Method and apparatus for determining the temperature of a fluid flowing through a vessel

Abstract

The subject of the present invention is a method for determining the temperature of a fluid (F) flowing through a vessel (1), comprising at least the following steps: - creating a thermal model of the vessel (1), the thermal model being suitable for calculating the time course of the surface temperature of a measurement site on the outer surface of the vessel (1) from a known time course of the fluid temperature, - continuously repeating the following steps: i. calculating the surface temperature of the measurement site on the outer surface of the vessel (1) using the thermal model based on the estimate of the fluid temperature, ii. measuring the surface temperature of the measurement site on the outer surface of the vessel (1), iii. correcting the estimate of the fluid temperature such that, in said thermal model, the measured surface temperature is the most likely one based on the corrected estimate of the fluid temperature, and iv. outputting a corrected estimate of the fluid temperature.

Description

[Technical Field]

[0001] The present invention relates to a method for determining the temperature of a fluid flowing through a vessel, as well as a system for carrying out the method according to the invention. [Background technology]

[0002] Determining the temperature of a fluid flowing inside a conduit, such as a pipe, is often a problem in the context of many industrial processes, where it may be advantageous or necessary to perform a non-invasive, indirect temperature measurement, i.e., to avoid, among other things, the use of a temperature sensor that protrudes into the fluid.

[0003] For example, U.S. Patent Nos. 5,999,049 and 6,249,523 disclose contact temperature sensors that are positioned on the exterior of a pipe with a flow therethrough and measure the temperature of the outer surface of the pipe as a measure of the temperature of the fluid. This external placement advantageously allows the temperature sensor to be replaced without interrupting the process. Furthermore, such non-invasive temperature measurement offers hygienic advantages, since no obstacles protrude into the flowing fluid, which could potentially form deposits on the surface and interfere with cleaning (pigging) the pipe interior. Additionally, no sealed pipes are required, which is particularly advantageous for high-pressure, high-temperature processes. Furthermore, non-invasive temperature measurement does not cause undesirable turbulence or pressure loss in the flowing fluid. However, a drawback is that temperature measurements on the outside of the pipe have very low accuracy with respect to the true temperature of the fluid inside the pipe. At best, the pipe temperature determined using a contact temperature sensor is only a rough approximation of the fluid temperature, especially for fluctuating temperature profiles. The difference then becomes greater the thicker the tube wall, the lower the thermal conductivity of the tube, and the lower the Reynolds number of the fluid.

[0004] Patent Document 3 also discloses a sensor for determining the temperature of a medium, which includes a first temperature sensor having a first thermal response characteristic and at least one second temperature sensor having a second thermal response characteristic different from the first thermal response characteristic, where a certain thermal resistance exists between both temperature sensors, and the signal difference between these temperature sensors is used as the basis for calculating the temperature of the medium. The disadvantages of this method are that at least two temperature sensors must be used and that the measurement setup cannot be adequately adapted to the conditions actually prevailing at the measurement location. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] German Patent Application Publication No. 102017116533 [Patent Document 2] DE 10029186 A1 [Patent Document 3] German Patent Application Publication No. 102017116505 Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is therefore to provide an alternative method and a corresponding system for determining the temperature of a fluid flowing through a duct, which requires simple, non-invasive measurements and is particularly suitable for determining dynamic temperature trends. [Means for solving the problem]

[0007] This problem is solved by the method and system according to claims 1 and 12. Advantageous developments of the invention are set out in the dependent claims.

[0008] The present invention includes the technical teaching that a method for determining the temperature of a fluid flowing through a vessel includes at least the following steps: - creating a thermal model of the vessel, the thermal model being suitable for calculating the time course of the surface temperature of a measurement location on the exterior of the vessel from the known time course of the fluid temperature; - Continuously repeat the following steps: i. calculating the surface temperature of the measurement location on the exterior surface of the vessel using a thermal model based on the estimated fluid temperature; ii. Measuring the surface temperature of the measurement site on the outer surface of the vessel; iii. correcting the estimate of fluid temperature so that, in said thermal model, the measured surface temperature is the most plausible one based on the corrected estimate of fluid temperature; iv Output a corrected estimate of the fluid temperature.

[0009] The core idea of ​​the present invention is to compare the temperature profile measured on the outer surface of the vessel with the corresponding estimated value obtained from a calculation using a thermal model, and to consider that when the estimated temperature profile converges to the measured temperature profile, the fluid temperature profile on which the calculation is based also converges to the true fluid temperature profile. The method according to the present invention is similar to a control loop as shown in Figure 1. The physical system consisting of the vessel 1 and the fluid F flowing therethrough is likened to a thermal model 1000. The fluid temperature T F The time transition of the surface temperature T on the outer surface of the tube body 1 must be specified. S The time course of the fluid F is detected by the known volumetric flow rate ν and the appropriately selected estimated fluid temperature T^. F Based on the initial value of and the surface temperature T^ using the thermal model 1000 S Then, at each time step, the measured surface temperature T S is the estimated surface temperature T^ S Based on this comparison, a feedback loop is implemented by the controller R, which controls the estimated fluid temperature T^ F The estimated value T^ is then passed to the thermal model 1000. F The true value (true value) T FFast convergence to the estimated fluid temperature T̂ can be achieved using a controller R, for example in the form of a Kalman filter, as will be explained in more detail below. F The corrected value of the true fluid temperature T must then be determined. F In particular, according to the invention, the average fluid temperature is determined, i.e., temperature gradients that may possibly exist within the cross section of the flow are leveled out.

[0010] In an advantageous embodiment of the method according to the invention, when creating the thermal model, the finite element method is used to determine a numerical solution of the heat conduction equation, and convective heat transfer and / or thermal radiation are taken into account in order to set the boundary conditions of the heat conduction equation on the outer and inner surfaces of the duct body. The heat conduction equation is:

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[0011] To take into account heat transfer at the vessel surface by radiation and absorption, the vessel can be simply described as, for example, a gray body.

[0012] If a device with a temperature sensor in thermal contact with the outer surface of the vessel is used to measure the surface temperature of the measurement site on the outer surface of the vessel, it is preferable to extend the thermal model of the vessel to include this device. For example, if the measurement current flowing through the temperature sensor is likely to cause resistive losses, the corresponding heat source density should be taken into account when solving the heat conduction equation.

[0013] The thermal model is particularly developed for a wide range of volumetric flow rates of the fluids flowing therein. With the foregoing in mind, it will be apparent to those skilled in the art that the present invention allows for the development of thermal models for any fluid (liquid or gas) and for any conduit of any different shape and material or material combination.

[0014] Alternatively or in addition to creating a thermal model using a numerical solution of the heat conduction equation, the time course of the fluid temperature and the time course of the surface temperature at the measurement site on the outer surface of the vessel may be measured simultaneously to create the thermal model. In this case, the time course of the fluid temperature is preferably pre-defined to suit the specific application in terms of the temperature range and the temperature gradient over time to be covered. Furthermore, various fluid volumetric flow rates or time courses of the volumetric flow rates may be pre-defined.

[0015] In an advantageous embodiment of the method according to the invention, the thermal model is formulated as a dynamic transfer system in a state space representation, and the continuous calculation of the surface temperature is carried out using the state space representation of the thermal model. The term "dynamic transfer system" refers here to a mathematical model of a process that transfers or converts an input signal into an output signal, where the time course of the fluid temperature is considered as the input signal and the corresponding time course of the surface temperature of the measurement site on the outer surface of the vessel is considered as the output signal. The state space representation of the transfer system is particularly suitable for system analysis in the time domain and is particularly efficient for control engineering applications. In the state space representation, all relationships between input, output, and state variables are expressed in the form of matrices and vectors.

[0016] For example, to formulate a thermal model in a state space representation, the following steps are performed: - Calculate the frequency response of the thermal model to various frequencies of harmonic variations in the fluid temperature at various volumetric flow rates of the fluid; - Perform curve fitting to model the frequency response with a transfer function, - Determine the corresponding linear differential equation by taking the inverse Laplace transform of the transfer function, - Obtain the state space representation by rewriting the differential equations into a system of first-order simultaneous differential equations.

[0017] In order to calculate the frequency response, in particular, a sinusoidal temperature profile is input as an input signal to the thermal model, and the steady-state output signal corresponds to the calculated surface temperature profile at the outer surface of the vessel. The frequency of the input signal is then, for example, 10 -3The frequency response is preferably harmonically varied (harmonic variation) in the range 0.1 Hz to 10 Hz. Furthermore, the frequency response is preferably calculated for a number of different fluid volumetric flow rates. Figure 2 shows an example of the phase response of the calculated frequency response (cross symbols) together with the corresponding modeling resulting from curve fitting using a transfer function (solid line). To enable the subsequent calculation steps of the method according to the invention to be performed quickly using a thermal model, the transfer function used for modeling preferably has three to five poles and / or zeros. The transfer function shown in the example of Figure 2 has four corresponding time constants θ, τ1, τ2 and τ3, as follows:

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[0018] Multiple times t with appropriate time increments Δt n+1 =t n To model the temperature dynamics in discrete time for +Δt, the state-space representation of the thermal model is expressed as a linear difference equation

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[0019] A Kalman filter is preferably used to correct the estimated fluid temperature. A Kalman filter is a mathematical method that iteratively estimates parameters describing the state of a system based on error-containing observations. It is used to estimate system variables that cannot be measured directly, while optimally reducing measurement errors (see, for example, "Indirect Measurement of the Temperature via Kalman Filter," XVIII IMEKO World Congress, Metrology for a Sustainable Development, September 17-22, 2006, Rio de Janeiro, Brazil). In the case of dynamic variables, a mathematical model (here, a thermal model of the vessel) can be added as an auxiliary condition to take into account the dynamic relationship between the system variables. In the concept of the method according to the present invention, the Kalman filter is used to best estimate the indirectly measurable fluid temperature from the error-containing surface temperature measurements of the vessel's outer surface, i.e., to correct the estimated fluid temperature profile so that the measured surface temperature profile in the thermal model is most plausible based on the corrected fluid temperature profile.

[0020] To do this, first, we create the expanded state vector

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[0021] When using a Kalman filter, the measured value z(t n ) is contaminated by noise with variance R. If only surface temperature measurements are taken, the observation matrix is

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[0022] Using the Kalman filter, n Fluid temperature y m (t n )=T F (t n ) the procedure preferably comprises the following steps: 0. n=0, preferably the surface temperature T determined at time t S Using the measured value z(t0) at (t0), for example, the value of the measurement noise variance R and the process noise q m,m along with the values ​​of the state vector y → (t0) and the corresponding covariance matrix P(t0):

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[0023] The use of the Kalman filter, in particular, allows the corrected predicted state to include an estimate of the fluid temperature, based on which the measured surface temperature is most likely in the thermal model. Figure 3 illustrates the effect of the method according to the invention using the Kalman filter. For example, the temperature profile of a fluid flowing through a cylindrical pipe as a duct is shown in this figure, along with the corresponding profile of the measured surface temperature of the outer surface of the pipe, which is used in the prior art as a measure of the fluid temperature, and the estimated fluid temperature determined by the method according to the invention.

[0024] Variables that change during operation of the device monitored using the method according to the invention, such as the volumetric fluid flow rate, can be measured by a separate sensor and taken into account. For example, the probability distribution of the temporal variation of the fluid temperature can be adjusted to accommodate changing operating conditions. In particular, when the volumetric fluid flow rate changes, there is a high probability that a change in the fluid temperature will also occur. This can be taken into account by increasing the assumed variance of the probability distribution of the change in fluid temperature with a change in the volumetric fluid flow rate.

[0025] Continuous measurements of the surface temperature at the measurement site on the outer surface of the vessel are preferably performed at a sampling rate of at least 2 Hz. It has been shown that frequent measurement acquisition, or high sampling rates and low noise measurements, are advantageous for the high effectiveness of the method according to the invention, i.e., the low noise and short response time of the fluid temperature determined by this method. Therefore, the surface temperature is preferably measured at a sampling rate of at least 2 Hz (Δt<0.5 s), which would otherwise be considered unusually high for temperature measurements. The noise of the surface temperature measurement is also preferably less than 0.1 K (Kelvin) (standard deviation of the measurement noise) or less than 0.01 K. 2 It will need to be smaller than the variance of the measurement noise, R.

[0026] In an advantageous embodiment, the volumetric flow rate of the fluid through the vessel is determined by continuous measurements, and the progression of the measured volumetric flow rate is taken into account when calculating the progression of the surface temperature.

[0027] The present invention further provides a system for determining the temperature of a fluid flowing through a vessel, configured to carry out a method according to the above-described embodiment, comprising at least: - a device for measuring the surface temperature of a measurement site on the outer surface of the vessel; a calculation unit with a display device for continuously determining and outputting an estimate of the fluid temperature according to the appropriate steps of the method according to the invention; In particular, the thermal model is stored in the memory of the computing unit.

[0028] The device for measuring the surface temperature preferably comprises a temperature sensor, in particular a thermocouple or platinum measuring resistor, which is in thermal contact with the measuring point on the outer surface of the vessel and is insulated from the vessel's surroundings by a thermal insulator. However, in principle, other methods of temperature measurement, for example based on a pyrometer, can also be used within the scope of the method according to the invention.

[0029] In an advantageous embodiment, the system comprises a device for measuring the volumetric flow rate of the fluid through the vessel, which device for measuring the volumetric flow rate may in particular be configured as an electromagnetic flowmeter. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 illustrates the method according to the invention in terms of a control loop. [Figure 2] FIG. 10 shows an example of a phase response of a calculated frequency response together with the corresponding modeling resulting from curve fitting using a transfer function. [Figure 3] FIG. 10 illustrates the effect that can be achieved by the method according to the invention using a Kalman filter. [Figure 4]1 is a schematic cross-sectional view of a system according to the present invention for determining the temperature of a fluid flowing through a vessel by carrying out a method according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0031] Further features that further enhance the present invention are detailed below with reference to FIG. 4 in conjunction with a description of a preferred embodiment of the present invention.

[0032] 4 shows a schematic cross-sectional view of a system 100 according to the invention for determining the temperature of a fluid F flowing through a vessel 1 by carrying out a method according to the invention. The vessel 1 is formed as a cylindrical pipe.

[0033] The system 100 includes a device 2 for measuring the surface temperature of a measurement site on the outer surface of the vessel 1. The device 2 includes a temperature sensor 21 in thermal contact with the outer surface of the vessel 1 and is insulated from the surroundings of the vessel 1 by an insulating material 22. The contact surface between the temperature sensor 21 and the vessel 1 defines the measurement site on the outer surface. The insulating material 22 is made of, for example, a plastic with low thermal conductivity. The device 2 is enclosed in a mechanically stable housing and is pressed against the vessel 1 by, for example, a fixture (not shown).

[0034] The system further comprises a calculation unit 3 equipped with a display device 5, which calculation unit: - calculating the surface temperature of the measurement site on the outer surface of the vessel 1 using the thermal model 1000 based on the estimated fluid temperature; - correcting the estimate of the fluid temperature so that the measured surface temperature is the most likely one based on the corrected estimate of the fluid temperature in the thermal model 1000; - outputting the corrected estimate of fluid temperature to the display device 5; It is formed as follows. In this case, the calculation unit 5 is furthermore configured to receive and evaluate the sensor signals of the temperature sensor 21 and the measuring electrodes 43, 44.

[0035] Additionally, the system comprises a device 4 for measuring the volumetric flow rate of the fluid F passing through the vessel 1, this device 4 being configured as an electromagnetic flowmeter. Using field coils 41, 42, a magnetic field can be generated that penetrates the vessel 1, and measuring electrodes 43, 44 arranged across the magnetic field serve to detect a measuring voltage that is inductively generated in the fluid.

[0036] The combination of two non-invasive measurement methods to simultaneously determine fluid temperature and fluid volumetric flow rate is a particular advantage of the system 100 according to the present invention, allowing for accurate and continuous process monitoring without disturbing the fluid flow inside the vessel 1.

[0037] The present invention is not limited in its implementation to the preferred embodiment described above. Rather, many variations are conceivable that utilize the solutions presented, even if they are essentially of a different type of implementation. The features and / or advantages, including any structural details, spatial arrangements or method steps derived from the claims, the specification or the drawings, may be essential to the invention, both individually and in various combinations. This application relates to the invention described in the claims, but the disclosure of this application also includes the following: 1. A method for determining the temperature of a fluid (F) flowing through a vessel (1), comprising: At least the following: - creating a thermal model (1000) of the vessel (1), the thermal model (1000) being suitable for calculating the time course of the surface temperature of a measurement location on the outer surface of the vessel (1) from a known time course of the fluid temperature; - below; i. calculating a surface temperature at the measurement location on the outer surface of the vessel (1) using the thermal model (1000) based on the estimated fluid temperature; ii. Measure the surface temperature of the measurement portion on the outer surface of the vessel (1); iii. modifying the estimate of fluid temperature so that in the thermal model (1000), the measured surface temperature is most likely based on the modified estimate of fluid temperature; iv outputting the corrected estimate of fluid temperature; continuously repeating the steps; A method comprising: 2. In the method according to item 1 above, A method characterized in that to create the thermal model (1000), a numerical solution of the heat conduction equation is determined using the finite element method, and convective heat transfer and / or thermal radiation are taken into account to set boundary conditions for the heat conduction equation on the outer and inner surfaces of the duct body (1). 3. In the method according to 1 or 2 above, A method characterized by simultaneously measuring the time course of fluid temperature and the time course of surface temperature at the measurement site on the outer surface of the vessel (1) to create the thermal model (1000). 4. In any one of the methods 1 to 3 above, The method comprises formulating the thermal model (1000) as a dynamic transfer system in a state space representation, and performing continuous calculations of surface temperatures using the state space representation of the thermal model (1000). 5. In the method according to the above item 4, To formulate the thermal model (1000) in a state space representation, - calculating a frequency response of the thermal model (1000) to various frequencies of harmonic variations in fluid temperature at various volumetric flow rates of the fluid (F); - performing curve fitting to model the frequency response with a transfer function; - determining a corresponding linear differential equation by performing an inverse Laplace transform on the transfer function; - Obtain a state space representation by rewriting the differential equations into a system of linear simultaneous differential equations. A method comprising the steps of: 6. In the method according to the above item 5, The method, wherein the transfer function has 3 to 5 poles and / or zeros. 7. In any one of the methods 1 to 6 above, The method of claim 1, further comprising: using a Kalman filter to modify the estimate of fluid temperature. 8. In any one of the methods 1 to 7 above, A continuous measurement of the surface temperature of the measurement site on the outer surface of the vessel (1) is carried out using a device (2) having a temperature sensor (21) in thermal contact with the measurement site, and the device (2) is taken into account when creating a thermal model (1000) of the vessel (1). A method characterized by: 9. In any one of the methods described above in 1 to 8, 10. A method according to claim 9, wherein said continuous measurement of the surface temperature of said measurement site on said outer surface of said vessel (1) is performed at a sampling rate of at least 2 Hz. 10. In any one of the methods described above in 1 to 9, The method comprises determining the volumetric flow rate of the fluid (F) through the vessel (1) by continuous measurement, and taking the course of the measured volumetric flow rate into account when calculating the course of the surface temperature. 11. A system (100) for determining the temperature of a fluid (F) flowing through a vessel (1), configured to carry out the method according to any one of claims 1 to 10, comprising at least: - a device (2) for measuring the surface temperature of a measurement portion on the outer surface of the conduit body (1); - A computing unit (3) equipped with a display device (5), i. calculating a surface temperature at the measurement location on the outer surface of the vessel using the thermal model based on the estimated fluid temperature; ii. modifying the estimate of fluid temperature so that in the thermal model (1000) the measured surface temperature is most likely based on the modified estimate of fluid temperature; iii. outputting the corrected estimate of fluid temperature to the display device (5); A computing unit; A system (100) having: 12. In the system (100) described in 11 above, The device (2) for measuring the surface temperature comprises a temperature sensor (21), in particular a thermocouple or a platinum measuring resistor, which is in thermal contact with the measurement site on the outer surface of the vessel (1) and is insulated from the surroundings of the vessel (1) by a thermal insulator (22). 13. 13. The system (100) according to claim 11 or 12, A system (100) comprising a device (4) for measuring the volumetric flow rate of the fluid (F) through the vessel (1). 14. In the system (100) described in 13 above, The system is characterized in that the device (4) for measuring the volumetric flow rate of the fluid (F) is configured as an electromagnetic flowmeter. [Explanation of symbols]

[0038] 100 systems 1 Conduit body 2 Temperature measuring device 21 Temperature sensor 22 Insulation 3 Computational Units 4. Volumetric flow measuring device 41,42 Field coil 43,44 Measuring electrode 5 Display device 1000 Thermal Model F fluid R Controller

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Claims

1. A method for determining the temperature of a fluid (F) flowing through a vessel (1), comprising: At least the following: - creating a thermal model (1000) of the vessel (1), the thermal model (1000) being suitable for calculating the time course of the surface temperature of a measurement point on the outer surface of the vessel (1) from the known time course of the fluid temperature; - below; i. calculating the surface temperature of the measurement site on the exterior surface of the vessel (1) using the thermal model (1000) based on the estimated fluid temperature; ii. Measure the surface temperature of the measurement site on the outer surface of the vessel (1); iii. correcting the estimated value of fluid temperature so that the calculated surface temperature profile at the measurement site on the outer surface of the vessel (1) based on the corrected estimated value of fluid temperature in the thermal model (1000) converges to the measured surface temperature profile; iv. outputting the corrected estimate of fluid temperature; continuously repeating the steps; Including, A method for determining the volumetric flow rate of the fluid (F) through the vessel (1) by continuous measurement, and taking the course of the measured volumetric flow rate into account when calculating the course of the surface temperature.

2. 10. The method of claim 1, A method characterized in that to create the thermal model (1000), a numerical solution of the heat conduction equation is determined using the finite element method, and convective heat transfer and / or thermal radiation are taken into account to set boundary conditions of the heat conduction equation on the outer and inner surfaces of the duct body (1).

3. 10. The method of claim 1, A method characterized by simultaneously measuring the time course of fluid temperature and the time course of surface temperature at the measurement site on the outer surface of the vessel body (1) to create the thermal model (1000).

4. 10. The method of claim 1, The method comprises formulating the thermal model (1000) as a dynamic transfer system in a state space representation, and performing continuous calculations of surface temperatures using the state space representation of the thermal model (1000).

5. 5. The method of claim 4, To formulate the thermal model (1000) in a state space representation, - calculating the frequency response of said thermal model (1000) to different frequencies of harmonic variations of the fluid temperature at different volumetric flow rates of said fluid (F); - performing a curve fitting to model said frequency response by a transfer function; determining the corresponding linear differential equation by inverse Laplace transforming said transfer function; - Obtain a state space representation by rewriting the differential equations into a system of linear simultaneous differential equations A method comprising the steps of:

6. 6. The method of claim 5, The method according to claim 1, wherein the transfer function has 3 to 5 poles and / or zeros.

7. 5. The method of claim 4, The method of claim 1, further comprising: using a Kalman filter to modify the estimate of fluid temperature.

8. 10. The method of claim 1, A continuous measurement of the surface temperature of the measurement site on the outer surface of the vessel (1) is carried out using a device (2) having a temperature sensor (21) in thermal contact with the measurement site, and the device (2) is taken into account when creating a thermal model (1000) of the vessel (1). A method characterized by:

9. 10. The method of claim 1, 10. A method according to claim 9, wherein said continuous measurement of the surface temperature of said measurement site on said outer surface of said vessel (1) is performed at a sampling rate of at least 2 Hz.

10. A system (100) for determining the temperature of a fluid (F) flowing through a vessel (1), configured to carry out the method according to any one of claims 1 to 9, comprising at least: a device (2) for measuring the surface temperature of the outer surface of the vessel (1) at a measurement point; a calculation unit (3) equipped with a display device (5), i. calculating the surface temperature of the measurement location on the exterior surface of the vessel (1) using the thermal model (1000) based on the estimated fluid temperature; ii. correcting the estimated value of fluid temperature so that the calculated surface temperature profile at the measurement site on the outer surface of the vessel (1) based on the corrected estimated value of fluid temperature in the thermal model (1000) converges to the measured surface temperature profile; iii. Outputting the corrected estimate of fluid temperature to the display device (5). A computing unit; and The system (100) comprises a device (4) for measuring the volumetric flow rate of the fluid (F) passing through the vessel (1), and is configured to determine the volumetric flow rate of the fluid (F) passing through the vessel (1) by continuous measurements using the device (4), and to take into account the progress of the measured volumetric flow rate when calculating the progress of the surface temperature.

11. 11. The system (100) of claim 10, The device (2) for measuring the surface temperature comprises a temperature sensor (21), in particular a thermocouple or a platinum measuring resistor, which is in thermal contact with the measurement site on the outer surface of the vessel (1) and is insulated from the surroundings of the vessel (1) by a thermal insulating material (22).

12. 11. The system (100) of claim 10, 10. A system, characterized in that the device (4) for measuring the volumetric flow rate of the fluid (F) is formed as an electromagnetic flowmeter.

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