Thermal liquid mass flowmeter with rectification function

Abstract

The utility model discloses a thermal liquid mass flowmeter with a rectification function, which comprises a base, a main flow channel is arranged in the base, a liquid inlet and a liquid outlet which are communicated with the main flow channel are respectively arranged at two ends of the base, a first bypass hole and a second bypass hole are arranged on the base, and the first bypass hole and the second bypass hole are communicated with the main flow channel. The first bypass hole and the second bypass hole are respectively communicated with the main flow channel, the first bypass hole is communicated with the second bypass hole through a drainage pipe, the drainage pipe is provided with a thermal flow sensing module used for detecting flow, the thermal flow sensing module is electrically connected with the control module, a rectifier is further arranged in the main flow channel, and the rectifier is electrically connected with the control module. The rectifier is positioned between the first bypass hole and the second bypass hole and is used for uniformly dividing a main runner area where the rectifier is positioned into a plurality of sub-channels; the device has the advantages of improving the fluid flowing state, reducing turbulence and improving the measurement precision and stability.

Description

Technical Field

[0001] The utility model relates to a flowmeter, in particular to a thermal liquid mass flowmeter with a rectifying function. Background Art

[0002] As an important flow measurement tool, the thermal flowmeter plays a key role in many industries such as chemical industry, petroleum, pharmaceutical, and food processing. Its basic principle is to measure the flow rate of the fluid by detecting the heat exchange between the heating module and the fluid. The heating module (such as a resistance wire or a hot film) is installed on the inner wall of the pipeline or close to the inner wall. When the fluid flows through, the temperature of the heating module will change. By measuring the temperature difference change between the upstream and downstream, the flow rate of the fluid can be indirectly calculated.

[0003] In practical applications, the fluid flow state has a direct impact on the measurement results. Ideally, the fluid flow under laminar flow conditions is more regular and stable, which is beneficial to improving the measurement accuracy. However, the actual working conditions are often more complex, and the fluid is usually in a turbulent state, which leads to uneven flow velocity distribution, generates vortices and other unstable factors, and then affects the accuracy and stability of the measurement.

[0004] The occurrence of turbulence is closely related to the Reynolds number. The Reynolds number is a dimensionless number used to measure the relative magnitude between the inertial force and the viscous force when the fluid flows. When the Reynolds number is high, the fluid is more likely to enter the turbulent state. In industrial applications, the increase in fluid velocity or the change in pipeline diameter will cause the Reynolds number to rise, thus triggering turbulence.

[0005] In addition, the geometric shape of the pipeline also has a great influence on the fluid flow state. For example, at the entrance of the pipeline, the fluid will experience a gradually stable transition zone after entering the straight pipe, while at complex structures such as elbows and tees, local turbulence will be generated, forming a vortex region, making the flow field extremely complex.

[0006] In summary, although the existing thermal flowmeters perform well in many application scenarios, under high Reynolds number conditions, the existing turbulence phenomenon will lead to a decrease in measurement accuracy. Therefore, developing a thermal mass flowmeter with a rectifying structure to improve the fluid flow state and reduce the influence of turbulence is of great significance for improving the measurement accuracy and stability. Summary of the Utility Model

[0007] The purpose of the utility model is to provide a thermal liquid mass flowmeter with a rectifying function, which can improve the fluid flow state, reduce turbulence, and improve the measurement accuracy and stability.

[0008] To achieve the above object, the present utility model provides the following technical solutions: A thermal liquid mass flowmeter with a rectifying function, comprising a base, a main flow channel is provided in the base, a liquid inlet and a liquid outlet respectively communicating with the main flow channel are provided at both ends of the base, a first bypass hole and a second bypass hole are further provided on the base, the first bypass hole and the second bypass hole respectively communicate with the main flow channel, and the first bypass hole is connected to the second bypass hole through a drainage pipe, a thermal flow sensing module for detecting flow is provided on the drainage pipe, the thermal flow sensing module is electrically connected to a control module, a rectifier is further provided in the main flow channel, the rectifier is located between the first bypass hole and the second bypass hole, and is used to evenly divide the main flow channel area where it is located into a plurality of sub-channels.

[0009] Preferably, the longitudinal section of the main flow channel is a circular structure, the rectifier includes a support column and a plurality of rib plates circumferentially and uniformly fixed on the outer side wall of the support column, the support column is coaxially distributed with the main flow channel, the outer side of the rib plate is fixed on the inner wall of the main flow channel, and the rib plate extends along the fluid flow direction to evenly divide the main flow channel into a plurality of sub-channels in a fan-shaped structure.

[0010] Preferably, the longitudinal section of the main flow channel is a circular structure, the rectifier includes a plurality of rib plates extending along the fluid flow direction, the plurality of rib plates are arranged in the main flow channel and are distributed in an intersecting manner to evenly divide the main flow channel into a plurality of sub-channels in a fan-shaped structure.

[0011] Preferably, both the support column and the rib plates are made of corrosion-resistant materials, and the corrosion-resistant materials are selected from one of stainless steel, titanium alloy or engineering plastics.

[0012] Preferably, the thermal flow sensing module includes a heating element and two temperature sensing elements, the heating element is arranged on the outer side wall of the drainage pipe, the two temperature sensing elements are also respectively arranged on the outer side wall of the drainage pipe, and the heating element is located between the two temperature sensing elements.

[0013] Preferably, the drainage pipe is a capillary tube.

[0014] Preferably, the temperature sensing element is a high-precision thermocouple or a platinum resistance.

[0015] Preferably, an adjustment cavity communicating with the liquid inlet and the main flow channel is provided in the base, a regulating valve is provided in the adjustment cavity, and the regulating valve is electrically connected to the control module.

[0016] Preferably, the regulating valve is a piezoelectric ceramic valve or an electric proportional valve.

[0017] Compared with the prior art, the advantages of the present utility model are as follows: The setting of the rectifier divides the single flow field in the main flow channel into multiple relatively independent sub-channels. The flow cross-sectional area of each sub-channel is relatively small. When the liquid enters the sub-channel from the main flow channel, the flow state will change from the original potential turbulence to laminar flow, avoiding the uneven distribution of the liquid flow velocity in the main flow channel, eliminating the possible vortices and dead zones, and helping to obtain a more consistent and regular flow field state. On the one hand, this reduces the turbulence degree of the fluid when passing through the rectifier, and on the other hand, it also makes the flow state more stable when flowing through the thermal flow sensing module later, avoiding the interference of flow field disturbance on the measurement; In addition, through the setting of the first bypass hole and the second bypass hole, the thermal flow sensing module is installed on the drainage pipe, making it independent of the main flow channel. In this way, the thermal flow sensing module will not be directly affected by the complex turbulence in the main flow channel, but is measured in the relatively stable drainage pipe, further improving the stability and reliability of the measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only the embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0019] Figure 1 is a three-dimensional structure schematic diagram of the present utility model;

[0020] Figure 2 is a cross-sectional view of the present utility model;

[0021] Figure 3 is a three-dimensional structure schematic diagram of the rectifier in one embodiment of the present utility model;

[0022] Figure 4 is a three-dimensional structure schematic diagram of the rectifier in another embodiment of the present utility model;

[0023] Figure 5 is a principle block diagram of the circuit part in the present utility model;

[0024] In the figure, 1, base; 2, main flow channel; 3, liquid inlet; 4, liquid outlet; 5, first bypass hole; 6, second bypass hole; 7, drainage pipe; 8, thermal flow sensing module; 9, control module; 10, rectifier; 11, support column; 12, rib plate; 13, sub-channel; 14, heating element; 15, temperature sensing element; 16, adjustment cavity; 17, regulating valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0026] Embodiment 1: As Figures 1 - 5 shown, a thermal liquid mass flowmeter with a rectifying function includes a base 1. A main flow channel 2 is formed in the base 1. A liquid inlet 3 and a liquid outlet 4 communicating with the main flow channel 2 are respectively arranged at both ends of the base 1. A first bypass hole 5 and a second bypass hole 6 are also arranged on the base 1. The first bypass hole 5 and the second bypass hole 6 are respectively communicated with the main flow channel 2, and the first bypass hole 5 is communicated with the second bypass hole 6 through a drainage pipe 7. A thermal flow sensing module 8 for detecting the flow rate is arranged on the drainage pipe 7. The thermal flow sensing module 8 is electrically connected to a control module 9. A rectifier 10 is further arranged in the main flow channel 2. The rectifier 10 is located between the first bypass hole 5 and the second bypass hole 6 and is used to evenly divide the area of the main flow channel 2 where it is located into several sub-channels 13.

[0027] Embodiment 2: As Figure 3 shown, different from Embodiment 1, the longitudinal section of the main flow channel 2 is a circular structure. The rectifier 10 includes a support column 11 and a plurality of rib plates 12 circumferentially and uniformly fixed on the outer side wall of the support column 11. The support column 11 is coaxially distributed with the main flow channel 2. The outer sides of the rib plates 12 are fixed on the inner wall of the main flow channel 2. The rib plates 12 extend along the fluid flow direction and evenly divide the main flow channel 2 into several sub-channels 13 in a fan-shaped structure.

[0028] In the above structure, the support column 11 and the rib plates 12 cooperate with each other, which can efficiently utilize the internal space of the circular pipeline and evenly divide it into multiple fan-shaped sub-channels 13. The design of the fan-shaped sub-channels 13 ensures that the flow cross-sectional areas of the respective sub-channels 13 are basically the same, so that the liquid can be evenly divided after entering the sub-channels 13, avoiding the non-uniformity of the flow velocity distribution. Moreover, the fan-shaped sub-channels 13 are conducive to gradually and smoothly transitioning the liquid flow with a certain turbulent potential energy to a laminar flow state. When the fluid passes through the gaps between the rib plates 12, it will be affected by the boundary layer resistance, and the turbulent potential energy will be gradually consumed, and the flow becomes more regular and orderly.

[0029] In the cross-section of the main flow channel 2, the rib plates 12 equally divide the circular pipe into multiple regions, and there is a fan-shaped sub-channel 13 in each region. This circumferential uniform distribution helps to ensure that the liquid flow rates between the sub-channels 13 are basically the same, making the flow state of the liquid in the entire main flow channel 2 more uniform and stable. The rib plates 12 extend along the fluid flow direction, enabling the liquid to continuously maintain its flow direction after entering the sub-channels 13, effectively reducing the change in the liquid's direction when passing through the flow rectifier 10. This design maximally avoids the energy loss and turbulence generation caused by a drastic change in the flow direction.

[0030] The setting of the support columns 11 provides central support for the entire flow rectifier 10, avoiding severe vibration and deformation of the rib plates 12 under high-flow-rate conditions.

[0031] Embodiment Three: As Figure 4 shown, different from Embodiment One, the longitudinal section of the main flow channel 2 is a circular structure. The flow rectifier 10 includes multiple rib plates 12 extending along the fluid flow direction. The multiple rib plates 12 are arranged in the main flow channel 2 and distributed in an intersecting manner to evenly divide the main flow channel 2 into several fan-shaped sub-channels 13.

[0032] The intersecting rib plate 12 structure also makes the distribution of the sub-channels 13 in the cross-section of the main flow channel 2 relatively uniform, which is conducive to the liquid being evenly dispersed into each sub-channel 13 after entering the main flow channel 2, avoiding the non-uniformity of the local flow rate distribution. Specifically, when the liquid flows through the sub-channels 13, it needs to continuously change its flow direction and pass through the narrow gaps between the rib plates 12. During this process, the fluid is continuously subjected to the viscous resistance of the pipe wall and the surface of the rib plates 12. This boundary layer resistance can effectively dissipate the turbulent kinetic energy of the fluid, prompting it to gradually change from the original potential turbulent state to a laminar flow state. At the same time, the flow cross-sectional area of each sub-channel 13 is small. Even when the overall Reynolds number is relatively high, the local Reynolds number in the sub-channels 13 will be significantly reduced, which is more conducive to suppressing the generation of turbulence and maintaining the laminar flow state.

[0033] In this embodiment, both the support columns 11 and the rib plates 12 are made of corrosion-resistant materials. The corrosion-resistant materials are selected from one of stainless steel, titanium alloy, or engineering plastics. This effectively prevents the corrosion and erosion of the fluid in the pipeline to the device, ensuring the long-term stability and service life of the flow rectification structure.

[0034] Embodiment Four: As Figures 1 - 5 shown, different from Embodiment Two, the thermal flow sensing module 8 includes a heating element 14 and two temperature sensing elements 15. The heating element 14 is arranged on the outer sidewall of the diversion pipe 7, and the two temperature sensing elements 15 are also respectively arranged on the outer sidewall of the diversion pipe 7, and the heating element 14 is located between the two temperature sensing elements 15.

[0035] In the above structure, both the heating element 14 and the temperature sensing element 15 are installed outside the drainage pipe 7, avoiding their direct exposure to the fluid medium, thus effectively preventing problems such as corrosion and blockage, and improving the reliability and service life of the system. The heating element 14 is located between the two temperature sensing elements 15, forming a symmetric temperature gradient distribution. When a constant heat is applied to the drainage pipe 7 through the heating element 14, the temperature detected by the upstream temperature sensing element 15 will be lower than that of the downstream temperature sensing element 15. The magnitude of this temperature difference is proportional to the fluid flow rate and can be used as a basis for measuring the mass flow rate.

[0036] The design with two temperature sensing elements 15 can effectively eliminate the systematic errors caused by environmental temperature fluctuations or heat loss. When the environmental temperature rises, the upstream and downstream temperatures will rise synchronously, but the temperature difference between them can still remain constant, thus not affecting the measurement result of the flow rate. In addition, the symmetric arrangement of the two temperature sensing elements 15 can reduce the error influence caused by the heat propagation of the drainage pipe 7 itself. The unidirectional heat dissipation will lead to an overestimation of the upstream temperature value and an underestimation of the downstream temperature, resulting in a large measurement deviation. After adopting the symmetric design, the heat loss amounts of the upstream and downstream are basically equal, and this kind of error can be minimized.

[0037] During the actual measurement process, the control module 9 will calculate the temperature difference between the upstream and downstream temperature sensing elements 15 based on the detected temperature values, and substitute this temperature difference value into the flow rate calculation model to obtain the current mass flow rate reading. The entire measurement process only needs to condition the temperature signal and does not require sampling the fluid itself or other invasive operations. Therefore, the measurement method is simpler and more reliable.

[0038] In this embodiment, the drainage pipe 7 is a capillary tube. The drainage pipe 7 adopts a capillary tube structure, making the cross-sectional area of the flow channel inside the drainage pipe 7 very small. Even under the condition of a relatively high total flow rate, the local Reynolds number inside the drainage pipe 7 will be reduced to a relatively low level, which is beneficial to maintaining the laminar flow state of the liquid inside the drainage pipe 7 and creating a good flow environment for the measurement of the thermal flow sensor.

[0039] In this embodiment, the temperature sensing element 15 is a high-precision thermocouple or platinum resistance.

[0040] In the thermal flow sensing module 8, the temperature sensing element 15 is selected as a high-precision thermocouple or platinum resistance. Both of these two sensors have extremely high temperature measurement accuracy and linearity, and can accurately detect the tiny temperature changes brought about by the liquid flow inside the drainage pipe 7, ensuring the accurate measurement of the mass flow rate.

[0041] The advantage of a thermocouple is that it does not require external power supply. Just by exposing the junction of two different metal materials to the measured temperature, the temperature change can be reflected through the tiny potential difference generated between the two materials. This passive sensing method is simple and reliable, and is not restricted by external power supply conditions. Platinum resistance, on the other hand, is favored for its excellent thermal stability and linear characteristics. It can maintain extremely high precision even under high-temperature conditions. At the same time, the integration of platinum resistance with the measurement circuit is more convenient, and no complex signal conditioning circuit is required.

[0042] During the actual measurement process, the thermal flow sensing module 8 will pass a constant heating power into the drainage pipe 7. When the liquid flows, due to heat exchange with the liquid, the temperature of the sensor will change. Based on the known heating power and the measured temperature change, the mass flow rate of the liquid in the drainage pipe 7 can be calculated inversely.

[0043] Since the liquid in the drainage pipe 7 is in laminar flow, the temperature field distribution is relatively uniform and stable. Combining with the use of a high-precision temperature sensing element 15, accurate measurement of the mass flow rate can be achieved. At the same time, the application of the capillary tube also reduces the pressure drop in the drainage pipe 7 and avoids interfering with the liquid flow in the main flow channel 2.

[0044] In this embodiment, an adjustment cavity 16 communicating with the liquid inlet 3 and the main flow channel 2 is provided in the base 1. A regulating valve 17 is arranged in the adjustment cavity 16, and the regulating valve 17 is electrically connected to the control module 9.

[0045] In the above structure, the setting of the adjustment cavity 16 enables the liquid to pass through the adjustment cavity 16 where the regulating valve 17 is located before entering the main flow channel 2. By controlling the opening degree of the regulating valve 17, the flow rate entering the main flow channel 2 can be accurately adjusted, thus realizing the dynamic adjustment of the measurement range.

[0046] When a larger flow rate needs to be measured, the control module 9 can be used to fully open the regulating valve 17, allowing most of the flow to directly enter the main flow channel 2. In the case of a smaller flow rate, the opening degree of the regulating valve 17 can be appropriately reduced to make more flow pass through the drainage pipe 7 for measurement. This passive shunt design expands the measurement range of the flowmeter, enabling it to be applicable to different working conditions.

[0047] In this embodiment, the regulating valve 17 is a piezoelectric ceramic valve or an electro-hydraulic proportional valve.

[0048] In the above structure, the introduction of the regulating valve 17 not only expands the measurement range of the flowmeter, but also helps to reduce the flow velocity in the drainage pipe 7, avoiding the problems of pipeline vibration and turbulence that may occur at high flow velocities, and providing a good and stable measurement environment for the sensor. At the same time, since the regulating chamber 16 and the main flow channel 2 are connected in series, the flow rate adjusted by the regulating valve 17 is a part of the total flow rate and will not affect the actual flow rate in the main flow channel 2, avoiding the generation of measurement errors.

[0049] Both the piezoelectric ceramic valve and the electro-hydraulic proportional valve can achieve continuous stepless adjustment of the valve opening, with fast response speed and high control accuracy, and are very suitable for application in the adjustment system of this flowmeter.

[0050] The working principle of the piezoelectric ceramic valve is to utilize the piezoelectric effect. When a voltage is applied, the piezoelectric ceramic will deform, thereby changing the valve opening. It has a compact structure, no wear, and fast response, and is an ideal actuator. The electro-hydraulic proportional valve, on the other hand, uses a precise servo motor system to drive the valve core to make continuous movement, and continuously adjusts the valve opening of the regulating valve 17 by changing the displacement of the valve core, with excellent repeat positioning accuracy.

[0051] The above description is only the implementation mode of this application, and does not limit the patent scope of this application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of this application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of this application.

Claims

1. A thermal liquid mass flowmeter with a rectifying function, comprising a base, a main flow channel is provided in the base, and two ends of the base are respectively provided with a liquid inlet and a liquid outlet connected to the main flow channel, characterized in that: The base is also provided with a first bypass hole and a second bypass hole, the first bypass hole and the second bypass hole are respectively connected to the main channel, and the first bypass hole is connected to the second bypass hole through a drainage tube, and the drainage tube is provided with a thermal flow sensor module for detecting the flow, and the thermal flow sensor module is electrically connected to the control module. A rectifier is also provided in the main channel, and the rectifier is located between the first bypass hole and the second bypass hole, and is used to evenly divide the main channel area where it is located into a number of sub-channels.

2. A thermal liquid mass flowmeter with rectification function according to claim 1, characterized in that: The longitudinal cross-section of the main channel is a circular structure. The rectifier includes a support column and a plurality of ribs uniformly fixed circumferentially on the outer wall of the support column. The support column is coaxially distributed with the main channel. The outer side of the rib is fixed on the inner wall of the main channel. The rib extends along the direction of fluid flow to evenly divide the main channel into a plurality of sub-channels with a fan-shaped structure.

3. A thermal liquid mass flowmeter with rectification function according to claim 1, characterized in that: The longitudinal section of the main channel is a circular structure. The rectifier includes a plurality of ribs extending along the direction of fluid flow. The plurality of ribs are arranged in the main channel and distributed in a mutually intersecting manner to evenly divide the main channel into a plurality of sub-channels with a fan-shaped structure.

4. A thermal liquid mass flowmeter with rectification function according to claim 2, characterized in that: The support column and the rib plate are both made of corrosion-resistant material, and the corrosion-resistant material is selected from one of stainless steel, titanium alloy or engineering plastic.

5. The thermal liquid mass flowmeter with rectification function according to claim 1, characterized in that: The thermal flow sensor module includes a heating element and two temperature sensing elements. The heating element is arranged on the outer wall of the drainage tube. The two temperature sensing elements are also arranged on the outer walls of the drainage tube respectively, and the heating element is located between the two temperature sensing elements.

6. A thermal liquid mass flowmeter with rectification function according to claim 5, characterized in that: The drainage tube is a capillary tube.

7. A thermal liquid mass flowmeter with rectification function according to claim 5, characterized in that: The temperature sensing element is a high-precision thermocouple or a platinum resistor.

8. The thermal liquid mass flowmeter with rectification function according to claim 1, characterized in that: The base is provided with a regulating cavity which is in communication with the liquid inlet and the main flow channel. The regulating cavity is provided with a regulating valve which is electrically connected to the control module.

9. A thermal liquid mass flowmeter with rectification function according to claim 8, characterized in that: The regulating valve is a piezoelectric ceramic valve or an electric proportional valve.

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