Laminar flow element for mass flowmeter, and mass flowmeter

Abstract

A laminar flow element for a mass flowmeter (1). The laminar flow element comprises a channel through which a fluid flows; the channel comprises a plurality of sub-channels; each sub-channel has the same size and the plurality of sub-channels are arranged in an array along the width direction and the height direction of the laminar flow element; the walls between the plurality of sub-channels have the same thickness; and the mass flowmeter (1) comprises an inflow port (2), a discharge port (3), and the laminar flow element located between the inflow port (2) and the discharge port (3).

Description

Laminar flow element for mass flow meter and mass flow meter TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of mass flow meters, and particularly relates to a laminar flow element for a mass flow meter and a mass flow meter. BACKGROUND

[0002] This section provides background information related to the present disclosure which is not necessarily prior art.

[0003] At present, commonly used mass flow meters are mainly divided into thermal mass flow meters, differential pressure mass flow meters and Coriolis mass flow meters according to their working principles.

[0004] Among them, the working principle of the differential pressure mass flow meter is to measure the pressure difference (i.e. pressure drop) before and after the fluid passes through a certain section of the pipeline, calculate the volumetric flow rate of the fluid, and then convert it to the mass flow rate under standard working conditions. When the fluid does laminar flow, the flow rate of the fluid is linearly related to the pressure drop, so the flow rate of the fluid can be obtained by measuring the pressure drop; when the fluid does turbulent flow, the flow rate of the fluid is nonlinearly related to the pressure drop, and the flow rate of the fluid cannot be obtained by measuring the pressure drop.

[0005] Therefore, in order to be able to obtain the flow rate of the fluid by measuring the pressure drop, a laminar flow element is provided in the mass flow meter, which can make the fluid flowing through the laminar flow element in a laminar state without turbulence or turbulence. The inlet and outlet of the laminar flow element are respectively provided with pressure taking points for measuring the pressure of the fluid entering and leaving the laminar flow element, obtaining the pressure drop of the fluid after flowing through the laminar flow element, and thus being able to calculate the mass flow rate of the fluid flowing through the mass flow meter under standard working conditions.

[0006] The commonly used laminar flow element of the existing mass flow meter is formed by uniformly stacking a plurality of sub-channels with a certain length and a rectangular cross-section along the height direction (y direction in FIG. 1) of the laminar flow element (as shown in FIG. 1). Ideally, laminar flow is generated in each sub-channel, so that the flow rate is linearly related to the pressure difference at both ends of the laminar flow element. However, because the laminar flow element is a multi-layer stacked layout, the width direction (z direction in FIG. 1) of each sub-channel in the cross-sectional channel of the laminar flow element is much larger than the height direction, and in actual flow, the fluid velocity and pressure distribution are not uniform along the width and height directions of the laminar flow element, causing flow resistance to the flow of the fluid, and even possibly generating turbulence, which reduces the linearity between the flow rate and the pressure difference of different flow sections, thereby affecting the accuracy of the measurement results of the mass flow meter.

[0007] SUMMARY

[0008] A general summary of the disclosure is provided in this section, but not an extensive overview of the disclosure or all of its features.

[0009] One object of the present disclosure is to provide a laminar flow element for a mass flow meter and a mass flow meter capable of improving the measurement accuracy of the mass flow meter.

[0010] According to one aspect of the present disclosure, a laminar flow element for a mass flow meter is provided, the laminar flow element having a channel for fluid to flow through, the channel comprising a plurality of sub-channels, each of the sub-channels being of the same size and the plurality of sub-channels being arranged in an array along a width direction and a height direction of the laminar flow element, the plurality of sub-channels having the same wall thickness therebetween.

[0011] In some examples according to the present disclosure, the laminar flow element is a honeycomb-shaped laminar flow element having a first channel for fluid to flow through, the first channel comprising a plurality of first sub-channels.

[0012] In some examples according to the present disclosure, the first sub-channels are of a hexagonal cross-sectional shape, and the first wall between each two adjacent first sub-channels of the plurality of first sub-channels is of the same thickness.

[0013] In some examples according to the present disclosure, the laminar flow element is a cross-shaped laminar flow element having a second channel for fluid to flow through, the second channel comprising a plurality of second sub-channels, the second sub-channels being of a square cross-sectional shape.

[0014] In some examples according to the present disclosure, the laminar flow element is a diamond-shaped laminar flow element having a third channel for fluid to flow through, the third channel comprising a plurality of third sub-channels, the third sub-channels being of a diamond cross-sectional shape.

[0015] In some examples according to the present disclosure, the laminar flow element is a pentagon-shaped laminar flow element having a fourth channel for fluid to flow through, the fourth channel comprising a plurality of fourth sub-channels, the fourth sub-channels being of a pentagon cross-sectional shape.

[0016] According to another aspect of the present disclosure, a mass flow meter is provided, the mass flow meter comprising an inlet, an outlet, and a laminar flow element located between the inlet and the outlet, the laminar flow element being the laminar flow element according to the above technical solution.

[0017] In some examples according to the present disclosure, a pressure tapping point is provided at the inlet and the outlet of the laminar flow element respectively, the pressure tapping point being connected to a pressure sensor within the mass flow meter.

[0018] In some examples according to the present disclosure, the mounting seat for mounting the laminar flow element in the mass flow meter has a rectangular cross-sectional shape.

[0019] In some examples according to the present disclosure, the mounting seat for mounting the laminar flow element in the mass flow meter has a circular cross-sectional shape.

[0020] The laminar flow element for a mass flow meter and the mass flow meter according to the present disclosure can achieve at least the following beneficial effects:

[0021] The channel of the laminar flow element according to the present disclosure has a plurality of sub-channels of the same size arranged in an array along the height and width directions of the laminar flow element, and the wall thickness between the plurality of sub-channels is the same, so that the fluid splitting dissipation loss is uniform; the vortex of the inflowing fluid is eliminated, the transverse variation of the velocity is minimized, and the linear relationship between the flow and the pressure difference is enhanced. The mass flow meter with the laminar flow element according to the present disclosure can thus improve the measurement accuracy.

[0022] The above and other objects, features and advantages of the present disclosure will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, which are given by way of illustration and therefore are not to be considered as limiting the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0023] The features and advantages of one or more embodiments of the present disclosure will become more fully apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0024] FIG. 1 is a lateral cross-sectional view of a rectangular laminar flow element of the prior art;

[0025] FIG. 2 is a lateral cross-sectional view of a mass flow meter with a honeycomb-shaped laminar flow element;

[0026] FIG. 3 is a partial enlarged view of a cross-section of a honeycomb-shaped laminar flow element;

[0027] FIG. 4 is a partial enlarged view of a cross-section of a cross-shaped laminar flow element;

[0028] FIG. 5 is a partial enlarged view of a cross-section of a diamond-shaped laminar flow element;

[0029] FIG. 6 is a partial enlarged view of a cross-section of a pentagon-shaped laminar flow element;

[0030] FIG. 7 is a comparison chart of the relationship between the pressure drop and the flow rate of the fluid flowing through a rectangular laminar flow element and a honeycomb-shaped laminar flow element at different flow rates;

[0031] FIG. 8 is an exemplary perspective view of a mass flow meter;

[0032] FIG. 9 is a longitudinal cross-sectional view of the mass flow meter of FIG. 8. DETAILED DESCRIPTION

[0033] The present disclosure will be described in detail by way of example with reference to the attached drawings below. In the several figures of the drawings, like reference numerals designate like parts and assemblies throughout the various figures. The following detailed description of the present disclosure is merely exemplary in nature and is not intended to limit the present disclosure and its applications or uses. The embodiments described in this specification are not the only possible implementations of the present disclosure. The example embodiments can be carried out in many different ways, and are not limited to the embodiments described in this specification. In some example embodiments, well-known processes, well-known device structures, and well-known techniques can not be described in detail.

[0034] In one aspect of the present disclosure, a laminar flow element for a mass flow meter is disclosed, the laminar flow element having a channel for fluid to flow through, the channel comprising a plurality of sub-channels, each of the sub-channels being of the same size and the plurality of sub-channels being arrayed along a width direction (z direction in FIG. 2) and a height direction (y direction in FIG. 2) of the laminar flow element, and each two adjacent sub-channels of the plurality of sub-channels having a uniform wall thickness therebetween. The laminar flow element having such a shape is capable of causing the fluid flowing through the laminar flow element to have a more uniform flow trajectory, forming a laminar flow, and improving the linearity between the flow rate of the fluid flowing through the laminar flow element and the pressure difference.

[0035] In one preferred embodiment of the present disclosure, as shown in FIG. 2, the laminar flow element is a honeycomb-shaped laminar flow element 10. The honeycomb-shaped laminar flow element 10 has a first channel for fluid to flow through, the first channel having a honeycomb-shaped cross section.

[0036] FIG. 3 shows a partial enlarged view of the honeycomb-shaped laminar flow element 10 of FIG. 2. As shown in FIGS. 2 and 3, the first channel comprises a plurality of first sub-channels 11 of the same size and uniformly arrayed, each of the first sub-channels 11 having a hexagonal cross section. As shown in FIG. 2, the plurality of first sub-channels 11 are arrayed along a width direction and a height direction of the honeycomb-shaped laminar flow element 10, and each two adjacent first sub-channels 11 of the plurality of first sub-channels 11 have a first wall 12 of the same thickness therebetween. The honeycomb-shaped laminar flow element 10 has a high cross-sectional channel capacity utilization rate of the hexagonal first sub-channels 11, causing the fluid flowing through the honeycomb-shaped laminar flow element 10 to have a uniform dissipation loss of flow splitting, eliminating vortex flow of the fluid flowing into the honeycomb-shaped laminar flow element 10, and minimizing the lateral variation of the velocity of the fluid, so that the fluid flowing through the honeycomb-shaped laminar flow element 10 is able to reach a better laminar flow state, and the linearity between the flow rate of the fluid and the pressure difference is enhanced.

[0037] In one preferred embodiment of the present disclosure, the width w of the first sub-passage 11 of the honeycomb-shaped laminar flow element 10 is preferably 0.3-0.5 mm, more preferably 0.4 mm; the thickness d of the first wall 12 between two adjacent first sub-passage 11 is preferably 0.08-0.12 mm, more preferably 0.1 mm.

[0038] In another preferred embodiment of the present disclosure, as shown in FIG. 4, the laminar flow element is a cross-shaped laminar flow element 20, which has a second passage for fluid flow, the second passage comprising a plurality of second sub-passage 21 of the same size and arranged uniformly, each second sub-passage 21 having a square cross-sectional shape. The plurality of second sub-passage 21 are arranged in an array along the width direction and the height direction of the cross-shaped laminar flow element 20, and the thickness of the second wall 22 between each two adjacent second sub-passage 21 in the plurality of second sub-passage 21 is the same. The thickness of the wall between the plurality of second sub-passage 21 of the cross-shaped laminar flow element 20 is uniformly distributed, the fluid flow splitting dissipation loss is uniform, the lateral variation of the velocity of the fluid flowing through the cross-shaped laminar flow element 20 is reduced, and the linear relationship between the flow rate and the pressure difference is enhanced.

[0039] In yet another preferred embodiment of the present disclosure, as shown in FIG. 5, the laminar flow element is a rhombus-shaped laminar flow element 30, which has a third passage for fluid flow, the third passage comprising a plurality of third sub-passage 31 of the same size and arranged uniformly, each third sub-passage 31 having a rhombus cross-sectional shape. The plurality of third sub-passage 31 are arranged in an array along the width direction and the height direction of the rhombus-shaped laminar flow element 30, and the thickness of the third wall 32 between each two adjacent third sub-passage 31 in the plurality of third sub-passage 31 is the same, reducing the lateral variation of the velocity of the fluid flowing through the rhombus-shaped laminar flow element 30, and enhancing the linear relationship between the flow rate and the pressure difference.

[0040] In other embodiments not shown, the third sub-passage can also have a parallelogram cross-sectional shape.

[0041] In yet another preferred embodiment of the present disclosure, as shown in FIG. 6, the laminar flow element is a pentagon-shaped laminar flow element 40, which has a fourth passage for fluid flow, the fourth passage comprising a plurality of fourth sub-passage 41 of the same size and arranged uniformly, each fourth sub-passage 41 having a pentagon cross-sectional shape. The plurality of fourth sub-passage 41 are arranged in an array along the width direction and the height direction of the pentagon-shaped laminar flow element 40, and the thickness of the fourth wall 42 between each two adjacent fourth sub-passage 41 in the plurality of fourth sub-passage 41 is the same, reducing the lateral variation of the velocity of the fluid flowing through the pentagon-shaped laminar flow element 40, and enhancing the linear relationship between the flow rate and the pressure difference.

[0042] It should be noted that the shape of the laminar flow element of the present disclosure is not limited to the above preferred embodiments. Any shape having a plurality of sub-channels arranged in the width direction and the height direction of the laminar flow element, and the wall thickness between the plurality of sub-channels being uniformly distributed, is within the scope of protection of the present disclosure.

[0043] Comparative Example

[0044] FIG. 1 shows a cross-sectional view of a prior art rectangular laminar flow element 100 having a fifth channel for fluid to flow through, the fifth channel including a plurality of fifth sub-channels 101 stacked in the height direction of the rectangular laminar flow element 100. The width direction (z direction in FIG. 1) dimension of each fifth sub-channel 101 is much larger than the height direction (y direction in FIG. 1) dimension, and when the fluid flows through the rectangular laminar flow element 100, the flow velocity and the pressure distribution of the fluid are unevenly distributed in the width direction of the rectangular laminar flow element 100, causing flow resistance to the flow of the fluid and even possibly generating turbulent flow, so that the linearity between the flow rate and the pressure difference of the fluid flowing through the rectangular laminar flow element 100 decreases, thereby affecting the measurement accuracy of the mass flow meter.

[0045] In order to evaluate the influence of the honeycomb-shaped laminar flow element 10 of the preferred embodiment of the present application on the linearity between the flow rate and the pressure drop of the fluid, the honeycomb-shaped laminar flow element 10 and the prior art rectangular laminar flow element 100 are simulated, and the obtained flow rate-pressure drop relationship curve is shown in FIG. 7.

[0046] In FIG. 7, the abscissa is the flow rate, with units of liters per minute (LPM), and the ordinate is the pressure drop, with units of mbar. Lines B and C are the simulation results of the rectangular laminar flow element 100, wherein curve B represents the actual flow rate and pressure drop values through the rectangular laminar flow element 100 at different flow rates, and dashed line C is a straight line obtained by linear fitting of curve B. Lines A', B', and C' are the simulation results of the honeycomb-shaped laminar flow element 10. Among them, solid line A' represents the relationship between the flow rate and the pressure drop in an ideal state, curve B' represents the actual flow rate and pressure drop values through the honeycomb-shaped laminar flow element 10 at different flow rates, and dashed line C' is a straight line obtained by linear fitting of curve B'. It is calculated that the R 2 value of curve B' is 0.98, and the R 2 value of curve B is 0.95.

[0047] The R 2 value is a statistical measure of the degree of approximation of the fitting line (also known as the regression line) to the actual data, and the R 2 value is equal to the ratio of the regression sum of squares to the total sum of squares. The closer the value of R 2 is to 1, the better the fitting degree of the regression straight line to the observed values; on the contrary, the smaller the value of R 2 , the worse the fitting degree of the regression straight line to the observed values.

[0048] From the simulation results, it can be seen that, compared with the rectangular laminar flow element 100, the linearity between the flow rate and pressure drop of the fluid flowing through the honeycomb laminar flow element 10 is better, that is, the fluid flowing through the honeycomb laminar flow element 10 can achieve a better laminar flow state, and thus the mass flow meter with the honeycomb laminar flow element 10 can ensure higher measurement accuracy.

[0049] Another aspect of the present disclosure, as shown in FIG. 8, provides a mass flow meter 1. The mass flow meter 1 has a flow inlet 2, a discharge outlet 3, and the laminar flow element described above. The laminar flow element is installed in a mounting seat 4 of the mass flow meter, and the mounting seat 4 is located between the flow inlet 2 and the discharge outlet 3.

[0050] FIG. 9 shows a longitudinal sectional view of the mass flow meter of FIG. 8. As shown in FIG. 9, the fluid flows into the mass flow meter 1 from the flow inlet 2 of the mass flow meter 1, and then flows out from the discharge outlet 3 after passing through the laminar flow element. The inlet and outlet of the laminar flow element are respectively provided with pressure tapping points 5, which are connected to a pressure sensor (not shown in the figure) in the mass flow meter 1. The pressure sensor measures the pressure at the inlet and outlet of the laminar flow element, and obtains the pressure drop of the fluid flowing through the laminar flow element, so as to calculate the flow rate of the fluid flowing through the mass flow meter 1.

[0051] Further, the mounting seat 4 of the present embodiment is not limited to the rectangular shape disclosed in the drawings, but can also have a circular cross section.

[0052] Compared with the prior art, the channel of the laminar flow element disclosed in the present embodiment has a plurality of sub-channels with the same size arranged in the height and width directions of the laminar flow element, and the wall thickness between the plurality of sub-channels is the same, so that the fluid splitting dissipation loss is uniform; the vortex of the inflowing fluid is eliminated, the transverse variation of the velocity is minimized, and the linear relationship between the flow rate and the pressure difference is enhanced. Therefore, the mass flow meter with the laminar flow element disclosed in the present embodiment can improve the measurement accuracy.

[0053] Although the present disclosure has been described with reference to the example embodiments, it should be understood that the present disclosure is not limited to the specific embodiments described and illustrated herein. Various modifications can be made to the example embodiments by those skilled in the art without departing from the scope of the claims. The features in the various embodiments can be combined with each other. Alternatively, some features in the embodiments can be omitted.

Claims

1. A laminar flow element for a mass flow meter, characterized by, The laminar flow element has a channel for fluid flow, the channel comprising a plurality of sub-channels, each of the sub-channels having the same size and the plurality of the sub-channels being arranged in an array along a width direction and a height direction of the laminar flow element, and the plurality of the sub-channels having the same wall thickness therebetween.

2. The laminar flow element of claim 1, wherein, The laminar flow element is a honeycomb-shaped laminar flow element (10) having a first channel for fluid flow, the first channel comprising a plurality of first sub-channels (11).

3. The laminar flow element of claim 2, wherein, The first sub-channels (11) have a hexagonal cross-sectional shape, and a first wall (12) between each two adjacent first sub-channels (11) of the plurality of the first sub-channels (11) has the same thickness.

4. The laminar flow element of claim 1, wherein, The laminar flow element is a cross-shaped laminar flow element (20) having a second channel for fluid flow, the second channel comprising a plurality of second sub-channels (21), the second sub-channels (21) having a square cross-sectional shape.

5. The laminar flow element of claim 1, wherein, The laminar flow element is a rhombus-shaped laminar flow element (30) having a third channel for fluid flow, the third channel comprising a plurality of third sub-channels (31), the third sub-channels (31) having a rhombus cross-sectional shape.

6. The laminar flow element of claim 1, wherein, The laminar flow element is a pentagon-shaped laminar flow element (40) having a fourth channel for fluid flow, the fourth channel comprising a plurality of fourth sub-channels (41), the fourth sub-channels (41) having a pentagon cross-sectional shape.

7. A mass flow meter characterized by, The mass flow meter (1) comprises a flow inlet (2), a discharge outlet (3), and a laminar flow element located between the flow inlet (2) and the discharge outlet (3), the laminar flow element being according to any one of claims 1-6.

8. The mass flow meter of claim 7, wherein, The laminar flow element is provided with a pressure tapping point (5) at the inlet and the outlet thereof, respectively, the pressure tapping point (5) being connected with a pressure sensor in the mass flow meter (1).

9. The mass flow meter of claim 7 or 8, wherein, The mounting seat (4) for mounting the laminar flow element in the mass flow meter (1) has a rectangular cross-sectional shape.

10. The mass flow meter of claim 7 or 8, wherein, The mounting seat (4) for mounting the laminar flow element in the mass flow meter (1) has a circular cross-sectional shape.

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