UTILIZATION OF RIVER CURRENT FOR SMALL SCALE ELECTRICITY GENERATION IN BANGLADESH By NAZMUL HUDA AL MAMUN JULY, 2001 A THESIS SUBMITTED TO THE DEPARTMENT OF MECHANICAL ENGINEERING BANGLADESH UNIVERSITY OF ENGINEERING & TECHNOLOGY (BUET) IN PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE DEGREE OF MASTER OF SCIENCE IN MECHANICAL ENGINEERING -- --. ---. 111111111 1111111111111111111111 III #95663# ----""'--~.- --~~--=--- DEPARTMENT OF MECHANICAL ENGINEERING BANGLADESH UNIVERSITY OF ENGINEERING & TECHNOLOGY (BUET), DHAKA .1"',, II ., "itf,t'l; " ,'"p," '~.l~,, , . '. CERTIFICATE OF APPROVAL The thesis titled "Utilization of River Current for Small Scale Electricity Generation in Bangladesh" submitted by Nazmul Huda Al Mamun, Student No. 9610025P, to the Mechanical Engineering Department of Bangladesh University of Engineering & Technology has been accepted as satisfactory for partial fulfillment of the requirements for the degree of Master of Science in Mechanical Engineering on July 19,2001. BOARD OF EXAMINERS ~_"-.Dr. Md. Quamrul Islam Chairman Professor. Department of Mechanical Engineering (Supervisor) BUET, Dhaka-1000 ~~ , Dr. Md. Abdur Rashid Sarkar Member Professor & Head Department of Mechanical Engineering BUET, Dhaka-1000 (/6O)Q~ . ~ Dr. A. K. M. SadrulISIaIl1 Member Professor, Department of Mechanical Engineering BUET, Dhaka-1000 .~+-.UJV.I Dr. Shahidul Islam Khan Member Professor & Head (External) Department of Electrical & Electronic Engineering BUET, Dhaka-) 000 Dr. Abul Fazal M. Saleh Member Professor, Institute of Flood Control & Drainage Research (External) BUET, Dhaka-1000 CANDIDATE'S DECLARATION It is hereby declared that this thesis or any part of it has not been submitted elsewhere for the award of any degree or diploma or publication. Signature of the Candidate ~o2JT/g/.2.lm1 Nazmul Huda AI Mamuu Candidate Counter Signature of the Supervisor Dr. Md. Quamrul Islam Professor, Department of Mechanical Engineering SUET, Dhaka-J 000 To My Parents & Sisters .; .. - ACKNOWLEDGEMENT At the very beginning, the author wish to express his gratitude to the Almighty Allah, who is the most Gracious and Merciful. The author then would like to take this opportunity of expressing his heartfelt gratitude and indebtedness to his thesis supervisor Dr. Md. Quamrul Islam, Professor, Department of Mechanical Engineering, BUET, Dhaka, for his valuable suggestions in the course of the present work. At the same time the author feels grateful to Dr. A K M Sadrul Islam, Professor, Department of Mechanical Engineering, BUET, Dhaka, for his continuous guidance, suggestions and encouragement. Without their help the entire project would be, but failure. , The author is highly indebted to Dr. Abul Fazal M. Saleh, Professor, Institute of Flood Control & Drainage Research, BUET, Dhaka for his valuable suggestions and kind cooperation during the project. The author expresses his gratitude to Prof. Dr. David Infield and Dr. D. J. Sharpe of CREST, Loughborough University, UK, for their assistance and valuable suggestions regarding the project. Thanks are due to many colleagues and friends specially Md. Mamun and Md. Zakir Hossain of BUET, Mr. Sultan Ahmed, Ph. D. student of the department and M A Mijan for their kind cooperation and help in various ways. The author is also grateful to the staff and workers of the department, and Welding and Foundry shop of BUET. The author feels obliged to express his gratitude to his parents and sisters who sheared the troubles. Finally, each and everybody related either directly or indirectly with the project deserve special thanks for their helpful cooperation, without which it would be impossible to carry out the project. CONTENTS Abstract i List of Symbols ii Greek Alphabets v Chapter I INTRODUCTION Chapter 2 LITERATURE REVIEW AND EXISTING THEORIES 2.1 LITERATURE REVIEW 4 2.2 EXISTING THEORIES 6 2.2.1 INTRODUCTION 6 2.2.2 AXIAL MOMENTUM THEORY 6 2.2.3 BLADE ELEMENT THEORY 13 2.2.4 STRIP THEORY 15 2.2.5 TIP AND HUB LOSSES 17 2.2.6 THRUST, TORQUE AND POWER COEFFICIENTS 20 2.2.7 RELA TlONS FOR MAXIMUM POWER 21 Chapter 3 RIVER CURRENT POTENTIAL IN BANGLADESH 3.1 LOCATION 23 32 THE RIVER SYSTEM 23 3.3 THE RIVER SITES 25 Chapter 4 RIVER CURRENT: A SOURCE OF ENERGY 4.1 POWER FROM FLOWING WATER 39 4.2 MINIUM USEFUL RIVER CURRENT 41 4.3 SITE SELECTION 42 4.4 MEASUREMENT OF RIVER CURRENT 42 Chapter 5 DESIGN & FABRICATION OF WATER CURRENT TURBINE 5.1 CHOICE OF TURBINE ROTOR 44 52 DESIGN OF TURBINE BLADE 44 5.3 CHOICE OF TURBING ROTOR 49 5.4 ROTOR SHAFT BEARING 49 Chapter 6 PERFORMANCE ANALYSIS 53 Chapter 7 COST ESTIMATION 63 Chapter 8 CONCLUSION 66 References 68 Appendix A Common Rivers in Bangladesh 72 Appmdix 13 11List a/Rivers in Bangladesh 74 Appendix C The Ganges, The Brahmaputra, The Meghna River Basin 80 Appendix D River Current Data 82 Appendix E Tahle (~l(CjC)l!lill'Angle of Attack & Li/i Coefficient a/Different A ir/i)ils 121 Appendix F C,. vs TSR/iJr dilferent nllmher ajhlades & Dif/erent Drag/Lifi Ratio 123 Appendix G t.J.:perimental Data 125 Appendix H Tohle jiJr Power 01ltPllt and Cost oj Energy 132 Appendix I Power Coefficient vs. Tip Speed Ralio al Different Velocities and Pitch Angles 134 •. '"1", ABSTRACT The power crisis in Bangladesh and elsewhere in the Third World highlights the need for new technologies, which local communities can use to improve their lifestyle. Many arid , \ areas are characterized by having large rivers or canals flowing through them. Under this project a study has been performed to assess the potential of electrical energy from river currents at different locations of Bangladesh. In this context 23 sites of different rivers have been considered as test cases. After getting an idea about the river current velocity at different rivers in Bangladesh, this thesis describes the development of a new, simple, and relatively inexpensive technology, which if used in right circumstances, can generate power from the rivers. The water current turbine- just can be thought of as a wind turbine inserted into the river current- a model of which has been tried and tested for power generation. The technical details especially the aerodynamic design of the turbine rotor has been introduced in the thesis. The turbine model consisting of three NACA 4412 blades with average rotor radius of 221 mm has been tested for harnessing the kinetic energy from water. It should be mentioned here that no twist angle has been introduced in the blade. A chapter of this thesis devoted to analyze the performance of the model illustrates the working range of a water turbine in terms of tip speed ratio under certain river current velocity and the effect of pitch angle in power generation. It has been found that the turbine will run at tip speed ratios between 3.2 to 6 when the pitch angle is 5° and the river current velocity of 0.65 m/s. But this operating region squeezes if the pitch angle is reduced to 00. Also the peak value of the power coefficient (Cp) is 40% when the pitch angle is 5°, but when there is no pitch angle power coefficient reduces by 10%. If the turbine is operated at a very low river current velocity in that case there is a remarkable shifting of the operating range. At a river current velocity of 0.25 mis, the turbine will run at tip speed ratios between 0.7 to 2. I'" Hence, the conclusion is drawn that selection of the turbine rotor should be such that the rotor can rotate at a high speed as possible because the faster the loaded rotor turns the cheaper will be the transmission. <~~~f '., , LIST OF SYMBOLS a axial interference factor a' tangential interference factor 2 A turbinc disk area, 1lR cross sectional far ahead of the rotor wake cross sectional area B number of blades C chord of the blade blade drag coefficicnt, dOl (0.5 pC W2 dr) blade lift coefficicnt, dLi (0.5 pC W2 dr) power cocfficient, PI (0.5 p A V;,) maximum power coefficient dA blade elemental area, C dr elemental power coefficient, dPI (0.5 p A V;) dCo elemental torque coefficient, dQI (0.5 p A V; R) dCl elemental thrust coefficient, dQI (0.5 p A V;) dO bladc elemental drag force dL blade elemental lift force dm differential mass dP blade elcmental power dQ blade elemental torque dT blade elemental thrust F Prandtl's loss factor tip loss factor . hub loss factor m mass of water flowing through the rotor in unit time N rpm of the rotor P turbine power pressure immediately in front of the rotor P pressure immediately behind the rotor III r local blade radius rhllh hub radius R rotor radius T thrust force U water velocity through the turbine V water velocity far behind the rotor V" undisturbed water velocity W relative water velocity IV • • GREEK ALPHABETS a angle of attack 131' blade twist angle llclT cfficiency of the rotor tip speed ratio dcsign tip speed ratio local tip speed ratio dcnsity of water IT solidity, BC/2m angle of relative water vclocity wake rotational velocity angular velocity of rotor v II ehapter 1: INTRODUCTION Bangladesh is a sub-tropical country located between 20°34' and 26°38'N latitude and 88"01' and 92°41'E longitude. It has an area of 148,393 Sq. km with a population of about 130 million. The pereapita GOP of the country is US$240 whereas the per capita consumption of commercial energy is 67 KGOE (Kilogram of Oil Equivalent) and generation of electricity is 90 kWh, which is one of the lowest among the developing countries [1]. In total, only 10% of households have electricity connections [2]; whereas the rest of the population depend on some sort of renewable sources of energy for cooking, lighting etc.