TABLE OF CONTENT
1.
Acknowledgment
2.
Introduction (Propellants)
3.
Types of propellant
·
Solid
·
Liquid
·
Gas (areosol)
4.
Working
5.
Classification
6.
Advantages and Disadvantages
7.
Differents types of Propellants used
in Satellite or Rocket
8.
Properties of Liquid Propellants
9.
Propellant Transport Service (LEP,
GEO)
§ LEO (Low earth orbit)
§ GEO (Geostationary orbit)
10.
Station keeping for
Fuel Propellants
11.
Propellants Space
Transportation application
12.
Propellant uses
examples
13.
Table of
Propellants
14.
Reference
ACKNOWLEDGEMENT
I would like to express my
gratitude for the many helpful comment and suggestions .I have received over
the last few days regarding the expository and critical expects of my term work
and especially for those comments which bear directly or may various argument
for the center thesis of term work. I am undebted to several people in this
regard.
Most importantly I would like to thank my
teacher Mr. Sukhjinder Singh, for his days of
supervision. His critical commentary on my work has played a major role in both
the content and presentation of our discussion and arguments.
I have extend my appreciation to the several
sources which provided various kinds of knowledge base support for me during
this period.
PROPELLANTS
Solid propellant Liquid propellant Gas propellant
Used in Satellite as well as a Rocket
INTRODUCTION
v
What is a
propellant?
Satellite or Rockets work
because every action has an equal and opposite reaction (according to Sir Issac
Newton's third principle). In order for the rocket to rush forward, something
has to rush backwards. That thing is the propellant. The propellant is a
material that spews out of the back of the spacecraft giving it thrust, or a
push forward.
Often the propellant is a kind of fuel which is burned with an oxidizer
to produce large volumes of very hot gas. These gasses expand until they rush
out of the back of the rocket, making thrust.
A propellant
is a material that is used to move ("propel") an object. This will
often involve a chemical reaction. It may be a gas, liquid, plasma,
or, before the chemical reaction. A solid
Common chemical propellants consist of a fuel, like gasoline, jet fuel and rocket fuel,
and an oxidizer.
A propellant is a material that is used to move an
object by applying a motive force
·
This may or may not involve a chemical reaction.
·
It may be a gas, liquid, plasma, or, before the chemical
reaction, a solid.
·
Common chemical propellants consist of a fuel, like gasoline,
jet fuel and rocket fuel, and an oxidizer.
The word propellant is the general
name for chemicals used to create thrust. The term propellant refers only to
chemicals that are stored within the vehicle prior to use, and excludes
atmospheric gas or other material that may be collected in operation.
Usually, a combustible substance that
produces heat and supplies ejection
particles, as in a rocket engine or in Satellite.
A propellant is both a
source of energy and a working substance; a fuel is chiefly a source of energy,
and a working substance is chiefly a means for expending energy. Because the
distinction is more decisive in rocket engines. So, the term propellant is used
primarily to describe chemicals carried by rockets for propulsive purposes.
Now, we discuss different types
of Propellant used in satellite. There are more types of propellant used in
satellite.
I.
Solid Propellant
II.
Liquid Propellant
III.
Gas (aerosol) Propellant
Propellants are classified as liquid
or as solid. Even if a propellant is burned as a gas, it may be carried under
pressure as a cryogenic
liquid to save space. For example, liquid oxygen and liquid hydrogen are
important high-energy liquid bipropellants.
Solid
Propellants
Any solid propellant consists of two parts:
• An oxidizer
• A fuel (or a reducer)
In solid propellants, the fuel
and oxidizer components are prepared separately and are then mixed together.
This is because the oxidizer is in powder form and the fuel is a fluid of
varying consistency. They are then blended together and poured into the rocket
case under carefully controlled conditions
In addition to fuel and oxidizer, some other compounds are
added to increase the efficiency of the propellants. To understand this, let us
see an example of solid propellants used in shuttles.
• The oxidizer is ammonium per chlorate (NH4ClO4)
(69.93 %).
• The fuel is a form of powdered aluminum (16 %).
• The catalyst (increases rate of combustion) is
iron oxidizer powder (0.07 %).
• The binder (holds mixture together) is polybutadiene
acrylic acid acrylonitrile (12.04 %).
• An epoxy-curing agent (1.96 %).
The binder and epoxy also burn as the fuel burns, thus
contributing to the thrust produced.
·
A solid propellant is a mixture of oxidizing and
reducing materials that can coexist in the solid state at ordinary temperatures. When
ignited, a propellant burns and generates hot gas. Although gun powders are
sometimes called propellants, the term solid propellant ordinarily
refers to materials used to furnish energy for rocket propulsion.
·
A solid propellant normally contains three essential
components: oxidizer, fuel, and additives.
Oxidizers commonly used in solid propellants are ammonium and
potassium perchlorates, ammonium and potassium nitrates, and
various organic nitrates, such as glyceryl trinitrate
(nitroglycerin).
·
Solid propellants are classified as composite or double base.
The composite types consist of an oxidizer of inorganic salt
in a matrix of organic fuels, such as ammonium
perchlorate suspended in a synthetic rubber. The double-base types are
usually high-strength, high-modulus gels of cellulose nitrate (guncotton) in
glyceryl trinitrate or a similar solvent.
Now let us see the
various different aspects of solid Propellants
Working of Solid Propellants
By changing the shape and size of the perforation we can
control the rate and duration of burning and thus control the thrust. More the
thrust required, larger will be the perforation but the fuel will burn for a
smaller time. Lesser the thrust required, smaller will be the perforation but
the fuel will burn for a very long time. The burning period and the thrust
depends upon the type of perforation in the fuel.
Let us see the
different classifications of solid propellants and merits and demerits of using
solid propellants.
Solid propellant
Classification of Solid Propellants
There are two types of solid propellants:
• Homogeneous solid propellants
• Composite solid propellants
Homogeneous
solid propellants
• Simple base homogeneous solid propellants
• Double base homogeneous solid propellants
·
Simple base
propellants are those propellants
which consist of only one compound having both oxidation and reduction properties. This
compound is usually nitrocellulose.
·
Double base
propellants consists of two
compounds, usually nitrocellulose and nitroglycerine, along with a plasticizer
(added to impart flexibility). The advantage of this type of propellant is that
it does not produce smoke. Thus increases energy and burning rate.
Composite
solid propellants
Composite propellants
are heterogeneous mixtures. These use crystallized or finely ground mineral
salt as oxidizer. This oxidizer forms the bulk of the propellant. The fuel used
is aluminum. A polymeric binder holds the propellant together. Sometimes catalyst is added to improve burning.
Advantages and Disadvantages
Advantages
• They are stable and easily storable.
• They do not require turbo pumps or complex propellant
feeding devices.
Disadvantages
• The solid propellant motor
cannot be shut down. The fuel once ignited burns till the end.
• The propellant is temperature sensitive.
Homogeneous solid
propellants
Composite solid propellants
Liquid Propellants
Liquid propellants are nothing but rocket propulsion fuels in
liquid state.
They are made up of 2 parts
• An oxidizer
• A fuel
Both the oxidizer and fuel are in liquid form.
Liquid propellants
are more difficult to handle than solid propellants and they require separate
oxidizer and fuel tanks. Lightweight pumps and injectors are used to spray the
propellants into the combustion chamber. The combustion of liquid propellants can be controlled easily
by controlling the rate at which the pumps spray the liquid into the combustion
chamber. Shutting off the pumps completely can easily stop the combustion. Thus
controlling, stopping and starting the combustion is very easy when liquid
propellants are used. A liquid propellant releases energy by chemical action to
supply motive power for jet propulsion. The three principal types of
propellants are monopropellant,
bipropellant, and hybrid propellant. Monopropellants are single liquids, either compounds or
solutions. Bipropellants consist of fuel and oxidizer carried separately in the vehicle
and brought together in the engine. Hybrid propellants use a combination of liquid and solid
materials to provide propulsion energy and working substance.
In order to start the combustion process spark plugs, igniters,
explosives are used.
Liquid propellants
used in launch vehicles can be classified into:
We will now see each of these propellants in detail
Petroleum
Before seeing how petroleum fuels impart thrust, let us first
see how they are manufactured:
Refining crude oil
produces petroleum fuels. Crude oil
simply means unprocessed oil. Crude oil
is a fossil fuel as it has been formed in the earth's crust by decaying of the
fossils of plants and animals. These fossils are subjected to high temperature
and pressure for millions of years to form crude oil.
The oil is made up of mixture of complex hydrocarbons
(compounds containing mainly carbon and hydrogen).
Crude oil
consists of large number of components mixed together. Therefore to obtain
kerosene which is used as a propellant various components of crude oil
will have to be separated.
To separate the components of crude oil
2 processes have been employed.
1. Fractional distillation
In this process various components of the crude oil
having different weight, sizes and boiling temperatures are heated. The vapors
formed enter a column called fractionating column. When a substance in the
vapor reaches a height where the temperature of the column is equal to that
substance's boiling point, it will condense to form a liquid. Thus this process
separates all the components.
2. Chemical processes
They can also be employed to separate the components of crude oil.
These include breaking of large hydrocarbons into smaller hydrocarbons,
combining small hydrocarbons to make larger one and rearranging to obtain
desired hydrocarbons.
After obtaining kerosene from one of the above processes it
is used in combination with liquid oxygen as the oxidizer. Kerosene obtained is
referred to as RP-1 (highly refined petroleum). RP-1 delivers a specific
impulse considerably less than cryogenic fuels. (See cryogenic
fuels).
Kerosene was used to power the first-stages of the Saturn 1B
and Saturn V rockets.
Fractional
distillation
Chemical process
Cryogenic
Propellants
In a cryogenic
propellant the fuel and the oxidizer are in the form of very cold, liquefied
gases. These liquefied gases are referred to as super cooled as they stay in
liquid form even though they are at a temperature lower than the freezing
point. Thus we can say that super cooled gases used as liquid fuels are called
cryogenic fuels.
These propellants are gases at normal atmospheric conditions.
But to store these propellants aboard a rocket is a very difficult task as they
have very low densities. Hence extremely huge tanks will be required to store
the propellants. Normally the propellant combination used is that of liquid
oxygen and liquid hydrogen, Liquid oxygen being
the oxidizer and liquid hydrogen being the fuel.
Working
of Cryogenic Propellants
For
using cryogenic propellants, special insulated containers and vents are used to
prevent gas from the evaporating liquids to escape. The liquid fuel and
oxidizer are fed from the storage tank to an expansion chamber. Then it is
injected into the combustion chamber. In this chamber, they are mixed and
ignited by a flame or spark. The fuel expands as it burns and the hot exhaust
gases are directed out of the nozzle to provide thrust.
·
Cryogenic propellants
have many advantages, which enable them to be used as propellants for space
vehicles.
Some
of the advantages are
1. High Energy
per unit mass
Propellants like oxygen and hydrogen
in liquid form give very high amounts of energy per unit mass due to which the
amount of fuel to be carried aboard the rockets decreases.
2. Clean Fuels
Hydrogen
and oxygen are extremely clean fuels. When they combine, they give out only
water. This water is thrown out of the nozzle in form of very hot vapor. Thus
the rocket is nothing but a high burning steam engine.
3. Economical
Use of oxygen and hydrogen
as fuels is very economical, as liquid oxygen costs less than gasoline.
Drawbacks of
Cryogenic Propellants
I.
Boil off
Rate
Since these propellants are in extremely low temperature
conditions they are very hard to handle. They must be protected from heat so as
to prevent boiling of gases. When liquid propellants are stored at temperatures
above their boiling point they vaporize. If these vapors are contained in a
tank, then the pressure increases with temperature.
Boil off rate is governed by heat leakage and
by the amount of propellant in the tanks. With partly filled tanks, the
percentage loss is higher. Heat leakage depends on surface area, while the
original mass of propellant in the tanks depends on volume. So by square/cube
law smaller the tank, the faster the liquids will boil off.
II.
Highly
reactive gases
Cryogens are highly concentrated gases and have a very high
reactivity. Liquid oxygen, which is used as an oxidizer, combines with most of
the organic materials to form explosive compounds. So lots of care must be
taken to ensure safety.
III.
Leakage
One of the most major concerns is leakage. At cryogenic
temperatures, which are roughly below 150 degrees Kelvin or equivalently (-190oF),
the seals of the container used for storing the propellants lose the ability to
maintain a seal properly.
IV.
Hydrogen
Embrittlement
Due to cryogenic propellants, various significant thermal
stresses are introduced into the launch vehicle. These stresses can damage the
structural integrity of the vehicle. Hydrogen reacts with certain materials to
alter its grain structure causing it to become brittle, in a process known as hydrogen embrittlement
V.
Zero
Gravity conditions
It is difficult to store cryogenic propellants in zero
gravity conditions. Zero gravity conditions, the liquid may flash into vapor,
and go away from the nozzle that dumps the gas overboard. This pushes the
propellant in liquid form, out of the nozzle resulting in wastage of large
amounts of fuel into space.
Hypergolic Propellants
A hypergolic
propellant is composed of a fuel and oxidizer that ignite when they come into
contact with each other. There is no need of an ignition mechanism in order to
bring about combustion.
In hypergolic propellants, the fuel part
normally includes:
The oxidizer is generally:
- Nitrogen
tetroxide N2O4 or
- Nitric
acid HNO3
The easy start and restart capability of hypergolic
propellants make them ideal for spacecraft maneuvering systems. They are also
used for orbital insertion as their combustion can be easily controlled and
thus allows the precise adjustments required for insertion into orbit. Hypergolic
propellants are also employed for altitude control.
As we now
know the properties of cryogenic and hypergolic propellants let us compare
them.
• Hypergolic propellants remain in liquid state at
normal temperatures. They do not need the temperature-controlled storage as in
case of cryogenic propellants.
• As compared to cryogenic propellants, hypergolic
propellants are less energetic. That is they produce less energy per unit mass.
For example: in a moon bound shuttle, 75% of the onboard mass would be fuel, in
case of cryogenic propellants. But in case of hypergolic propellants, the
number raises to 90%.
• In comparison to cryogenic propellants, hypergolic
propellants are very poisonous. They react with living tissues as well cause
injuries. So it is mandatory for technicians to wear full-body Self-Contained
Atmospheric Protection Ensemble (SCAPE) suits.
• They are corrosive
therefore storage requires special containers and safety facilities. It is
necessary that they be stored safely, with no possible contacts between the
fuel parts.
As we have seen all the three types of liquid propellants.
Now let us see what are hybrid propellants and how do they differ from solid
and liquid propellants.
Gas propellants
Different types of propellant used
in
Setallite as well as rocket
Aluminum, powdered
The commonest
fuel for solid-propellant rocket motors. It consists of
round particles, 5–60 micrometers in diameter, and is used in a variety of
composite propellants. During combustion the aluminum particles are oxidized into aluminum
oxide, which tends to stick together to form larger particles. The aluminum
increases the propellant density and combustion temperature, and thereby the specific impulse (a measure of the efficiency of
a rocket engine).
Chemical fuel
A substance
that requires an oxidizer in order to achieve combustion and
develop thrust. Chemical fuels include those used by liquid-propellant rocket engines and solid-propellant rocket motors, jets, and
internal-combustion engines. They contrast with nuclear fuel.
Gaseous propellant
A working
substance used in a gaseous-propellant rocket engine. Nitrogen,
argon, krypton, dry air, and Freon 14 have all been employed in spacecraft.
Hybrid propellant
A form of
chemical rocket propellant in which the fuel and oxidizer are in different physical states. One
of the substances is solid, usually the fuel, while the other, usually the
oxidizer, is liquid. The liquid is injected into the solid, whose fuel
reservoir also serves as the combustion chamber.
Hydrazine (N2H4)
Hydrazine is used as a liquid rocket fuel, both as a monopropellant, especially in attitude control thrusters, and as a bipropellant. As a monopropellant in catalytic decomposition engines, it ignited by passing it over a heated catalyst (alumina pellets impregnated with iridium) that decomposes the fuel and produces ammonia, nitrogen, and hydrogen exhaust gases.
Hydrazine is also used as a corrosion inhibitor in boilers, to cure rubber, and in the production of plastics, explosives, and fungicides.
Liquid
hydrogen (H2)
Hydrogen
in its liquid state, used as a cryogenic rocket fuel;
hydrogen gas turns to liquid under standard atmospheric pressure at -262.9°C.
When oxidized by liquid oxygen,
liquid hydrogen delivers about 40% more thrust per unit mass than other liquid
fuels, such as kerosene.
Hydrogen
 |
Hydrogen diffusion flame
in the Natural Gas
|
A colorless, highly
flammable, gaseous element.
Hydrogen is the first and lightest element in the periodic
table. It was named by Antoine Lavoisier
from the hydro ("water") and genes
("forming").
Hydrogen is the most abundant element in the universe (see elements, cosmic abundance) and one of the most important to life as we know it.
Hydrogen is the most abundant element in the universe (see elements, cosmic abundance) and one of the most important to life as we know it.
Hydrogen is the only element whose isotopes
have been given different names.
atomic number
|
1
|
relative atomic mass
|
1.0079
|
electron configuration
|
1s2
|
atomic radius
|
78 pm
|
relative density
|
0.08988
|
melting point
|
-259.14°C (-434.45°F)
|
boiling point
|
-252.87°C (-455.17°F)
|
oxidation states
|
1, -1
|
Liquid
oxygen (O2)
Oxygen
in its liquid state, used as the oxidizer
in many liquid-propellant
rocket engines. Oxygen gas turns to liquid under standard
atmospheric pressure at -183°C. Molecular weight: 32; density: 1.141 g/ml. Commonly
referred to in rocketry as LOX.
A good liquid propellant
is one with a high specific impulse.
This implies a high combustion temperature and exhaust gases with small
molecular weights. However, another important factor is the density of the
propellant. Lower density propellants require larger storage tanks, thus
increasing the mass of the launch vehicle. Storage temperature is also
important. Also, some propellants are very corrosive, however, materials that
are resistant to certain propellants have been identified for use in rocket
construction.
PROPERTIES OF LIQUID
ROCKET PROPELLANTS
|
|||||
Compound
|
chemical
formula |
molecular
weight |
density
|
melting
point |
boiling
point |
O2
|
32.00
|
1.141 g/ml
|
-218.8 °C
|
-183.0 °C
|
|
N2O4
|
92.01
|
1.45 g/ml
|
-9.3 °C
|
21.15 °C
|
|
HNO3
|
63.01
|
1.55 g/ml
|
-41.6 °C
|
83 °C
|
|
H2
|
2.016
|
0.071 g/ml
|
-259.3 °C
|
-252.9 °C
|
|
N2H4
|
32.05
|
1.004 g/ml
|
1.4 °C
|
113.5 °C
|
|
CH3NHNH2
|
46.07
|
0.866 g/ml
|
-52.4 °C
|
87.5 °C
|
|
dimethyl hydrazine
|
(CH3)2NNH2
|
60.10
|
0.791 g/ml
|
-58 °C
|
63.9 °C
|
C12H26
|
170.34
|
0.749 g/ml
|
-9.6 °C
|
216.3 °C
|
|
Gas Propellants
1).
2). 
Fuel propellants for LEO to GEO transport services:-
The Space Shuttle can't go any higher
than low Earth orbit (LEO), a few hundred kilometers up. Communications
satellites going up to geostationary orbit (GEO) 36,000 km (22,500 miles) up,
must be relaunched from LEO, using a chemically fueled orbital transfer
vehicle. The fuel for this vehicle weighs twice as much as the satellite.
That's right, every one ton of shuttle payload consists of 1/3 ton of cargo
plus 2/3 ton of fuel, if its cargo is going up to GEO from LEO.
Thus, all Earth launch rockets, no
matter how small, will be able to launch satellites for any orbital
destination, including the geostationary market and even beyond Earth orbit,
e.g., to an asteroid. Indeed, since they don't have to launch second stage fuel
propellants, tank and rocket engine, they can increase their satellite launch
capability -- launch bigger satellites.
·
In the competitive communications world, companies and
individuals all over the world strive to offer a market for more convenient and
enhanced communications.
·
Responding to these needs are companies like Motorola and
Microsoft drawing up plans for constellations of satellites in low Earth orbit,
e.g., for cellular communications, and in direct competition to the traditional
phone companies (e.g., AT&T, MCI, Sprint, British Telecom, Telstra).
·
Bigger satellites, discussed later in this chapter, will
offer more competitive, personal services. However, the bigger the satellites,
the more stationkeeping propellants they will need, and the more fuel required
to deliver them.
·
Many satellites in geosynchronous orbit end their life when
they run out of stationkeeping propellants. Many of these satellites would be
valuable to less developed nations. Retrofitting them with a new stationkeeping
thruster and moving them to a new orbit slot where they can be resold would be
a profitable business.
·
Any payload going anywhere in space above low
Earth orbit is a market for transportation services, including exploratory
probes (scientific and commercial), next generation mining operations, and
delivery of all kinds of products everywhere.
·
Some entities may be willing to pay for retrieval
and disposal of their failed satellite before it plunges to Earth, for reasons
of liability.
·
Indeed, with all the orbital debris, some funding
mechanism might be set up to support a garbage truck going around and
collecting debris.
·
Space station operations, both government and
private, will be another large consumer.
Propellant
Usage Examples
Converse of object
- Contain: No differences
were found between inhalers containing either
propellant.
- Use: Light shells with a high
range using standard propellants.
- Replace: But as
solid-fuel replaces liquid-fuel
propellants in
- Have: The satellites have sufficient on-board propellant to
maintain their orbit stations for at least 5 years.
Adjective
modifier
- Solid: Until solid propellants were developed for such
big rockets, this was a universal problem.
·
Liquid:
These use liquid propellant set off by a jolt of
high current through tungsten wire.
- Smokeless: These,
together with the development of smokeless propellants
in rifle caliber cartridges, assisted Maxim's work.
·
Flammable:
Apparently, so I am told, CFCs have been replaced in these aerosols by flammable propellants.
Modifies
a noun
- Missile: In addition,
Iraqi attempts to buy ammonium perchlorate, an oxidiser for solid propellant missiles, were successful, at
least on paper.
- Tank: We are working closely
with our suppliers on the design of the propellant tank sections, which are largely wound
carbon fiber structures.
- Gas: The Concept Colts use a
one piece aluminum canister that contains the smoke chemical and inert propellant gas required to make smoke.
- Charge: The Magazines
Magazines stored 500 6 Inch shells and their cased propellant charges.
- Rocket: The first of these
will be on Friday 5 August and will feature the new Churchill Mk 3 liquid propellant rocket engine.
·
Engine:
The first of these will be on Friday 5 August and will feature the new
Churchill Mk 3 liquid propellant rocket engine.
Noun
used with modifier
- Aerosol: As part of the
service offering TDG will manage stocks of aerosol propellant at one of its operating centers in
- Rocket: Helium pressurized
rocket propellant and rocket fuel
provides takeoff and thruster power.
·
Chemical:
Able to dispense with normal chemical propellants,
the EM tank should be capable of extremely rapid firing.
- Gas: AUDICLEAN remains
sterile between uses and, as it contains no gas propellants, is delivered at room temperature, for
your complete comfort.
- Fuel: The motor contains
solid fuel propellant and can accelerate
the rocket to several hundred miles an hour in some cases.
- Liquid-fuel:
But as solid-fuel replaces liquid-fuel propellants
in
Solid
propellant table which is used in satellite as well as Rocket:-
Solid Propellant Tables
|
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Calculated Variation In
Adiabatic Combustion Temperature
For An Oxygen Reaction With Certain Elements As Reported By Grosse
|
Reference:-
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