Heat exchanger for combustible cooling medium

Abstract

To provide a heat exchanger for an air conditioning system evading safety risk.SOLUTION: A heat exchanger for an air conditioning system has a hollow rectangular parallelepiped housing with a refrigerant pipe arranged inside, the hollow rectangular parallelepiped housing has a fin provided inside a closed side surface, at least one portion of the range outside this closed side surface is capable of being in a state of being actuation coupled to a passenger compartment, the hollow rectangular parallelepiped housing is designed as a module capable of being partitioned from the passenger compartment to be air tight, only a permanently sealed portion of the refrigerant pipe is arranged inside the hollow rectangular parallelepiped housing, points in the coupling unit are arranged completely outside the hollow rectangular parallelepiped housing in respective cases, and the hollow rectangular parallelepiped housing is provided with a sealing frame and a sealing plate so that the coupling unit of the refrigerant pipes is partitioned from the vehicle chamber and arranged in a range ventilated toward outside the periphery when the heat exchanger is fixed to an installation position.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a heat exchanger for a flammable refrigerant, preferably for use in a railway vehicle, which has a hollow rectangular casing in which refrigerant tubes designed as a tube-and-fin pack or as a tube-in-tube and fin pack are placed, the hollow rectangular casing being provided with fins on the inside of a closed side, at least a part of the outside of the closed side being capable of being brought into operative connection with the vehicle interior.

[0002] Flammable refrigerants have not been used in railcar air conditioners until now due to the associated risks, particularly the risk of explosion and fire. One possibility for minimizing these risks and thus enabling their use in railcars is the application of a secondary circuit system. In this case, the required cooling (or heating) power is provided by a primary circuit using a flammable refrigerant of a known compression-type refrigerant circuit, but this primary circuit is located outside the vehicle and is not directly connected to the interior of the vehicle. This cooling power is transferred to a secondary circuit by means of a heat exchanger. This secondary circuit is typically a brine circuit using, for example, a water-glycol mixture as the refrigerant.

[0003] Patent Document 1 describes an apparatus for heating and cooling a bus using an air conditioning system with a primary refrigerant circuit. The refrigeration machine with the primary refrigerant circuit is located under the floor of the passenger compartment. The primary refrigerant circuit is operatively connected to a secondary refrigerant circuit via an intermediate heat exchanger. This secondary refrigerant circuit is located mostly inside the bus and is used to control the temperature in the passenger compartment.

[0004] A chiller for a work vehicle is known from DE 10 200 04 133 A1. A primary refrigerant circuit is arranged outside the work cabin and is operatively connected via an intermediate heat exchanger to a secondary refrigerant circuit, which is arranged primarily inside the work cabin and takes over temperature control.

[0005] Patent Document 3 relates to a railway vehicle with a primary refrigerant circuit arranged outside the vehicle and structurally separated from the passenger compartment. A secondary refrigerant circuit is arranged at least partially inside the railway vehicle. Heat exchange between the primary and secondary refrigerant circuits is preferably performed via an intermediate heat exchanger arranged under the floor. As a result, the primary refrigerant circuit is completely wired outside the interior of the railway vehicle.

[0006] This type of air conditioning system design makes good use of available installation space. Furthermore, refrigerants can be used in circuits outside the passenger compartment, but for safety reasons are not or rarely used in air conditioners located inside the passenger compartment, to avoid problems that could arise from uncontrolled refrigerant leakage in the event of a malfunction. This is the case, for example, with propane, which is very suitable as a refrigerant from a functional standpoint, but is rarely used due to its flammability.

[0007] However, such designs also have significant drawbacks: heat losses due to the use of a secondary circuit; reduced efficiency and increased power consumption; increased mass due to the additional internal heat exchanger and required refrigerant; and increased costs due to the additional components required. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] DE19625927C2 [Patent Document 2] EP1520737A1 [Patent Document 3] WO2018 / 137908A1 Summary of the Invention

[0009] The object of the present invention is to create a heat exchanger for air conditioning systems that avoids the safety risks present in previous heat exchangers, so that the secondary circuit can be omitted and a direct system implemented instead. Preferably, the heat exchanger is suitable for rail vehicles.

[0010] The problem is solved by the heat exchanger having a hollow rectangular casing designed as a module that can be airtightly separated from the vehicle cabin, where only the permanently sealed portions of the refrigerant pipes are arranged inside the hollow rectangular casing, and their connecting portions are each arranged completely outside the hollow rectangular casing, and when the heat exchanger is fixed in its installation position, the hollow rectangular casing is provided with at least one sealing frame and / or at least two sealing plates, and the connecting portions of the refrigerant pipes are installed in an area that is airtightly separated from the vehicle cabin and ventilated to the outside and the surroundings.

[0011] In a first variant, the sealing frame is formed by two closed side walls arranged opposite each other and two end walls arranged perpendicular to the side walls and opposite each other on the open side of a hollow rectangular casing, the hollow rectangular casing being provided with a sealing coating on each of the surfaces of the two end walls.

[0012] In a second variant, the sealing frame is formed by a separation area, which is arranged on the closed side and is designed with a peripheral flange.

[0013] This allows the production of a heat exchanger for an air conditioning system, preferably a heat exchanger for a rail vehicle, which can use a direct evaporation flammable refrigerant. The entire air duct to the passenger compartment is designed to be pressure-tight and gas-tight with respect to the refrigerant transport area, thus establishing a reliable seal between the passenger compartment and the flammable refrigerant.

[0014] In one embodiment, the refrigerant tubes are separately attached to and sealed to opposite open end walls of a hollow rectangular parallelepiped housing.

[0015] The tube-and-fin pack is considered to be permanently sealed. In heat exchanger embodiments with a tube-and-fin pack, only the tube-and-fin pack is located in the airflow toward the passenger compartment and is connected by a direct path. All other components of the refrigerant circuit (pipes, joints, and other components) are located outside the airflow toward the passenger compartment and are hermetically separated.

[0016] In one embodiment, the refrigerant pipes are designed as a tube-in-tube configuration, with the inner pipe being designed as a pipe with multiple outer windings, and each winding of the pipe within the hollow rectangular housing being surrounded by an outer pipe. Each outer pipe is open on both sides, ensuring that any leakage in the event of a malfunction can be vented to the surrounding area. In the event of a leak from the inner pipe, the gaseous refrigerant in the outer pipe is vented to the outside and hermetically separated from the passenger compartment. The gaseous refrigerant in the outer pipe is directed to an area hermetically separated from the passenger compartment, preventing it from entering the air duct to the passenger compartment.

[0017] For this purpose, the tube-in-tube configuration may be designed such that the inner tube has preferably straight or cylindrically curved ribs which, after expansion, can come into mechanical or thermal contact with the outer tube, leaving behind an air-spaced void.

[0018] With regard to the above technical features, the heat exchanger can be designed in three basic variants:

[0019] In the first variant, two different designs are possible for sealing and holding the tube. For example, the inside of the sheet metal plate can be provided with a rubber or alternatively plastic wall, or the sheet metal plate can be provided with a plastic bushing to orient / seal the tube. This can be a simple tube design or a tube-in-tube design.

[0020] In the second variant, the sheet metal is placed on the outside for retention, and the rubber or plastic is placed on the inside. In this way, in both variants, the tube can be implemented both as a simple tube or as a tube-in-tube design. In this second variant, there is no need to have a coating on the inside, nor is there a need to have a plastic bushing to seal the tube to the outer retaining plate. In this design, the sealing function is performed by the rubber on the inside.

[0021] In a third variant, instead of the combination of a sheet metal element and a rubber or plastic element, two sheet metal parts are used. The sealing plates, which are provided here as an alternative or complement to the sealing frame, are arranged on opposite end walls of the open surface of the hollow rectangular housing. The sealing plates are placed in retaining plates that form a support structure for the end walls relative to the interior of the hollow rectangular housing and are fixed to the hollow rectangular housing by elastic connections at their periphery in the form of flexible sealing seams.

[0022] Each sealing plate has openings for the feedthrough of the refrigerant pipes. The openings in the sealing plates are punched, laser cut, or drilled and are designed to allow the expanded refrigerant pipes to be inserted therein. Similarly, the openings in the sealing plates may be designed with a withdrawal portion as a collar to accommodate the expanded refrigerant pipes. [Brief explanation of the drawings]

[0023] In the following, examples of embodiments of the invention will be explained in more detail with reference to the drawings. [Figure 1] 1 shows a first embodiment of a heat exchanger in a side view. [Figure 2] 2 shows a perspective view of the heat exchanger shown in FIG. 1. [Figure 3] 2 shows a second embodiment of a heat exchanger in a side view. [Figure 4] 4 shows a perspective view of the heat exchanger shown in FIG. 3. [Figure 5]1 shows a third embodiment of a heat exchanger in a side view. [Figure 6] 6 shows an enlarged detail of the heat exchanger shown in FIG. 5 in two alternative embodiments. [Figure 7] FIG. 10 shows a fourth embodiment of a heat exchanger in a perspective view. DETAILED DESCRIPTION OF THE INVENTION

[0024] The heat exchanger shown in the drawings is suitable for air conditioning systems with a direct refrigerant circuit and is primarily intended for use in rail vehicles. Such design principles are already known. However, in the present application, it is important to specifically implement the basic concept. Consequently, the heat exchanger includes a hermetically sealed module designed to function as an element for conducting air into the passenger compartment. This module has a hollow rectangular parallelepiped housing with a sealing element.

[0025] 1 and 2, the sealing frame of a heat exchanger with a tube-and-fin pack is formed by two closed side walls (1) and (2) arranged opposite each other and two end walls (3) and (4) arranged perpendicular to the walls (1) and (2) and opposite each other on the end faces of the hollow rectangular parallelepiped housing. Each wall surface is provided with a sealing coating. For this purpose, according to FIG. 1, end wall (3) has a sealing coating (5), and end wall (4) has a sealing coating (6).

[0026] Only the permanently gas-tight sections of the refrigerant pipes are located inside the hollow rectangular enclosure. Alternatively, they may be designed as a tube-and-fin pack (Figs. 1-4) or as a tube-in-tube configuration (Figs. 5, 6). The corresponding tube packs are designated by the reference number (7). Each connection of the refrigerant pipes is located completely outside the hollow rectangular enclosure.

[0027] The hollow rectangular parallelepiped housing is provided with fins on the inside of a closed side surface (8) that extends perpendicular to the two closed walls (1), (2). A corresponding set of fins is designated by reference numeral (9). Although not shown in more detail, when the hollow rectangular parallelepiped housing is fixed in its installed position, at least a portion of the outside of the closed side surface (8) is operatively connected to the vehicle cabin so that the refrigerant pipe connections are located in an area airtightly separated from the vehicle cabin.

[0028] The refrigerant pipes are separately mounted in the opposing open end walls of the hollow rectangular housing and are separately sealed. This can be achieved in various ways. For example, sheet metal plates located on the end faces can be provided to support the refrigerant pipes. The sealing can be achieved, for example, by a sealing coating, by a seal, or by a plastic element. Regardless of the specific design, the separation of the sealing and retention functions ensures the required functional reliability.

[0029] Figures 3 and 4 show a slightly modified design of a heat exchanger with a hollow rectangular parallelepiped housing. The refrigerant pipes are also designed as a tube-and-fin pack. However, the sealing frame is now formed by a separation section (10) which is arranged on the closed side (8) and is designed with a peripheral flange. Preferably, this separation section (10) is made of a hard rubber material and has a reinforced connection in part with the flange.

[0030] In this design according to Figures 3 and 4, the two end walls (3), (4) have a sealing function. The sealing frame is therefore the area visible towards the outside (air direction) of the rubber part marked with reference number (10). Here, the end plates have a supporting function and constitute the left and right walls respectively.

[0031] Figure 5 shows a heat exchanger with refrigerant tubes in a tube-in-tube and fin pack design. The basic structure largely corresponds to the design shown in Figures 1 and 2. As a result, the sealing frame is formed by two closed side walls (1) and (2) arranged opposite each other and two end walls (3) and (4) arranged perpendicular to the side walls (1) and (2) and opposite each other on the open surface of the hollow rectangular parallelepiped housing. The heat exchanger also includes a tube pack (7) inside the hollow rectangular parallelepiped housing and a fin pack (9) arranged inside the closed side (8).

[0032] In this tube-in-tube and fin pack, the inner tube (13) is designed as a tube with multiple outer coils, each of which is enclosed in a hollow rectangular casing by an outer tube (14) with open ends.

[0033] Figure 6 shows details of an effective connection for sealing a pipe feedthrough, here illustrated using the example of a design with an inner pipe (13) and an outer pipe (14). The sealing of the pipe feedthrough may also be performed in the same way as for a single pipe. In the right illustration, the sealing element is designed as a surface seal (11), while in the left illustration, the sealing element is designed as an annular seal (12).

[0034] Furthermore, the inner tube 13 has ribs (not shown) for thermal contact with the outer tube 14. The ribs may be, for example, straight or curved to a cylindrical shape. The open end of the outer tube 14 allows leakage to escape in the event of a fault, and this leakage escape arrangement offers significant safety advantages over known designs, especially when flammable refrigerants (e.g., propane) are used.

[0035] FIG. 7 shows a further design of a heat exchanger with a hollow rectangular parallelepiped housing, which is designed to function as an element for directing air into the passenger compartment. Also, in the variant shown here, the refrigerant pipes are designed as a tube-and-fin pack. However, instead of a sealing frame, two sealing plates (15) and (16) are used to form a module that can be hermetically sealed. The sealing plates (15) and (16) are each located at the end of the fin stack and are not rigidly connected to the support structure of the heat exchanger. The retention and sealing functions are therefore separate from each other and are achieved using different components.

[0036] To ensure a sufficient adhesive substrate (sealant bond), the sealing plates (15) and (16) are designed with projections extending from the periphery to the edge and tube regions relative to the outer dimensions of the fins. The sealing plates (15) and (16) are designed to be at least as large as the dimensions of the fins. To the extent that they are designed to be taller, sealing of the fin pack is achieved by adjusting the seal between the upper side wall (1) and / or the lower side wall (2) of the heat exchanger. However, if the side walls (1) and / or (2) of the heat exchanger are designed to be removable, they can then be sealed by the sealing plates (15) and (16) in a simple manner.

[0037] The sealing plates 15 and 16 have openings 17 for the feedthrough of the refrigerant tubes of the tube pack 7. The openings 17 are designed so that the expanded refrigerant tubes can be inserted therein. This ensures that the two sealing plates 15 and 16 press tightly and tightly against the refrigerant tubes. This can be achieved by forming punched, laser cut, or drilled openings 17 in the sealing plates 15 and 16 as tube feedthroughs.

[0038] Similarly, the sealing plates 15, 16 may be designed with curved fin sections at the tube feedthroughs associated with the expanded refrigerant tubes. The curved fins are used to align the drawing collars at the openings of the finned tubes with the respective sealing plates 15 or 16, thereby providing better bearing support for the refrigerant tube feedthroughs.

[0039] Furthermore, the opening (17) with the withdrawal section may be designed as a collar to receive the expanded refrigerant tube, thereby providing a better cylindrical support for the refrigerant tube, reducing the notching effect and improving the sealing effect.

[0040] In the embodiment according to Figure 7, the end walls are each designed as separate components in the form of retaining plates (18), (19), which functionally form the support structure for the respective end wall.

[0041] Two sealing plates (15), (16) are provided on each of the opposing open surfaces of the hollow rectangular parallelepiped housing, and these sealing plates (15), (16) are arranged inside the retaining plates (18), (19) with respect to the interior of the hollow rectangular parallelepiped housing. As a result, the retaining plates (18), (19) arranged on the outside have openings through which both ventilation to the outside environment and pressure equalization with the outside environment are possible.

[0042] In the assembled state, the sealing plates (15), (16) are preferably attached to the hollow rectangular housing by circumferentially elastic connections designed as flexible sealing seams (20), thereby avoiding direct fixed connections to the support structure of the heat exchanger. Regardless of the specific design of the seals, the circumferential sealing seams are permanently fixed and provide a seal against pressure fluctuations or pressure waves up to at least + / - 10 kPa.

[0043] The open area between the sealing plates (15, 16) located on both sides of the heat exchanger and the supporting outer wall can be designed in various ways, for example, by a sealing mat inserted into the gap, by a periphery-elastic injection adhesive, by filling the entire gap with an elastic sealing compound, or by a seal glued on one side. Further sealing is possible, for example, by using a heat-resistant fleece between the sealing plates (15, 16) and the retaining plates (18, 19). The actual sealing is then performed by the retaining plates (18, 19) when the heat exchanger is in a fixed installation position relative to the housing, creating a sealable area. [Explanation of symbols]

[0044] 1 Side wall 2 Side wall 3 End wall 4 End wall 5. Sealing Coating 6. Sealing Coating 7 tube pack 8 side surface 9 Fin Pack 10 Separation area 11 Sealing element / surface sealing part 12 sealing element / annular seal 13 Inner tube 14 Outer tube 15 Sealing plate 16 Sealing plate 17 Opening of sealing plate 18 Holding plate 19 Holding plate 20 Elastic outer periphery connection

Claims

1. A heat exchanger for a flammable refrigerant, preferably for use in a railway vehicle, comprising: The heat exchanger has a hollow rectangular casing in which refrigerant pipes designed as a tube-and-fin pack or a tube-in-tube-and-fin pack are arranged, the hollow rectangular casing being provided with fins on the inside of a closed side thereof, and at least a part of an area outside the closed side thereof can be brought into a state of being operatively connected to the vehicle interior, the hollow rectangular casing being designed as a module that can be airtightly separated from the vehicle interior, only permanently sealed parts of the refrigerant pipes are arranged inside the hollow rectangular casing, and the points of their connections are in each case completely located outside the hollow rectangular casing, and the hollow rectangular casing is provided with at least one sealing frame and / or at least two sealing plates so that when the heat exchanger is fixed in its installation position, the connections of the refrigerant pipes are arranged in an area separated from the vehicle interior and ventilated outwards to the surroundings.

2. 2. The heat exchanger according to claim 1, characterized in that the sealing frame is formed by two closed side walls (1, 2) arranged opposite each other and two end walls (3, 4) arranged perpendicular to the side walls (1, 2) and opposite each other on the open surface of the hollow rectangular parallelepiped housing.

3. 2. The heat exchanger according to claim 1, characterized in that the sealing frame is formed by a separation section (10) arranged on the closed side (8), having a peripheral flange, made of hard rubber or plastic material, and having a reinforced connection partly by the flange.

4. 2. The heat exchanger according to claim 1, characterized in that when the refrigerant pipes are designed as a tube-and-fin pack, the hollow rectangular parallelepiped housing is provided with a sealing coating (5, 6) on each of the two end walls (3, 4).

5. 2. The heat exchanger according to claim 1, wherein the refrigerant pipes are separately attached to the opposite open end walls (3, 4) of the hollow rectangular housing and are separately sealed, the sealing elements being designed as areal seals (11) or individual annular seals (12).

6. 2. The heat exchanger according to claim 1, wherein the refrigerant tubes are designed as a tube-in-tube-and-fin pack, such that the inner tube (13) is designed as a tube with multiple outer coils, and each tube coil portion of the tube coil is surrounded by a respective outer tube (14), and each outer tube (14) has an open end face outside the hollow rectangular parallelepiped housing.

7. 2. The heat exchanger according to claim 1, characterized in that the refrigerant tubes are designed in a tube-in-tube and fin pack configuration, such that the inner tube (13) has a ribbed pattern in thermal contact with the outer tube (14).

8. 2. The heat exchanger according to claim 1, characterized in that sealing plates (15, 16) with openings (17) for the feedthrough of the refrigerant pipes are arranged on each of the opposing end wall portions of the open surface of the hollow rectangular parallelepiped housing, the sealing plates (15, 16) being arranged in retaining plates (18, 19) that form a support structure for the end wall portions relative to the interior of the hollow rectangular parallelepiped housing and are fixed to the hollow rectangular parallelepiped housing by elastic connecting portions (20).

9. 9. The heat exchanger according to claim 8, wherein the sealing plates (15, 16) are fixed to the hollow rectangular parallelepiped housing by flexible sealing seams (20) around their peripheries.

10. 9. A heat exchanger according to claim 8, characterized in that the free areas between the sealing plates (15, 16) of the heat exchanger and the supporting side walls are formed by a sealing mat inserted in the gap, or by a periphery elastic injection adhesive, or by filling the entire gap with an elastic sealing compound, or by a sealing part glued on one side.

11. 9. Heat exchanger according to claim 8, characterized in that an additional seal is formed by means of a heat-resistant fleece arranged between the sealing plates (15, 16) and the retaining plates (18, 19).

12. 9. A heat exchanger according to claim 8, characterized in that the openings (17) in the sealing plates (15, 16) are made by punching, laser cutting or drilling so that the expanded refrigerant pipes can be introduced into the openings (17).

13. 9. A heat exchanger according to claim 8, characterized in that the openings (17) in the sealing plates (15, 16) are provided with withdrawals as collars for receiving the expanded refrigerant tubes.

14. 9. A heat exchanger according to claim 8, characterized in that curved fin sections are arranged in the openings (17) in the sealing plates (15, 16).

15. 9. A heat exchanger according to claim 8, characterized in that openings for ventilation and pressure compensation are arranged in the retaining plates (18, 19).

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