METHOD FOR DETERMINING A CIRCULATION VOLUME FLOW DELIVERED BY A HEATING CIRCULATION PUMP

Description

[0001] The invention relates to a method for determining the circulating volume flow in a heating system conveyed by means of a heating circulation pump, a computer program, a storage medium, a control and regulation device, and a heating system.

[0002] Heating systems usually have a heating circulation pump. The pressure generated by the heating circulation pump overcomes the flow resistance of the heating circuit and ensures a circulating volume flow of the heat transfer fluid within the heating circuit. Water is used as the heat transfer fluid in most heating systems. The circulating volume flow of the heat transfer fluid delivered by the heating circulation pump is a necessary input variable with a low error tolerance for controlling a heating system.

[0003] DE10 2016 009 179 A1 discloses a method for determining the degree of turbulence in the flow of a turbomachine. This method identified the potential for optimization of the turbomachine's assembly, for example, when a flow edge has formed as a result of non-concentric assembly of the pump flange with the mating flange of the piping system, generating turbulence in the turbomachine. Since turbulence increases power consumption and thus reduces efficiency, knowing the degree of turbulence also makes it possible to improve the efficiency of the turbomachine. For example, by analyzing and improving the installation and assembly situation, e.g., by using flow-calming agents. Deviations from measured sensor values ​​and calculated variables are used to determine the degree of turbulence.According to the state of the art, the circulating volume flow delivered by the heating circulation pump is recorded by means of a flow sensor and made available to the control system via an electronic interface.

[0004] It has been shown that aging processes and / or contamination in the heat transfer medium, for example, due to solids, can reduce the measurement accuracy of the flow sensor, which can lead to incorrect regulation of the heat generator. If the flow sensor fails, the heater can no longer be operated until it is replaced, as the circulating flow rate is a necessary input variable for the control system.

[0005] Based on this, it is the object of the invention to at least partially alleviate the problems described with reference to the prior art and, in particular, to propose a method for determining a circulating volume flow conveyed by a heating circulation pump, which method enables a simple and robust construction of a heating system and / or reduces its complexity.

[0006] This object is achieved by the features of the independent patent claims. Further advantageous embodiments of the solution proposed here are specified in the independent patent claims. It is pointed out that the features listed in the dependent patent claims can be combined with one another in any technologically expedient manner and define further embodiments of the invention. Furthermore, the features specified in the patent claims are further specified and explained in the description, with further preferred embodiments of the invention being presented.

[0007] To achieve the object, a method for preventing incorrect regulation of a heat generator by determining a circulating volume flow conveyed by a heating circulation pump in a heating system having at least one heat generator contributes, which method comprises at least the following steps: a) repeatedly and simultaneously recording a calculated value of the circulating volume flow determined on the basis of operating parameters of the heating circulation pump, and a reference value for the circulating volume flow of the heating circulation pump determined on the basis of the chemical output of the at least one heat generator during operation of the heating system; b) creating a set of points Pn(Xn;Yn), where Xn is a parameter characterising the operating state of the heating circulation pump and Yn corresponds to the difference between the calculated value and the reference value of the circulating volume flow; c) carrying out a regression analysis of the set of points Pn and determining a correction function fk(x); d) correcting the calculated value of the circulating volume flow using the correction function fk(x).

[0008] During regular operation, steps a) - d) of the proposed method are performed at least once in the specified order. It is also possible to repeat step a) or steps a) and b) several times before performing further steps.

[0009] Heating circulation pumps are capable of calculating the pumped circulating flow rate using internal algorithms. However, the circulating flow rate calculated in this way is inaccurate and therefore cannot be used to control the heating system. The inaccuracies are due, for example, to component and / or measurement tolerances. The method proposed here makes it possible to correct the inaccuracies in this calculated value of the circulating flow rate and, if necessary, to continuously provide a corrected and thus sufficiently accurate calculated value of the circulating flow rate for use in the control system during operation of the heating system.

[0010] In step a), two values ​​are recorded simultaneously several times during operation of the heating system. The first value is a parameter characterizing the operating status of the heating circulation pump.

[0011] The parameter characterizing the operating state of the heating circulation pump can be the electrical power consumed by the heating circulation pump. An advantage of this design is the easy availability of the electrical power consumed by the heating circulation pump.

[0012] The parameter characterizing the operating state of the heating circulation pump can be a calculated value of the circulation volume flow.

[0013] The parameter characterizing the operating state of the heating circulation pump can be a function (or temporal change) of the electrical power consumed by the heating circulation pump. A preferred example is a logarithmic function, in particular the natural logarithm of the electrical power consumed by the heating circulation pump.

[0014] It is considered advantageous if the first recorded value, for example, the electrical power consumed by the heating circulation pump or the calculated value of the circulating volume flow, is determined internally by the heating circulation pump, because transmission to a process-executing (control) device can be carried out via a single electronic interface of the heating circulation pump, thus enabling a simpler heating device design. "Internal" determination specifically means that the necessary means for determining and processing the required values / data are provided in / on the heating circulation pump or the heating system.

[0015] As a second value, a reference value is recorded (essentially) simultaneously or in parallel with the first value. It is proposed to use a circulating volume flow delivered by the heating circulation pump as a reference value based on the chemical power generated during burner operation. The chemical power is suitable for correcting the initial value because it is independent of the component and measurement tolerances of the heating circulation pump.

[0016] The chemical output can be determined by taking into account an operating parameter of a gas delivery device that supplies a combustible mixture to the burner. The operating parameter can be the speed, particularly in the case of a gas delivery device designed as a blower.

[0017] In one embodiment, the chemical output can be calculated based on the amount of fuel burned by the burner and the specific chemical energy of the fuel. The fuel quantity can be determined using a suitable sensor, for example, a flow sensor in the gas supply.

[0018] The circulation volume flow delivered by the heating circulation pump can be calculated using the following relationship: dV HP = P ch × η We ρ Wt × c Wt × T VL − T RL These include: dV HP is the circulating volume flow delivered by the heating circulation pump P ch is the chemical power η We is the efficiency of the heat generator ρ Wt is the density of the heat transfer medium c Wt is the specific heat capacity of the heat transfer medium T VL is the flow temperature in the heating circuit T RL is the return temperature in the heating circuit

[0019] The efficiency of the heat generator is a function of the flow temperature T VL , the return temperature T RL and the operating parameters of the gas conveying device that supplies the combustible mixture to the burner.

[0020] However, a value for the circulating volume flow delivered by the heating circulation pump, which was determined on the basis of the chemical performance, cannot be used directly for the control of the heating system, since this is only available for a heat generator in operation and, moreover, does not adequately capture the dynamics of the heating system.

[0021] In step b), a set of points is created in a two-dimensional coordinate system based on the values ​​recorded in step a). The abscissa (x) of the coordinate system represents the parameter that characterizes the operating state of the heating circulation pump, and the ordinate (y) represents the difference between the recorded reference value of the circulation volume flow and the recorded calculated value of the circulation volume flow.

[0022] In step c), a regression analysis of the set of points determined in step b) is performed. The regression analysis determines a correction function fk(x).

[0023] The regression analysis is preferably a simple linear regression analysis, so the correction function to be determined has the form: fk(x) = ax + b. The result of the regression analysis is the coefficients a and b. A linear regression analysis accurately represents the error function to be corrected and is easy to perform. Alternatively, a multiple linear regression analysis can also be performed.

[0024] In step c), other regression analyses can also be used. The selection depends, for example, on the pump characteristics regarding the internal flow rate calculation. For example, an exponential function, particularly a quadratic function, can also be used as the basis for the regression analysis.

[0025] In step d), the calculated value of the circulating volume flow can now be corrected using the determined correction function fk(x). The correction of the calculated value for a specific operating state of the heating circulation pump (identified by the parameter characterizing the operating state) is performed by adding the function value of the correction function to the calculated value. The heating system can be controlled using the corrected calculated value. The use of a flow sensor measuring the circulating volume flow is unnecessary, and a simpler heating system design is enabled.

[0026] By means of the regression analysis, a correction of the calculated value of the circulation volume flow of the heating circulation pump using the correction function fk(x) is also possible for operating conditions in which the reference value is not available.

[0027] It is understood that the recording of the values ​​according to step a) preferably takes place only after the heat generator has reached a stable state after it has been switched on. This can be ensured, for example, by starting the process only after a defined settling time after the heat generator has been started up.

[0028] The recording of the calculated value and reference value in step a) can take place at defined intervals of the parameter characterizing the operating state of the heating circulation pump. This provides a good database for the regression of the correction function. The regression analysis is preferably only carried out after a minimum number of recorded points has been reached. For example, the performance of a regression analysis according to step c) can only take place or be blocked until a minimum number of points of 5 or 10 have been recorded. The defined intervals of the parameter characterizing the operating state of the heating circulation pump for the recording of the calculated value and reference value depend on the selection of the parameter characterizing the operating state of the heating circulation pump.For example, if the pump's electrical power consumption is selected as the parameter characterizing the operating state of the heating circulation pump, a reasonable defined interval can be between 0.1 watts and 3 watts, preferably between 0.3 watts and 2 watts, or between 0.5 watts and 1.5 watts. The defined interval can be freely determined depending on the desired accuracy of the regression analysis.

[0029] In another or alternative embodiment, the parameter characterizing the operating state of the heating circulation pump can be the rotational speed of the heating circulation pump. The defined interval for recording the reference value and the calculated value could then be between 50 rpm [revolutions per minute] and 200 rpm, for example, 100 rpm.

[0030] According to a preferred embodiment of the method, several calculated values ​​and reference values ​​are combined by averaging at a parameter characterizing the operating state of the heating circulation pump, and thus at a support point for the regression analysis. This can increase the accuracy of the correction. In particular, a support point is only included after a minimum number of calculated and reference values ​​have been recorded. It is understood that if the calculated value is used as the parameter characterizing the operating state of the heating circulation pump, only the reference value is subjected to averaging.

[0031] The proposed method is preferably carried out continuously or at regular intervals during operation of the heating system. By continuously adjusting the correction function, changes in the wear status of the heating circulation pump can also be continuously detected.

[0032] According to another embodiment, the function value of the correction function is compared with the function value of a pump-specific error function, and the smaller of the two values ​​is used for the correction. The pump-specific error function represents a previously determined worst-case calculation error during the calculation and, in a simple case, is a concrete value.

[0033] The pump-specific error function can also be used if no determined correction function fk(x) (as disclosed here) is available. This ensures safe operation of the heating system even after a new installation if the proposed procedure could not yet be implemented or could not be fully implemented, for example, because the minimum number of points has not yet been achieved.

[0034] According to a further aspect, a computer program is also proposed which is configured to carry out a method presented here. In other words, this relates in particular to a computer program (product) comprising instructions which, when executed by a computer, cause the computer to carry out a method described here.

[0035] According to a further aspect, a machine-readable storage medium on which the computer program is stored is also proposed.

[0036] The machine-readable storage medium is usually a computer-readable data carrier.

[0037] According to a further aspect, a control device for a heating device is also proposed, configured to carry out a method presented here. For this purpose, the control device can, for example, have or be equipped with a processor. In this context, the processor can, for example, execute the method stored in a memory (of the control device). The pump-specific error function is preferably stored in the same memory.

[0038] According to a further aspect, a heating system with a control and regulation device as presented here is also proposed. The control and regulation device is often a component of a heating device in the heating system. The heating device is, in particular, a gas heating device with a gas burner and a conveying device that can convey a mixture of gas and combustion air (combustible mixture) to a gas burner.

[0039] According to a further aspect, which, however, does not belong to the invention, the use of a recorded gas volume flow of a gas delivery device of a heater is proposed for correcting a calculated value of a circulating volume flow in a heating system, determined based on operating parameters of a heating circulation pump. Preferably, the chemical output of the heater is calculated using the recorded gas volume flow, and the circulating volume flow of the heater is determined from this. The gas volume flow is, in particular, the volume flow of the fuel or the combustible gas mixture. The calculated value of the circulating volume flow, determined based on operating parameters of a heating circulation pump, is preferably calculated internally by the heating circulation pump.

[0040] The explanations of the proposed method can be used in full to characterize or specify the devices and / or uses in question.

[0041] This disclosure therefore provides a method for determining a circulating volume flow delivered by a heating circulation pump, a computer program, a control device, and a heater for implementing the method, which at least partially solve the problems described with reference to the prior art. In particular, the method, the computer program, the control device, and the heater each contribute at least to simplifying the leak test and reducing costs. Furthermore, the high degree of automation of the proposed method largely eliminates faulty tests, thus increasing operational reliability.

[0042] The invention and the technical environment are now explained in detail with reference to the figures.

[0043] They represent schematically: Fig. 1 : a sequence of a procedure proposed here, Fig. 2 : a set of points according to step b) and a corresponding correction function fk(x), and Fig. 3 : a heating system proposed here.

[0044] Fig. 1 shows an exemplary and schematic sequence of a method proposed here. The sequence of steps a), b), c), and d) represented by blocks 110, 120, 130, and 140 can occur during a regular operating sequence. As an example, the method is subsequently implemented by a control unit of a heater.

[0045] In block 110, (three) values ​​can be simultaneously recorded: a parameter determined by the heating circulation pump using internal algorithms, a parameter characterizing the operating state of the heating circulation pump (calculated value B), and a reference value R determined based on the speed of the conveying device that supplies the combustible gas mixture to the heater's burner. The parameter characterizing the operating state of the heating circulation pump can be the electrical power consumption of the heating circulation pump. A relationship between the recorded speed of the conveying device and the corresponding reference value of the circulating volume flow, based on the chemical performance of the heater, was stored in advance for the specific heater and can be retrieved by the control unit implementing the method.

[0046] A minimum averaging number of three was defined in advance. Thus, for the parameter characterizing the operating state of the heating circulation pump, the corresponding differences between the reference value (e.g., determined via chemical performance) and the calculated value of the circulating volume flow are recorded several times (Yn1, Yn2, Yn3) depending on stability criteria. Subsequently, the average Ynd of the reference values ​​Yn1, Yn2, Yn3 recorded for the operating state characterizing the parameter (Xn) is calculated. The average of the difference between the reference value (e.g., determined via chemical performance) and the calculated value of the circulating volume flow is also calculated.

[0047] In block 120, a set of points Pn(Xn;Yn) is created based on the pairs of parameters characterizing the operating state and the averaged difference acquired in block 110. The points Pn(Xn;Yn) to be created can thus be composed as follows: Xn = a parameter characterizing the operating state of the heating circulation pump (e.g. the electrical power consumption of the heating circulation pump), and Yn = difference between the reference value (e.g. determined via the chemical power) and the calculated value of the circulation volume flow.

[0048] Fig. 2 shows an example of a set of points Pn created in block 120. This is shown in a coordinate system, where the abscissa axis corresponds to the parameter characterizing the operating state of the heating circulation pump and the ordinate to the difference formed between the calculated value of the circulating volume flow of the heating circulation pump and the reference value (BR).

[0049] The correction function fk(x) can now be determined by linear regression of the set of points Pn. The correction function fk(x) is a linear function of the form y(x) = a*x+b. The coefficients a and b are determined during linear regression.

[0050] The correction function fk(B) provides a correction offset value fk for each calculation value B. The correction offset value fk(B) can be added to the corresponding calculation value B to determine the corresponding corrected calculation value.

[0051] Fig. 3shows a schematic representation of a proposed heating system 1. The heating system 1 has a heat generator 11. A gas volume flow of a combustible mixture is supplied to the heat generator 11 via an air intake duct 21 and a gas supply 31. A gas conveying device 22, which in the present example is designed as a fan, is arranged in the air intake duct 21. A gas valve 32 is arranged in the gas supply 31, which controls the amount of gas supplied to the air intake duct 21. Downstream of the gas valve 32 in the direction of flow, the gas supply 31 has a gas sensor 33 for measuring the amount of gas supplied. The exhaust gas from the combustion in the heat generator 11 is discharged via an exhaust system 12.

[0052] The heating system 1 has a heating circuit 4 having a heating circulation pump 42, which generates a circulating volume flow in the heating circuit 4. The heating circuit 4 leads via a heat exchanger 41, which transfers the heat generated by the heat generator 11 into the heating circuit 4. The heat exchanger 41 is shown only schematically here and can also have multiple heat exchangers 41, for example a primary and a condensation heat exchanger. Consumers 43, for example convectors, through which the heat is released, are also arranged in the heating circuit 4. A circulation direction 44 of the heating circuit 4 is shown with an arrow. Furthermore, a return temperature sensor 45 is arranged in the heating circuit 4 upstream of the heat exchanger 41 in the direction of flow, and a flow temperature sensor 46 is arranged downstream of the heat exchanger 41. These sensor 46 measure the temperature of the heat transfer medium in the heating circuit 4 upstream and downstream of the heat exchanger 41.

[0053] The heating system has a control and regulation device 5 which is electrically connected at least to the gas sensor 33, the gas conveying device 22, the heating circulation pump 42, the flow temperature sensor 46 and the return temperature sensor 45.

[0054] The control unit 5 is configured to implement the method proposed here according to blocks 110, 120, 130, and 140. In block 120, the control unit records a calculated value B, a circulating volume flow determined internally by the heating circulation pump 42. At the same time, a reference value is recorded, which is determined based on the chemical output of the heat generator 11. For this purpose, the gas quantity provided by the gas sensor 33 and / or an operating parameter of the gas conveying device 22, in particular its speed if designed as a fan, can be used. In addition, the temperature values ​​provided by the flow temperature sensor 46 and the return temperature sensor 45 can be used to determine the chemical output. Using these values, a reference value for the circulating volume flow of the heating circulation pump 42 can be recorded, based on the chemical output of the heat generator 11.

[0055] The process steps according to blocks 120, 130, and 140 can now be executed internally by the control unit 5. The correction function fk(x) thus determined and the resulting corrected calculated value of the circulating volume flow can now be used by the control unit 5 to control the heating system 1. List of reference symbols

[0056] 1Heating system 11Heat generator 12Exhaust system 21Air intake duct 22Gas conveyor 31Gas supply 32Gas valve 33Gas sensor 4Heating circuit 41Heat exchanger 42Heating circulation pump 43Consumer 44Circulation direction 45Return temperature sensor 46Supply temperature sensor 5Regulating and control unit

Claims

1. Method for preventing incorrect regulation of a heat generator (11) by determining a circulating volume flow delivered by a heating circulation pump (42) in a heating system (1) having at least one heat generator (11), comprising at least the following steps: a) simultaneously recording several times a calculated value of the circulating volume flow determined on the basis of operating parameters of the heating circulation pump (42) and a reference value of the circulating volume flow determined on the basis of the chemical output of the at least one heat generator (11) during operation of the heating system (1); b) creating a set of points Pn(Xn;Yn), where Xn is a parameter characterising the operating state of the heating circulation pump (42) and Yn corresponds to the difference between the calculated value and the reference value of the circulating volume flow; c) Performing a regression analysis of the set of points Pn and determining a correction function fk(X) ; d) Correct the calculated value of the circulating volume flow using the correction function fk(X).

2. Method according to claim 1, wherein in step b) the parameter characterising the operating state of the heating circulation pump (42) is an electrical power Pel consumed by the heating circulation pump (42), a speed of the heating circulation pump (42); a function of the electrical power f(Pel) consumed by the heating circulation pump (42) or the speed of the heating circulation pump (42); or the calculated value of the circulation volume flow.

3. The method according to claim 2, wherein the function of the electrical power f(Pel) consumed by the heating circulating pump (42) is the natural logarithm of the electrical power consumed by the heating circulating pump.

4. Method according to one of the preceding claims, wherein the reference value is determined by means of the chemical power by the amount of fuel burnt by the burner and the specific chemical energy of the fuel of the at least one heat generator (11).

5. Method according to claim 4, wherein the chemical power (Pch) is determined by including a gas volume flow of a gas conveying device (22) of the at least one heat generator (11).

6. The method according to any one of the preceding claims, wherein the regression analysis in step c) is a linear regression analysis.

7. Method according to one of the preceding claims, wherein, before carrying out step c), an average minimum number of detected reference values and calculation values are averaged for each parameter characterising the operating state of the heating circulation pump (42).

8. Method according to one of the preceding claims, characterised in that step c) only takes place after a minimum number of points P has been recorded.

9. Method according to one of the preceding claims, wherein the method is carried out continuously during operation of the heating system (1).

10. Regulating and control device (5) for a heating system (1) comprising a heating circulation pump (42) and a heat generator (11), wherein the regulating and control device (5) is set up to carry out a method according to one of claims 1 to 9.

11. A computer program comprising instructions which, when the program is executed by a regulating and control device (5) according to claim 10 in a heating system (1) comprising a heating circulation pump (42) and a heat generator (11), cause the regulation and control device to execute a method according to any one of claims 1 to 9.

12. A machine-readable storage medium on which a computer program according to claim 11 is stored.

13. Heating system (1), comprising a regulating and control device (5) according to claim 10.