Flow rate estimating device and flow rate estimating method

Abstract

A flow rate estimating device (20) comprises: a first flow rate calculating unit (64) that calculates a first flow rate value (Q1) of a gas (G) flowing through a pipe (10) when the gas forms a laminar flow; a second flow rate calculating unit (66) that calculates a second flow rate value (Q2) of the gas when the gas forms a turbulent flow; and an estimating unit (68) that estimates the flow rate of the gas by performing weighted averaging of the first flow rate value and the second flow rate value using an apportionment ratio (α) corresponding to a pipe width (D) and pipe length (L) of the pipe.

Description

Flow rate estimation device and flow rate estimation method

[0001] The present invention relates to a flow rate estimation device and a flow rate estimation method.

[0002] Japanese Patent Laid-Open Publication No. 2001-194193 discloses a flow meter having a laminar flow meter provided upstream of a measuring pipe and a vortex flow meter provided downstream of the measuring pipe, which is capable of measuring a wide range of flow rates from very low to very high.

[0003] According to the flowmeter disclosed in JP 2001-194193 A, a pipe (a thin tube) is provided for measuring flow rates using a laminar flow meter. To expand the flow measurement range to flow rates where laminar flow is not generated in a single pipe, it is necessary to use multiple pipes in which laminar flow is generated. This poses a problem of increasing the size of the flowmeter. Furthermore, a vortex generator is attached inside the measuring pipe downstream of the laminar flow meter for measuring flow rates using a vortex flow meter. This further increases the size of the flowmeter. The increased size of the flowmeter also leads to increased costs.

[0004] The present invention aims to solve the above-mentioned problems.

[0005] A first aspect of the present invention is a flow rate estimation device comprising: a first flow rate calculation unit that calculates a first flow rate value of a gas circulating within a pipeline when the gas forms a laminar flow; a second flow rate calculation unit that calculates a second flow rate value of the gas when the gas forms a turbulent flow; and an estimation unit that estimates the flow rate of the gas by taking a weighted average of the first flow rate value and the second flow rate value using a proportional distribution ratio according to the pipeline width and pipeline length of the pipeline.

[0006] A second aspect of the present invention is a flow rate estimation method, including a first flow rate calculation step of calculating a first flow rate value of a gas flowing through a pipeline when the gas forms a laminar flow, a second flow rate calculation step of calculating a second flow rate value of the gas when the gas forms a turbulent flow, and an estimation step of estimating the flow rate of the gas by taking a weighted average of the first flow rate value and the second flow rate value using a proportional distribution ratio according to the pipeline width and pipeline length.

[0007] According to the present invention, the flow rate estimating device can be made smaller.

[0008] The above objects, features and advantages will be easily understood from the following description of the embodiments, which will be described with reference to the accompanying drawings.

[0009] FIG. 1 is a diagram schematically showing a pipeline and a flow rate estimation device used to estimate the flow rate of gas flowing through the pipeline. FIG. 2A is a diagram for explaining the rectangular cross section of the pipeline. FIG. 2B is a diagram showing the rectangular cross section of the pipeline. FIG. 2C is a diagram for explaining the pipeline width. FIG. 3 is a diagram illustrating a plate-like member on which the pipeline is formed. FIG. 4 is a diagram for explaining a case where there are multiple pipelines. FIG. 5 is a flowchart showing the processing procedure for gas flow rate estimation processing. FIGS. 6A and 6B are diagrams showing evaluation results of flow rate estimation when laminar flow and turbulent flow are mixed in the pipeline.

[0010] 1 is a diagram schematically illustrating a pipeline 10 and a flow rate estimation device 20 used to estimate the flow rate of a gas G flowing through the pipeline 10. The gas G flows into the pipeline 10 in a flow direction F, flows through the pipeline 10, and flows out of the pipeline 10.

[0011] When the width D of the conduit 10 is sufficiently wide, the gas G flowing through the conduit 10 forms a turbulent flow due to the inertial force of the gas G. In this case, the flow rate of the gas G depends on the effective cross-sectional area of ​​the conduit 10. The effective cross-sectional area is a function of the width D of the conduit 10. In other words, the flow rate of the gas G that forms a turbulent flow depends on the width D of the conduit 10, as will be described later. For example, the wider the width D of the conduit 10, the greater the flow rate of the gas G.

[0012] When the width D of the conduit 10 is extremely narrow, the minute flow rate of gas G flowing through the conduit 10 forms a laminar flow due to the viscosity of the gas G. In this case, the flow rate of the gas G depends on the width D and length L of the conduit 10, as will be described later. That is, the narrower the width D of the conduit 10, the smaller the flow rate of the gas G. Furthermore, the longer the conduit length L of the conduit 10, the smaller the flow rate of the gas G. Note that when the width D of the conduit 10 is neither too narrow nor too wide, laminar flow and turbulent flow coexist within the conduit 10.

[0013] The first temperature sensor 30 measures the temperature T1 of the gas G flowing through the pipeline 10. In Fig. 1, the first temperature sensor 30 is arranged outside the pipeline 10 on the assumption that the same measurement value will be obtained as when the first temperature sensor 30 is arranged inside the pipeline 10. The second temperature sensor 32 is arranged in or near the pipeline 10 and measures the temperature T2 of the pipeline 10. The third temperature sensor 34 is arranged around the pipeline 10 and measures the temperature T3 around the pipeline 10.

[0014] The first pressure sensor 36 is disposed at or near the gas inlet of the pipeline 10 and measures a first pressure P1 of the gas G flowing into the pipeline 10. The second pressure sensor 38 is disposed at or near the gas outlet of the pipeline 10 and measures a second pressure P2 of the gas G flowing out of the pipeline 10.

[0015] The flow rate estimation device 20 has a calculation unit 50 and a storage unit 52. The calculation unit 50 includes a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). In other words, the calculation unit 50 includes processing circuitry.

[0016] The storage unit 52 includes a volatile memory such as a random access memory (RAM) and a non-volatile memory such as a read-only memory (ROM) or flash memory. The volatile memory is used as a working memory for the processor. The non-volatile memory stores programs executed by the processor and necessary data such as the apportionment rate α (described later).

[0017] The calculation unit 50 has a pressure acquisition unit 60, a temperature acquisition unit 62, a first flow rate calculation unit 64, a second flow rate calculation unit 66, and an estimation unit 68. When the calculation unit 50 executes a program stored in the storage unit 52, the pressure acquisition unit 60, the temperature acquisition unit 62, the first flow rate calculation unit 64, the second flow rate calculation unit 66, and the estimation unit 68 are realized.

[0018] At least some of the pressure acquisition unit 60, the temperature acquisition unit 62, the first flow rate calculation unit 64, the second flow rate calculation unit 66, and the estimation unit 68 may be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array), or an electronic circuit including discrete devices.

[0019] The pressure acquisition unit 60 acquires a first pressure P1 of the gas G flowing into the pipeline 10 from the first pressure sensor 36 via communication or the like. The pressure acquisition unit 60 acquires a second pressure P2 of the gas G flowing out of the pipeline 10 from the second pressure sensor 38 via communication or the like.

[0020] The temperature acquisition unit 62 acquires the temperature T1 of the gas G flowing through the pipeline 10 from the first temperature sensor 30 via communication or the like. The temperature acquisition unit 62 acquires the temperature T2 of the pipeline 10 from the second temperature sensor 32 via communication or the like. The temperature acquisition unit 62 acquires the temperature T3 around the pipeline 10 from the third temperature sensor 34 via communication or the like.

[0021] The first flow rate calculation unit 64 calculates a first flow rate value Q1 of the gas G when the gas G flowing through the conduit 10 forms a laminar flow. When the gas G forms a laminar flow, the first flow rate value Q1 can be calculated using the Hagen-Poiseuille equation (1). As shown in equation (1), the first flow rate value Q1 is calculated based on the first pressure P1 and the second pressure P2, the conduit width D and the conduit length L of the conduit 10, the viscosity coefficient η of the gas G, and a temperature correction term f(T). The temperature correction term f(T) is determined based on the temperature T1 of the gas G.

[0022] The second flow rate calculation unit 66 calculates a second flow rate value Q2 of the gas G when the gas G flowing through the conduit 10 forms a turbulent flow. When the gas G forms a turbulent flow, the second flow rate value Q2 can be calculated using equation (2) or equation (3). As shown in equations (2) and (3), the second flow rate value Q2 is calculated based on the first pressure P1 and the second pressure P2, the effective cross-sectional area S of the conduit 10, and a temperature correction term g(T). The temperature correction term g(T) is determined based on the temperature T1 of the gas G.

[0023] When the flow of gas G that forms a turbulent flow is a subsonic flow, Equation (2) is used, and when it is a sonic flow, Equation (3) is used. When the pressure ratio (critical pressure ratio P1 / P2) expressed by the ratio of the first pressure P1 to the second pressure P2 is smaller than a predetermined ratio (e.g., 1.893), the flow of gas G is a subsonic flow. When the pressure ratio is equal to or greater than the predetermined ratio, the flow of gas G is a sonic flow.

[0024] When the flow of the gas G is laminar, referring to equation (1), the first flow rate calculation unit 64 calculates the first flow rate value Q1 based on the pressure difference between the first pressure P1 and the second pressure P2. When the flow of the gas G is turbulent and subsonic, referring to equation (2), the second flow rate calculation unit 66 calculates the second flow rate value Q2 based on the square root of the pressure difference between the first pressure P1 and the second pressure P2. When the flow of the gas G is turbulent and sonic, referring to equation (3), the second flow rate calculation unit 66 calculates the second flow rate value Q2 based on the first pressure P1.

[0025] The estimation unit 68 calculates the weighted average value QWA by weighting the first flow rate value Q1 and the second flow rate value Q2 using a proportional division ratio α corresponding to the pipe width D and pipe length L of the pipe 10. The proportional division ratio α is a value between zero and one. The weighted average value QWA of the first flow rate value Q1 and the second flow rate value Q2 is obtained by adding together the value obtained by multiplying the first flow rate value Q1 by the proportional division ratio α and the value obtained by multiplying the second flow rate value Q2 by the value obtained by subtracting the proportional division ratio α from one. In other words, the weighted average value QWA obtained by weighting the first flow rate value Q1 and the second flow rate value Q2 is calculated using equation (4). QWA=Q1·α+Q2·(1−α) (4)

[0026] As described above, the flow of gas G circulating within the conduit 10 can be a laminar flow, a turbulent flow, or a mixture of laminar and turbulent flow, depending on the conduit width D of the conduit 10. When the flow of gas G circulating within the conduit 10 is a laminar flow, the value of the proportionate ratio α in equation (4) is 1. When the flow of gas G circulating within the conduit 10 is turbulent, the value of the proportionate ratio α in equation (4) is zero.

[0027] When laminar flow and turbulent flow coexist in the pipeline 10, the proportionate ratio α is greater than zero and less than 1. That is, the flow rate Q of the gas G is estimated using a weighted average value QWA obtained by weighting the first flow rate value Q1 and the second flow rate value Q2. Evaluation results for estimating the flow rate Q using the weighted average value QWA will be described later with reference to Figures 6A and 6B.

[0028] As described above, when the conduit width D of the conduit 10 is sufficiently wide, the gas G flowing through the conduit 10 forms a turbulent flow. When the conduit width D is extremely narrow, the gas G flowing through the conduit 10 forms a laminar flow. Therefore, the narrower the conduit width D, the larger the proportionate ratio α. Furthermore, when laminar flow and turbulent flow coexist in the conduit 10, the narrower the conduit width D or the longer the conduit length L, the greater the viscosity of the gas G's influence on the flow of the gas G through the conduit 10, and therefore the larger the proportionate ratio α.

[0029] The allocation ratio α is determined by an experiment in which a predetermined flow rate of gas G is circulated through the pipeline 10. As described above, the allocation ratio α determined by the experiment is stored in the memory unit 52. The estimation unit 68 uses the allocation ratio α stored in the memory unit 52 to calculate the weighted average value QWA of the first flow rate value Q1 and the second flow rate value Q2.

[0030] The estimation unit 68 can estimate the weighted average value QWA obtained using equation (4) as the flow rate Q of the gas G. It is preferable that the flow rate Q of the gas G takes into consideration the linear expansion coefficient of the pipe 10 and the heat exchange between the pipe 10 and the surroundings of the pipe 10. In this case, the estimation unit 68 estimates the flow rate Q of the gas G by correcting the weighted average value QWA based on the temperature T2 of the pipe 10 and the temperature T3 of the surroundings of the pipe 10. That is, the estimation unit 68 estimates the flow rate Q of the gas G by using equation (5) based on the weighted average value QWA obtained using equation (4) and a temperature correction term h(T) corresponding to the temperatures T2 and T3. Q=QWA·h(T) (5)

[0031] When the cross-sectional shape of the conduit 10 is circular, the conduit width D of the conduit 10 described above is the diameter of the circle. For example, when the gas G flowing through the conduit 10 forms a laminar flow, the flow rate Q of the gas G is very small, and the conduit width D of the conduit 10 for a very small flow rate is extremely narrow. The narrower the conduit width D, the more difficult and costly it is to manufacture a conduit 10 with a circular cross-sectional shape. When the conduit width D is narrow, a conduit 10 with a rectangular cross-sectional shape is easier to manufacture than a conduit 10 with a circular cross-sectional shape. The conduit width D of the conduit 10 having a rectangular cross-section RS will be described using Figures 2A, 2B, and 2C.

[0032] 2A is a diagram illustrating a rectangular cross section RS of the conduit 10. The rectangular cross section RS is a cross section of the conduit 10 cut perpendicular to the flow direction F of the gas G flowing through the conduit 10 having a conduit length L. FIG. 2A illustrates the width W, height H, perimeter C, and area A of the rectangular cross section RS of the rectangular cross section RS.

[0033] 2B is a diagram showing a rectangular cross section RS of the pipeline 10. The perimeter C of the rectangular cross section RS is expressed by equation (6) based on the width W and height H of the rectangular cross section RS. The area A of the rectangular cross section RS is expressed by equation (7) based on the width W and height H of the rectangular cross section RS. C=2(W+H) (6) A=WH (7)

[0034] FIG. 2C is a diagram for explaining the pipe width D of the pipe 10. FIG. 2C shows a circular cross section CS of an equivalent pipe 10E equivalent to the pipe 10. Generally, the diameter of a circular cross section CS having the same perimeter C and area A as the perimeter C and area A of the rectangular cross section RS is known as the equivalent diameter of the rectangular cross section RS. In this embodiment, the equivalent diameter of the rectangular cross section RS is used as the pipe width D of the pipe 10. Therefore, the pipe width D of the pipe 10 is expressed by equation (8). Using equations (6), (7), and (8), the pipe width D of the pipe 10 is expressed by equation (9). D=4A / C (8) D=2WH / (W+H) (9)

[0035] 3 is a diagram illustrating a plate-like member 80 in which the duct 10 is formed. Since the duct 10 is formed in a thin, flat plate-like member 80, the duct 10 has a narrow duct width D and a rectangular cross section RS.

[0036] The plate-like member 80 is obtained by stacking a plurality of thin metal plates. Rectangular grooves are formed in each thin metal plate by etching. Adjacent thin metal plates are overlapped with each other, so that the grooves function as part of the pipeline 10. A partial pipeline is formed by overlapping a thin metal plate having a groove that functions as part of the pipeline 10 with an adjacent thin metal plate. The pipeline 10 is formed by stacking a plurality of thin metal plates and connecting the plurality of partial pipelines.

[0037] The plate-shaped member 80 has a recess 82 on each of two flat surfaces of the plate-shaped member 80. That is, a recess 82a is provided on one flat surface of the plate-shaped member 80, and a recess 82b is provided on the other flat surface.

[0038] One end 10h of the conduit 10 is formed in a portion of the peripheral wall 82w of the recess 82a. The other end (not shown) of the conduit 10 is formed in a portion of the peripheral wall of the recess 82b. The gas G flows, for example, from one end 10h to the other end of the conduit 10. The total length of the conduit 10 from one end 10h to the other end corresponds to the conduit length L described above.

[0039] The width D and length L of the conduit 10 are determined by experiment or finite element method analysis. For example, the width D and length L are determined so that the flow rate Q is 0.1 mL / min when the maximum pressure difference between the first pressure P1 and the second pressure P2 of the gas G flowing through the conduit 10 is 100 kPa. In this case, the width D is determined, for example, by taking into consideration the limits of processing accuracy by the etching described above.

[0040] The conduit length L is determined according to the above-mentioned flow rate Q. For example, the conduit width D and conduit length L are determined so as to satisfy L = 7000 D. In this conduit 10, when the pressure difference is 10 kPa, the flow rate Q is 0.01 mL / min, which is 1 / 10 of 0.1 mL / min.

[0041] The same applies when the conduit width D and the conduit length L are determined so that the flow rate Q is 1000 mL / min when the maximum pressure difference between the first pressure P1 and the second pressure P2 is 100 kPa. In this case, the conduit width D and the conduit length L are determined so that, for example, L = 500 D is satisfied. In this conduit 10, the flow rate Q when the pressure difference is 10 kPa is 100 mL / min, which is 1 / 10 of 1000 mL / min.

[0042] 3 shows one end 10h of the conduit 10 formed on the peripheral wall 82w of the recess 82a of the plate-like member 80. The conduit 10 has a rectangular cross-section RS. Therefore, the width and height of the one end 10h of the conduit 10 match the width W and height H of the rectangular cross-section RS described above. The width and height of the other end of the conduit 10 formed on the peripheral wall of the recess 82b also match the width W and height H of the rectangular cross-section RS described above.

[0043] It is preferable that the aspect ratio R of the rectangle formed by the periphery of the rectangular cross section RS is 1 or more and 2 or less. As expressed by formula (10), the aspect ratio R is the ratio of the long side to the short side of the width W and height H of the rectangular cross section RS. In other words, the aspect ratio R is always 1 or more. When the aspect ratio R is greater than 2, the center of the rectangular cross section RS is farther away from the short side of the rectangular cross section RS, and the inertial force of the gas G described above becomes stronger. Therefore, it is preferable that the aspect ratio R is 1 or more and 2 or less. Furthermore, according to experiments and finite element method analysis, it is more preferable that the aspect ratio R is 1 or more and 1.6 or less. R = max{W, H} / min{W, H} ... (10)

[0044] As described above, the conduit width D and conduit length L of the conduit 10 are determined by experiment or finite element method analysis. As a result, it is conceivable that the conduit length L will be too long. In such a case, the conduit length L can be reduced by widening the conduit width D. However, widening the conduit width D changes the allocation ratio α. As described above, the allocation ratio α is determined by an experiment in which a predetermined flow rate of gas G is passed through the conduit 10. In this way, it is necessary to determine the allocation ratio α when the conduit width D is widened.

[0045] In order to reduce the pipeline length L without increasing the pipeline width D, multiple pipelines 10 having the same pipeline width D and pipeline length L may be provided. Fig. 4 is a diagram for explaining a case where multiple pipelines 10 are provided. In the example shown in Fig. 4, by providing two pipelines 10 in parallel, the pipeline length L can be reduced to half compared to when one pipeline 10 is used.

[0046] The proportionate distribution rate α is determined according to the pipe width D and pipe length L of each of the multiple pipes 10. Therefore, in the example shown in Fig. 4, the pipe width D and pipe length L are the same for all of the pipes 10, and therefore the same proportionate distribution rate α is used.

[0047] 5 is a flowchart showing the procedure for estimating the flow rate of the gas G. This procedure is performed by the calculation unit 50 of the flow rate estimation device 20 by executing a program stored in the storage unit 52. This procedure is executed in response to an instruction from the user of the flow rate estimation device 20 or a higher-level device of the flow rate estimation device 20.

[0048] When this processing procedure starts, in step S1, the pressure acquisition unit 60 acquires a first pressure P1 of the gas G flowing into the pipeline 10 from the first pressure sensor 36. In step S2, the pressure acquisition unit 60 acquires a second pressure P2 of the gas G flowing out of the pipeline 10 from the second pressure sensor 38.

[0049] In step S3, the temperature acquisition unit 62 acquires the temperature T1 of the gas G flowing through the pipeline 10 from the first temperature sensor 30. In step S4, the temperature acquisition unit 62 acquires the temperature T2 of the pipeline 10 and the temperature T3 of the surroundings of the pipeline 10 from the second temperature sensor 32 and the third temperature sensor 34, respectively.

[0050] In step S5, the first flow rate calculation unit 64 calculates a first flow rate value Q1 of the gas G when the gas G flowing through the pipeline 10 forms a laminar flow. Specifically, the first flow rate value Q1 is calculated using equation (1). In step S6, the second flow rate calculation unit 66 calculates a second flow rate value Q2 of the gas G when the gas G flowing through the pipeline 10 forms a turbulent flow. Specifically, the second flow rate value Q2 is calculated using equation (2) or equation (3). In step S7, the estimation unit 68 estimates the flow rate Q of the gas G by calculating a weighted average of the first flow rate value Q1 and the second flow rate value Q2 using the proportional division ratio α. Specifically, the flow rate Q is calculated using equations (4) and (5). When the processing of step S7 is completed, this processing procedure ends.

[0051] 6A and 6B are diagrams showing evaluation results of flow rate estimation when laminar flow and turbulent flow are mixed in the pipeline 10. The values ​​on the horizontal axis represent the actual flow rate Q of the gas G, and the values ​​on the vertical axis represent the estimated flow rate Q of the gas G. Graph 100 showing the ideal relationship between the estimated flow rate Q of the gas G and the actual flow rate Q of the gas G is shown in FIG. 100. In the graph 100, the estimated flow rate Q matches the actual flow rate Q of the gas G, and therefore the graph 100 shows a proportional relationship.

[0052] 6A and 6B show a graph 102 representing the relationship between the estimated flow rate Q of the gas G and the actual flow rate Q of the gas G when a first flow rate value Q1 is used as the estimated flow rate Q of the gas G. Furthermore, 6A and 6B show a graph 104 representing the relationship between the estimated flow rate Q of the gas G and the actual flow rate Q of the gas G when a second flow rate value Q2 is used as the estimated flow rate Q of the gas G.

[0053] Furthermore, Figures 6A and 6B show a graph 110 that represents the relationship between the estimated flow rate Q of gas G and the actual flow rate Q of gas G when the flow rate Q of gas G estimated using equations (4) and (5) is used as the estimated flow rate Q of gas G.

[0054] 6A shows the evaluation results of flow rate estimation using a conduit 10 in which the conduit width D and conduit length L are determined so that the flow rate Q is 100 mL / min when the maximum pressure difference between the first pressure P1 and the second pressure P2 is 100 kPa. In other words, the maximum flow rate of this conduit 10 is 100 mL / min. In the example shown in FIG. 6A , a graph 110 corresponding to the flow rate Q estimated using a weighted average value QWA with an allocation ratio α of 0.86 is nearly identical to a graph 100 showing the ideal relationship between the estimated flow rate Q of the gas G and the actual flow rate Q of the gas G.

[0055] 6B shows the evaluation results of flow rate estimation using two conduits 10 of the same dimensions, in which the conduit width D and conduit length L are determined so that the flow rate Q is 1000 mL / min when the maximum pressure difference between the first pressure P1 and the second pressure P2 is 100 kPa. In other words, the maximum flow rate of these two conduits 10 is 1000 mL / min. In the example shown in FIG. 6B , a graph 110 corresponding to the flow rate Q estimated using the weighted average value QWA with the allocation ratio α set to 0.58 is nearly identical to a graph 100 showing the ideal relationship between the estimated flow rate Q of the gas G and the actual flow rate Q of the gas G.

[0056] As shown in FIGS. 6A and 6B, it can be seen that the flow rate Q estimated using equations (4) and (5) is a good value.

[0057] A group of conduits may be used that can select either a conduit 10 corresponding to a maximum flow rate of 100 mL / min or a conduit 10 corresponding to a maximum flow rate of 1000 mL / min. This can widen the flow rate measurement range of the flow rate estimation device 20. A solenoid valve may be used to switch the conduits 10. The same applies when conduits 10 corresponding to different maximum flow rates are used.

[0058] In this embodiment, the value calculated using equation (1) is used as is for the first flow rate value Q1, and the value calculated using equation (2) or (3) is used as is for the second flow rate value Q2. As described with reference to FIGS. 6A and 6B , the estimated flow rate Q and the actual flow rate Q of the gas G are approximately proportional to each other. Therefore, values ​​obtained by normalizing the first flow rate value Q1 and the second flow rate value Q2 to a range of, for example, 0 to 1 may be used for the weighted average. In other words, the values ​​calculated using equations (1), (2), and (3) do not need to be used as is for the first flow rate value Q1 and the second flow rate value Q2.

[0059] Therefore, values ​​calculated by removing the constant terms from each of Equations (1), (2), and (3) may be used as the first flow rate value Q1 and the second flow rate value Q2. In this case, the first flow rate value Q1 and the second flow rate value Q2 can be corrected by multiplying each calculated value by an appropriate coefficient.

[0060] For example, Equation (11), in which the constant term is removed from Equation (1), may be used as the first flow rate value Q1. Furthermore, when the flow of gas G that forms turbulence is a subsonic flow, Equation (12), in which the constant term is removed from Equation (2), may be used as the second flow rate value Q2. When the flow of gas G that forms turbulence is a sonic flow, Equation (13), in which the constant term is removed from Equation (3), may be used as the second flow rate value Q2.

[0061] In addition to the above disclosure, the following additional notes are disclosed.

[0062] (Supplementary Note 1) A flow rate estimation device (20) includes a first flow rate calculation unit (64) that calculates a first flow rate value (Q1) of a gas (G) flowing through a conduit (10) when the gas forms a laminar flow, a second flow rate calculation unit (66) that calculates a second flow rate value (Q2) of the gas when the gas forms a turbulent flow, and an estimation unit (68) that estimates the flow rate of the gas by taking a weighted average of the first flow rate value and the second flow rate value using a proportional ratio (α) corresponding to the conduit width (D) and conduit length (L) of the conduit. This configuration allows for more accurate estimation of the gas flow rate than conventional methods. Furthermore, the conduit length of the conduit 10 can be reduced, allowing for a reduction in the size of the flow rate estimation device.

[0063] (Supplementary Note 2) In the flow rate estimation device described in Supplementary Note 1, the estimation unit may weight-average the first flow rate value and the second flow rate value by summing a value obtained by multiplying the first flow rate value by the proportional ratio, which is equal to or greater than zero and equal to or less than one, and a value obtained by multiplying the second flow rate value by a value obtained by subtracting the proportional ratio from 1. With this configuration, the gas flow rate can be easily estimated.

[0064] (Supplementary Note 3) In the flow rate estimating device according to Supplementary Note 2, the proportional distribution ratio may be larger as the pipe width is narrower or the pipe length is longer. With this configuration, the flow rate of the gas can be easily estimated.

[0065] (Supplementary Note 4) In the flow rate estimating device according to Supplementary Note 1, when there are a plurality of the conduits, the proportionate ratio may be determined according to the conduit width and the conduit length of each of the plurality of conduits. With this configuration, even when a plurality of conduits of the same dimensions are provided, there is no need to change the proportionate ratio.

[0066] (Supplementary Note 5) The flow rate estimation device according to Supplementary Note 1 may further include a pressure acquisition unit (60) that acquires a first pressure (P1) of the gas flowing into the pipeline from a first pressure sensor (36) and acquires a second pressure (P2) of the gas flowing out of the pipeline from a second pressure sensor (38), wherein the first flow rate calculation unit calculates the first flow rate value based on a pressure difference between the first pressure and the second pressure, and the second flow rate calculation unit calculates the second flow rate value based on the square root of the pressure difference or the first pressure. With this configuration, the flow rate of the gas can be estimated regardless of whether the gas flowing through the pipeline forms a laminar flow, a turbulent flow, or a mixed flow of laminar and turbulent flows.

[0067] (Supplementary Note 6) The flow rate estimation device according to Supplementary Note 5 may further include a temperature acquisition unit (62) that acquires a temperature (T1) of the gas, wherein the first flow rate calculation unit calculates the first flow rate value based on the pressure difference and the temperature of the gas, the second flow rate calculation unit calculates the second flow rate value based on the pressure difference or the first pressure and the temperature of the gas, and when a pressure ratio of the first pressure to the second pressure is smaller than a predetermined ratio, the second flow rate calculation unit calculates the second flow rate value using the pressure difference, and when the pressure ratio is equal to or greater than the predetermined ratio, the second flow rate calculation unit calculates the second flow rate value using the first pressure. This configuration allows for more accurate estimation of the gas flow rate by taking into account changes in the temperature of the gas.

[0068] (Supplementary Note 7) In the flow rate estimation device according to any one of Supplementary Notes 1 to 6, the estimation unit may estimate the flow rate of the gas by correcting a weighted average (QWA) obtained by weighting the first flow rate value and the second flow rate value based on a temperature (T2) of the conduit and a temperature (T3) around the conduit. With this configuration, the flow rate of the gas can be estimated more accurately by taking into account temperature changes in the conduit and the surrounding area of ​​the conduit.

[0069] (Supplementary Note 8) In the flow rate estimation device described in Supplementary Note 1, the conduit may have a rectangular cross section (RS) and be formed within a plate-like member (80), and the aspect ratio (R) of the rectangle formed by the periphery of the rectangular cross section may be 1 or more and 2 or less.

[0070] (Supplementary Note 9) The flow rate estimation method includes a first flow rate calculation step of calculating a first flow rate value of the gas when the gas circulating through a conduit forms a laminar flow, a second flow rate calculation step of calculating a second flow rate value of the gas when the gas forms a turbulent flow, and an estimation step of estimating the flow rate of the gas by weighted averaging the first flow rate value and the second flow rate value using a proportionate distribution ratio according to the conduit width and conduit length. This configuration allows the flow rate of the gas to be estimated more accurately than conventional methods. Furthermore, the conduit length of the conduit 10 can be reduced.

[0071] (Supplementary Note 10) In the flow rate estimation method described in Supplementary Note 9, in the estimating step, a value obtained by multiplying the first flow rate value by the proportional ratio between zero and 1 and a value obtained by multiplying the second flow rate value by a value obtained by subtracting the proportional ratio from 1, may be summed to calculate a weighted average of the first flow rate value and the second flow rate value. With this configuration, the flow rate of the gas can be easily estimated.

[0072] (Supplementary Note 11) In the flow rate estimation method according to Supplementary Note 10, the proportional division ratio may be larger as the pipe width is narrower or the pipe length is longer. With this configuration, the flow rate of the gas can be easily estimated.

[0073] (Supplementary Note 12) In the flow rate estimation method described in Supplementary Note 9, when there are a plurality of the conduits, the proportionate division ratio may be determined according to the conduit width and the conduit length of each of the plurality of conduits. With this configuration, even when a plurality of conduits of the same dimensions are provided, there is no need to change the proportionate division ratio.

[0074] (Supplementary Note 13) The flow rate estimation method according to Supplementary Note 9 may further include a pressure acquisition step of acquiring from a first pressure sensor a first pressure of the gas flowing into the conduit and acquiring from a second pressure sensor a second pressure of the gas flowing out of the conduit, wherein the first flow rate calculation step calculates the first flow rate value based on a pressure difference between the first pressure and the second pressure, and the second flow rate calculation step calculates the second flow rate value based on the square root of the pressure difference or the first pressure. With this configuration, the flow rate of the gas can be estimated regardless of whether the gas flowing through the conduit forms a laminar flow, a turbulent flow, or a mixed flow of laminar and turbulent flows.

[0075] (Supplementary Note 14) The flow rate estimation method according to Supplementary Note 13 may further include a temperature acquisition step of acquiring a temperature of the gas, wherein the first flow rate calculation step calculates the first flow rate value based on the pressure difference and the temperature of the gas, the second flow rate calculation step calculates the second flow rate value based on the pressure difference or the first pressure and the temperature of the gas, and the second flow rate value may be calculated using the pressure difference if a pressure ratio of the first pressure to the second pressure is smaller than a predetermined ratio, and the second flow rate value may be calculated using the first pressure if the pressure ratio is equal to or greater than the predetermined ratio. With this configuration, the flow rate of the gas can be estimated more accurately by taking into account changes in the temperature of the gas.

[0076] (Supplementary Note 15) In the flow rate estimation method described in any one of Supplementary Notes 9 to 14, in the estimation step, the flow rate of the gas may be estimated by correcting a value obtained by taking a weighted average of the first flow rate value and the second flow rate value based on a temperature of the conduit and a temperature around the conduit.

[0077] The present invention is not limited to the above disclosure, and various configurations can be adopted without departing from the gist of the present invention.

Claims

1. A flow rate estimation device (20) comprising: a first flow rate calculation unit (64) that calculates a first flow rate value (Q1) of a gas (G) flowing through a pipeline (10) when the gas forms a laminar flow; a second flow rate calculation unit (66) that calculates a second flow rate value (Q2) of the gas when the gas forms a turbulent flow; and an estimation unit (68) that estimates a flow rate of the gas by taking a weighted average of the first flow rate value and the second flow rate value using an apportionment ratio (α) corresponding to a pipeline width (D) and a pipeline length (L) of the pipeline.

2. A flow rate estimation device as described in claim 1, wherein the estimation unit calculates a weighted average of the first flow rate value and the second flow rate value by summing a value obtained by multiplying the first flow rate value by the apportionment rate, which is between zero and 1, and a value obtained by multiplying the second flow rate value by a value obtained by subtracting the apportionment rate from 1.

3. A flow rate estimation device according to claim 2, wherein the apportionment ratio is larger as the pipe width is narrower or the pipe length is longer.

4. A flow rate estimation device as claimed in claim 1, wherein, when there are a plurality of said pipelines, the apportionment ratio is determined according to the pipeline width and the pipeline length for each of the plurality of said pipelines.

5. A flow rate estimation device as claimed in claim 1, further comprising a pressure acquisition unit (60) that acquires a first pressure (P1) of the gas flowing into the pipeline from a first pressure sensor (36) and acquires a second pressure (P2) of the gas flowing out of the pipeline from a second pressure sensor (38), wherein the first flow rate calculation unit calculates the first flow rate value based on a pressure difference between the first pressure and the second pressure, and the second flow rate calculation unit calculates the second flow rate value based on the square root of the pressure difference or the first pressure.

6. A flow rate estimation device as set forth in claim 5, further comprising a temperature acquisition unit (62) for acquiring a temperature (T1) of the gas, wherein the first flow rate calculation unit calculates the first flow rate value based on the pressure difference and the temperature of the gas, the second flow rate calculation unit calculates the second flow rate value based on the pressure difference or the first pressure and the temperature of the gas, and when a pressure ratio of the first pressure to the second pressure is smaller than a predetermined ratio, the second flow rate calculation unit calculates the second flow rate value using the pressure difference, and when the pressure ratio is equal to or greater than the predetermined ratio, the second flow rate calculation unit calculates the second flow rate value using the first pressure.

7. A flow rate estimation device according to any one of claims 1 to 6, wherein the estimation unit estimates the flow rate of the gas by correcting a weighted average value (QWA) obtained by weighting the first flow rate value and the second flow rate value, based on a temperature (T2) of the pipeline and an ambient temperature (T3) of the pipeline.

8. A flow rate estimation device as claimed in claim 1, wherein the pipeline has a rectangular cross section (RS) and is formed within a plate-like member (80), and the aspect ratio (R) of the rectangle formed by the periphery of the rectangular cross section is 1 or more and 2 or less.

9. A flow rate estimation method comprising: a first flow rate calculation step of calculating a first flow rate value of a gas when the gas circulating within a pipeline forms a laminar flow; a second flow rate calculation step of calculating a second flow rate value of the gas when the gas forms a turbulent flow; and an estimation step of estimating a flow rate of the gas by taking a weighted average of the first flow rate value and the second flow rate value using a proportional ratio according to the pipeline width and pipeline length.

10. A flow rate estimation method as set forth in claim 9, wherein in the estimation step, the first flow rate value and the second flow rate value are weighted-averaged by summing a value obtained by multiplying the first flow rate value by the apportionment rate, which is between zero and 1, and a value obtained by multiplying the second flow rate value by a value obtained by subtracting the apportionment rate from 1.

11. A flow rate estimation method according to claim 10, wherein the apportionment ratio is larger as the pipe width is narrower or the pipe length is longer.

12. A flow rate estimation method as claimed in claim 9, wherein, when there are a plurality of said pipelines, the apportionment ratio is determined according to the pipeline width and the pipeline length for each of the plurality of said pipelines.

13. A flow rate estimation method as set forth in claim 9, further comprising a pressure acquisition step of acquiring from a first pressure sensor a first pressure of the gas flowing into the pipeline and acquiring from a second pressure sensor a second pressure of the gas flowing out of the pipeline, wherein in the first flow rate calculation step, the first flow rate value is calculated based on a pressure difference between the first pressure and the second pressure, and in the second flow rate calculation step, the second flow rate value is calculated based on the square root of the pressure difference or the first pressure.

14. A flow rate estimation method as set forth in claim 13, further comprising a temperature acquisition step of acquiring a temperature of the gas, wherein in the first flow rate calculation step, the first flow rate value is calculated based on the pressure difference and the temperature of the gas, and in the second flow rate calculation step, the second flow rate value is calculated based on the pressure difference or the first pressure and the temperature of the gas, and when a pressure ratio of the first pressure to the second pressure is smaller than a predetermined ratio, the second flow rate value is calculated using the pressure difference, and when the pressure ratio is equal to or greater than the predetermined ratio, the second flow rate value is calculated using the first pressure.

15. A flow rate estimation method according to any one of claims 9 to 14, wherein in the estimation step, the flow rate of the gas is estimated by correcting a value obtained by taking a weighted average of the first flow rate value and the second flow rate value based on the temperature of the pipeline and the temperature around the pipeline.

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