kan and orekhov: energy loss balance in a centrifugal …

IRRIGATSIYA va MELIORATSIYA№(1).2019

ISSN 2181-8584

Journal of Irrigation and Melioration

1

Kan and Orekhov: ENERGY LOSS BALANCE IN A CENTRIFUGAL PUMP WHEN THE ROTATION SPEED

Published by 2030 Uzbekistan Research Online, 2018

IRRIGATION AND MELIORATION

Khamidov M.Kh., Nazaraliev D.V., Balla D., Hamidov A.M. SOIL PROTECTION AND WATER-SAVING TECHNOLOGIES IN AGRICULTURAL CROPSIRRIGATION ON ERODED SOILS.............................................................................................................4

Serikbaev B.S., Sherov A.G., Fatkhulloev A.M., Gafarova A.I., Mihalikova M. MODERNIZATION OF IRRIGATION SYSTEMS MANAGEMENT TO IMPROVE THEIR RELIABILITY...........8

Abdurakhmanov B.U., Karimov A.Kh., Amirova I.A. WATER AND POWER PRODUCTIVITY OF GRAPE PRODUCTION IN FERGANA VALLEY......................11

HYDRAULIC ENGINEERING STRUCTURES AND PUMPING STATIONS

Mirsaidov M.M., Sultanov T.Z., Yuldoshev B.Sh., Kisekka IsayaESTIMATION OF EARTH DAMS DYNAMICS OF UNDER MULTICOMPONENT KINEMATIC EFFECT.....16

Bacchelli M., Lilliu G.THE USE OF GEOMEMBRANES TO INCREASE EFFICIENCY, RELIABILITY AND SAFETY OFHYDROTECHNICAL STRUCTURES...........................................................................................................21

Mirsaidov M.M., Sultanov T.Z., Yarashov J.A., Toshmatov E.S., Yuldoshev B.Sh., Takhirov S.M., Rumi D.F.ASSESSMENT OF STRESS-STRAIN STATE OF EARTH DAMS WITH ACCOUNT FORGEOMETRICAL NONLINEARITY UNDER STATIC LOADS........................................................................26

Yangiev A.A., Adzhimuratov D.S., Kovar P.THEORETICAL STUDIES OF SWIRLING FLOW RATES FOR A CONFUSER SECTION OFHIGH-PRESSURE VORTEX MINE SPILLWAYS..........................................................................................31

Kan E.K., Orekhov G.V.ENERGY LOSS BALANCE IN A CENTRIFUGAL PUMP WHEN THE ROTATION SPEED OF THEIMPELLER CHANGES..............................................................................................................................36

Mamazhanov M., Uralov B., Khidirov S., Siderenko G.I.THE EFFECT OF HYDROABRASIVE WEAR OF CENTRIFUGAL AND AXIAL PUMPS UNITS ONOPERATION EFFICIENCY OF IRRIGATING PUMPING STATIONS..........................................................40

ELECTRIFICATION AND AUTOMATION OF AGRICULTURE AND WATER RESOURCES MANAGEMENT

Isakov A.J., Ochilov D.V., Kadbin N.E.INCREASE OF THE EFFECIENCY AND RATIONAL USE OF ELECTRICAL ENERGY ANDELECTRICAL EQUIPMENT.......................................................................................................................45

ECONOMICS OF WATER MANAGEMENT AND USE OF LAND RESOURCES

Chertovitsky A.S., Narbaev Sh.K., Shapira M.TASKS ON LAND USE MODERNIZATION IN UZBEKISTAN UP TO 2030.................................................48

№(1).2019. Journal "Irrigatsiya va melioratsiya"3

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Irrigation and Melioration, Vol. 4 [2018], Iss. 4, Art. 18

https://uzjournals.edu.uz/tiiame/vol4/iss4/18

Introduction. The most important parameter of a pump to judge the energy efficiency of its

operation is the coefficient of efficiency - the ratio of the hydraulic energy received by fluid to the mechanical energy applied to the shaft. It is generally accepted that when the rotation speed is less than 50%, the volume and hydraulic efficiency does not change and in calculations it is recommended to take them as constants [1-9]. But, as the operating experience [10] shows, in practice, a change in efficiency occurs with minor changes in speed.This is evidenced by the results of various studies conducted in this area recently [11-13]. The purpose of laboratory research was to study the effect of changes in rotation speed of the pump shaft on various types of pump efficiency, and of the pump plant as a whole. It should be borne in mind that the pump efficiency primarily depends on the size of the pump, and then on the volute casing shapes, construction of impellers and etc. Therefore, the regularities obtained are true for the pump under test, and can be applied to full-scale pumps with a high degree of conventionality. For the analysis, the qualitative component is important, and then follows the quantitative component of experimental results.

Research methods: To reveal the pattern of change, to assess it qualitatively, the experiments were conducted on a special stand equipped with a frequency converter. The pump efficiency accounts for the hydraulic, volume and mechanicallosses that occur at energy transfer to the pumped fluid. A total of 75 tests were conducted. According to the experiment results, the regularities of change in various types of efficiency when the rotation speed of the pump shaft changed were revealed. Theirgraphicaldependenciesarepresented.In the experiments, we used a centrifugal single-stage horizontal pump of CEA 70/33 (Lowara) type powered by a three-phase AC 220 V and connected via a frequency converter.

To determine the relation pattern between the efficiency and the changed value of rotation speed, the balance of energy losses in the pump was analyzed.

Research results: As is well known, the efficiency of the pump is the ratio of useful power to pump power [1-9,14-17]. The efficiency of the pump takes into account the hydraulic, volume and mechanical losses that occur at energy transfer to the pumped fluid. The pump efficiency is equal to the product of the hydraulic,

ENERGY LOSS BALANCE IN A CENTRIFUGAL PUMP WHEN THE ROTATION SPEED OF THE IMPELLER CHANGES

Kan E.K1., Orekhov G.V2.

1Tashkent Institute of Irrigation and Agricultural Mechanization Engineers (TIIAME), Uzbekistan2Moskow State (National Research) University of Civil Engineering

AbstractOne of the effective methods of rational and economical operation of pumping stations is the regulation by

varying rotation speed of the impeller shaft of the pump. When the rotational speed is changed the pump parameters change and, naturally, the balance of energy loss also changes. The paper presents the results of analysis of the energy loss balance in the pump when rotation speed of the pump shaft is changed.

Key words: pump, pumping stations, pump parameters, efficiency, regulation, rotation speed

volume and mechanical efficiency [1,4,7,14-15].МVhP

�� (1)Volumetric losses. Volume losses

qQ

Q

v

�� are due to all

leakages which are pumped by the impeller. Volume losses include leakage through the annular seal at the impeller inlet and fluid recirculation at part load creates high losses due to an exchange ofmomentum between stalled and non-separated fluid zones. In centrifugal pumps, the leakages occur in the impeller seal between the pumping area and suction zone1,4,7,14-15].

qQ

Q

v

�� (2)

Where, O� - is the volume efficiency, Q - is the pump

capacity, q-is the leakage volume.Hydraulic losses. Hydraulic losses due to friction and

turbulent dissipation in all components between suction and discharge nozzle are covered by the hydraulic efficiency ηh 1,4,7,14-15].

НН

Н

h

�� (3)

Where,ηh -is the hydraulic efficiency of the pump, H - is the

pump head , НН

Н

h

��

- is the loss of head in the pump.Mechanical losses. Mechanical losses are caused by

friction of the outer walls of the impeller disks against the fluid in which they rotate, the shaft friction in bearings and seals 1,4,7,14-15].

The efficiency of the pump plant, i.e. a pump connected to the engine is equal to:

(4)

motmvhдвн

a

u

а

N

N��

The efficiency of the electric motor can be determined from the catalog data of the electric motor depending on the capacity.

The capacity, pressure and power of the pump vary depending on changes in the rotation speed of its impeller according to the laws of proportionality [ 1]:

(5)

��

�

�

��

�

�

��

�

�

��

�

��

01

0

11

*�

�

n

n

Q

Q

(6)

��

�

�

��

�

�

��

�

�

��

�

��

1

2

11

*Г

Г

n

n

H

H

�

�



3



(7) �

�

�

�

��

�

�

��

�

�

��

�

�

��

�

�

��

�

��

01

0

1

3

11

**�

�

�

�

Г

Г

n

n

N

N

where Q, H, N, ηv, ηh are the capacity, pressure, power, volume and hydraulic pump efficiency at speed n,

Q1, H1, N1, ηv1, ηh1 - are the capacity, pressure, power, volume and hydraulic pump efficiency at speedn1.

To determine the dependence of the change in rotation speed on thepump plant parameters, a series of experiments was conducted at the training stand “Automation of pumping stations of water supply systems”. The sequence of the experiments is as follows: for testing, a pump with a frequency converter on a stand equipped with devices and instruments for measuring capacity, pressure, vacuum and power consumption is used. After starting the pump, the flow rate is controlled by varying the rotation speed using a frequency converter; the pressure, capacity, power of electric motor and efficiency of the pump plant corresponding to these values are measured.

A total of 75 tests were conducted. As a result of the experiments, the dependences characterizing the change in the pumping unit parameters (pressure, capacity, power, efficiency) from the change in the rotation speed were specified. In preliminary calculations, at speed change of less than 50%, the volume and hydraulic efficiency is assumed to be constant. But as shown by experimental studies at training stand, even at minor changes in speed (less than 20-10%), the value of the efficiency changes as well.To assess and compare the changes in pump efficiency when the speed changes, the relative indices are used. In this case, all values are determined in relation to the baseline (at the nominal speed and maximum efficiency).

Below are the results of the analysis of changes in

volume efficiency ��

�

�

��

�

�

01

0

�

� from changes in rotation speed

��

�

�

��

�

�

1nn (Fig. 1) and changes in hydraulic efficiency

��

�

�

��

�

�

1G

G

�

�

from changes in rotation speed ��

�

�

��

�

�

1nn (Fig. 2). An analysis

of the graph obtained from the tests results shows that the curve in Fig. 2 has three characteristic sections:

The 1st section corresponds to the variation range of rotation speed (up to 35%) at which there is no change in hydraulic efficiency;

The 2ndsection corresponds to the frequency range within 35-75%, i.e., up to 0.35 <n/n1 <0.75), characterized by intensive decrease in hydraulic efficiency;

Fig. 1. The graph of changes in volume efficiency ��

�

�

��

�

�

1v

v

�

�

relative to changes in speed ��

�

�

��

�

�

1nn

Fig. 2. The graph of changes in hydraulic efficiency 1h

h

�

�


�

�

��

�

�

1nn

Fig. 3.The graph of changes in hydraulic efficiency 1Г

Г

�

�


�

�

��

�

�

1nn

for the 2nd section (at 35-75 % change in speed)

Fig. 4. The graph of changes in mechanical efficiency

1М

М

�

� relative to changes in speed ��

�

�

��

�

�

1nn

The 3rdsection corresponds to the variation range of shaft rotation speed by more than 75% ; here the changes in hydraulic efficiency are insignificant.

Thus, a change in hydraulic efficiency occurs when the speed changes by more than 35% and less than 75%.

To determine the pattern of change in pump plant efficiency at rotation speed change of the impeller, Microsoft Excel 2010 program was used. The results are presented in Table1.



4



From Table 1 it is seen that of all types of trend lines, the greatest values of the approximation parameters R2 have logarithmic dependencies, but power

Fig. 5. The graph of changes in overall efficiency of the pump

1p

p

�

�


�

�

��

�

�

1nn

Fig. 6. The graph of changes in different types of efficiency �

�

�

�

��

�

�

1nn

relative tochanges in speed ��

�

�

��

�

�

1nn

Approximation results of graphical dependenciesTable 1.

№ Trend line parameters

linear logarithmic power

dependence R2 dependence R2 dependence R2

1 Change in hydraulic efficiency

Y=0.28x+0.76 0.82 y=0.18ln(x)+1.03 0.89 y=1.04х0.20 0.88

2 Change in mechanical efficiency

Y=0.16x-0,07 0.97 Y=0.73ln(x)+1.03 1,0 Y=1.15x1,23 0.96

3 Change in volume efficiency Y=0.41x+0.64 0.88 Y=0.26ln(x)+1.03 0.94 Y=1.04x0.29 0.93

4 Change in pump efficiency Y=1,39x-0,28 0.97 Y=0.86ln(x)+1.03 0.99 Y=1.24x1,73 0.96

dependencies are more convenient for practical use.So, the dependences of parameter change of

various types of efficiency of the pump have the following form:

Change in hydraulic efficiency:

(8)

20.0

11

)(04,1n

n

Г

Г�

�

�

Change in mechanical efficiency:

(9)

23.1

11

)(15,1nn

М

М�

�

�

Change in volume efficiency:

(10)

29.0

101

0 )(04,1nn

��

�

Change in pump efficiency:

(11)

73.1

11

)(24,1n

n

н

н

��

�

Conclusions1. An effective method to regulate the pump

parameters is to change the rotation speed of the driving shaft of the pump (of electric motor) [12-13,19-20].

2. To reveal the dependence of the change in rotation speed on the pump plantparameters, a series of experiments were conducted on the training stand “Automation of pumping stations of water supply systems”. Experimental studies have shown that even minor changes in rotation speed of the impeller (less than 50%) lead to a change in efficiency. Various types of pump efficiency at decreasing speeds vary to different degrees. At speed variation, the mechanical efficiency is subject to the greatest change. The hydraulic efficiency is the least affected. For example, when rotation speed is changed by 50%, the hydraulic efficiency changes by 5-7%, the volume efficiency decreases by 30%, and the mechanical efficiency decreases by 45%. The overall efficiency of the pump decreases by 55%.

3. Thus, when choosing a method to control the pumping plants (especially in land-reclamation area) and evaluating the effectiveness of their application, it is necessary to take into account the possibility of reducing efficiency when regulating speed change.

Journal "Sustainable Agriculture"ARCHITECTURE. LANDSCAPE ARCHITECTURE



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References1. K.I. Lysov, I.A. Chayuk, G.E. Muskevich. Operation of land-reclamation pumping plants. - M. "Agropromizdat", 1988, - 255 p.2. V.F. Cheboevsky, K.P. Vishnevsky. Design of pumping stations and testing of pumping station.- Moscow: Kolos, 2000 - 376 p.3. V.F. CHebaevskiy. Pumps and pumping stations. – Moskow: Agropromizdat, 1989 . - 415 p. 4. A.K.Mikhailov, V.V. Malushenko, Vane pumps Theory calculation and design. - Moscow: Mechanical Engineering, 1977. - 283 p. 5. M.Mamajonov. Pumps and pumping stations. - Tashkent: Science and Technologies,2012. - 372 p.6. M.M.Muхаmmаdiеv, M.Mаmаjоnоv, T.SH. Mаjidоv. Hydraulic Machines. - Tashkent:TIIAME, 2010. - 193 p.7. G.I.Krivchenko, Hydraulic Machines: Hydraulic Turbines and Pump. -Moscow:Energoatomizdat, 1983. – 320 p.8. Z.Husain, Z. Abdullah, Z. Alimuddin. Basic Fluid Mechanics and Hydraulic Machines. - Hyderabad: BS Publications, 2008. - 231 p.9. A. I. Kolesnikov. Energy-saving in industrial and municipal enterprises: Textbook. - M.: INFRA-M, 2005. - 124 p.10. T.Sh. Mazhidov, E.K. Kan, A.A. Ergashev. Results of field studies of a pumping unit with a frequency converter. //Journal “Irrigation and Land Reclamation”. - Tashkent, TIIAME, 2016, - № 01 (36). Pp. 31-34.11. G.V. Ledukhovsky, A. A. Pospelov. On the performance calculation of the energy-saving devices of centrifugal pumps with frequency regulation of productivity//“Heat Supply News”, 2013. - № 10 (158). – Pp.155-171.12. К.A. Evtukh, E.V. Vyazunov, A.F. Barkhatov, About the economic efficiency of the replacement of pressure throttling units at the oil pumping stations by adjustable frequency-controlled actuators or hydro-clutches// Oil and Oil Products Pipeline Transportation: Science & Technologies, 2014 .- № 2. - pp. 15–21. 13. M. Kozlov, A. Chistyakov, Effectiveness of implementation systems with variable frequency drives//J: Modern automation technologies, 2001. - № 1. - p. 76-80.14. G. Paresh, M. Octo. Practical Centrifugal Pumps Design, Operation ahd Maintenance.- Elsevier Newnes, 2005. - 246 p. 15. J.F. Gulich. Centrifugal Pumps. - Springer-Verlag Berlin, 2008 - 964 p. 16. M.C. Sanks, G. Tchobanoglous, B.E. Bosserman. Pumping Station Design: Second Editon .- Butterworth- Heinemann, 2010. - 1067 p.17. V.Y. Karelin, A.V. Minaev. Pumps and pumping stations - Moscow:Strojizdat, 1986, - 320 p.18. A.O.To‘rabekov. Machine lift system - T: Uzgiprovodxoz, 2009. –225 p.19. D.V. Sotnikov.Improving the efficiency of pumping stations// Vestnik TGU. - Tambov, 2016. - pp. 2954-2956.20. M.M. Muxammadiev, B.U. Urishev. Energy efficient technologies in the operation of pumping stations - Tashkent, 2012. - 115 р.

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kan and orekhov: energy loss balance in a centrifugal …

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