Fly Wheels and Super Fly Wheels: Energy Storage Systems

Topics: Internal combustion engine, Energy storage, Kinetic energy Pages: 15 (2432 words) Published: March 3, 2014
ENERGY STORAGE SYSTEMS – Vol. I – Flywheels and Super-Fly Wheels - B. Kaftanoğlu

FLYWHEELS AND SUPER-FLYWHEELS
B. Kaftanoğlu
Middle East Technical University, Ankara, TURKEY
Keywords: Flywheel, super-flywheel, energy storage, composites. Contents

U
SA NE
M SC
PL O
E –
C EO
H
AP LS
TE S
R
S

1. Introduction
2. Applications
3. Flywheel design
4. Historical perspective of flywheel design
5. Stress Analysis and Specific Energy Calculations of Flywheels 5.1. Stress Analysis of Isotropic Multi-hyperbolic Flywheels 5.2. Interference Fit for Multi-hyperbolic Flywheels
5.3. Specific Energy for Multi-hyperbolic Flywheels
5.4. Stress Analysis of Composite Multi-rim Flyweels
5.5. Elastic Constants and Allowable Stresses for Multi-rim Flywheels 5.6. Specific Energy for Multi-rim Flywheels
6. Sample solutions for Design Optimization of Flywheels
7. Discussions of Design Optimization
7. 1. Multi-hyperbolic Flywheels
7.2. Multi-rim Flywheels
8. Concluding remarks
Acknowledgements
Appendix
Glossary
Bibliography
Biographical Sketch
Summary

This chapter introduces the use of the flywheels for mechanical energy storage. The need for flywheels is discussed and the amounts of energy stored by different techniques are compared with that stored by flywheels. Some historical information is given and previous work is briefly surveyed. Then design of clasical flywheels is introduced. The design of super flywheels made out of composite materials are discussed and theory for multi-hyperbolic and multi-rim flywheels are presented.. 1. Introduction

Strorage of energy is necessary in many applications because of the following needs: Energy may be available when it is not needed, and conversely energy may be needed when it is not available.

©Encyclopedia of Life Support Systems (EOLSS)

ENERGY STORAGE SYSTEMS – Vol. I – Flywheels and Super-Fly Wheels - B. Kaftanoğlu

Quality of the available energy may not meet the characteristics of the required energy, such as when an intermittent energy supply is available whereas a smoother energy supply is needed like in internal combustion engines. The needed energy may exhibit some peaks where the supply may be uniform in character.

Smaller size power plants can be used if peak power requirements can be handled by stored energy.
For one or more of the above reasons energy storage is needed. Energy can be stored in many ways. Some of these alternative ways of storing energy are listed below in Table 1 [1]:

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Storage type
Specific energy (Wh/kg)
7.7
Compression of gases
7.7
Hydraulic accumulator
Elastic deformation:
0.09
Steel spring
8.8
Natural rubber band
Electrochemical reaction:
17.9
Lead-acid battery
30.6
Nickel-cadmium battery
Kinetic energy:
55.5
Maraging steel flywheel
4340 steel flywheel
33.3
Composite flywheel
213.8*
*
Using longitudional strength of Kevlar without any shape factor Table 1. Energy Storage Types.

It is seen that the kinetic energy storage using flywheels provides the highest specific energy compared to other alternatives. Especially, the flywheels manufactured by using composite materials provide the most efficient means.

2. Applications

Flywheel, being among the oldest inventions of mankind, has been defined as a heavy wheel used to oppose and moderate any fluctuation of speed in various kinds of machinery. Archeologists claim that they have found one in the Middle East estimated to be 5500 years old. It was apparently used as a potter’s wheel to keep it spinning between the occasional kicks of the potter’s foot. This striking example indicates that the principle of the flywheel, that a spinning wheel can store mechanical energy, has been understood long before Newton formalized the basic principles of mechanics. Since their usage in the ancient potter’s wheel, flywheels have found various applications that contributed to the mechanical developments...


Bibliography: [1] Cheng, C.G. and Hirschfeld, F. (1978): For the Latest in Energy Stroge, Try the Flywheel, Mech.
[2] Penner, S.S. and Icerman, L.(1975): Energy. Volume II, Non-nuclear Energy Technologies. AddisonWesley Publishing Company. [A book on various aspects of energy technologies including energy
storage]
[3] Time, 56 May 6, 1974[A magazine news on application of flywheels to trolleybus.]
[4]U.S
the University of California, (1975): Flywheel Tech. Symp. Proc., 5.Pages 76-88 [A paper on application
of flywheels to cars.]
[5] Commission of the European Communities,(1974).Pages 361-374 of 8th Proc. Symp. Fusion Tech. [A
research paper on details of of the design and construction of a very high capacy flywheel.]
[6] Seireg, A. and Surana, K.S.(1970): Optimum Design of Rotating Disk. J.Engr. for Industry,
Transactions of the ASME, Vol.92, pp.1-10
optimization.]
[7] Soylu, R.(1981): Specific Energy Optimization in Flywheels
[9] Surana, K.S. and Seireg, A.(1971): Design of Rotating Disks with Integral Shafts. J. Engr. For
Industry, Transactions of the ASME, Vol.93, pp.805-813, 1971
[10] Kaftanoğlu, B., Soylu, R., Oral, S.,(1989): “Mechanical Energy Storage Using Flywheels and
Design Optimization”, Energy Storage Systems, B
University (METU) Ankara with high honors (1960) and received D.I.C., Ph.D. degrees of Imperial
College, University of London (1966)
69) he joined ME Dept. of METU. He had important duties as Chairman of ME Dept. (1973 – 77),
Founder Director of the Centre for Computer Aided Design, Manufacturing and Robotics (1984 – 1992),
Director of the Graduate School for Natural and Applied Sciences (1984 – 87) and Vice-President (1987
– 1992) at METU where he is still active
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