DE102019204492A1 - Method for operating a heat pump, heat pump, ventilation system and vehicle - Google Patents

Abstract

The invention relates to a method for operating a heat pump (2), wherein in a first operating mode of the heat pump (2) a refrigerant evaporates in an evaporator (4) of the heat pump (2), the refrigerant absorbing thermal energy (28) from the environment (30). Furthermore, the refrigerant is fed via a compressor (12) of the heat pump (2) into a condenser (6) of the heat pump (2), in which the refrigerant cools and condenses, the refrigerant emitting thermal energy (28) (32). In the first operating mode of the heat pump (2), the refrigerant is also fed back into the evaporator (4) via an expansion valve (14) of the heat pump (2).
In order to achieve an improved method for operating the heat pump (2), it is proposed that in a second operating mode of the heat pump (2) thermal energy (28) is supplied to the refrigerant by means of a heating element (18) of the heat pump (2). The refrigerant is then fed via the compressor (12) into the condenser (6) of the heat pump (2), in which the refrigerant cools down and condenses, the refrigerant emitting thermal energy (28) (32). In a second operating mode of the heat pump (2), the refrigerant is also fed back into the heating element (18) via the expansion valve (14) of the heat pump (2).

Description

The invention relates to a method for operating a heat pump, in which, in a first operating mode of the heat pump, a refrigerant evaporates in an evaporator of the heat pump, the refrigerant absorbing thermal energy from the environment. The refrigerant is fed via a compressor of the heat pump into a condenser of the heat pump, in which the refrigerant cools down and condenses, the refrigerant emitting thermal energy. In the first operating mode of the heat pump, the refrigerant is then fed back into the evaporator via an expansion valve of the heat pump.

In the first operating mode of the heat pump, a refrigerant circuit is established in which the refrigerant passes through the elements of the heat pump in the sequence evaporator - compressor - condenser - expansion module. This sequence is usually repeated several times.

A heat pump can, for example, be used in a ventilation system to heat air by means of the thermal energy specified by the refrigerant in the condenser. For this purpose, the condenser is arranged in an air duct of the ventilation system.

One problem is that the compressor can only be operated at ambient temperatures above a predetermined limit value. This means that the heat pump can only be operated at ambient temperatures above the specified limit value.

If the heat pump is used in a ventilation system - as described above - an electrical heating element, which is also arranged in the air duct of the ventilation system, is generally necessary in addition to the heat pump.

At ambient temperatures below the specified limit, the heat pump is deactivated and the heating element activated. The heating element is then used to heat the air directly. To do this, the heating element converts electrical energy into thermal energy and releases it into the air.

The heating element arranged in the air duct is large and heavy. Especially in the mobile sector, i. H. especially with vehicles, there is an effort to save weight and space. Large and heavy heating elements oppose this.

Another disadvantage is that the heat transfer from the surface of the heating element arranged in the air duct to air is relatively poor. In order to ensure sufficient heating of the air, high temperatures of the surface of the heating element are necessary. Because of the high temperatures, safety elements such as thermostats and / or Esti switches have to be provided.

An object of the invention is to provide an improved method for operating a heat pump which can be used in a larger temperature range than before. Due to the improved method, a heating element that can be used in parallel with the heat pump in the air duct of a ventilation system can preferably be dispensed with.

The object is achieved by a method of the type mentioned at the beginning, in which, according to the invention, in a second operating mode of the heat pump, thermal energy is supplied to the refrigerant by means of a heating element of the heat pump. Furthermore, the refrigerant is fed via the compressor into the condenser of the heat pump, in which the refrigerant cools down and condenses, the refrigerant emitting thermal energy. In the second operating mode of the heat pump, the refrigerant is then fed back into the heating element via the expansion valve of the heat pump.

In this way, the heat pump can be operated in a wider temperature range than before. In particular, the heat pump can be operated in the second operating mode according to the invention at ambient temperatures below the predetermined limit value.

In this way, in ventilation systems, there is no need to provide a separate heating element in the air duct in addition to the heat pump.

Furthermore, the heat transfer to the refrigerant that applies to the heating element of the heat pump is better / more effective than heat transfer to air. The heating element of the heat pump can therefore be significantly smaller and lighter than a heating element that is separate from the heat pump. In this way, weight and space can be saved.

In the first operating mode of the heat pump, a refrigerant circuit is preferably established in which the refrigerant removes the elements of the heat pump in the sequence evaporator - compressor - Condenser - expansion module passes through. This sequence can be repeated several times.

In the second operating mode of the heat pump, a refrigerant circuit is preferably established in which the refrigerant passes through the elements of the heat pump in the sequence heating element - compressor - condenser - expansion module. This sequence can be repeated several times.

It is preferred if the heating element converts electrical energy into thermal energy. That is, the heating element is preferably an electrical heating element.

In principle, the heating element can also be another heating element. For example, the heating element could also be operated with a hot fluid.

The refrigerant is expediently heated above its condensation point by means of the heating element. In particular, the refrigerant can be overheated by means of the heating element. In this way, condensation in the direction of flow of the refrigerant upstream of the condenser can be avoided.

In the second operating mode of the heat pump, thermal energy can be supplied at least partially to the refrigerant by means of the heating element. For example, in the second operating mode of the heat pump, thermal energy can be supplied to the refrigerant exclusively by means of the heating element.

It is preferable to switch between the first and the second operating mode using directional control valves.

The heat pump is expediently operated at ambient temperatures above a predetermined limit value in the first operating mode.

It is also useful if the heat pump is operated in the second operating mode at ambient temperatures below the specified limit value.

The invention is also directed to a heat pump with an evaporator and a condenser. An evaporator-side refrigerant line of the heat pump runs through the evaporator. In addition, a refrigerant line on the condenser side leads through the condenser. The evaporator-side refrigerant line is connected, on the one hand, via a compressor and, on the other hand, via an expansion valve to the condenser-side refrigerant line to form a refrigerant circuit.

According to the invention, the heat pump comprises a heating element. In addition, the heat pump comprises a further refrigerant line that leads through the heating element. The further refrigerant line is connected in parallel to the evaporator-side refrigerant line.

In this way, the heat pump can be operated in a larger temperature range than before.

A circuit for a refrigerant can be understood as a refrigerant circuit.

It is useful if the additional refrigerant line is connected to the condenser-side refrigerant line on the one hand via the compressor and on the other hand via the expansion valve. In particular, the further refrigerant line can be connected to the condenser-side refrigerant line to form a further refrigerant circuit.

It is preferred if the heating element is an electrical heating element.

The refrigerant lines of the heat pump expediently carry a refrigerant when the heat pump is in operation.

The heating element is preferably set up to supply thermal energy to a refrigerant carried in the further refrigerant line. In particular, the heating element can be set up to supply thermal energy to a refrigerant passed through the heating element.

The heat pump advantageously comprises a first directional valve, which is preferably arranged between the evaporator and the compressor. In particular, the first directional control valve can be arranged in the coolant line between the evaporator and the compressor.

It is also advantageous if the heat pump includes a second directional valve, which is preferably arranged between the expansion valve and the evaporator. In particular, the second directional control valve can be arranged in the coolant line between the expansion valve and the evaporator.

The further coolant line is expediently connected on the one hand to the first directional control valve and on the other hand to the second directional control valve.

In particular, the further coolant line can be connected in parallel to the first coolant line via the directional control valves. Furthermore, the further coolant line can be connected to the second coolant line - in particular to the second coolant circuit - via the directional control valves.

The directional control valves are expediently set up to switch between the first-mentioned refrigerant circuit and the further refrigerant circuit.

It is advantageous if the directional control valves are set up to activate the first-mentioned refrigerant circuit and, in particular at the same time, to deactivate the further refrigerant circuit. In this way, thermal energy can be supplied to the refrigerant in the evaporator.

It is also advantageous if the directional control valves are set up to deactivate the first-mentioned refrigerant circuit and, in particular at the same time, to activate the further refrigerant circuit. In this way, thermal energy can be supplied to the refrigerant by means of the heating element.

The directional control valves can be set up to activate both refrigerant circuits, in particular simultaneously. In this way, thermal energy can be supplied to at least part of the refrigerant by means of the heating element. Furthermore, in this way, thermal energy can be supplied to part of the refrigerant in the evaporator.

The directional control valves can also be set up to deactivate both refrigerant circuits, in particular at the same time. In this way the heat pump can be deactivated.

It is advantageous if the directional control valves can be controlled by means of electrical signals.

The directional control valves can be designed as solenoid valves, for example. In principle, however, other directional control valves are also conceivable.

At least one of the directional valves is preferably designed as a 3-way valve. In particular, each of the directional control valves can be designed as a 3-way valve.

Furthermore, the invention is directed to a ventilation system with the aforementioned heat pump and / or one of its developments. The ventilation system also has an air duct in which the condenser of the heat pump is arranged.

The heat pump, in particular its condenser, is expediently set up to heat air in the air duct.

Due to the design of the heat pump according to the invention, an electrical heating element separate from the heat pump for direct heating of air can be dispensed with in the air duct.

In this way, space and weight can be saved.

The ventilation system can be a ventilation system with a heating function. The ventilation system can also be an air conditioning system. In particular, the heat pump - in particular in a further operating mode - can also be used as a cooling device.

The invention is also directed to a vehicle with the aforementioned ventilation system and / or one of its developments. The vehicle also includes an interior, the air duct of the ventilation system opening into the interior.

Appropriately, air to be conducted into the interior is passed through the air duct. The thermal energy released by the refrigerant in the condenser can heat the air in the air duct. Then the heated air can be supplied to the interior.

The vehicle can be designed as a rail vehicle, for example. The vehicle can also be designed as a bus, truck or other vehicle.

The description of advantageous embodiments of the invention given so far contains numerous features, some of which are reproduced in several combined form in the individual subclaims. These features can, however, expediently also be viewed individually and combined to form further useful combinations. In particular, these features can be combined individually and in any suitable combination with the method according to the invention and the heat pump according to the invention, the ventilation system and the vehicle. Process features are thus also to be seen objectively formulated as a property of the corresponding device unit and vice versa.

Even if in the description or in the patent claims some terms are used in the singular or in connection with a numerical word, the scope of the invention for these terms is not to be restricted to the singular or the respective numerical word.

The properties, features and advantages of this invention described above and the manner in which they are achieved will become clearer and more clearly understandable in connection with the following description of the exemplary embodiments, which are explained in more detail in connection with the drawings. The exemplary embodiments serve to explain the invention and do not restrict the invention to the combination of features specified therein, not even with regard to functional features. In addition, suitable characteristics of each Embodiment also considered explicitly in isolation, removed from one embodiment, introduced into another embodiment to supplement it and combined with any of the claims.

• 1 eine Wärmepumpe und
• 2 ein Fahrzeug mit einer Belüftungsanlage, welche die Wärmepumpe aus 1 aufweist.

Show it:

• 1 a heat pump and
• 2 a vehicle with a ventilation system, which the heat pump from 1 having.

1 shows schematically a heat pump 2 . The heat pump 2 has an evaporator 4th and a condenser 6th on.

The heat pump 2 also has an evaporator-side refrigerant line 8th on that by the evaporator 4th leads through. Next, the heat pump 2 a condenser-side refrigerant line 10 on by the condenser 6th leads through.

The evaporator-side refrigerant line 8th can inside the evaporator 4th for example meander. Also the refrigerant line on the condenser side 10 can be inside the condenser 6th for example meander (not shown).

The evaporator-side refrigerant line 8th is on the one hand via a compressor 12 and on the other hand via an expansion valve 14th with the condenser-side refrigerant line 10 connected. In particular, the evaporator-side refrigerant line is 8th with the condenser-side refrigerant line 10 to a refrigerant circuit 16 connected. The refrigerant circuit 16 is in 1 indicated by arrows.

The heat pump 2 also has a heating element 18th on. The heating element 18th is designed as an electrical heating element.

Furthermore, the heat pump 2 another refrigerant line 20th on by the heating element 18th leads through.

The further refrigerant line 20th is to the evaporator-side refrigerant line 8th connected in parallel.

The further refrigerant line 20th is on the one hand via the compressor 12 and on the other hand via the expansion valve 14th with the condenser-side refrigerant line 10 connected. In particular, there is the further refrigerant line 20th with the condenser-side refrigerant line 10 to another refrigerant circuit 22nd connected. The further refrigerant circuit 22nd is in 1 indicated by arrows.

The heat pump 2 has a first directional control valve 24 on, which is between the evaporator 4th and the compressor 12 is arranged.

Also, the heat pump has 2 a second directional valve 26th on, which between the expansion valve 14th and the evaporator 4th is arranged.

The further coolant line 20th is on the one hand to the first directional control valve 24 and on the other hand to the second directional control valve 26th connected. This is how the further coolant line is 20th to the evaporator-side refrigerant line 8th connected in parallel. This is how the further coolant line is 20th also with the condenser-side refrigerant line 10 to the further refrigerant circuit 22nd connected.

The directional control valves 24 , 26th can be controlled by means of electrical signals. In this example the directional control valves are 24 , 26th each designed as a solenoid valve.

The directional control valves 24 , 26th are set up between the first-mentioned refrigerant circuit 16 and the second refrigerant circuit 22nd to switch.

The refrigerant lines 8th , 10 , 20th the heat pump 2 carry a refrigerant when the heat pump is in operation.

The heat pump 2 has (at least) two operating modes.

In the first operating mode of the heat pump 2 the refrigerant passes through the first-mentioned refrigerant cycle 16 guided. This means that in the first operating mode the first-mentioned refrigerant circuit 16 is activated and the other refrigerant circuit 22nd is deactivated.

In the first operating mode of the heat pump 2 the refrigerant evaporates in the evaporator 4th , the refrigerant being thermal energy 28 from the environment (recording 30th ). Then the refrigerant goes through the compressor 12 into the condenser 6th guided. In the condenser 6th cools down the refrigerant and condenses out, whereby the refrigerant has thermal energy 28 submits (submission 32 ). The refrigerant is then released through the expansion valve 14th back into the vaporizer 4th guided.

In the second operating mode of the heat pump 2 the refrigerant is passed through the second refrigerant circuit 22nd guided. That means that the refrigerant is in the second operating mode of the heat pump 2 - instead of the vaporizer 4th - by the heating element 18th to be led. This also means that im second operating mode, the first-mentioned refrigerant circuit 16 is deactivated and the other refrigerant circuit 22nd is activated.

In the second operating mode of the heat pump 2 is by means of the heating element 18th the heat pump 2 the refrigerant thermal energy 28 supplied (not shown). To do this, the heating element converts 18th electrical energy into thermal energy. By means of the heating element 18th the refrigerant is heated above its condensation point.

Then the refrigerant goes through the compressor 12 into the condenser 6th guided. In the condenser 6th cools down the refrigerant and condenses out, whereby the refrigerant has thermal energy 28 submits (submission 32 ). The refrigerant is then released through the expansion valve 14th back into the heating element 18th guided.

At ambient temperatures above a specified limit, the heat pump will 2 operated in the first operating mode.

At ambient temperatures below the specified limit, the heat pump will 2 operated in the second operating mode.

You can switch between the operating modes using the directional control valves 24 , 26th be switched.

That means that using the directional control valves 24 , 26th between the first-mentioned refrigerant circuit 16 and the further refrigerant circuit 22nd can be switched.

It is also possible that the heat pump 2 - in addition to or instead of the second operating mode - has a third operating mode.

In the third operating mode of the heat pump 2 can the refrigerant through the first-mentioned refrigerant circuit 16 and through the further refrigerant circuit 22nd be guided. That is, in the third operating mode of the heat pump 2 the refrigerant can partly through the first-mentioned refrigerant circuit 16 and partly through the further refrigerant circuit 22nd be guided. In this way, in the third operating mode, part of the refrigerant can use the evaporator 4th flow through and part of the refrigerant the heating element 18th flow through.

2 shows a vehicle 34 with a ventilation system 36 which the heat pump 2 out 1 having.

The following description is essentially limited to the differences from the exemplary embodiment 1 , to which reference is made for features and functions that remain the same. Elements that essentially remain the same are designated with the same reference numerals and features that are not mentioned have been adopted in the following exemplary embodiment without being described again.

The vehicle 34 is designed as a rail vehicle in this example. Saving space and weight is particularly important in rail vehicles.

The ventilation system 36 has an air duct 38 on. The liquefier 6th the heat pump 2 is in the air duct 38 arranged.

The vehicle 34 has an interior 40 in which the air duct 38 the ventilation system 36 flows out.

Through the air duct 38 becomes air 42 guided. For example, through the air duct 38 guided air 42 air 42 be from the environment. The flow of air 42 through the air duct 38 through is in 2 represented by arrows.

When the heat pump is in operation 2 releases the refrigerant when it is in the condenser 6th located, thermal energy 28 from (delivery 32 , see. 1 ). The levy 32 of thermal energy 28 takes place both in the first and in the second operating mode of the heat pump (or also in the third operating mode, if available). In this way the can through the air duct 38 guided air 42 be heated. The heated air is then released into the interior 40 directed.

In both operating modes, ie at ambient temperatures above and below the specified limit value, the through the air duct 38 guided air 42 thus by means of the heat pump 2 , especially by means of their condenser 6th to be heated.

In the air duct 38 can use a separate heating unit for direct heating of the air 42 in addition to the heat pump 2 be waived.

In this way, space and weight can be saved.

Although the invention has been illustrated and described in more detail by the preferred exemplary embodiments, the invention is not restricted by the disclosed examples and other variations can be derived therefrom by the person skilled in the art without departing from the scope of protection of the invention.

List of reference symbols

2

Heat pump

4th

Evaporator

6

Condenser

8th

Evaporator-side refrigerant line

10

refrigerant line on the condenser side

12th

compressor

14th

Expansion valve

16

Refrigerant circulation

18th

Heating element

20th

further refrigerant line

22nd

further refrigerant circuit

24

Valve

26th

Valve

28

thermal energy

30th

admission

32

Submission

34

vehicle

36

Ventilation system

38

Air duct

40

inner space

42

air

Claims (15)

Method for operating a heat pump (2), wherein in a first operating mode of the heat pump (2) - a refrigerant evaporates in an evaporator (4) of the heat pump (2), the refrigerant absorbing thermal energy (28) from the environment (30) - the refrigerant is fed via a compressor (12) of the heat pump (2) into a condenser (6) of the heat pump (2), in which the refrigerant cools down and condenses, the refrigerant emitting thermal energy (28) (32), - The refrigerant is fed back into the evaporator (4) via an expansion valve (14) of the heat pump (2), characterized in that in a second operating mode of the heat pump (2) - by means of a heating element (18) of the heat pump (2) Thermal energy (28) is supplied to the refrigerant, - the refrigerant is fed via the compressor (12) into the condenser (6) of the heat pump (2), in which the refrigerant cools and condenses, the refrigerant emitting thermal energy (28) ( 32) - The refrigerant is fed back into the heating element (18) via the expansion valve (14) of the heat pump (2). Procedure according to Claim 1 , characterized in that the heating element (18) converts electrical energy into thermal energy (28). Procedure according to Claim 1 or 2 , characterized in that the refrigerant is heated above its condensation point by means of the heating element (18). Method according to one of the preceding claims, characterized in that a switch is made between the first and the second operating mode using directional control valves (24, 26). Method according to one of the preceding claims, characterized in that the heat pump (2) is operated at ambient temperatures above a predetermined limit value in the first operating mode and is operated at ambient temperatures below the predetermined limit value in the second operating mode. Heat pump (2) with an evaporator (4) and a condenser (6), an evaporator-side refrigerant line (8) of the heat pump (2) passing through the evaporator (4) and a condenser-side refrigerant line (10) passing through the condenser (6) , wherein the evaporator-side refrigerant line (8) is connected on the one hand via a compressor (12) and on the other hand via an expansion valve (14) to the condenser-side refrigerant line (10) to form a refrigerant circuit (16), characterized by a heating element (18) and a further refrigerant line (20), which leads through the heating element (18) and which is connected in parallel to the evaporator-side refrigerant line (8). Heat pump (2) Claim 6 , characterized in that the further refrigerant line (20) is connected on the one hand via the compressor (12) and on the other hand via the expansion valve (14) to the condenser-side refrigerant line (10) to form a further refrigerant circuit (22). Heat pump (2) Claim 6 or 7th , characterized in that the heating element (18) is an electrical heating element. Heat pump according to one of the Claims 6 to 8th , characterized by a first directional valve (24), which is arranged between the evaporator (4) and the compressor (12), and a second directional valve (26) which is arranged between the expansion valve (14) and the evaporator (4), the other Coolant line (20) is connected on the one hand to the first directional valve (24) and on the other hand to the second directional valve (26). Heat pump (2) Claim 7 and Claim 9 , characterized in that the directional control valves (24, 26) are set up to switch between the first-mentioned refrigerant circuit (16) and the further refrigerant circuit (22). Heat pump (2) Claim 9 or 10 , characterized in that the directional control valves (24, 26) can be controlled by means of electrical signals. Heat pump (2) after one of the Claims 9 to 11 , characterized in that the directional control valves (24, 26) are designed as solenoid valves. Ventilation system (36) with a heat pump (2) according to one of the Claims 6 to 12 and an air duct (38) in which the condenser (6) of the heat pump (2) is arranged. Vehicle (34) with a ventilation system (36) after Claim 13 and an interior space (40), the air duct (38) of the ventilation system (36) opening into the interior space (40). Vehicle (34) after Claim 14 , which is designed as a rail vehicle.

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