube enclosed within the outer tube and extending in the first direction, and a partition plate configured to divide a first space formed between the inner tube and the outer tube into a plurality of areas in the first direction, the inner tube having a through-hole configured toto bring a second space formed within the inner tube into communication with the first space, wherein the second space is configured to communicate with the connection opening at an end section in the first direction of the inner tube, and wherein two adjacent areas in the first direction of the plurality of areas are configured to communicate with each other via the opening.

[0008] One embodiment of an air conditioning system with a heat exchanger of the present disclosure is an air conditioning system in which the majority of heat transfer tubes extend in the direction of gravity and the refrigerant distributor is located in the direction of gravity below the majority of heat transfer tubes.

[0009] The heat exchanger and air conditioning system of the present disclosure facilitate the flow of stagnant oil towards the connection opening by establishing communication between the majority of areas within the first chamber. This eliminates the uneven distribution of stagnant oil and also corrects an uneven flow of refrigerant. Brief description of the drawings [ Fig. 1] Fig. Figure 1 shows an example of a refrigerant circuit diagram of the air conditioning system 100 according to embodiment 1. [ Fig. 2] Fig. Figure 2 is an explanatory representation of the environmental structure of the refrigerant distributor 30 of the external heat exchanger 3 of the air conditioning system 100 according to embodiment 1. [ Fig. 3] Fig. Figure 3 is an explanatory representation of the cross-sectional configuration of section DD in Fig. 2. [ Fig. 4] Fig. Figure 4 is an explanatory illustration of another example of the cross-sectional configuration of the refrigerant distributor 30, which is shown in Fig. 3 is shown. [ Fig. 5] Fig. Figure 5 is an explanatory illustration of another example of the cross-sectional configuration of the refrigerant distributor 30, which is shown in Fig. 3 is shown. Embodiments of the invention

[0010] The following describes, with reference to the drawings, an air conditioning system with a heat exchanger according to the embodiments. In the drawings, identical elements are identified by the same reference numerals, and explanations are repeated only where necessary. The present disclosure may include any combination of the configurations described below in the respective embodiments. Design 1.<Klimaanlage 100>

[0011] Fig. Figure 1 shows an example of a refrigerant circuit diagram of the air conditioning system 100 according to embodiment 1. As in Fig. As shown in Figure 1, the air conditioner 100 has an outdoor unit 10 and a plurality of indoor units 11, 12, and 13. These indoor units 11, 12, and 13 are connected in parallel. The refrigerant circulates within the outdoor unit 10 and the plurality of indoor units 11, 12, and 13. The air conditioner 100 is a multi-unit air conditioner. It should be noted that embodiment 1 does not limit the number of indoor units 11, 12, and 13 connected to the outdoor unit 10.

[0012] The air conditioning unit 100 has a refrigerant circuit that connects a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, an expansion valve 5, an indoor heat exchanger 6, and an accumulator 8 via refrigerant pipes 26 and 27. Both the outdoor heat exchanger 3 and the indoor heat exchanger 6 are configured to exchange heat between the refrigerant flowing through them and the air generated by the fans 4 and 7, respectively.

[0013] During cooling operation, the refrigerant compressed by compressor 1 flows as a high-temperature, high-pressure gas from the refrigerant pipe 26, which connects the four-way valve 2 to the outdoor heat exchanger 3, through the four-way valve 2 and into the outdoor heat exchanger 3. After exchanging heat with the airflow generated by the fan 4, the refrigerant that has entered the outdoor heat exchanger 3 flows out of the refrigerant pipe 27, which connects the outdoor heat exchanger 3 to the expansion valve 5. In heating operation, i.e., when the outdoor heat exchanger 3 functions as an evaporator, the refrigerant flow direction is opposite to that described above for the condenser. <Außenwärmetauscher 3>

[0014] Fig. Figure 2 is an explanatory representation of the environmental structure of the refrigerant distributor 30 in the outdoor heat exchanger 3 of the air conditioning system 100 according to embodiment 1. Fig. Figure 3 is an explanatory representation of the cross-sectional configuration of section DD from Fig. 2. The outdoor heat exchanger 3, installed in the outdoor unit 10 of the air conditioner 100, exchanges heat between the outside air, drawn in by the fan 4 from the air inlet opening, and the refrigerant. Although the configuration of the outdoor unit 10 is not restricted, the outdoor heat exchanger 3 can, for example, be arranged along the side surface of the outdoor unit 10's housing. The fan 4 is located on the top of the outdoor unit 10, near the air outlet opening formed on the upper surface of the housing. Air flows in from the side surface of the housing, which serves as the air inlet, passes through the outdoor heat exchanger 3, and is expelled from the air outlet opening after passing through the fan 4 located on the top. Fig. In figure 3, the arrow schematically represents the airflow through the outdoor unit 10.

[0015] As in Fig. As shown in Figure 2, the external heat exchanger 3 has a refrigerant distributor 30 and a plurality of heat transfer tubes 31. The plurality of heat transfer tubes 31 are flat tubes arranged in the x-direction. The refrigerant distributor 30 extends in the x-direction and has a connection opening 36 at one end section, which is connected to a refrigerant tube 26. Fins may also be mounted between the plurality of heat transfer tubes 31. Additionally, another refrigerant distributor 30B is connected to the other end section of the plurality of heat transfer tubes 31. The refrigerant distributor 30B connected to the other end section of the plurality of heat transfer tubes 31 may have a different structure than the one shown in Figure 2. Fig. The refrigerant distributor 30A shown in Figure 2 is arranged such that its longitudinal direction is aligned with the horizontal. The majority of heat transfer tubes 31 are spaced apart from one another, with one end of each tube inserted into an inlet hole 37 of the refrigerant distributor 30. Additionally, as shown in Figure 2, the refrigerant distributor 30 is arranged such that its longitudinal direction is aligned with the horizontal direction. The majority of heat transfer tubes 31 are spaced apart from one another, with one end of each tube inserted into an inlet hole 37 of the refrigerant distributor 30. Fig. 2 shown, the refrigerant distributor 30A is arranged in the direction of gravity below the majority of heat transfer pipes 31. <Kältemittelverteiler 30>

[0016] As in Fig. As shown in Figure 2, the refrigerant distributor 30 has a double-pipe structure with an inner pipe 33 and an outer pipe 34. The outer pipe 34 has a plurality of inlet holes 37 on its surface oriented in the z-direction, and the plurality of heat transfer pipes 31 are connected to these inlet holes 37. These plurality of heat transfer pipes 31 are connected to the first chamber 40, which is formed between the inner pipe 33 and the outer pipe 34. The first chamber 40 and the plurality of heat transfer pipes 31 are in communication with each other, allowing the refrigerant flowing through the plurality of heat transfer pipes 31 to flow into the first chamber 40.

[0017] The inner tube 33 is arranged such that its tube axis is aligned with the x-direction. The inner tube 33 is, for example, a hollow tube structure, wherein at an end section 42a the second chamber 42c inside and the end section chamber 43 of the refrigerant distributor 30, which communicates with the connection opening 36, are in communication with each other. In addition, the side surface of the inner tube 33 has a plurality of through-holes 35. These through-holes 35 are formed along the axis of the inner tube 33 and establish communication between the second chamber 42c of the inner tube 33 and the first chamber 40.

[0018] The gap formed between the inner tube 33 and the outer tube 34 is designated as the first chamber 40 and is subdivided in the x-direction into a plurality of regions 41A, 41B, 41C by partition plates 38A, 38B, 38C, 38D. The partition plates 38A, 38B, 38C, 38D can be collectively referred to as partition plate 38. Each of the regions 41A, 41B, and 41C is a region bounded by partition plate 38, the inner surface of the outer tube 34, and the outer surface of the inner tube 33. Adjacent regions 41A and 41B are separated from each other by partition plate 38B, and adjacent regions 41B and 41C are separated from each other by partition plate 38C. Furthermore, the area 41A located at the end section is separated by the end section chamber 43 and the partition plate 38A. The area 41C located at the other end section is separated by the end section chamber 44 and the partition plate 38D.

[0019] The end section room 43 and each of the majority of areas 41A, 41B and 41C are in communication with each other via an opening 39, which is provided at the location where the partition plate 38 is installed.

[0020] Each of the plurality of areas 41A, 41B, and 41C communicates with the plurality of heat transfer tubes 31 and furthermore communicates with the second chamber 42c of the inner tube 33 via the through-hole 35. In embodiment 1, the multiple areas 41 connected to the plurality of heat transfer tubes 31 are configured as three areas; however, there can also be two areas or four or more areas.

[0021] As in Fig. As shown in Figure 2, in the refrigerant distributor 30, one end section 42a of the inner tube 33 is located in the end section space 43, and the other end section 42b is located in the end section space 44. The second space 42c of the inner tube 33 is connected to the end section space 43, which communicates at least with the connection opening 36. The other end section space 44 may or may not communicate with the second space 42c of the inner tube 33. Furthermore, the end section 42b of the inner tube 33 may be closed, and the refrigerant distributor 30 may be configured such that the end section space 44 is not provided. One end section 42a of the inner tube 33 is open and configured so that the refrigerant in the second space 42c can flow into the connection opening 36. (Passage hole 35)

[0022] As in the Fig. 2 and Fig. As shown in Figure 3, the inner tube 33 has through-holes 35, also referred to as orifice holes, which are spaced apart from one another on the side surface of the inner tube 33. The through-hole 35 is located in the x-direction directly below the heat transfer tube 31. Furthermore, the through-hole 35 can be arranged between the heat transfer tubes 31. By arranging the through-hole 35 between the heat transfer tubes 31, the refrigerant distribution capability can be improved when a two-phase gas-liquid refrigerant flows into the refrigerant distributor 30, compared to the case where the through-hole 35 is provided directly below the heat transfer tube 31 on the inner tube 33.

[0023] As in Fig. As shown in Figure 3, the through-hole 35 on the side surface of the inner tube 33 is open obliquely downwards when the tube axes of the several heat transfer tubes 31 are arranged so that they extend in the z-direction. Inside the inner tube 33, which is also referred to as the shower tube, both gaseous and liquid refrigerant are present when a gas-liquid two-phase refrigerant flows in. In embodiment 1, the through-hole 35 is located near the angle θ_AL of the liquid refrigerant level AL.

[0024] Fig. Figure 3 shows an example where the through-hole 35 is located at an angle θ of the liquid level AL of the liquid refrigerant. The angle θ at which the through-hole 35 is located, as seen from the center point of the inner tube 33, is the angle from the lower end of the inner tube 33, through the center point of the inner tube 33, to the position where the through-hole 35 is located. For example, it is suitable to provide the through-hole within a range of 10° ≤ θ ≤ 80°.

[0025] More precisely, the angle at which the through-hole 35 is provided is determined by formula (1). Formula (1) is a predictive formula that reflects the inventors' experimental results and is based on Nusselt's formula for calculating liquid films. [Math. 1] θ=(1.2393x2−37.264x+318.71)[(Ja3GaPrL3)1 / 4vLLD3.5]0.142±20° where x is the distance projected onto a horizontal line that runs perpendicular to the longitudinal direction of the tube and passes through the center point of the inner tube 33 for the through hole 35, Yes, the Jacob number is, Ga is the Galileo number, PrL is the Prandtl number of the liquid, vL is the dynamic viscosity coefficient of the liquid, L is the approach length of the inner tube, D is the inner diameter of the inner tube, Ga=gD3 / v L2,Ja=CpL / ΔivGa=gD3 / vL2, Ja=CpL / Δiv CpL is the specific heat capacity at constant pressure, Δiv is the enthalpy of vaporization or latent heat, L < 5D.

[0026] The state variables and physical material properties are calculated under the assumption that they are based on the pressure at which the refrigerant flows into the refrigerant distributor 30.

[0027] If the liquid phase of the refrigerant flowing into the inner tube 33 is a semi-annular flow and the through-hole 35 is provided at the bottom of the inner tube 33 (θ = 0°), the distribution of the liquid refrigerant quantity at each of the plurality of through-holes 35 provided along the x-direction in the inner tube 33 is greater on the side closer to the connection hole 36 than on the farther side.

[0028] If the through-hole 35 is provided at the position θ = 90° of the inner tube 33, the distribution of the liquid refrigerant quantity for each of the plurality of through-holes 35 provided along the x-direction on the inner tube 33 is smaller on the side closer to the connection hole 36 than on the side further away.

[0029] In contrast, in embodiment 1, as in Fig. Figure 3 shows that the through-hole 35 is provided near the liquid level AL of the inner tube 33. The through-hole 35 is provided only once in a vertical cross-section of the inner tube 33. Even if the through-hole 35 is provided at the position of the liquid level AL of the inner tube 33, and even if the refrigerant flow pattern is a semicircular flow, the distribution of the liquid refrigerant quantity is expected to be uniform at each of the plurality of through-holes 35 provided along the x-direction in the inner tube 33. Although the position of the through-hole 35 in the air conditioning system 100 according to embodiment 1 is not restricted, it is, as shown in Fig. As shown in Figure 3, by arranging the through-hole 35 at a position of 10° ≦ θ ≦ 80° in a cross-section perpendicular to the pipe axis of the inner pipe 33, it is possible to distribute the gas and liquid in the inner pipe 33 evenly into the space formed between the outer pipe 34 and the inner pipe 33. (Outer tube 34)

[0030] The outer tube 34 has a tubular shape with a cavity inside, with both end faces 34a and 34b closed in the x-direction. It has a first element 34f, which forms the outer contour on the side to which the heat transfer tube 31 is connected, and a second element 34e, which is arranged to close the open section of the first element 34f. As shown in Fig. As shown in Figure 3, the first element 34f has a U-shaped cross-section that is perpendicular to the x-axis. The second element 34e is inserted into the open part of the U-shaped section, connected, and forms a hollow, tubular structure. (Divider plate 38)

[0031] The separating plate 38 is inserted into and connected to the first element 34f of the outer tube 34. In the Fig. In the refrigerant distributor 30 shown in Figure 3, an opening 39 is formed between the lower edge 38a of the partition plate 38 and the second element 34e. The opening 39 is formed at the lower end section of a plurality of areas 41A, 41B, and 41C in the z-direction; in other words, it is located at the part furthest from the heat transfer tube 31. If the refrigerant distributor 30 is arranged with the vertical axis pointing upwards in the z-direction, the oil stagnating in the plurality of areas 41A, 41B, and 41C can flow through the opening 39.

[0032] In Fig. In section 3, the second element 34e is arranged such that it abuts the partition plate 38, but the configuration is not limited to this shape, and the second element 34e can also be configured to abut an end section 34fa of the first element 34f. At a minimum, the first element 34f is configured such that its cross-section has an open side facing opposite to the z-axis, and the heat transfer tube 31 is attached at one end on the z-axis side. It forms a hollow outer tube 34 by being closed by other elements.

[0033] Fig. Figure 4 is an explanatory illustration of another example of the cross-sectional structure of the in Fig. 3 refrigerant distributor shown 30. In Fig. 4 The partition plate 38 has an opening 39 at a position located in the z-direction away from the second element 34e. The opening 39 can be located anywhere on the partition plate 38. However, to allow the oil stagnating in the area 41 to drain away, it is desirable that the opening 39 be located in the z-direction below the through-hole 35, and it is even more desirable that it be located below the inner tube 33.

[0034] Fig. Figure 5 is an explanatory illustration of another example of the cross-sectional configuration of the in Fig. 3 refrigerant distributor shown 30. The arrows in the illustration in Fig. Figure 5 schematically illustrates the flow of the refrigerant. In the Fig. In the example shown in Figure 5, the separating plate 38 has a cutout 38b which is provided in part of the rim 38a, and the opening 39 is formed by the cutout 38b and the second element 34e.

[0035] The opening 39 can also be formed by providing a groove in the inner surface of the first element 34f or the second element 34e. Alternatively, the opening 39 can be formed in another way, for example by forming a slot in the separating plate 38. (How it works)

[0036] The in Fig. Figure 2(b) schematically shows the tendency of the refrigerant pressure distribution in the respective areas of the refrigerant distributor 30 with respect to the position in the x-direction of the heat exchanger 3.

[0037] Curve A represents the distribution of the outlet pressure of the refrigerant distributor 30B, which functions as a liquid distributor when the heat exchanger 3 operates as an evaporator. In other words, the outlet pressure of the refrigerant distributor 30B is the pressure at the inlet of the majority of heat transfer tubes 31. There is a tendency for the outlet pressure of the refrigerant distributor 30B to decrease as one moves further from the end section where the refrigerant enters the distributor 30B towards the other end section.

[0038] Curve B represents the outlet pressure of the majority of heat transfer tubes 31 and the internal pressures of the majority of sections 41A, 41B, and 41C. The majority of sections 41A, 41B, and 41C tend to have a lower internal pressure, corresponding to the pressure distribution on the liquid distributor side. Furthermore, oil stagnation occurs in these majority of sections 41A, 41B, and 41C. Section 41C, which is furthest from the connection opening 36, tends to have a lower internal pressure and is less prone to oil discharge.

[0039] A curve C illustrates the pressure distribution in the second chamber 42c, i.e., the interior of the inner tube 33. Since the second chamber 42c has a plurality of through holes 35 along the tube axis, there is a tendency for the pressure to decrease from the upstream side towards the end section 42a, which serves as the outlet.

[0040] Each section of the refrigerant distributor 30 tends to exhibit the pressure distribution described above. In particular, in section 41C, the pressure difference ΔP to the second chamber 42c inside the inner tube 33 is small, which restricts the flow of refrigerant and oil and causes a tendency for oil stagnation. With increasing oil stagnation, the volume within section 41 decreases, leading to higher flow resistance and a reduction in refrigerant flow rate. Furthermore, the heat transfer tube 31 connected to section 41C shows a tendency toward reduced heat exchange efficiency, resulting in a decreased overall heat exchange capacity of the heat exchanger 3. Additionally, measurements of the temperature distribution of the heat exchanger 3 operating as an evaporator revealed a tendency toward higher temperatures in the section corresponding to section 41C when each section 41 is isolated and there is no communication between them.That is to say, in the case of a refrigerant distributor 30 according to embodiment 1, which cannot discharge oil, the problem was insufficient evaporation of the refrigerant in the heat transfer pipe 31, which is connected to the area 41C, in which there is hardly any refrigerant flow.

[0041] In the refrigerant distributor 30 of the heat exchanger 3 according to embodiment 1, the communication between sections 41A, 41B, and 41C via the opening 39 allows the stagnant oil to move towards the connection opening 36. This suppresses oil stagnation in section 41C, reduces flow resistance in section 41C, and promotes refrigerant flow. This, in turn, enables adequate heat exchange in the heat transfer tube 31 connected to section 41C, allowing the heat exchanger 3 to achieve its intended heat transfer capacity.

[0042] In the heat exchanger 3 according to embodiment 1, the refrigerant distributor 30A is arranged in the direction of gravity below the heat transfer pipe 31 and tends to accumulate oil in its lower region. Additionally, as shown in Fig. As shown in Figure 5, the heat exchanger 3 of embodiment 1 also has a refrigerant distributor 30B on the inlet side and below the heat transfer pipe 31, the structure of the refrigerant distributor 30B being similar to that of the refrigerant distributor 30A. This configuration ensures the refrigerant distribution function even when a refrigerant containing liquid refrigerant is inlet, as shown in Figure 5. Fig. As explained in section 2, oil stagnation can be suppressed by the inflow of gaseous refrigerant. However, the other refrigerant distributor 30B can also be located above the heat transfer pipe 31; in this case, its structure may differ from that of the refrigerant distributor 30A.

[0043] Although the external heat exchanger 3 is used as an example in embodiment 1, the structure of the refrigerant distributor 30 can also be applied to an internal heat exchanger, in which case oil stagnation in the refrigerant distributor from which the gaseous refrigerant flows can also be suppressed.

[0044] The above description relates to embodiments that have been given merely as examples and do not serve to limit the scope of protection of the claims. These embodiments can be implemented in a variety of ways, and within a framework that does not deviate from the essence of the embodiments, various omissions, substitutions, and modifications are possible. These embodiments and their modifications are included in the scope of protection and spirit of the present disclosure. Reference symbol list

[0045] 1: Compressor, 2: Four-way valve, 3: (Outdoor air) heat exchanger, 4: Fan, 5: Expansion valve, 6: Indoor heat exchanger, 7: Fan, 8: Accumulator, 10: Outdoor unit, 11: Indoor unit, 12: Indoor unit, 26: Refrigerant pipe, 27: Refrigerant pipe, 30: Refrigerant distributor, 30A: Refrigerant distributor, 30B: Refrigerant distributor, 31: Heat transfer pipe, 33: Inner pipe, 34: Outer pipe, 34a: End face, 34b: End face, 34e: Second element, 34f: First element, 34fa: End section, 35: Through hole, 36: Connection opening, 37: Inlet hole, 38: Dividing plate, 38A: Dividing plate, 38B: Dividing plate, 38C: Dividing plate 38D: Partition plate, 38a: Edge, 38b: Cutout, 38d: Partition plate, 39: Opening, 40: First room, 41: Area, 41A: Area, 41B: Area, 41C: Area, 42a: End section, 42b: End section, 42c: Second room, 43: End section room, 44: End section room, 100: Air conditioning. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2019 / 239445

[0004]

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