HEAT PUMP SYSTEM AND METHOD FOR OPERATING A HEAT PUMP SYSTEM

Abstract

In a method for operating a heat pump system, heat can be supplied to a heating circuit medium using a heat pump; a heating circuit medium flows through a heating circuit; in a first operating mode of the heat pump system, heat is supplied to at least one heat sink located in the heating circuit between a flow line of the heating circuit and a return line of the heating circuit; in a second operating mode of the heat pump system, heat is supplied to a buffer located in the heating circuit between the flow line and the return line and in parallel with the at least one heat sink. In a third operating mode of the heat pump system, an electrical heating device is used to supply heat to the heating circuit medium located in the buffer in order to start the heat pump.

Description

The invention relates to a heat pump system according to the preamble of patent claim 1 and a method for operating a heat pump system according to the preamble of patent claim 3.

A heat pump system of the above-mentioned type is known from the patent document DE 10 2017 003 355 A1. Said heat pump system (from a concrete perspective) consists of a heat pump for heating a heating circuit medium, a heating circuit through which the heating medium flows, at least one heat sink arranged on the heating circuit between a flow line of the heating circuit and a return line of the heating circuit, and a buffer arranged on the heating circuit between the flow line and the return line and parallel to the at least one heat sink. An electrical heating device is thereby provided for heating the heating circuit medium located in the buffer. A heat exchanger, which is heated by the electrical heating device and through which heating circuit medium coming from the buffer can flow, is additionally provided between the heat pump and the heating circuit.

A further heat pump system is known from the patent document DE 10 2018 102 670 A1. From a procedural aspect, heat can be supplied to a heating circuit medium by means of a heat pump in the case of this heat pump system (in particular when heating is required). The heating circuit medium additionally flows through a heating circuit. In a first operating mode of the heat pump system, heat is further supplied at least to a heat sink arranged on the heating circuit between a flow line of the heating circuit and a return line of the heating circuit. In a second operating mode of the heat pump system, heat is furthermore supplied to a buffer arranged on the heating circuit between the flow line and the return line and parallel to the at least one heat sink.

The invention is based on the object of improving a heat pump system of the above-mentioned type or a method for operating a heat pump system of the above-mentioned type, respectively. In particular, a heat pump system, which can be accessed or started particularly well, respectively, initially (thus after its installation) or after a longer standstill, is to be created.

This object is solved by means of a heat pump system of the above-mentioned type by means of the object features listed in the characterizing part of patent claim 1 or by means of a method for operating a heat pump system of the above-mentioned type by means of the method features listed in the characterizing part of patent claim 3, respectively.

According to the invention, a distribution device is thus concretely arranged on the flow line for transmitting the heating circuit medium optionally to the at least one heat sink and/or to the buffer, and a temperature sensor is arranged on a return line-side inlet of the heat exchanger. Procedurally, it is provided according to the invention that in a third operating mode of the heat pump system (also referred to as start-up phase), heat is supplied to the heating circuit medium located in the buffer by means of an electrical heating device, which is preferably arranged on the heating circuit, particularly preferably on the flow line thereof, in order to start the heat pump.

In other words, the solution according to the invention is thus characterized in that the buffer, in addition to its preferably provided, actual basic function, namely being able to provide heat for defrosting the evaporator of the heat pump if needed without negatively impacting the so-called heat sink (thus in particular of the heaters or of the hot water tank, respectively) (the term defrosting buffer can also be used in this case for the buffer), is now initially heated electrically itself prior to the actual start of the heat pump, in order to be able to ensure that the heating circuit medium, which flows back to the heat pump via the return line, is not too cold. This is important because a low return temperature on the heat exchanger, which connects the heat pump to the heating circuit and which is formed as condenser, also leads to a low condensing pressure. So that the compressor can work properly, however, (which requires in particular a stable lubricant film), a minimum pressure has to be ensured on the condenser or a minimum pressure difference on the compressor, respectively.

Other advantageous further developments of the heat pump system according to the invention or of the method according to the invention for operating a heat pump system, respectively, follow from the dependent patent claims.

The heat pump system according to the invention or the method according to the invention for operating a heat pump system, respectively, will be described in more detail below on the basis of the graphic representation of a preferred exemplary embodiment.

Schematically,

FIG. 1 shows the heat pump system according to the invention comprising the electrical heating device on the flow line.

On the one hand, the invention concretely relates to a heat pump system, comprising a heat pump 1 for heating a heating circuit medium, a heating circuit 2 through which the heating circuit medium flows, at least one heat sink 3 arranged on the heating circuit 2 between a flow line 2.1 of the heating circuit 2 and a return line 2.2 of the heating circuit 2, and a buffer 4 arranged on the heating circuit 2 between the flow line 2.1 and the return line 2.2 and parallel to the at least one heat sink 3, see FIG. 1.

An electrical heating device 5 for heating the heating circuit medium located in the buffer 4 is furthermore provided.

It is preferred thereby that the electrical heating device 5 is arranged on the heating circuit 2, in particular on the flow line 2.1 thereof. It is further preferred that the electrical heating device 5 has an electrical heating resistor for converting electrical into thermal energy. Such an electrical heating resistor is able to heat the heating circuit medium particularly quickly and to thus also make the heat pump system ready for operation again particularly quickly after a longer standstill.

A heat exchanger 6, which is heated by the electrical heating device 5 and through which heating circuit medium coming from the buffer 4 can flow, is further provided between the heat pump 1 and the heating circuit 2. The heat exchanger 6 is thereby preferably formed so as to work as condenser of the heat pump 1.

It is additionally preferred that the heat pump 1, in addition to the buffer 4, is formed to be connected to a hot water tank (not illustrated separately). A heat exchanger, through which the heating circuit medium flows, is thereby preferably arranged in the hot water tank in order to heat non-potable water (drinking water). It is furthermore preferably provided that the buffer 4 is formed only for receiving heating circuit medium. It is further preferably provided that the buffer 4, together with the electrical heating device 5 and with the heating circuit pump 7, is arranged in a (common) housing (not illustrated separately), in particular the housing of the heat pump (set up in a building). This makes it possible to form the heat pump system in a particularly space-saving manner. It is furthermore preferred that the buffer has a volume of less than 50 liters, preferably less than 30 liters, particularly preferably less than 20 liters. In the present case, the volume is approximately 15 liters. The hot water tank is further preferably optionally likewise arranged in the housing of the heat pump or is formed to be set up separately.

It is furthermore preferred that the heat sink 3 is optionally formed as heater and/or as floor heating circuit. It is additionally preferred that the buffer 4 is formed as defrost buffer. The amount of heating circuit medium in the bypass path is increased thereby, which improves the controllability of the return temperature in the fourth operating mode (which will be described below). It is likewise provided that a valve device 8, preferably and in particular a 4/3-way valve, is arranged on the flow line 2.1 in order to transmit the heating circuit medium optionally to the at least one heat sink 3 and/or to the buffer 4. The valve device 8 is thereby preferably formed to separate a building heating section comprising the heat sink 3 from a bypass section comprising the buffer 4.

It is furthermore preferred that a heating circuit pump 7 is provided on the heating circuit 2, preferably on the return line 2.2 thereof, for conveying the heating circuit medium. A temperature sensor 9 is further arranged on a return line-side inlet 6.1 of the heat exchanger 6.

The invention furthermore relates to a method for operating a heat pump system, in the case of which heat can be supplied to a heating circuit medium by means of a heat pump 1, in the case of which the heating circuit medium flows through a heating circuit 2, in the case of which heat is supplied to at least one heat sink 3 (in particular heater or floor heating circuit), which is arranged on the heating circuit 2 between a flow line 2.1 of the heating circuit 2 and a return line 2.2 of the heating circuit 2 in a first operating mode of the heat pump system, in the case of which heat is supplied to a buffer 4, which is arranged on the heating circuit 2 between the flow line 2.1 and the return line 2.2 and parallel to the at least one heat sink 3 in a second operating mode of the heat pump system.

It is now procedurally essential for the invention that in a third operating mode of the heat pump system for starting the heat pump 1, heat is supplied to the heating circuit medium located in the buffer 4 by means of an electrical heating device 5.

It is preferred thereby that heat is supplied to the heating circuit medium located in the buffer 4 via the heating circuit medium, which is heated by the electrical heating device 5, which is arranged on the heating circuit 2, in particular on the flow line 2.1 thereof. It is likewise preferred that, to start the heat pump 1, the heating circuit medium heated by the electrical heating device 5 is conveyed to a heat exchanger 6, which connects the heat pump 1 to the heating circuit 2. The heat exchanger 6 thereby preferably works as condenser of the heat pump 1.

All in all, it is particularly advantageous thereby that, to start the heat pump (thus in the third operating mode), only the comparatively small buffer 4 is used, which, as described above, particularly preferably has less than a 20 liter capacity, instead of the heating circuit 2 itself because significantly more heating circuit water (quickly more than 200 liters) would then need to be heated electrically.

It is furthermore preferred that the third operating mode is activated when a predefined lower limit temperature on the heat exchanger 6 is fallen below. It is thereby furthermore preferred that 10° C. is used as lower limit temperature. This serves the purpose of being able to make the heat pump system itself completely ready for operation as quickly as possible even in the case of low temperatures. It is furthermore preferred that the third operating mode is deactivated when a predefined upper limit temperature on the heat exchanger 6 is exceeded. 12° C. is thereby preferably used as upper limit temperature.

When taking an even closer look, it is preferably provided that the temperature on the heat exchanger 6 is initially checked by means of the temperature sensor 9 when the heat pump is to be started when heat is demanded. If this temperature lies above the lower limit temperature (preferably 10° C.), the heat pump operation can be started directly (thus first or second operating mode). If this temperature lies below the lower limit temperature, the heating circuit pump 7 can in fact be activated, but the heat pump 1 initially remains turned off. In order to then be able to bring the heating circuit to the lower limit temperature required for a safe start of the heat pump 1 at the heat exchanger 6, the electrical heating device 5 is turned on and the heating circuit medium is heated therewith (third operating mode). It is thereby particularly preferably provided that the heat pump 1 is started when the lower limit temperature is reached. The electrical heating device 5 is thereby preferably only turned off (end of the third operating mode) as soon as the upper limit temperature (preferably 12° C.) is measured at the heat exchanger 6.

Alternatively, it can also be provided, however, that the electrical heating device 5 is operated alone between the lower and upper limit temperature, and the heat pump 1 is started only when reaching the upper limit temperature.

It is furthermore preferred that in the third operating mode, heating circuit medium supplied only to the buffer 4 [and not to the heat sink 3!] is heated by means of the electrical heating device 5. In addition, it is preferably provided that in the third operating mode, only heating circuit medium from the buffer 4 is supplied to the heat exchanger 6.

It is furthermore preferred that in a fourth operating mode of the heat pump system following the third operating mode, heating circuit medium is supplied to the heat exchanger 6 optionally from the heat sink 3 and/or from the buffer 4, depending on the heat demand. It is thereby particularly preferably provided that at the beginning of the fourth operating mode, more heating circuit medium is supplied to the buffer 4 than to the heat sink 3, and that towards the end of the fourth operating mode more heating circuit medium is removed from the heat sink 3 than from the buffer 4. Such a mixed operation of the heat pump system, in the case of which the electrical heating device 5 is turned off or will be turned off, respectively, and thus does not supply any heat to the heating circuit medium, is advantageous because it can be or is ensured thereby, respectively, that the above-mentioned lower limit temperature is not fallen below immediately again by means of cold water coming from the heat sink 3 in the return line 2.2 of the heating circuit 2 upon ending the third operating mode. The exact control of the mixture of the respective removal quantity from the heat sink 3 and the buffer 4 thereby preferably takes place with the help of the valve device 8 and the temperature sensor 9. It is thereby further also preferably provided that the fourth operating mode is ended when the heating circuit medium is no longer removed from the buffer 4, but only (thus exclusively) from the heat sink 3 due to the temperature conditions on the heat exchanger 6.

The heat pump system according to the invention and the method according to the invention for operating a heat pump system thus make it possible to operate a heat pump system so that, on the one hand, it can be accessed or started, respectively, particularly well initially or after a longer standstill.

LIST OF REFERENCE NUMERALS

• • 1 heat pump
  • 2 heating circuit
  • 2.1 flow line
  • 2.2 return line
  • 3 heat sink
  • 4 buffer
  • 5 electrical heating device
  • 6 heat exchanger
  • 6.1 return line-side inlet
  • 7 heating circuit pump
  • 8 valve device
  • 9 temperature sensor

Claims

1. A heat pump system, comprising a heat pump (1) for heating a heating circuit medium, a heating circuit (2) through which the heating circuit medium flows, at least one heat sink (3) arranged on the heating circuit (2) between a flow line (2.1) of the heating circuit (2) and a return line (2.2) of the heating circuit (2), and a buffer (4) arranged on the heating circuit (2) between the flow line (2.1) and the return line (2.2) and parallel to the at least one heat sink (3), wherein an electrical heating device (5) is provided for heating the heating circuit medium located in the buffer (4), wherein a heat exchanger (6), through which heating circuit medium heated by the electrical heating device (5) and coming from the buffer (4) can flow, is provided between the heat pump (1) and the heating circuit (2),

wherein

a valve device (8) is arranged on the flow line (2.1) for transmitting the heating circuit medium optionally to the at least one heat sink (3) and/or to the buffer (4), and wherein

a temperature sensor (9) is arranged on a return line-side inlet (6.1) of the heat exchanger (6).

2. The heat pump system according to claim 1,

wherein

the electrical heating device (5) is arranged on the heating circuit (2), in particular on the flow line (2.1) thereof.

3. A method for operating a heat pump system, in the case of which heat can be supplied to a heating circuit medium by means of a heat pump (1), in the case of which the heating circuit medium flows through a heating circuit (2), in the case of which heat is supplied to at least one heat sink (3), which is arranged on the heating circuit (2) between a flow line (2.1) of the heating circuit (2) and a return line (2.2) of the heating circuit (2) in a first operating mode of the heat pump system, in the case of which heat is supplied to a buffer (4), which is arranged on the heating circuit (2) between the flow line (2.1) and the return line (2.2) and parallel to the at least one heat sink (3) in a second operating mode of the heat pump system,

wherein

in a third operating mode of the heat pump system, heat is supplied to the heating circuit medium located in the buffer (4) by means of an electrical heating device (5), in order to start the heat pump (1).

4. The method according to claim 3,

wherein

heat is supplied to the heating circuit medium located in the buffer (4) via the heating circuit medium, which is heated by the electrical heating device (5), which is arranged on the heating circuit (2), in particular on the flow line (2.1) thereof.

5. The method according to claim 3,

wherein

at least at the beginning of the third operating mode, heating circuit medium supplied only to the buffer (4) is heated by means of the electrical heating device (5).

6. The method according to claim 3,

wherein

to start the heat pump (1), the heating circuit medium heated by the electrical heating device (5) is conveyed to a heat exchanger (6), which connects the heat pump (1) to the heating circuit (2).

7. The method according to claim 6,

wherein

in the third operating mode, only heating circuit medium from the buffer (4) is supplied to the heat exchanger (6).

8. The method according to claim 6,

wherein

in a fourth operating mode of the heat pump system following the third operating mode, heating circuit medium is supplied to the heat exchanger (6) optionally from the heat sink (3) and/or from the buffer (4), depending on the heat demand.

9. The method according to claim 6,

wherein

the third operating mode is activated when a predefined lower limit temperature on the heat exchanger (6) is fallen below.

10. The method according to claim 6,

wherein

the third operating mode is deactivated when a predefined upper limit temperature on the heat exchanger (6) is exceeded.

11. The method according to claim 8,

wherein

in the fourth operating mode, the electrical heating device (5) is turned off.

12. The method according to claim 8,

wherein

at the beginning of the fourth operating mode, more heating circuit medium is supplied to the buffer (4) than to the heat sink (3), and wherein towards the end of the fourth operating mode more heating circuit medium is removed from the heat sink (3) than from the buffer (4).

13. The method according to claim 8,

wherein

the fourth operating mode is ended when the heating circuit medium is no longer removed from the buffer (4), but only from the heat sink (3) due to the temperature conditions on the heat exchanger (6).