Design and Implementation of Real-time Flow ...

This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/JSEN.2015.2442651, IEEE Sensors Journal

> Accepted for Publication in IEEE Sensors Journal (Ref. No.Sensors-12139-2015)
Accepted for Publication in IEEE Sensors Journal (Ref. No.Sensors-12139-2015) < technique of mass flow rate measurement with reasonably high accuracy without the need for calibrated flow meters. In this technique, the gas under measurement is allowed to exit through an initially pressurized plenum and its mass flow rate is determined from temperature and pressure measurement. R. Abdul Rahim et al [13] have developed an optical fiber based multiple fan beam optical tomography to measure mass flow rate of a fluid. U.R. Prasanna et al [15] have proposed a novel method of fluid flow measurement by compensating the pressure drop across the ends of measuring unit using a compensating pump. This technique is very accurate since null deflection type measurement is used. R. R. Rhinehart et al [16] have proposed a power law approach for online or offline calibration of orifice type flow meters. S. C. Bera et al [18] have proposed a flow measurement and control technique using thyristor operated pump as final control element and motor current as the flow sensing parameter. In this technique, it has been shown that the load current of the electric motor in an electric motor operated pump is linearly related with flow rate of a liquid produced by the pump through a pipeline when a tuned flow control loop is used. Qi-Li Hou et al [20] have described a digital drive and signal processing technique to design and develop a coriolis mass flow meter. In this technique, the stalling problem of coriolis flow meter tube has been eliminated by using positive-negative step signal for flow tube oscillation digital zero crossing detection technique has been used for measurement frequency and phase difference of sensor output signals. MEMS type flow sensor [22] is a low cost electronic flow sensor with high accuracy and reliability and has gained popularity. P. Saccomandi [23] et al have described an opto electronic bidirectional air flow sensor in infant artificial ventilation where two photodiodes combined with a T shaped target in differential modes are used as flow sensor. E. Schena [24] et al have utilized the micro bending of an optical fiber placed inside the flow tube combined with LED and quadrant position detector to design a flow sensor for measuring low flow rates. Rotameter [1-5] is one type of variable area type flow meter wherein the height of the float in a transparent vertical conical tube is linearly related with the flow rate of fluid through the tube. But it is generally used as a local indicator and has number of constraints such as vertical mounting, transparent tube and viscosity effect etc. It requires special type of transducers for its remote indication. Linear variable differential transformer (LVDT) is generally used in transmitting rotameter reading to a remote location. However, LVDT type rotameter transducer has very small range in measuring the displacement of rotameter float in flow measurement. This type of rotameter transducer may have also many other disadvantages such as requirement of ac excitation at high frequency, requirement of phase sensitive rectifier, error due to leakage flux, hysteresis loss and eddy current loss. N. Mandal et al [21] have designed and tested a flow transmitter using a direct self-inductance type Rotameter transducer. Hall probe sensor may be used to measure the flow rate of the rotameter. V. N. Petoussis et al [14] have developed a new Hall effect sensor where the effect of offset

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due to initial mechanical stress has been reduced by using spinning current principle and have given a general discussion [17] on development of the new Hall effect sensor. N. Mandal et al [19] have designed such a system using rotameter and Hall probe sensor. In the present paper, a modified technique of rotameter transducer has been designed and developed in order to avoid the difficulties of conventional LVDT type and inductance type rotameter transducer. In this technique, a thin circular permanent magnet is placed inside the float of the Rotameter and a Hall probe sensor measures the variation of magnetic field due to the movement of the float. The float along with the magnet changes its equilibrium position linearly with the change of flow rate with respect to the Hall probe sensor mounted on the outside top surface of the rotameter tube. Therefore, with the increase of flow rate, the float rises along the rotameter tube and the distance between the float magnet and the Hall probe sensor decreases with the increase of magnetic field intensity sensed by the Hall sensor. Hence, the Hall sensor output increases with the increase of flow rate. In order to design a PC based flow indicator the Hall sensor output has been amplified by a signal conditioner circuit and sent to PC through opto-isolator and DAS card. A virtual flow indicator has been designed using Labtech Note Book Pro Software and PC based SCADA. A theoretical equation has been derived to explain the performance of the developed flow indicating system. The proposed flow transducer and indicator system has been experimentally tested. Experimental results are reported in the paper and have been found to follow the theoretical equation with good linearity and repeatability. II. METHOD OF APPROACH The rotameter is variable obstruction type flow measuring instrument, which consists of a conical transparent tube placed in vertical position in a pipeline through which fluid is flowing. The tube consists of float, which is a solid inverted conical object of density greater than the fluid, so that at no flow it takes its minimum position closing the inlet pipe. When fluid flows through the pipeline, the float takes an equilibrium position under the action of three forces [1-5], namely downward gravitational force, upward buoyant force and upward drag force. Under this condition, the height of the upper surface of the float from its position at zero flow is linearly related with flow rate. Let the float of rotameter is attached with a circular permanent magnet as shown in Fig.1 (a) so that the magnet moves upwards with the float when flow rate of a fluid increases. Therefore, magnetic field intensity at an axial point of the ring magnet increases with increase of flow rate. Let a Hall sensor is placed at this axial point outside the rotameter tube to measure this variation of magnetic field intensity as shown in Fig.1 (a) and Fig.2. Now to understand the variation of magnetic field at an axial point of a ring magnet, an experimental set-up as shown in Fig.1 (b) is made.

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This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/JSEN.2015.2442651, IEEE Sensors Journal

> Accepted for Publication ublication in IEEE Sensors Journal (Ref. No.Sensors-12139 12139-2015)
Accepted for Publication ublication in IEEE Sensors Journal (Ref. No.Sensors-12139 12139-2015) < Now the distance of the Hall probe from the float magnet is x = H −h

K

Q = K2H −

Vh

(3)

(8)

1 2 1

where H is the distance of the Hall sensor from the float surface at its minimum position at no flow. Hence, from equations (1) and (3) we have, Bx =

K1 K1 = x 2 ( H − h )2

(4)

Now the Hall voltage Vh of the Hall all sensor is proportional to

Bx if the current passing through the sensor be kept constant. Hence, we have the following equation. Vh = K 3 B x

4

where, K = K 2 ( K 4 ) 2

(9)

Assuming, y = 1 , the equation (8) is reduced to 1

Vh 2 Q = K2H − K y

(10)

or, y = − aQ + b (11) where, a = 1 & b = K 2 H (12) K K The signal conditioner circuit using INA101 has very low noise instrumentation amplifier is shown in Fig. 3.

(5)

where K3 is the constant of proportionality. From equations (2), (4) and (5) we have, Vh =

(6)

K4  Q  H −  K2  

2

where K 4 = K1 K3 = constant.

Fig. 3.Circuit Circuit diagram of Hall sensor based flow transducer. transducer

Thus, the output (Vh ) of Hall sensor is nonlinearly related with volume flow rate (Q). Since at low flow rate, the float height (h) is small so we may assume that H ≫ h . Hence, the equation (6) may be approximated as Vh =

K4 H2

 2Q  1 +  K 2H  

(7)

Thus at low flow, the Hall sensor output put is linearly related with flow rate. III. DESIGN In the present design, a circular permanent mag magnet is selected of inner radius a = 11mm , depth d = 8mm , and width w = 11mm as shown in Fig.1 and value of H in Fig.2 is 250mm. The Hall sensor used in this work is a Solid-state Solid Hall-effect effect sensor (SS490) with size 0.160 × 0.118 inch, having power consumption of 7mA at 5V DC. It has a positive posit temperature coefficient of (+0.02% / 0 C ) with accuracy < 3% and operating temperature −400 C to +1500 C . The float is made of stainless steel. From equation (6) we have,

Let the signal conditioner circuit be calibrated for flow rate in the range from Q1 L/min (liter per minute) to Q2 L/min for which the sensor output varies from Vh1 mV to Vh 2 mV and the signal conditioner output changes from 1 volt to 5 volt. Hence, the gain of the signal conditioner circuit is given by, K′ =

4 V h 2 − V h1

(13)

If V0 be the signal conditioner output in volts for flow rate Q L/min and Hall sensor output Vh mV then Vh is given by, Vh =

V0 − 1 + V h1 K′

(14)

From equations (11) & (14), we have,

Q=

b − [1 / (

V0 − 1 + V h1 )]1/ 2 K′ a

(15)

IV. EXPERIMENT Experiment is performed in two steps with the experimental set up as shown in Fig. 4. Here, tap water is used as a process fluid at room temperature. The set up consists of an underground tank and an overhead tank each of 300-litre 300

1530-437X (c) 2015 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.

This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/JSEN.2015.2442651, IEEE Sensors Journal

> Accepted for Publication in IEEE Sensors Journal (Ref. No.Sensors-12139-2015) < capacity. The tanks are connected with 25 mm diameter pipeline through 25 mm ball valve, rotameter (2-24 L/min) and a pump (1φ, 230 V, 370 watt).

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TABLE I EXPERIMENTAL DATA FOR STATIC CHARACTERISTIC OF FLOW TRANSDUCER Sl No .

Flow rate (L/min)

1 2 3 4 5 6 7 8 9 10 11 12 13

2 4 6 8 10 12 13 14 16 18 20 23 24

Set 1 Increa Decre sing asing 1.51 2.01 2.51 3.11 4.22 6.07 7.47 10.75 16.73 37.28 61.01 144.9 200

Hall Probe voltage (mV) Set 2 Set 3 Increa Decreasi Increas Decrea sing ng ing sing

1.5 2.01 2.51 3.11 4.22 6.07 7.48 10.75 16.73 37.28 61 144.9 200

1.5 2.01 2.5 3.11 4.22 6.07 7.48 10.75 16.73 37.28 61 144.9 200.1

1.51 2.01 2.5 3.11 4.22 6.07 7.48 10.75 16.73 37.28 61.01 144.9 200.1

1.51 2.01 2.51 3.11 4.21 6.07 7.48 10.75 16.73 37.28 61 144.9 200

1.5 2.01 2.5 3.11 4.22 6.07 7.48 10.75 16.73 37.28 61 144.9 200

250 Increasing

Fig. 4.Experimental set up.

150

Comparing (11) and (16) we have

(16)

a = 0.04 V −0.5 min/ L

and

1

Increasing Decreasing

2 2

Increasing

3

Decreasing

3

50

0

0

5

10

15

20

Fig. 5.Characteristic graph obtained by plotting Hall voltage against flow rate. -3

6

x 10

5

4

3

2

1

0

5

10

15

20

Q [L/min]

Fig. 6.Standard deviation curve of the Hall Probe based flow transducer.

b = 0.8807 V −0.5 . 1/ 2 Hence, Q = 0.8807 − (1 / V h ) 0.04

25

Q [L/min]

0

y = − 0.04 Q + 0.8807

1

Decreasing

100

S tandard Deviation

In the first step, the characteristics of the proposed Hall sensor based rotameter transducer unit are determined and in the second step, the transducer is connected with PC through signal conditioner, opto isolator and DAS card and the corresponding static characteristic of the whole flow indicating system is determined. To determine the characteristic of the flow transducer, the flow rate through the pipeline is increased in steps by opening the inlet valve (V1) and at each step the Hall sensor output is measured by digital multimeter. The characteristic graph obtained by plotting Hall sensor output against flow rate is shown in Fig. 5. Experiment was repeated both in increasing and decreasing modes for six times and the standard deviation curve for six observations is shown in Fig.6.The experimental data are shown in Table-I. The linearization characteristics obtained by plotting inverse square root of Hall sensor output voltage against flow rates are shown in Fig.7 (a) and 7(c). The percentage deviation from linearity of the characteristic of Fig. 7(a) is shown in Fig.7 (b). In Fig. 7(a), the inverse square root characteristic for average value of Hall sensor outputs in three increasing and three decreasing modes is shown and in Fig.7(c) the characteristics for three increasing and three decreasing modes are shown. From the experimental graph, shown in Fig.7(a), it is observed that the reciprocal of square root of Hall sensor output voltage is related with flow rate by the following equation.

Hall Sensor Voltage [mV]

200

(17)

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This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/JSEN.2015.2442651, IEEE Sensors Journal

> Accepted for Publication in IEEE Sensors Journal (Ref. No.Sensors-12139-2015)
Accepted for Publication in IEEE Sensors Journal (Ref. No.Sensors-12139-2015)
Accepted for Publication in IEEE Sensors Journal (Ref. No.Sensors-12139-2015) < The conventional magnet type rotameter transducer generally consists of a magnetic float, which is magnetically coupled with the shaft of a potentiometer. Thus, the float movement is converted into potentiometer movement and a suitable mechanical arrangement is needed to transmit the rotameter reading in the form of current signal. This system may suffer from error due to miscoupling between magnetic float and potentiometer head. The proposed transducer does not suffer from this error with much more simpler design. This design is also very simple compared to that of LVDT type rotameter. Hence, the cost of the transducer in commercial form may be reduced to a small value compared to other conventional rotameter transducers. The novelty of the proposed Hall sensor type rotameter transducer may be assumed to lie in the fact that the proposed transducer is a non-contact type rotameter transducer with better reliability and longevity compared to these conventional rotameter transducers. The only disadvantage of the proposed sensor is the non-linear output, which can be easily linearized by using any linearization technique that can be easily designed through any electronic circuit or microprocessor, or microcontroller or PC based software technique. In the present paper, a PC based linearization technique has been described by using Lab Tech Note Book Pro software. The operation of the proposed measuring system depends on effect of temperature on Hall probe. Since the Hall probe is kept in atmosphere and its temperature coefficient is very small so the effect of temperature on the net Hall voltage may be considered negligible for small change of atmospheric temperature. However, for large change of temperature between winter and summer the sensor may be required to be recalibrated. To avoid this, bridge circuit based or IC based temperature compensating circuit may be used or the sensor may be kept in a constant temperature enclosure. It may be mentioned that only the linear portions of the graphs for flow rate upto 18 L/min have been shown in Fig.7 (a) and Fig.7(c). The nonlinearity at higher flow rate may be due to the fact that at higher flow rate the distance between float magnet and Hall sensor decreases to a small value for which equation (1) is not valid. At low flow rate, this distance is large for which equation (1) is valid. So during plotting of the graphs shown in Figs. 7(a) and (b) obtained from Fig.5 the experimental data above 18 L/min flow rates are omitted. It is observed that the linear graphs shown in Figs.7 (a) and (c), slightly deviates from linearity at some points in increasing and decreasing modes that may be due to human errors such as error in taking reading by digital mill voltmeter, error in taking reading of rotameter, error in placement of Hall sensor etc. There may be some other errors due to earth’s magnetic field interference, electromagnetic interference etc. The graph shown in Fig.7(a) represents the average values of measured data in three increasing and three decreasing modes shown in Table-I and in Fig.7(c) the characteristic for three increasing and decreasing modes are shown. It is observed that increasing and decreasing characteristics almost coincide with one another. All these graphs appear to show that within certain limiting value of flow rate, inverse square root of Hall sensor

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output bears a good linear relation with flow rate with percentage deviation from linearity lying almost within ± 2% as shown in Fig.7 (b). PC based SCADA software used in the proposed monitoring system is Lab Tech Note Book Pro Software. The data acquisition card used in this software is ADVANTECH make, PCL-818L, 40 kS/s, 12bit, 16 channel, ISA multifunction card which can take both analog and digital input with 0.1% accuracy for ± 10 volt and ± 5 volt analog input ranges and 0.2% accuracy for ± 2.5 volt and ± 1.25 volt analog input ranges. The icon-based blocks available in this software are used for signal processing of the analog input signal obtained from the output of the signal conditioning circuit of the proposed Hall probe sensor as shown in Fig.8. It may be mentioned here that the same software or similar other software may also be used for designing a control loop. VI. CONCLUSION The design of the measurement system is very simple. The Hall sensor & permanent magnet are now available at a very low cost, so the cost of the flow transducer will be low. The lifetime of the transducer will be high since the Hall sensor is not in contact with the liquid and permanent magnet has long life stability. The PC based linearization technique of the measuring circuit has been found to operate with good repeatability. The measuring system can be incorporated in a control loop with virtual controller designed by using the same software. Hence, it may be concluded that the proposed PC based flow indicator may be assumed to have good acceptability in industry in modern PC based Instrumentation system within certain limiting range of flow rate for which equation (1) is valid. The proposed measuring instrument may have some drawbacks such as limited range depending on size of float and magnet, measurement error due to deviation from inverse square law, shifting of position of Hall sensor from face to face position with float. The range of the measuring instrument may be extended by modification of design of rotameter. ACKNOWLEDGMENT The authors are thankful to the All India Council of Technical Education (AICTE), MHRD, Govt. of India for their financial assistance in the present investigation and the Department of Electronics Engineering, Indian School of Mines, Dhanbad, (Officially declared as IIT Dhanbad) for providing the facilities to carry out this work.

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1530-437X (c) 2015 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.

This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/JSEN.2015.2442651, IEEE Sensors Journal

> Accepted for Publication in IEEE Sensors Journal (Ref. No.Sensors-12139-2015) < [5] [6] [7] [8]

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E. O. Doeblin, “Measurement system application and design”, 4th edition, McGraw Hill Publishing Company, 1990. US Department of the Interior Bureau of Reclamation, “Water Measurement Manual” 3rd edition, Chapter-3. “LabTech Data Acquisition and Process Control Software” (4/94 Release), Laboratory Technology Inc, 1994 edition. F. Cascetta “Effect of fluid pressure on coriolis mass flow meters performance” ISA Transactions, Elsevier, vol 35, Issue 4, 1996, pp. 365370. F. Cascetta, A. Palombo, G. Scalabrini, “Water flow measurement in large bore pipes: An experimental comparison between two different types of insertion flow meters” ISA Transactions, Elsevier, vol. 42, Issue 2, April 2003, pp 171–179. S.G. Etemad, J. Thibault, S.H. Hashemabadi “Calculation of the Pitot tube correction factor for Newtonian and non-Newtonian fluids” ISA Transactions, Elsevier, vol. 42, Issue 4, October 2003, pp. 505-512. C. Clark., M. Zamora., R. Cheesewright., and M. Henry., “The dynamic performance of a new ultra-fast response Coriolis flow meter”, Flow measurement and instrumentation, Elsevier, U.K, vol. 17, Issue 6, Dec., 2006, pp. 315-414. Thomas Povey, Paul F. Beard, “A novel experimental technique for accurate mass flow rate measurement” Flow Measurement and Instrumentation, Elsevier, vol. 19, Issue 5, Oct. 2008, pp. 251-259. R. Abdul Rahim, L.C. Leong, K.S. Chan, M.H. Rahiman, J.F. Pang, “Real time mass flow rate measurement using multiple fan beam optical tomography” ISA Transactions, Elsevier, vol. 47, Issue 1, January 2008, pp. 3–14. Vlassis N. Petoussis, Panos D. Dimitropoulos and George Stamoulis “A Novel Hall Effect Sensor Using Elaborate Offset Cancellation Method”, Sensors & Transducers Journal, vol. 100, Issue 1, January 2009, pp. 8591. U.R. Prasanna, L. Umanand , “Non-disruptive and null-deflection mass flow measurement by a pressure compensation technique” Flow Measurement and Instrumentation, Elsevier, vol. 21, Issue 1, March 2010, pp. 54-61. R. R. Rhinehart, S. Gebreyohannes, U. M. Sridhar, A. Patrachari, Md. S. Rahaman, “A power law approach to orifice flow rate calibration” ISA Transactions, Elsevier, vol. 50, Issue 2, April 2011, pp. 329–341. Vlassis N. Petoussis, Panos D. Dimitropoulos, and George Stamoulis, “General Development of a New Hall Effect Sensor” Sensors & Transducers Journal, vol. 127, Issue 4, April 2011, pp. 36-44. S.C. Bera, N. Mandal, and R. Sarkar, “A novel technique of using a thyristor driven pump as the final control element and flow indicator of a flow control loop” ISA Transactions, Elsevier, vol. 50, Issue 3, July 2011, pp. 496–503. K. Chakraborty, N. Mandal, and R. Sarkar, “Design of an Electronic Flow Transmitter Using LVDT & Hall Sensor”, Int. Journal of Electronics & Comm. Tech., vol. 4, Issue - 1, 2013. Qi-Li Hou, Ke-Jun Xu, Min Fang, Cui Liu, Wen-Jun Xiong, “Development of Coriolis mass flow meter with digital drive and signal processing technology” ISA Transactions, Elsevier, vol. 52, Issue 5, Sept. 2013, pp. 692–700. N. Mandal, B. Kumar, R. Sarkar, and S. C. Bera, “Design of Flow Transmitter Using an Improved Inductance Bridge Network and Rotameter as a Sensor,” IEEE Trans. on Instrum. and Meas., vol. 63, no.12, pp. 3127-3136, Dec. 2014. N. T. Nguyen, “Micromachined flow sensors - a review”. Flow measurement and Instrumentation, Elsevier, vol. 8, Issue 1, May 1997, pp. 7–16. P.Saccomandi, E. Schena, and S. Silvestri, “A novel target-type low pressure drop bidirectional optoelectronic air flow sensor for infant artificial ventilation: Measurement principle and static calibration”, AIP, Rev. of Sci. Instrum., vol. 82, no.2 (024301), Feb. 2011. E. Schena, P. Saccomandi, and S. Silvestri, “A high sensitivity fiber optic macro-bend based gas flow rate transducer for low flow rates: Theory, working principle, and static calibration” AIP, Rev. of Sci. Instrum., vol. 84, no.2 (024301), Feb. 2013.

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Sunita Sinha was born in India in 1986. She received the B.Tech degree in electronics and communication engineering from MJP Rohilkhand University, Bareilly, India, in 2011 and the M.Tech degree in electronics design and technology from Tezpur Central University, Tezpur (Assam), India, in 2013.She is currently pursuing the Ph.D(Engg.) degree with the Department of Electronics Engineering, Indian School of Mines (Government of India, MHRD), Deemed University, Dhanbad, India. Her research interests include Transducer Development and controller design for process plant.

Deblina Banerjee was born in India in 1988. She received the B.Tech. degree in Instrumentation and Control Engineering from Haldia Institute of Technology under WBUT, India, in 2009, and the M.Tech. degree in Control and Automation Engineering from Asansol Engineering College, under WBUT India, in 2013. She is currently pursuing the Ph.D. (Engg.) degree with the Department of Electronics Engineering, Indian School of Mines (Government of India, MHRD), Deemed University, Dhanbad, India. Her current research interests include transducer development, calibration of transducer and controller design.

Nirupama Mandal (M’15) was born in India in 1978. She received the B.Sc. (Hons.) degree in physics, the B.Tech. degree in instrumentation engineering, the M.Tech. degree in instrumentation and control engineering, and the Ph.D. (Tech.) degree in instrumentation engineering from the University of Calcutta, Kolkata, India, in 2001, 2004, 2006, and 2012, respectively. She was an Assistant Professor and the Head of the Department of Electronics and Instrumentation Engineering at Asansol Engineering College, Asansol, India, for eight and a half years, and joined the Department of Electronics Engineering at the Indian School of Mines (Government of India, MHRD), Deemed University, Dhanbad, India, as an Assistant Professor in 2013. She has authored 15 papers in international journals and 15 papers in international and national conference proceedings. Her current research interests include transducer design, PC-based instrumentation, controller design, and process modeling.

1530-437X (c) 2015 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.

This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/JSEN.2015.2442651, IEEE Sensors Journal

> Accepted for Publication ublication in IEEE Sensors Journal (Ref. No.Sensors-12139 12139-2015)