DE102020112293A1 - Heat exchanger for a motor vehicle - Google Patents

Abstract

In order to create a heat exchanger (10) for a heat pump (110), in particular for air-conditioning an interior or vehicle interior (101), which enables melt water to drain off quickly and completely, it is proposed that a porous material be placed over a collecting pipe (50) on the bottom (60) to accommodate melt water (210) produced during a defrosting process of the heat exchanger (10).

Description

The invention relates to a heat exchanger for a heat pump, in particular for air conditioning a vehicle interior, having a plurality of pipes aligned parallel to one another for conducting a refrigerant, with fins which are thermally coupled to the pipes being arranged between the pipes. The invention also relates to a motor vehicle.

In electrically powered vehicles, heat pumps are often used to heat the passenger compartment. Here, the heat required to heat the passenger compartment is extracted from the vehicle environment and fed to the passenger compartment. In this process, a heat exchanger thermally coupled to the vehicle environment cools down in such a way that the dew point of the air in the vehicle environment is not reached and condensate is formed on the heat exchanger. The heat exchanger can cool down further, so that frost is formed on the surface of the heat exchanger.

Due to the formation of frost, the surface of the heat exchanger is increasingly icing up and thus prevents efficient operation of the heat pump. In order to allow air to flow through the heat exchanger again, defrosting cycles or defrosting processes are necessary in which the iced-up heat exchanger is heated up. As a result, the ice melts and air can flow through the heat exchanger again. In addition, the formation of condensate on the heat exchanger can reduce the efficiency of the heat pump.

Furthermore, the fastest and most complete drainage of melt water or condensate from the heat exchanger is essential in order to shorten the defrosting cycle. Heat exchangers usually consist of several tubes arranged parallel to one another, which are connected to one another by a large number of fins. The tubes open into a collecting tube at the bottom. The flowing melt water can accumulate between the lamellae due to capillary forces and prevent it from flowing away. A permanent column of melt water can form between the lamellas in the area of the header pipe at the bottom and negatively affect the efficiency of the heat exchanger. The drainage of the melt water can be made more difficult or prevented by the collecting pipe at the bottom.

The invention is based on the object of creating a heat exchanger which enables melt water to flow off quickly and completely. This object is achieved by the features specified in claim 1. Further advantageous refinements of the invention are described in the subclaims.

According to one aspect of the invention, a heat exchanger for a heat pump, in particular for air conditioning an interior or vehicle interior, is provided. The heat exchanger has a multiplicity of tubes, which are aligned parallel to one another, for guiding a refrigerant, with fins, which are thermally coupled to the tubes, being arranged between the tubes. The ends of the tubes open in a fluid-conducting manner in each case in a collecting tube. In particular, the tubes can run in the vertical direction and be arranged between two header tubes. A coolant can be distributed via a first collecting pipe over the pipes into a second or bottom collecting pipe. The fins arranged between the tubes enable more efficient heat transfer. According to the invention, a porous material for receiving melt water that is produced during a defrosting process of the heat exchanger is arranged above a collecting pipe at the bottom.

If the heat pump is in defrost mode, melt water forms on a surface of the heat exchanger. In order to achieve the lowest possible blockage of the heat exchanger for the subsequent icing cycle, the largest possible amount of melt water should be removed from the heat exchanger. This increases the time after which the heat exchanger would freeze up in the next cycle and the efficiency of the heat pump. In addition, the heat exchanger can be operated more efficiently when there is less ice over the fins.

The porous material can preferably be arranged between lamellae and the collecting tube on the bottom. For this purpose, a section of the heat exchanger can be designed without fins, so that the porous material can be inserted into the section.

By introducing the porous material, the formation of the bottom-side water column above the bottom-side manifold and the blocking of the heat exchanger can be prevented. Due to the capillary effect of the porous material, melt water and / or condensate can be withdrawn from the fins of the heat exchanger. The porous material thus functions as a passive pump for the melt water and / or condensate and enables the melt water and / or condensate to be discharged more quickly from the heat exchanger during the defrosting process. This allowed the time to expire Heat exchanger and the amount of water in the heat exchanger can be reduced.

The porous material can be produced in a particularly cost-effective manner and integrated into the heat exchanger if it is produced from a metal filter fabric, a metal foam or a ceramic foam. Such a solution requires only minor adjustments and can reduce the water column on the bottom end lamellas.

According to one embodiment, the porous material is designed to receive, store and / or discharge the melt water or condensate, the porous material being arranged between the bottom end lamellas and the bottom collecting pipe. As a result, the porous material can be positioned in a section between the lamellae and the collecting pipe on the bottom side in such a way that, in addition to the gravitational pull, the capillary forces of the pores of the porous material exert a conveying effect on the melt water.

For example, the porous material can be attached to the underside of the end lamella as a metal mesh in a U-shape. The end lamellas and the porous material can be as close to one another as possible.

The porous material can be designed in small parts or in several parts. For example, a part of the porous material can be arranged between each two tubes.

Alternatively or additionally, the porous material can extend over a plurality of tubes and / or over an entire length of the collecting tube on the bottom.

The porous material can be attached to the heat exchanger in a technically particularly simple manner if it can be connected to at least one bottom end lamella and / or the bottom header tube by means of at least one adhesive connection or solder connection. A small use of adhesive or soldering liquid can ensure that the melt water runs off optimally along the porous material. The melt water absorbed by the porous material can be drained, stored and / or evaporated.

According to a further embodiment, the porous material is I-shaped, U-shaped or L-shaped and has an I-shaped receiving section for receiving the melt water. Depending on the configuration of the porous material, recesses can be provided for guiding the tubes. By using the porous material in a U-shape, the melt water can be released more efficiently from the heat exchanger into the environment. The two side surfaces or side sections of the U-shape can be located on round lamellas in some areas and encompass the collecting tube on the bottom side.

An I-shaped porous material can preferably have a rod-shaped or rectangular shape. In this case, recesses can be provided in order to pass the tubes through transversely to the extent of the porous material. The I-shaped porous material can extend over the entire width of the ambient heat exchanger. In particular, the I-shaped porous material can be shaped like a comb and extend into the spaces between the tubes. The spaces between the tubes are delimited by the respective end lamellas and the header tube on the bottom.

As an alternative or in addition, the porous material can be designed as a rectangular or solid material in order to enable the melt water to be temporarily stored. Furthermore, the porous material can be L-shaped in order to enable the melt water to flow away in a controlled manner on one side. The side section of the L-shape can open into a reservoir or a reservoir section.

The volume of the porous material can preferably be selected such that a sufficient mass of water can be stored in the free pores. Furthermore, the porous material can be designed in such a way that water can drip off as easily as possible.

The porous material can discharge the melt water particularly efficiently if the receiving section opens into at least one vertical side section in the air flow direction of the heat exchanger or transversely to the air flow direction. Such a porous material is designed, for example, L-shaped or U-shaped and enables the melt water to flow away transversely to a direction of expansion or longitudinal direction of the collecting pipe on the bottom.

According to a further exemplary embodiment, the receiving section opens directly or via at least one vertical side section into at least one storage section. This measure can prevent the melt water from escaping into the vehicle environment in an uncontrolled manner. In particular, the melt water in the storage section can escape in a controlled manner from the porous material by evaporation or evaporation. The amount of heat required for this can be introduced into the porous material, for example, by a vehicle-mounted heat source or by solar radiation.

The melt water absorbed by the porous material can escape particularly efficiently if the porous material is arranged in an area of a heat-emitting component. The porous material can adjoin components with a large surface area that give off heat. In this way, such components or parts can be cooled, the stored melt water not freezing and being able to evaporate or evaporate from the porous medium.

For example, the heat-emitting component can be configured as power electronics, an internal combustion engine component or a section of a main cooling system of the vehicle.

According to a further embodiment, radiator shutters are arranged in front of the heat exchanger in the air flow direction, the radiator shutters being closable during a drying process of the porous medium in such a way that an air flow can be guided through the porous material. Radiator shutters are used in particular in vehicles that are particularly fuel-efficient. Such a radiator shutter can be used to direct a resulting air flow through the porous material in order to dry it. For this purpose, the radiator shutter can be arranged over an entire surface of the heat exchanger, a recess being provided in the radiator shutter in the area of the porous material. This can be done, for example, by removing one or more slats of the radiator shutter.

During a defrosting process, the radiator shutter can generally be closed so that the heat generated melts the frost or ice and the heat is not released into the air or the cold air causes the meltwater to freeze again. By closing the radiator shutter down to the porous material, an air flow through the porous medium can still be maintained. As a result, an increased air mass flow flows through the porous material, as a result of which the melt water can escape from the porous material particularly efficiently.

According to a further aspect of the invention, a motor vehicle is provided which has a heat pump with a heat exchanger according to the invention.

The bottom of the heat exchanger of the heat pump has a section without fins in which a porous material is inserted. The porous material is used to suck up or divert melt water that would collect on the fins of the heat exchanger. This can prevent a permanent formation of a water column on the bottom, which can impair the efficiency of the heat pump. In particular, the melt water can be guided out of the heat exchanger in a controlled manner through the porous material.

However, the heat exchanger is not restricted to use in motor vehicles. The heat exchanger is particularly suitable for stationary and mobile heat pump applications. For example, the heat exchanger can be used in a house, a factory, in a watercraft, a temperature-controlled container, a cargo hold and the like. The heat exchanger can be used, for example, as an interior heat exchanger if it functions as an evaporator.

• 1 eine schematische Draufsicht auf einen Wärmeübertrager mit einer ausgebildeten Wassersäule,
• 2 eine schematische Draufsicht auf einen erfindungsgemäßen Wärmeübertrager gemäß einer ersten Ausführungsform,
• 3 eine perspektivische Darstellung eines erfindungsgemäßen Wärmeübertragers gemäß einer zweiten Ausführungsform,
• 4 eine Draufsicht auf einen erfindungsgemäßen Wärmeübertrager gemäß einer dritten Ausführungsform,
• 5 eine weitere Draufsicht auf einen erfindungsgemäßen Wärmeübertrager gemäß einer vierten Ausführungsform, und
• 6 eine Seitenansicht eines erfindungsgemäßen Kraftfahrzeugs gemäß einer Ausführungsform.

Exemplary embodiments of the invention are explained in more detail below with reference to the drawings. Show it:

• 1 a schematic top view of a heat exchanger with a formed water column,
• 2 a schematic plan view of a heat exchanger according to the invention according to a first embodiment,
• 3 a perspective view of a heat exchanger according to the invention according to a second embodiment,
• 4th a plan view of a heat exchanger according to the invention according to a third embodiment,
• 5 a further plan view of a heat exchanger according to the invention according to a fourth embodiment, and
• 6th a side view of a motor vehicle according to the invention according to one embodiment.

In the figures, the same structural elements have the same reference numbers in each case.

In the 1 is a schematic plan view of a heat exchanger 200 with a trained water column 210 shown according to the prior art. The heat exchanger 200 has several tubes running parallel to one another 220 on which by slats 230 are spaced from each other. In particular, it is a section of the heat exchanger on the bottom 200 shown, so that a bottom manifold 240 is visible in which the pipes 220 flow out.

If a defrosting process is carried out, an on the heat exchanger 200 removing the formed layer of ice creates melt water, which from the heat exchanger 200 must drain. In particular in the area of the collecting pipe at the bottom 240 can become a water column 210 form. The water of the water column 210 can due to the manifold on the bottom 240 difficult to drain and may freeze again after the defrosting process has ended.

the 2 shows a schematic plan view of a heat exchanger according to the invention 10 according to a first embodiment. The heat exchanger 10 can be, for example, in an, in 6th on-board heat pump shown 110 be used. The heat exchanger 10 see in thermal contact with an environment U and can the environment U Withdraw heat or heat to the environment U hand over.

The heat exchanger 10 has a multiplicity of tubes aligned parallel to one another 20th for carrying a refrigerant. The pipes 20th can for example be designed as flat tubes. Between the pipes 20th are slats 30th arranged. The slats 30th are thermal with the pipes 20th coupled and increase a surface area of the pipes 20th for heat transport out of the refrigerant or into the refrigerant.

The pipes 20th run in the vertical direction V and open at the end in manifolds 40 , 50 . The refrigerant can thus from an upper or first manifold 40 in the pipes 20th be led into it. The pipes open out at the bottom 20th in a bottom or second manifold 50 . The refrigerant can thus from the upper header 40 over the pipes 20th into the collecting pipe at the bottom 50 flow.

The heat exchanger 10 has a section or receiving section 31 on which one without slats 30th is executed. The receiving section 31 is in the vertical direction V above the bottom manifold 50 arranged. In the section 31 is a porous material 60 put in. The porous material 60 can for example be made of a metal filter fabric, a metal foam or a ceramic foam. The porous material 60 is between the bottom end lamellas 32 and the collecting pipe at the bottom 50 arranged.

In the in 2 illustrated embodiment is the porous material 60 I-shaped and designed in one piece. A porous material extends here 60 Over an entire width B of the heat exchanger 10 .

By introducing the porous material 60 can form the bottom water column 210 above the collecting pipe at the bottom 50 and the blocking of the heat exchanger 10 be prevented. Due to the capillary action of the porous material 60 can melt water the lamellae 30th of the heat exchanger 10 be withdrawn.

The porous material 60 can through a connection 70 , such as an adhesive connection or solder connection, with at least one bottom end lamella 32 and / or the collecting pipe at the bottom 50 be connected.

The porous material 60 has an I-shaped receiving section 61 to absorb the meltwater.

the 3 shows a perspective view of a heat exchanger according to the invention 10 according to a second embodiment. The porous material 60 is as a metal mesh with a U-shape on the end lamella 32 attached. The end lamellas can 32 and the porous material 60 are as close together as possible. The receiving section 61 opens in the direction of an air flow direction L. each end in a side section 62 , 63 . This allows a volume of the porous material 60 enlarged and a drainage of melt water can be simplified. The side sections 62 , 63 reach around or cover the collecting pipe on the bottom 50 area by area.

The porous material 60 can be thermally connected to the manifold on the bottom 50 and / or the tubes 20th be coupled.

In the second embodiment, the material is porous 60 designed in several parts, so that between two tubes 20th a section 64 of the porous material 60 is positioned.

In the 4th is a plan view of a heat exchanger according to the invention 10 shown according to a third embodiment. In contrast to the exemplary embodiments already illustrated, the porous material has 60 a receiving section 61 on, which is in a memory section 65 for meltwater flows out. The memory section 65 can be designed as an enlarged side section.

At the storage section 65 is an exothermic component 120 arranged. For example, the exothermic component 120 as power electronics, an internal combustion engine component or a section of a main cooling system of a motor vehicle 100 be designed, which in the 6th is shown.

The exothermic component 120 can heat in the form of power dissipation to that in the storage section 65 stored melt water of the heat exchanger 10 release and thus accelerated evaporation or evaporation of the melt water from the storage section 65 enable.

In the 5 is another plan view of a heat exchanger according to the invention 10 shown according to a fourth embodiment. It is in the direction of air flow L. in front of the heat exchanger 10 a radiator shutter 140 arranged. The radiator shutter 140 is shown in a closed state.

During a drying process of the porous medium 60 is the radiator shutter 140 closable in such a way that an air flow through the porous material 60 is directed. The slats 30th of the heat exchanger 10 remain through the radiator shutter during the drying process 140 covered.

The corresponding air flow, in the air flow direction L. , through the multi-part porous medium 60 is illustrated in the form of arrows. The porous medium 60 here has several between each two tubes 20th arranged sections 64 on.

the 6th shows a side view of a motor vehicle according to the invention 100 according to one embodiment. The car 100 has a heat pump 110 for air conditioning a vehicle interior 101 on. This is what the heat pump 110 a heat exchanger 10 and an indoor heat exchanger 102 on which via a refrigerant circuit 103 are thermally coupled to one another. The refrigerant in the refrigerant circuit 103 can be conveyed or pumped, whereby the heat exchanger 10 the environment U Extract heat and the interior heat exchanger 102 can feed to the vehicle interior 101 to air-condition. The heat can be transported from the environment U in the vehicle interior 101 or from the vehicle interior 101 in the nearby areas U take place.

List of reference symbols

100

Motor vehicle

101

Vehicle interior

102

Indoor heat exchanger

103

Refrigerant circulation

110

Heat pump

120

heat-emitting component

140

Radiator shutter

200

State-of-the-art heat exchanger

210

Water column / melt water

220

Prior art pipe

230

Slats according to the state of the art

240

bottom-side manifold according to the prior art

10

Heat exchanger

20th

pipe

30th

Slats

31

Receiving section

32

End lamella

40

first / upper manifold

50

second / bottom manifold

60

porous medium

61

Receiving section of the porous medium

62

first side portion of the porous medium

63

second side portion of the porous medium

64

Section of a multipart porous medium

65

Storage section of the porous medium

70

link

L.

Air flow direction

U

Surroundings

V

Vertical direction

Claims (10)

Heat exchanger (10) for a heat pump (110), in particular for air conditioning a vehicle interior (101), having a plurality of pipes (20) aligned parallel to one another for conveying a refrigerant, fins (30) being arranged between the pipes (20), which are thermally coupled to the tubes (20), the ends of the tubes (20) each opening in a fluid-conducting manner into a collecting tube (40, 50), characterized in that a porous material (60) for receiving during a defrosting process of the heat exchanger (10) resulting melt water (210) is arranged. Heat exchanger after Claim 1 wherein the porous material (60) is made of a metal filter fabric, a metal foam, a porous high-temperature plastic or a ceramic foam. Heat exchanger after Claim 1 or 2 wherein the porous material (60) for receiving, Storage and / or is set up to discharge the melt water (210), the porous material (60) being arranged between the bottom end lamellas (32) and the bottom collecting pipe (50). Heat exchanger after Claim 3 , wherein the porous material (60) can be connected to at least one bottom end lamella (32), at least one tube (20) and / or the bottom manifold (50) by at least one connection (70), in particular an adhesive connection or soldered connection. Heat exchanger according to one of the Claims 1 until 4th wherein the porous material (60) is I-shaped, U-shaped or L-shaped and has an I-shaped receiving section (61) for receiving the melt water (210). Heat exchanger after Claim 5 , wherein the receiving section (61) opens in the air flow direction (L) of the heat exchanger (10) or transversely to the air flow direction (L) in at least one vertical side section (62, 63). Heat exchanger after Claim 5 or 6th , wherein the receiving section (61) opens directly or via at least one vertical side section (62, 63) in at least one storage section (65). Heat exchanger according to one of the Claims 1 until 7th wherein the porous material (60) is arranged in a region of an exothermic component (120). Heat exchanger according to one of the Claims 1 until 8th , a radiator louvre (140) being arranged in front of the heat exchanger (10) in the air flow direction (L), the radiator louvre (140) being closable during a drying process of the porous medium (60) in such a way that an air flow through the porous material (60) is controllable. Motor vehicle (100) which has a heat pump (110) with a heat exchanger (10) according to one of the preceding claims.

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