Please follow Links:
(1)
http://science.howstuffworks.com/environmental/gree
n-science/solar-cooking1.htm
(2)
http://www.engineeringtoolbox.com/boiling-pointwater-d_926.html
(3)
http://auto.howstuffworks.com/motorcycle1.htm
(4)
http://auto.howstuffworks.com/autoparts/towing/towing-capacity/information/fpte5.htm
(5)
http://home.howstuffworks.com/rice-cooker3.htm
(6)
http://www.gh-ia.com/induction_heating.html
(7)
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A Lay man’s calculations:
A parabolic cooker can get even hotter, up to 400 degrees F
(204 degrees C), which is hot enough to fry food or bake bread.
As per Engineering Toolbox.com –
PRESSURE
PSI
250
BAR
17
BOILING POINT
Deg F
deg C
401
205
Normally, (as per information to the best of my knowledge
from my Engg friends) in the two wheeler Piston head the
energy generated is 40 Bar. This is used to move the vehicle
forward. Vehicle Weight + riders’ weight + friction on road +
traffic jam + speed breakers + resistance from wind in speed –
Where as in our project, the energy required to rotate the
armature in the Electrical Generator is comparatively less. So
we can expect that the energy generated with the vapor input
can generate electricity.
Capacity
The size of the combustion chamber in a motorcycle engine is
directly related to its power output. The upper limit is about
1500 cubic centimeters (cc), while the lower limit is about 50
cc. The latter engines are usually found on small motorcycles
(mopeds) that offer 100-miles-to-the-gallon fuel economy but
only reach top speeds of 30 to 35 miles per hour.
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STEAM WITH SOLAR ENERGY
When water is heated to the point of vaporizing, the vaporized
water takes up more space. The liquid contents will vaporize
and eventually expand to the point where the can will explode
to release the pressure inside. When this pressure is used to
perform a particular task -- like turning a turbine or causing a
kettle to whistle -- steam technology is harnessing steam
power. The methods of heating, containing, channeling and
using steam have changed, but the basic principle remains the
same.
Other inventors soon set out to perfect a method by which a
steam engine could create the rotary motion necessary to
produce electricity. They soon discovered that there was a limit
to the number of revolutions per minute a steam-driven piston
could provide. But the solution to this problem was to be
found, ironically enough, in the very technology Hero proposed
in A.D. 75: the steam turbine.
Cooking With Light
Using stoves and ovens, we can cook foods like meat,
vegetables, beans, rice, bread and fruit in just about any way.
We can bake, stew, steam, fry and braise. Using a solar cooker,
we can do the same things, but by using sunlight instead of gas
or electricity.
Sunlight isn't hot in and of itself. It's just radiation, or light
waves -- basically energy generated by fluctuating electric and
magnetic fields. It feels warm on your skin, but that's because
of what happens when those light waves hit the molecules in
your skin. This interaction is similar to the concept that makes
one form of solar cooker, the box cooker, generate high
temperatures from sunlight.
At its simplest, the sunlight-to-heat conversion occurs when
photons (particles of light) moving around within light waves
interact with molecules moving around in a substance. The
electromagnetic rays emitted by the sun have a lot of energy in
them. When they strike matter, whether solid or liquid, all of
this energy causes the molecules in that matter to vibrate. They
get excited and start jumping around. This activity generates
heat. Solar cookers use a couple of different methods to
harness this heat.
The box cooker is a simple type of solar cooker. At maybe 3 to
5 feet (1 to 1.5 meters) across, it's essentially a sun-powered
oven -- an enclosed box that heats up and seals in that heat. At
its most basic, the box cooker consists of an open-topped box
that's black on the inside, and a piece of glass or transparent
plastic that sits on top. It often also has several reflectors (flat,
metallic or mirrored surfaces) positioned outside the box to
collect and direct additional sunlight onto the glass.
To cook, you leave this box in the sun with a pot of food inside,
the pot sitting on top of the black bottom of the box. When
sunlight enters the box through the glass top, the light waves
strike the bottom, making it scorching hot. Dark colors are
better at absorbing heat, that's why the inside is black. The
molecules that make up the box get excited and generate more
heat. The box traps the heat, and the oven gets hotter and
hotter. The effect is the same as what goes on in a standard
oven: The food cooks.
Box cookers can reach up to 300 degrees F (150 degrees C)
[source: SHEI]. That's hot enough to safely cook meat.
HSW 2009
A parabolic cooker can get even hotter, up to 400 degrees F
(204 degrees C), which is hot enough to fry food or bake bread.
This slightly more complicated design uses curved, reflective
surfaces to focus lots of sunlight into a small area. It works a lot
like a stove, and it's big, sometimes up to several feet across.
A pot of food sits on an arm that holds it in the center of the
curved reflectors, suspended slightly above the bottom point of
the oven, where all the light is concentrated. This small point
gets so hot -- and the molecules vibrate so much -- that the
heat waves move upward in a steady stream to strike the
bottom of the pot.
Both parabolic and box cookers are quite large, making them
difficult to carry around. And box cookers are heavy because of
the glass. A panel cooker, which uses parabolic reflectors
positioned above a box-type oven, tends to be smaller and
lighter. The cooking pot goes in a plastic bag while it cooks,
which acts as a heat trap (like the transparent top on a box
cooker). People sometimes use these types of cookers in camping.
Camping is something of a side job for solar cookers, though.
The more central applications have to do poverty, hunger and
disease.
How can cooking with sunlight help?
SOLAR ENERGY
Solar Energy, the energy generated by the sun. This energy is in
the form of electromagnetic radiation and travels to the earth
in waves of various lengths. Some of the radiation becomes
evident as heat, some as visible light. All life on earth depends
ultimately on the sun's radiation. It warms the earth and
provides the energy that green plants use to make their food.
(Without plants, there would be no animals, since all animals
must feed on plants or on plant-eating organisms.)
Since ancient times attempts have been made—with varying
success—to put the energy from the sun to practical use. In the
third century B.C., the Greek mathematician and physicist
Archimedes is said to have used the sun's rays reflected from
mirrors to set fire to an invading Roman fleet. In the 19th
century, John Ericsson, designer of the ironclad warship
Monitor, built an engine that was powered by the sun's energy.
Solar Heat
Solar heat supplies energy for a variety of uses. The
preservation of fruits, vegetables, meat, and fish by sun drying
has been practiced for centuries. Some industrial products are
also dried by the heat of the sun. In some warm, arid regions,
the heat of the sun is used to evaporate seawater or brines to
recover salt and other minerals.
Water for domestic use can be heated by solar energy by the
use of roof-mounted devices consisting of heat collectors
through which water pipes pass. As the water is heated it flows
into storage tanks. Heat collectors can also be used to heat
homes and other buildings. The sun's heat is transferred to a
fluid—usually water or air—which then heats the interior of the
building. For heating at night and on cloudy days, some form of
heat storage is necessary. A common storage system consists of
an insulated tank to hold solar-heated water. In many regions,
additional heat from a conventional heating system is required
for extended cloudy or cold periods.
Industrial installations that use large arrays of mirrors to
produce intense solar heating have been developed in a
number of countries. A large solar furnace at Odeillo, in the
French Pyrenees, uses an array of thousands of movable
mirrors to direct sunlight on a parabolic mirror. This mirror
focuses the sunlight on an oven, yielding temperatures of more
than 6,000° F. (3,300° C.). The furnace is used to study the
effects of high temperatures on certain substances and for
various industrial processes.
In the southwestern United States, a few experimental
installations have been built that use a large array of computercontrolled mirrors to concentrate sunlight onto a boiler atop a
high tower. Steam produced in the boiler powers a turbine that
generates electricity.
Photovoltaic, or Solar, Cells
Photovoltaic cells convert sunlight directly into electricity. The
cells are made of a semiconductor material, usually silicon. A
solar battery consists of an array of solar cells connected
together to generate electric power.
Solar batteries are the source of power on most artificial
satellites. Solar batteries are used in remote locations as a
source of power for navigational buoys, irrigation pumps, and
other equipment. Small solar batteries are used in some
calculators and wrist watches.
To a very limited extent solar batteries have been used to
supply electric power to businesses and residences. However,
photovoltaic cells are relatively costly to manufacture and are
thus not practical for generating large amounts of electricity
commercially. Research in the use of photovoltaic cells for solar
energy is directed toward finding ways of increasing the
efficiency of the cells and of reducing their cost.
Boiling point
440F:
PeanutOil†
: Sunflower Oil†
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Induction Heaters:
Induction heating, used for many applications beyond rice
cookers, is achieved when this current passes through metal
coils, typically made of copper. The movement of the current
through these coils creates a magnetic field. It is into this
magnetic field that the rice cooker's pan is inserted. The
magnetic field produces an electrical current inside the cooking
pan, and this generates heat. Heat can also be produced from
this process if the rice cooker's pan is made out of a magnetic
material. This is due to a phenomenon called hysteresis, in
which magnetic materials show a resistance to any fast-paced
changes of their magnetic level. This resistance creates friction,
which contributes to the cooking heat.
Induction heating improves rice cookers in three main ways:
1. The temperature-sensing methods can be more accurate,
allowing for fine-tuned adjustments in temperature.
2. The heat distribution area can encompass the inner
cooking pan, not just radiate upwards from below, to
produce more evenly cooked food.
3. The level of heat being created in the cooking pan can be
changed in an instant by strengthening or weakening the
magnetic field that is generating it.
These elements create the biggest bonus of the induction
heating rice cooker. In the event of a human measuring error,
an induction heating rice cooker can make minute adjustments
to both the time and the temperature of the selected program
because of its sensitivity to temperature, and its precise ability
to control it.
What is Induction Heating?
Induction heating is a process which is used to bond, harden or
soften metals or other conductive materials. For many modern
manufacturing processes, induction heating offers an attractive
combination of speed, consistency and control.
The basic principles of induction heating have been understood
and applied to manufacturing since the 1920s. During World
War II, the technology developed rapidly to meet urgent
wartime requirements for a fast, reliable process to harden
metal engine parts. More recently, the focus on lean
manufacturing techniques and emphasis on improved quality
control have led to a rediscovery of induction technology, along
with the development of precisely controlled, all solid state
induction power supplies.
What makes this heating method so unique? In the most
common heating methods, a torch or open flame is directly
applied to the metal part. But with induction heating, heat is
actually "induced" within the part itself by circulating electrical
currents.
Induction heating relies on the unique characteristics of radio
frequency (RF) energy - that portion of the electromagnetic
spectrum below infrared and microwave energy. Since heat is
transferred to the product via electromagnetic waves, the part
never comes into direct contact with any flame, the inductor
itself does not get hot (watch video at upper right), and there is
no product contamination. When properly set up, the process
becomes very repeatable and controllable.
How Induction Heating Works
How exactly does induction heating
work? It helps to have a basic
understanding of the principles of
electricity. When an alternating
electrical current is applied to the
primary of a transformer, an alternating magnetic field is
created. According to Faraday's Law, if the secondary of the
transformer is located within the magnetic field, an electric
current will be induced.
In a basic induction heating setup shown at right, a solid state
RF power supply sends an AC current through an inductor
(often a copper coil), and the part to be heated (the work piece)
is placed inside the inductor. The inductor serves as the
transformer primary and the part to be heated becomes a short
circuit secondary. When a metal part is placed within the
inductor and enters the magnetic field, circulating eddy
currents are induced within the part.
As shown in the second diagram, these eddy currents flow
against the electrical resistivity of the metal, generating precise
and localized heat without any direct contact between the part
and the inductor. This heating occurs with both magnetic and
non-magnetic parts, and is often referred to as the "Joule
effect", referring to Joule's first law – a scientific formula
expressing the relationship between heat produced by
electrical current passed through a
conductor.
Secondarily, additional heat is
produced within magnetic parts
through hysteresis – internal friction
that is created when magnetic parts
pass through the inductor. Magnetic
materials naturally offer electrical resistance to the rapidly
changing magnetic fields within the inductor. This resistance
produces internal friction which in turn produces heat.
In the process of heating the material, there is therefore no
contact between the inductor and the part, and neither are
there any combustion gases. The material to be heated can be
located in a setting isolated from the power supply; submerged
in a liquid, covered by isolated substances, in gaseous
atmospheres or even in a vacuum.
Important Factors to Consider
The efficiency of an induction heating system for a specific
application depends on several factors: the characteristics of
the part itself, the design of the inductor, the capacity of the
power supply, and the amount of temperature change required
for the application.
The Characteristics of the Part
METAL OR PLASTIC
First, induction heating works directly only with conductive
materials, normally metals. Plastics and other non-conductive
materials can often be heated indirectly by first heating a
conductive metal subsector which transfers heat to the nonconductive material.
MAGNETIC OR NON-MAGNETIC
It is easier to heat magnetic materials. In addition to the heat
induced by eddy currents, magnetic materials also produce
heat through what is called the hysteresis effect (described
above). This effect ceases to occur at temperatures above the
"Curie" point - the temperature at which a magnetic material
loses its magnetic properties. The relative resistance of
magnetic materials is rated on a “permeability” scale of 100 to
500; while non-magnetic have a permeability of 1, magnetic
materials can have permeability as high as 500.
THICK OR THIN
With conductive materials, about 85% of the
heating effect occurs on the surface or "skin"
of the part; the heating intensity diminishes
as the distance from the surface increases.
So small or thin parts generally heat more
quickly than large thick parts, especially if the
larger parts need to be heated all the way
through.
Research has shown a relationship between the frequency of
the alternating current and
the heating depth of penetration: the higher the frequency, the
shallower the heating in the part. Frequencies of 100 to 400
kHz produce relatively high-energy heat, ideal for quickly
heating small parts or the surface/skin of larger parts. For deep,
penetrating heat, longer heating cycles at lower frequencies of
5 to 30 kHz have been shown to be most effective.
RESISTIVITY
If you use the exact same induction process to heat two same
size pieces of steel and copper, the results will be quite
different. Why? Steel – along with carbon, tin and tungsten
– has high electrical resistivity. Because these metals strongly
resist the current flow, heat builds up quickly. Low resistivity
metals such as copper, brass and aluminum take longer
to heat. Resistivity increases with temperature, so a very hot
piece of steel will be more
receptive to induction heating than a cold piece.
Inductor Design
It is within the inductor that the varying magnetic field required
for induction heating is developed through the flow of
alternating current. So inductor design is one of the most
important aspects of the overall system. A well-designed
inductor provides the proper heating pattern for your part and
maximizes the efficiency of the induction heating power supply,
while still allowing easy insertion and removal of the part.
Power Supply Capacity
The size of the induction power supply required for heating a
particular part can be easily calculated. First, one must
determine how much energy needs to be transferred to the
work-piece. This depends on the mass of the material being
heated, the specific heat of the material, and the rise in
temperature required. Heat losses from conduction, convection
and radiation should also be considered.
Degree of Temperature Change Required
Finally, the efficiency of induction heating for specific
application depends on the amount of temperature change
required. A wide range of temperature changes can be
accommodated; as a rule of thumb, more induction heating
power is generally utilized to increase the degree of
temperature change.