DE102020112376A1 - Heat pump system - Google Patents

Abstract

The invention relates to a heat pump system for heating and / or cooling, in particular a building or part of a building, comprising a first heat exchanger (11), in particular plate heat exchanger, a second heat exchanger (12), and a low-pressure switch (15), the low-pressure switch (15 ) is arranged on the first heat exchanger (11) and is configured to switch off the heat pump system, in particular a compressor (10) thereof, when a certain switch-off low pressure is reached or not reached.

Description

The invention relates to a heat pump system for heating and / or cooling a building or part of a building, a method for operating a corresponding heat pump system and a building or part of a building comprising a corresponding heat pump system.

During the operation of a heat pump system, certain (possibly unforeseen) influences can lead to temperatures (evaporation temperatures) of a refrigerant in a heat exchanger (e.g. plate heat exchanger) being so low that a corresponding secondary medium (e.g. water) freezes can. This can happen in particular in the defrosting operating states (by reversing the cycle) and in cooling mode. For example, a loss of refrigerant in connection with a software malfunction or a deteriorating measurement quality of a (low-pressure side) pressure transmitter can contribute to this. Freezing of the secondary medium in the heat exchanger (e.g. plate heat exchanger) can in turn lead to internal leakage of the two media (between which heat is exchanged), which can cause refrigerant and water, for example, to mix due to pressure differences. The consequences can be severe damage to the heat pump system as well as the leakage of refrigerant, for example into a person occupied by people. This is a safety risk, especially with flammable refrigerants.

In the prior art it is known to install pressure switches in a suction line upstream of a compressor (see. For example US 747 85 40 B).

For this purpose, the compressor (compressor) should usually be protected. For this reason, the pressure switch is in accordance with US 747 85 40 B integrated into the regulation of the compressor and arranged on the suction side of the compressor.

JP 2013 079 749 A describes a pressure sensor which, in one embodiment, is arranged in the vicinity of a heat exchanger (plate heat exchanger). This pressure sensor is integrated into the control of the compressor. Among other things, the pressure sensor is intended to prevent a wall temperature in the heat exchanger (evaporator) from becoming so low that there is a risk of the heat exchanger freezing (on the secondary side).

Overall, the reliability or safety of the operation of the known heat pump systems, in particular protection against (unintentional) freezing, is considered to be in need of improvement.

It is the object of the invention to propose a heat pump system in which a comparatively reliable or safe operation, in particular a comparatively good protection against unwanted freezing, is achieved. A further object of the invention is to propose a corresponding method and a corresponding building or part of a building.

This object is achieved in particular by the features of claim 1.

In particular, the object is achieved by a heat pump system for heating and / or cooling (preferably for both heating and cooling), in particular a building or part of a building, comprising a first heat exchanger (in particular refrigerant-liquid heat exchanger and / or plate heat exchanger) second heat exchanger (in particular refrigerant-air heat exchanger), and a low-pressure switch, the low-pressure switch being arranged and configured on the first heat exchanger, in particular on a low-pressure side thereof, preferably in a cooling mode and / or defrosting mode, the heat pump system, in particular a Compressor of the same, when reaching or falling below a certain cut-off low pressure (at least partially, in particular completely) to switch off.

A core idea of the invention is to provide a low-pressure switch on the first heat exchanger (in particular evaporator in defrosting or cooling mode) and to configure it in such a way that the heat pump system (or its compressor) is switched off when a certain shut-off low pressure is reached or fallen below will.

A low-pressure switch is to be understood in particular as a switch which carries out a switching process when a certain (low) pressure is present, in particular a switch-off process. For this purpose, the low-pressure switch can have a pressure measuring device and a (possibly separate or additional) disconnection device. As an alternative or in addition, the pressure switch can also be configured in such a way that, depending on the design, it switches (off) when a certain pressure is present or not reached.

In embodiments, the low-pressure switch can therefore be designed without a pressure sensor (that is, without a sensor that is configured to measure a pressure, the sensor being able, for example, to determine at least three or at least 10 different pressure values and in particular to output them accordingly).

An arrangement on the (first) heat exchanger is to be understood in particular to mean that the low-pressure switch is arranged in or (directly) on a heat exchanger housing. An arrangement on the heat exchanger can also mean that the low-pressure switch is arranged directly on or at a distance of 20 cm or less, preferably 10 cm or less, more preferably 5 cm or less, from the first heat exchanger (for example a housing of the same) .

In addition to the two heat exchangers (which serve as condensers or evaporators), the heat pump system preferably comprises at least one compressor and at least one expansion element.

In the compressor, a refrigerant is brought from a low pressure level to a higher pressure level. The pressure increase and mechanical work of the compressor can increase the temperature (pressure gas temperature) of the refrigerant at the compressor outlet. The compressor (compressor) can be in various designs (e.g. as a rotary piston, scroll, reciprocating piston compressor and / or as a one-stage, two-stage or multi-stage compressor).

In the condenser, the superheated refrigerant is first cooled, then condensed and subcooled. The energy is transferred to a secondary medium (e.g. comprising water or a water-glycol mixture). This energy can then be supplied to a living room and / or service water.

The expansion element in the refrigeration circuit can be, for example, an expansion valve (e.g. thermally and / or electronically regulated). It can regulate an injection into the evaporator and ensure that no (liquid) refrigerant escapes from the evaporator. The expansion element can also be designed differently (e.g. ejector).

The evaporator (in cooling or defrosting mode) or first heat exchanger is preferably designed as a plate heat exchanger. However, this can also be implemented in any other form. The refrigerant absorbs energy in the first heat exchanger (or evaporator in cooling or defrosting mode). This energy is supplied by the secondary side (preferably as a water or a water-glycol mixture).

The cooling circuit of the heat pump system can also contain: a dryer and / or filter and / or further expansion elements and / or a refrigerant collector and / or a refrigerant separator and / or an oil separator and / or at least one refrigerant separator and / or an intermediate heat exchanger.

A low-pressure switch is preferably provided on the first heat exchanger (plate heat exchanger), the cut-out point of which is selected in such a way that evaporation temperatures that can lead to freezing of the secondary medium (e.g. comprising water, possibly mixed with glycol) are excluded are. The low-pressure switch is preferably installed directly on the first heat exchanger (plate heat exchanger) (in contrast to a method of installation known per se in the suction line upstream of the compressor). The heating mode, in which lower evaporation temperatures are permitted, does not have to be impaired (as these occur on the second heat exchanger).

If a safety shutdown of the compressor takes place via a low-pressure sensor of a compressor control, this has the particular disadvantage that information is processed via device software that may not be implemented according to safety standards. An error case must then be expected.

If device software is not tailored to meet safety standards, no satisfactory protection mechanism (e.g. according to DIN EN ISO 13849-1 ) to be guaranteed. According to the present invention, the security category is preferably according to DIN EN ISO 13849-1 (preferably using appropriate hardware).

The low-pressure switch is preferably not integrated into a regulation (or control) of the compressor. In particular, the low-pressure switch is therefore not integrated into a regulation of the compressor in such a way that a specific output (in which case, in particular, no zero output in the switched-off state should be meant here) of the compressor would depend on the low-pressure switch. The only possible interaction between the low-pressure switch and the compressor is that the compressor is switched off when the low-pressure switch is triggered. The low-pressure switch cannot be integrated into (any) control of the heat pump system. The low-pressure switch preferably has the (sole) function of switching off the heat pump system or the compressor when the switch-off low pressure is reached or undershot. This creates an independent safety chain or a self-sufficient safety system that is independent of the control of the heat pump system, which improves overall reliability and safety during operation (especially in the event of malfunctions).

In one embodiment, the low-pressure switch can be arranged on a low-pressure side of the first heat exchanger (plate heat exchanger) in a cooling mode and / or defrosting mode. This ensures particularly reliable and safe operation.

Alternatively, the low-pressure switch can be arranged on a high-pressure side of the first heat exchanger (plate heat exchanger or evaporator in cooling mode) in cooling mode and / or defrosting mode.

According to the embodiment, the first heat exchanger (plate heat exchanger) functions as an evaporator in a cooling mode and / or defrosting mode.

The shutdown low pressure can be predefined, in particular fixed or constant, by the structure and / or the installation of the low pressure switch.

Furthermore, the shutdown low pressure can be adapted to specific operating conditions, in which case pressure-temperature characteristics stored in the heat pump system and / or a, preferably electronic, calculation unit of the heat pump system can be used.

The switch-off low pressure can correspond to a pressure at which there is an (evaporation) temperature that represents a limit temperature, below which in the cooling and / or defrosting operation, a medium (e.g. comprising water or water-glycol- Mixture) on a secondary side of the first heat exchanger ( 11 ) leads.

The above-mentioned object is also achieved by a method for operating a heat pump system for heating and / or cooling, preferably both for heating and for cooling, in particular a building or part of a building, preferably of the above type, comprising a first heat exchanger, in particular plate heat exchanger, a second heat exchanger and a low-pressure switch, the low-pressure switch being arranged on the first heat exchanger, in particular on a low-pressure side of the same, preferably in a cooling mode and / or defrosting mode, and the heat pump system, in particular a compressor of the same, when reaching or falling below a certain shutdown Switches off the low pressure.

The above-mentioned object is also achieved by a building or part of a building, comprising a heat pump system of the above type. The building is preferably a residential building.

The heat pump system is preferably a component or is used for heating a building or part of a building (in particular living space) and / or service water. Such a use is (hereby) also disclosed and claimed according to the invention.

The second heat exchanger may not be a plate heat exchanger. The second heat exchanger can be, for example, a lamellar tube heat exchanger.

Further embodiments emerge from the subclaims.

• 1 eine schematische Darstellung einer erfindungsgemäßen Wärmepumpen-Anlage.

The invention is described below using an exemplary embodiment which is explained in more detail using the figures. Here show:

• 1 a schematic representation of a heat pump system according to the invention.

In the following description, the same reference numerals are used for parts that are the same and have the same effect.

The heat pump system according to 1 includes a compressor 10 , a first heat exchanger (plate heat exchanger) 11 and a second heat exchanger 12th . Between the first and second heat exchanger 11 , 12th can the refrigerant in a refrigerant circuit 14th expand.

Via a valve (according to the design 4-2-way valve) 13th the compressor can be switched on in such a way that cooling or defrosting can take place (with the first heat exchanger 11 then acts as an evaporator and the second heat exchanger 12th as a condenser) or in a heating mode (with the first heat exchanger 11 then as a condenser and second heat exchanger 12th acts as an evaporator).

On the first heat exchanger 11 is a low pressure switch 15th arranged (whereby two possible alternatives of the arrangement are shown at the same time; if necessary, two low-pressure switches can also be provided at the marked points). When a predetermined low pressure is reached or not reached, the low pressure switch switches 15th the compressor 10 away.

The heat pump system (in an interconnection as in 1 shown) nor check valves 16 , a liquid receiver 17th , a condensate heater 18th , a filter dryer 19th as well as an (electronic) expansion valve 20th for cooling operation, and an (electronic) expansion valve 21 for heating operation. The expansion valves 20th , 21 can be used in conjunction with a pressure sensor 22nd (opposite on the suction side the compressor 10 ) be connected. Another pressure sensor can be installed on the pressure side of the compressor 23 be provided. Alternative to the two expansion valves 20th , 21 a single bi-flow expansion valve can also be used. This can cause a 1 result in a slightly different refrigeration circuit diagram.

The second heat exchanger 12th can for example for the exchange of heat between refrigerants of the refrigerant circuit 14th and gas (e.g. air). The gas can, for example, via an inlet 25th flow in and through an exit 26th emanate. The first heat exchanger 11 is preferably for exchange with one in a secondary circuit 24 flowing fluid (z. B. water or water-glycol mixture) formed.

At this point it should be pointed out that all of the parts described above, seen on their own and in any combination, in particular the details shown in the drawings, are claimed to be essential to the invention. Changes to this are familiar to the person skilled in the art.

List of reference symbols

10

compressor

11

first heat exchanger

12th

second heat exchanger

13th

Valve

14th

Refrigerant circuit

15th

Low pressure switch

16

Test valve

17th

Liquid pick-up

18th

Condensate heater

19th

Filter drier

20th

Expansion valve (cooling)

21

Expansion valve (heating)

22nd

Pressure sensor (low pressure)

23

Pressure sensor (high pressure)

24

Secondary circuit

25th

entry

26th

exit

QUOTES INCLUDED IN THE DESCRIPTION

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

Patent literature cited

• US 7478540 [0003, 0004]
• JP 2013079749 A [0005]

Non-patent literature cited

• DIN EN ISO 13849-1 [0022]

Claims (10)

Heat pump system for heating and / or cooling, in particular a building or part of a building, comprising a first heat exchanger (11), in particular plate heat exchanger, a second heat exchanger (12), and a low pressure switch (15), the low pressure switch (15) on the first heat exchanger (11) is arranged and configured to switch off the heat pump system, in particular a compressor (10) of the same, when a certain switch-off low pressure is reached or not reached. Heat pump system Claim 1 , wherein the low-pressure switch (15) is not involved in a regulation of the heat pump system or at least not in a regulation of the compressor (10). Heat pump system Claim 1 or 2 , wherein the low-pressure switch (15) is arranged on a low-pressure side of the first heat exchanger (11) in a cooling mode and / or defrosting mode. Heat pump system Claim 1 or 2 , wherein the low-pressure switch (15) is arranged on a high-pressure side of the first heat exchanger (11) in a cooling mode and / or defrosting mode. Heat pump system according to one of the preceding claims, wherein the first heat exchanger (11) functions as an evaporator in a cooling mode and / or defrosting mode. Heat pump system according to one of the preceding claims, wherein the shutdown low pressure is predefined, in particular fixed or constant, by the structure and the installation of the low pressure switch (15). Heat pump system according to one of the preceding claims, wherein the shutdown low pressure can be adapted to certain operating conditions, in which case pressure-temperature characteristics stored in the heat pump system and / or a, preferably electronic, calculation unit of the heat pump system can be used . Heat pump system according to one of the preceding claims, wherein the cut-off low pressure corresponds to a pressure at which a temperature is present that represents a limit temperature, which, in the cooling and / or defrosting mode, falls below this pressure to freeze a medium on a secondary side of the first heat exchanger ( 11) leads .. A method for operating a heat pump system for heating and / or cooling, in particular a building or part of a building, preferably according to one of the preceding claims, comprising a first heat exchanger (11), in particular plate heat exchanger, a second heat exchanger (12), and a low pressure switch (15) ), the low-pressure switch (15) being arranged on the first heat exchanger (11), in particular on a low-pressure side of the same, preferably in a cooling mode and / or defrosting mode, and the heat pump system, in particular a compressor (10) thereof, when it reaches or falls below one certain shut-off low pressure switches off. Building or part of a building, comprising a heat pump system according to one of the Claims 1 until 8th .

Images