Method for detecting gas in a heating circuit of an air conditioning device, computer program and air conditioning device

Abstract

A method for detecting gas in a heating circuit (2) of an air conditioning unit (1) is proposed. The heating circuit (2) includes a circulation pump (5) for circulating a liquid heat transfer fluid within the heating circuit (2). The power consumption of the circulation pump (5) is measured, and if it falls below a power limit (19), a significant proportion of gas is inferred in the heating circuit (2). The circulation pump (5) is operated at a predetermined test speed when the power consumption is measured, and / or the power limit (19) is defined as a function of the speed of the circulation pump (5). Furthermore, a tolerance (20) for the power consumption is included in the comparison with the power limit (19). Changes in the measured power consumption are determined by regularly measuring the power consumption at intervals, and the tolerance (20) is adjusted accordingly.

Description

[0001] The invention relates to a method for detecting gas in a heating circuit of an air conditioner, a computer program and an air conditioner.

[0002] Heating circuits are designed to transport heat, for example from a heating appliance to a consumer such as a radiator or underfloor heating system, and contain a heat transfer medium, often water. A heating circuit can contain air or other gases that restrict heat transfer, which may have entered the circuit during filling or through leaks. Therefore, heating circuits must be regularly vented / degassed to ensure proper operation and, in particular, efficient heat transfer. Besides restricting heat transfer, gas or gas bubbles in a heating circuit can also cause unwanted noise emissions, for example, in the area of ​​a circulation pump.

[0003] Methods are known for detecting gas in a heating circuit filled with a liquid heat transfer fluid. A sensor for detecting gas in a liquid flow can be used in this process.

[0004] As an example, DE 20 2022 100 810 U1 presents a heat pump system with a heat pump in which a consumer circuit is connected to a refrigerant circuit of the heat pump. A sensor located in the consumer circuit for detecting gaseous refrigerant can initiate a safety measure if a threshold value is exceeded. This safety measure can, among other things, consist of a degassing process. A disadvantage of using a sensor is the complexity of the system and the risk of sensor failure. A similar method is described in DE 10 2022 112 153 A1.

[0005] EP 3 275 524 A1 attempts to solve the problem by means of a vacuum degassing device for a liquid and a method for its operation, particularly for a cooling circuit of a fuel cell. For this purpose, a degassing chamber is provided in which the liquid to be degassed is depressurized by means of a vacuum generation device, allowing dissolved gases to escape. Additionally, the proposed method allows the gas content or gas saturation state of the liquid to be monitored and / or determined. However, maintaining and introducing the liquid into a degassing chamber, combined with generating a vacuum for it, is complex and unsuitable for a building's heating circuit.

[0006] EP 3 211 330 A1 describes a method and a device for the automatic detection of air bubbles or air inclusions in a system in which a liquid is circulated by a circulation pump. The pressure in the area of ​​an expansion vessel is measured. In addition, other system parameters related to one or more measured pressure changes are analyzed, and it is checked whether these remain within predefined limits. A disadvantage is that pressure measurement in the expansion vessel is complex.

[0007] German patent DE 10 2014 226 450 A1 describes a method for performing an automatic hydraulic balancing of a heating system. A diagnostic procedure allows for the assignment of temperature sensors in the return line to heat consumers and checks whether the heat consumers are adequately supplied with water or contain air. However, the diagnostic procedure does not allow for sufficiently precise detection of air in the heating circuit.

[0008] German patent DE 10 2011 111 945 A1 describes a method for cooling a fuel cell with a liquid cooling medium. The presence of gases, particularly hazardous hydrogen, in the cooling medium is detected based on the power consumption of the coolant delivery system. The proposed method is not sufficiently precise and is not adapted to the conditions occurring in the heating circuit of an air conditioning unit.

[0009] Based on this, the object of the invention is to propose a method for detecting gas in a heating circuit of an air conditioning unit, a computer program, and an air conditioning unit that at least partially overcome the problems of the prior art described above. In particular, a simple, long-term stable, safe, and cost-effective method for detecting gas in a heating circuit is to be provided. Furthermore, the method should require as few or no structural modifications to the air conditioning unit as possible and be suitable for at least partial automation. The method should also be suitable for easy implementation in existing air conditioning units.

[0010] These problems are solved by the features of the independent claims. Further advantageous embodiments of the solution proposed here are specified in the independent claims. It should be noted that the features listed in the dependent claims can be combined with one another in any technologically meaningful way and define further embodiments of the invention. Furthermore, the features specified in the claims are further specified and explained in the description, which also presents further preferred embodiments of the invention.

[0011] This involves a method for detecting gas in the heating circuit of an air conditioning unit. The heating circuit includes at least one circulation pump for circulating a liquid heat transfer fluid. The power consumption of the circulation pump is measured, and if it falls below a (predefined) power limit, a significant proportion of gas in the heating circuit is inferred. The circulation pump is operated at a predefined test speed when the power consumption is measured, and / or the power limit is defined as a function of the pump speed. Furthermore, a tolerance for the power consumption is included in the comparison with the power limit. Changes in the measured power consumption are determined by regularly measuring the power consumption at intervals, and the tolerance is adjusted accordingly.

[0012] The procedure can be carried out continuously, intermittently, and / or at regular intervals while the air conditioning unit is in operation. The procedure is primarily used to detect gas components or gas bubbles in a heat transfer fluid circulating in a heating circuit. The heat transfer fluid can be, in particular, heating water. The gas to be detected can be, in particular, air. However, other gases, such as a refrigerant from the refrigeration circuit of an air conditioning unit configured as a heat pump, can also be detected.

[0013] An air conditioning unit is a device for heating or cooling a building or individual rooms within it. For example, an air conditioning unit can be a (gas-powered) heater designed to burn a fuel gas, such as natural gas or hydrogen, with the addition of ambient air to generate heat energy, for instance, to heat a heat transfer fluid in a heating circuit or to provide hot water. An air conditioning unit can also be an air conditioner or a heat pump system. The heat pump can be a split heat pump with an outdoor and an indoor unit, or a monobloc unit. The air conditioning unit may include a heat exchanger that can transfer heat to or extract heat from the heating circuit.

[0014] It is proposed to record the power consumption of the heating circuit's circulation pump. As the proportion of gas in the heating circuit increases, the circulation pump's power consumption decreases because less heat transfer fluid is being circulated. Therefore, by comparing the recorded power consumption of the circulation pump with a power threshold, a relevant proportion of gas in the heating circuit can be identified. A relevant proportion of gas in the heating circuit is defined as a proportion at which an impairment of the air conditioner's operation and / or a significant restriction of heat transfer is to be expected. To ensure comparability, the circulation pump can be run at a test speed to record its power consumption. For this purpose, one or more test speeds and corresponding power thresholds can be stored in the air conditioner's memory or in a control unit of the air conditioner.Alternatively or cumulatively, the power limit can be specified as a function of the circulation pump's speed. The power consumption of a circulation pump can be defined as a parameter in the pump control system and / or determined by measuring current and voltage.

[0015] The specified tolerance is included in the comparison of power consumption and power limit. This tolerance can compensate for fluctuations in the measured power consumption due to operating conditions or environmental parameters. The tolerance can be incorporated, for example, by subtracting it from the power limit. Alternatively, the power limit can be defined with the tolerance already included and compared to the measured power consumption of the circulation pump during the process.

[0016] It has been shown that the hydraulic pressure loss of a heating circuit can increase, for example, due to contamination or limescale buildup. As a result, the power consumption of the circulation pump gradually decreases over a longer period. To prevent falsely detecting gas in the heating circuit due to this, changes in the measured power consumption are determined by regularly recording it at intervals, and the tolerance is adjusted to compensate for these changes. Since the gradual change in power consumption occurs over a long period, often several years, a suitable interval for recording the power consumption is weekly or monthly. Furthermore, by averaging the measured power consumption over a long period, the effects of gas in the heating circuit on the measured power consumption can be averaged out.Alternatively or cumulatively, the recording of power consumption can also be triggered by an event, for example, degassing of the heating circuit.

[0017] According to an advantageous embodiment, information about a drop below the performance limit due to the power consumption of the circulation pump and / or the detection of a relevant proportion of gas in the heating circuit can be displayed via a display device, made available for retrieval via a network, and / or sent as a message. The network can be, in particular, the internet. Advantageously, a user, system operator, and / or a servicing company can thus be informed, and, if necessary, a maintenance appointment for venting can be scheduled and carried out independently.

[0018] According to one design, if the power limit is undershot by the power consumption of the circulation pump and / or a relevant proportion of gas is detected in the heating circuit, a degassing process can be initiated.

[0019] According to a further embodiment, degassing of the heating circuit can be achieved by varying the speed of a circulation pump within the circuit. Varying the pump speed can promote or even generate turbulent flow, with the resulting low-pressure areas facilitating the outgassing of gases (air, refrigerant) from the heat transfer fluid. The resulting gas bubbles can be collected in a designated area of ​​the heating circuit and removed from the circuit by opening a valve in that area, particularly automatically.

[0020] The term "degassing" here refers to the extensive or practically complete removal of gaseous substances from a heating circuit, particularly the removal of air. Other gaseous substances, such as fuel gas or refrigerant (e.g., R290), may also be present, having entered the heating circuit from a connected refrigeration circuit through a heat exchanger leak, and are thereby removed.

[0021] According to another aspect, an air conditioning unit is proposed which includes at least one heating circuit, a control and regulation unit, and a circulation pump, as well as means adapted to perform the steps of a procedure proposed herein or which are suitable for carrying out a procedure proposed herein. In particular, the air conditioning unit is configured to carry out a procedure proposed herein.

[0022] In addition, a computer program is proposed that is designed to carry out the procedure presented here. In other words, this specifically concerns a computer program (product) comprising commands that, when executed by a computer, cause it to perform the procedure proposed here. The computer program can be executed, in particular, on a control unit of the air conditioning system. Advantageously, the electrical power consumption of the circulation pump is already available to this unit or can be queried from a pump controller.

[0023] Another aspect that is proposed is a machine-readable storage medium on which the computer program is stored. This machine-readable storage medium is typically a computer-readable data carrier.

[0024] The control unit of the air conditioning system is configured to carry out a procedure proposed herein. For this purpose, the control unit may, for example, include a processor. In this context, the processor can, for example, execute the procedure stored in a memory (of the control unit). Advantageously, data for carrying out a procedure proposed herein, such as one or more performance limits, can also be stored in the memory of the control unit, or data can be stored there during the execution of the procedure.

[0025] The air conditioner has a control and regulation unit. The heating unit can be, in particular, a gas-fired heater. The gas-fired heater can have a burner and a delivery system that supplies a mixture of combustion gas (hydrogen) and combustion air to the burner.

[0026] The details, features, and advantageous configurations discussed in connection with the process may also occur in the air conditioning unit and / or the computer program, and vice versa. In this respect, full reference is made to the explanations provided therein for a more detailed characterization of the features.

[0027] This document describes a method for detecting gas in the heating circuit of an air conditioning unit, a computer program, and an air conditioning unit, which at least partially solve the problems described with reference to the state of the art. In particular, the method, the air conditioning unit, the computer program, and the control unit contribute to providing a particularly simple way to detect gas in a heating circuit. A significant advantage is that no additional sensors or other components are required to implement the method. Therefore, the method can also be easily integrated into existing systems as part of a software installation.

[0028] The invention and its technical context are explained in more detail below with reference to the accompanying figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the situations described in the figures and combine them with other components and findings from the present description. It should be emphasized that the figures, and especially the depicted dimensions, are only schematic. They show: Fig. 1: an air conditioning unit proposed here, Fig. 2: a heating circuit, and Fig. 3: parameter profiles that can occur when carrying out a procedure proposed here.

[0029] Fig. 1Figure 1 shows an exemplary and schematic representation of a proposed air conditioning unit 1, implemented here as a gas-fired heating unit. This unit can include a heat generator 3 and a heat exchanger 12. The heat generator 3 can generate heat by burning a fuel gas such as natural gas or hydrogen and transfer it to the heating circuit 2 via the heat exchanger 12. The heating circuit 2 has a flow pipe 8 through which water heated by the heat generator 2 and heat exchanger 12 is supplied as a heat transfer medium to consumers such as radiators or surface heating systems (underfloor heating, wall heating) and subsequently returned via a return pipe 9.

[0030] A circulation pump 5 is arranged in heating circuit 2, which circulates the water in the heating circuit in a flow direction 13. A degassing zone 6 can be arranged in heating circuit 2, in which gas bubbles contained in heating circuit 2 can collect. The gas collected in the degassing zone 6 can escape through a valve 7 located at the highest geodetic point of the degassing zone 6. It should be noted that due to the schematic representation of the Fig. 1 the geodetic position of valve 7 in the Fig. 1 is not apparent.

[0031] The air conditioning unit 1 comprises a control and regulating unit 4, which can execute a procedure proposed here. For this purpose, the control and regulating unit 4 can be electrically connected to the heat generator 3, the circulation pump 5, the valve 7, a display device 10 and a network 11.

[0032] Fig. 2Figure 2 shows, as an example, heating circuit 2 with heat exchanger 12, a secondary heat exchanger 15 (which can be configured for heat exchange with a mass flow of domestic hot water), and circulation pump 5. Due to air present in heating circuit 2, heat exchanger 12 has one coil 14 that is filled with air. This air-filled coil 14 therefore does not participate in heat exchange with the heat generator 3, significantly reducing the transferable thermal output of the heat generator 3. Because of the lack of heat dissipation in the area of ​​the air-filled coil 14, overheating can also lead to damage to heat exchanger 12 or adjacent components.

[0033] Fig. 3 The diagram shows an exemplary and schematic parameter profile that can occur when carrying out a procedure proposed here. The diagram illustrates the electrical power consumption. ForThe power consumption of the circulation pump 5 at a defined test speed over the operating time N of the air conditioning unit 1 is measured. An example of a first electrical power consumption 17 and a second electrical power consumption 18 of the circulation pump 5 is shown. The first electrical power consumption 17 represents the power consumption For The circulation pump 5 is in a degassed state after a new installation of heating circuit 2. The second electrical power consumption 18 shows the electrical power consumption For with an air-filled winding 14, also after new installation. The initial electrical power consumption 17 can be understood as the power limit 19. Furthermore, a tolerance 20 is shown, which is added to the power limit 19 when comparing the measured electrical power consumption with it, or which is subtracted from the measured electrical power consumption. For can be deducted.

[0034] Power consumption decreases over the service life. For of the circulation pump 5 due to dirt and limescale deposits, which can cause an increase in hydraulic pressure loss. This change in electrical power consumption For The change in power consumption over the service life N is shown in a first curve 16. According to a method proposed here, this change can be determined by regularly recording the power consumption at intervals. The determined change can be included in the gas detection in heating circuit 2 by adjusting the tolerance 20 accordingly. In particular, the change in power consumption can be added to the tolerance 20. As a result, a second curve 21 can be determined, which represents the power limit value 19 minus the adjusted tolerance 20.

[0035] According to one embodiment of the method, a degassing process can be initiated when gas is detected in heating circuit 2. For this purpose, the circulation pump 5 can be controlled at varying speeds, which, due to the resulting pressure turbulence and associated negative pressures, promote the release of gas from the heat transfer fluid. Subsequently, the valve 7 of the degassing section 6 can be opened, and the gas can escape from heating circuit 2. This advantageously enables fully automated degassing.

[0036] If gas is detected in heating circuit 2, information about this can be sent as a message or made available for retrieval, for example by an app on a mobile device, via the display device 10 of the air conditioning unit 1 or via the network 11, in particular the Internet, as part of the procedure. Reference symbol list

[0037] 1 Air conditioner 2 Heating circuit 3 Heat generator 4 Control unit 5 Circulating pump 6 Degassing section 7 Valve 8 Flow 9 Return 10 Display unit 11 Network 12 Heat exchanger 13 Flow direction 14 Air-filled heat exchanger coil 15 Secondary heat exchanger 16 First curve 17 First power consumption 18 Second power consumption 19 Power limit 20 Tolerance 21 Second curve

Claims

1. Method for detecting gas in a heating circuit (2) of an air conditioning unit (1), comprising a circulation pump (5) for circulating a liquid heat transfer medium in the heating circuit (2) , wherein the power consumption of the circulation pump (5) is detected and, if it falls below a power limit value (19), a relevant proportion of gas in the heating circuit (2) is inferred, wherein the circulation pump (5) is operated at a predetermined test speed when the power consumption is detected, and / or the power limit value (19) is predetermined as a function of the speed of the circulation pump (5), characterised in that a tolerance (20) of the power consumption is included in a comparison with the power limit value (19), a change in the detected power consumption is determined by regularly detecting the power consumption at intervals, and the tolerance (20) is adjusted on the basis of the change.

2. Method according to claim 1, wherein, if the power limit value (19) is undershot, degassing of the heating circuit (2) is initiated and / or information about the undershooting of the power limit value (19) is displayed on a display device (10) and / or made available for retrieval via a network (11) or sent as a message.

3. Method according to one of the preceding claims, wherein the power limit value (19) is determined in advance by measuring the power consumption following a degassing process of the heating circuit (2).

4. Air conditioning unit (1) comprising a heating circuit (2), a control and regulation device (4) and a circulation pump (5), as well as means for carrying out the method according to claim 1.

5. Computer programme comprising commands that cause an air conditioning unit (1) according to claim 4 to carry out the method according to claim 1.

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