- Back to Home »
- Electricity form speed breakers
Posted by : Unknown
Tuesday, May 7, 2013
Abstract
In this technological era, all
the modern equipments and advancements rely on the electricity. Electricity
serves as a back bone to these achievements. Can we imagine a second without
electricity? Calculate the losses caused by the shortage of electricity.
Currently there are various
methods for electricity generation. Here is a novel method for generating
electricity from speed breakers which is eco-friendly.
In our design, the speed
breakers have to be made with springs. When a vehicle loads a speed breaker it
compresses air and this air is used to drive the impeller. This serves as a
source for the alternator.
Thus in this article, going to
present a new method of electricity generation. Hope this design will be
implemented soon!!!
Speed breakers
In Indian roads, currently we
have speed breakers of rigid type, made of steel or with tar. When a heavy load
crosses the speed breaker it remains unreformed, which alone limits the speed
of vehicles The national highways come with minimum 8 meters wide, 0.015m
thickness. We are proposing slight changes in the current roads.
Proposed design
Here we are making the speed
breaker of vibrating type, when a vehicle crosses the speed breaker, it gets
depressed and then it gets back to its original position.
Dimensions
Height of speed breaker
: 0.2m
Width of speed breaker
: 0.4m
Length of speed breaker
: 4m
Material used for speed breaker:
Steel
Speed breaker -design
The speed breakers are fitted
with helical spring at the base. The shape of speed breaker is trapezoidal,
because when a vehicle comes to point A, the load will be acting between A and
B. This compresses the speed breaker; this goes down due to the presence of
spring. When a vehicle is in between B & C, there will be maximum load on
the speed breaker. At the C & D, there will be minimum load on speed
breaker.
A hollow trench has to be dig
out with dimensions slightly greater than the size of speed breaker. The
dimensions are
Height: 0.35m
Length : 4m
Width :0.45m
The bottom layer of the trench
is filled with concrete or with wooden plates of 0.5m. This is for cushion
effect. Above this layer helical springs of n windings is wounded.
The speed breaker is assumed to
be a uniformly distributed load.
The self (dead) weight of speed
breaker can be represented as
When a vehicle with a maximum
load passes, it loads the speed breaker it is represented as
Therefore the total weight on
the speed breaker is found to be the sum of initial (dead) weight and the
weight of the vehicle (load applied).
Total weight (w) = Dead weight +
Vehicle weight
For the design of speed breaker,
the design weight can be found by the product of factor of safety and its total
weight. The factor of safety determines the maximum level that the beam (speed
breaker) can be loaded.
Spring design
The actual height of spring is
0.3m before loading. The deflection of the spring is given by
δ = 64 w *n*N*R^3 /(Gd^4)
Where
Δ-deflection (in our case
maximum δ =0.1m)
w=designed load
R= mean diameter of coil
d =diameter of wire
n=no of spring turns
G= Modulus of rigidity = 8*10^4
N/mm2
N= No. of springs
Impact of vehicle on speed breaker
Maximum load on speed breaker
Vehicle leaving the speed breaker
The no of turns in the spring to
get the deflection of 0.1m is given by
n= δGd^4/(64 w*N*R^3)
After the vehicle crosses the
speed breaker, the air inside the base will be compressed.
Pneumatic design
When the load is on the speed
breaker, the volume of air compressed by it is found by,
Volume of compressed air =
Volume of air in base – Volume of spring
d^2/4p= l*b*h – N*n*
= x m^3/s
The x m^3/s air released is
taken through the outlet at one end of speed breaker. A pneumatic cylinder with
an FRL unit is connected to the outlet of this pipe. When the pressure in the
FRL unit exceeds the defined level the valve opens and the pressurized air is
given to the nozzle.
The diameter of the inlet (nozzle)
must be greater than the outlet.
di>d0
Here the pressure energy is
converted to kinetic energy i.e. pressure→high velocity. The atmospheric air is
compressed by the speed breaker and is used to drive the impeller.
Impeller-design
When air with higher velocity
strikes the vanes of impeller, it starts rotating. The energy available at the
inlet is only kinetic energy and the outlet is atmospheric. The impeller has
1.
Nozzle
2.
Runner and bucket
3.
Casing
The amount of air striking the
vanes of runner is controlled by providing a spear in nozzle
Runner
It consists of a circular disc
on the periphery of which have number of buckets evenly spaced are fixed. Each
bucket is divided in to 2 symmetrical parts by a dividing wall is know as
splitter. The splitter divides air jet in to two equal parts. The buckets are
shaped in such a way that jet gets deflected through 160 or 170 degree.
Materials used are cast iron, caste steel, or stainless.
Casing
This can be provided to
safeguard against accidents. When air jet strikes the runner revolves for a
longer time due to inertia.
Alternator
An electrical generator is a
machine which converts mechanical energy in to electrical energy. The energy
conversion is based on the principle of production of dynamically induced
e.m.f. According to Faraday’s laws of electromagnetic induction, whenever a
conductor cuts magnetic flux, dynamically induced e.m.f. is produced in it.
This e.m.f causes a current to flow if the conductor circuit is closed.
Two basic essential parts of an
electric generator are
1.
A magnetic field and
2.
A conductor or conductors which can so as to move to
cut the flux.
Alternator varies from d.c
generator in the aspect of stationary armature mounted on a stationary element
called stator and field windings on a rotating element called rotor. So slip
rings, brushes and commutator are eliminated.
Generation of induced e.m.f:
When the rotor rotates, the stator conductors are cut by the magnetic flux,
hence they have induced e.m.f. produced in them.
Speed and frequency
In an alternator, there exists a
definite relationship between the rotational speed (N) of the rotor, the
frequency(f) of the generated e.m.f. and the number of poles (P).
Consider the armature conductor
marked x situated at the centre of a N-pole rotating in clockwise direction.
The conductor being, situated at the place of maximum flux density will have
maximum e.m.f. induced in it.
The direction of the induced
e.m.f. is given by Fleming’s right hand rule. I.e. the thumb indicates the
direction of the motion of the conductor relative to the field.
When the conductor is in the
interpolar gap as at gap A, it has minimum e.m.f. induced in it, because flux
density is minimum. Again when it is at the centre of a S- pole, it has maximum
e.m.f induced in it, because flux density at B is maximum. But the direction of
e.m.f. when the conductor is over a N- pole is opposite to that when it is over
a S- pole. Obviously one cycle of e.m.f. is induced in a conductor when one
pair of poles passes over it. In other words, the e.m.f. in an armature
conductor goes through one cycle in angular distance equal to twice the
pole-pitch.
Let
P= total no of magnetic poles
N= rotative speed of the rotor
in r.p.m
f= frequency of generated e.m.f.
in Hz
Since one cycle of e.m.f is
produced when a pair of poles passes past a conductor the no of cycles of e.m.f
produced in one revolution of the rotor is equal to the no of pair of poles.
No of cycles/revolution = P/2
And
No of revolutions/second =
N/60Frequency = (P/2)*(N/60) = P*N/120 hz
Thus the mechanical energy from
speed breaker serves as an input source to the alternator which generates the
electricity of 10kw
Conclusion
In this article, written about a
new approach of generation of electricity from the speed breaker. This can
generate up to 100Kwatts of power which can be used for various purposes. Here
we have converted the mechanical energy to pneumatic energy then to electrical
energy. This design will help to reduce the cost of electricity
generation.