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1. EDUCATION HOLE PRESENTS
ENGINEERING CHEMISTRY
Unit-V

2. Fuels........................................................................................................................................ 3
Classification of fuels .......................................................................................................................3
Solid fuels.............................................................................................................................................................3
Liquid fuel.............................................................................................................................................................4
Gaseous fuels.......................................................................................................................................................4
Biofuels.................................................................................................................................................................5
Fossil fuels............................................................................................................................................................5
Nuclear............................................................................................................................................6
Fission ..................................................................................................................................................................6
Fusion...................................................................................................................................................................7
Analysis of Coal ....................................................................................................................... 7
Chemical properties of coal..............................................................................................................8
Moisture...............................................................................................................................................................8
Volatile matter .....................................................................................................................................................8
Ash .......................................................................................................................................................................9
Fixed carbon.........................................................................................................................................................9
Chemical analysis .................................................................................................................................................9
Physical and mechanical properties......................................................................................... 9
Relative density ...............................................................................................................................9
Particle size distribution ................................................................................................................ 10
Float-sink test................................................................................................................................ 10
Abrasion testing............................................................................................................................. 10
Special combustion tests ....................................................................................................... 10
Ash fusion test............................................................................................................................... 11
Crucible swelling index (free swelling index) .....................................................................................................11
Determination of Calorific values .......................................................................................... 11
Heating value................................................................................................................................. 11
Higher heating value..........................................................................................................................................12
Lower heating value...........................................................................................................................................12
Gross heating value............................................................................................................................................13
Measuring heating values..................................................................................................................................13
Relation between heating values.......................................................................................................................13
Biogas ................................................................................................................................... 14
Biomass......................................................................................................................................... 15
Cement and its application ............................................................................................................ 16
Applications of cement.......................................................................................................... 16

3. Plaster of paris............................................................................................................................... 16
Lubricant ....................................................................................................................................... 17
Types of Lubricants ............................................................................................................................................17
Application of UNICORN Brand Lubricants ........................................................................................................18
Corrosion............................................................................................................................... 18
Fuels
Fuels are any materials that store potential energy in forms that can be practicably released and
used as heat energy. The concept originally applied solely to those materials storing energy in the
form of chemical energy that could be released through combustion, but the concept has since
been also applied to other sources of heat energy such as nuclear energy (via nuclear fission or
nuclear fusion), as well as releases of chemical energy released through non-combustion
oxidation (such as in cellular biology or in fuel cells). The heat energy released by many fuels is
harnessed into mechanical energy via an engine. Other times the heat itself is valued for warmth,
cooking, or industrial processes, as well as the illumination that comes with combustion. Fuels
are also used in the cells of organisms in a process known as cellular respiration, where organic
molecules are oxidized to release un-usable energy. Hydrocarbons are by far the most common
source of fuel used by humans, but other substances, including radioactive metals, are also
utilized. Fuels are contrasted with other methods of storing potential energy, such as those that
directly release electrical energy (such as batteries and capacitors) or mechanical energy (such as
flywheels, springs, compressed air, or water in a reservoir).
Classification of fuels
Solid fuels
Solid fuel refers to various types of solid material that are used as fuel to produce energy and
provide heating, usually released through combustion. Solid fuels include wood (see wood fuel),
charcoal, peat, coal, Hexamine fuel tablets, and pellets made from wood (see wood pellets), corn,
wheat, rye and other grains. Solid-fuel rocket technology also uses solid fuel (see solid
propellants). Solid fuels have been used by humanity for many years to create fire. Coal was the
fuel source which enabled the industrial revolution, from firing furnaces, to running steam
engines. Wood was also extensively used to run steam locomotives. Both peat and coal are still
used in electricity generation today. The use of some solid fuels (e.g. coal) is restricted or

4. prohibited in some urban areas, due to unsafe levels of toxic emissions. The use of other solid
fuels such as wood is decreasing as heating technology and the availability of good quality fuel
improves. In some areas, smokeless coal is often the only solid fuel used. In Ireland, peat
briquettes are used as smokeless fuel. They are also used to start a coal fire.
Liquid fuel
Liquid fuels are combustible or energy-generating molecules that can be harnessed to create
mechanical energy, usually producing kinetic energy; they also must take the shape of their
container. It is the fumes of liquid fuels that are flammable instead of the fluid. Most liquid fuels
in widespread use are derived from fossil fuels; however, there are several types, such as
hydrogen fuel (for automotive uses), ethanol, and biodiesel, which are also categorized as a
liquid fuel. Many liquid fuels play a primary role in transportation and the economy.
Some common properties of liquid fuels are that they are easy to transport, and can be handled
with relative ease. Also they are relatively easy to use for all engineering applications, and home
use. (Fuels like Kerosene are rationed and available in government subsidized shops in India for
home use.) Liquid fuels are also used most popularly in Internal combustion engines. Most liquid
fuels used currently are produced from petroleum. The most notable of these is gasoline.
Scientists generally accept that petroleum formed from the fossilized remains of dead plants and
animals by exposure to heat and pressure in the Earth's crust. Conventional diesel is similar to
gasoline in that it is a mixture of aliphatic hydrocarbons extracted from petroleum. Kerosene is
used in kerosene lamps and as a fuel for cooking, heating, and small engines. Natural gas,
composed chiefly of methane, can be compressed to a liquid and used as a substitute for other
traditional liquid fuels. LP gas is a mixture of propane and butane, both of which are easily-
compressible gases under standard atmospheric conditions. It offers many of the advantages of
compressed natural gas (CNG), but is denser than air, does not burn as cleanly, and is much more
easily compressed. Commonly used for cooking and space heating, LP gas and compressed
propane are seeing increased use in motorized vehicles; propane is the third most commonly
used motor fuel globally.
Gaseous fuels
Fuel gas is any one of a number of fuels that under ordinary conditions are gaseous. Many fuel
gases are composed of hydrocarbons (such as methane or propane), hydrogen, carbon monoxide,
or mixtures thereof. Such gases are sources of potential heat energy or light energy that can be
readily transmitted and distributed through pipes from the point of origin directly to the place of
consumption. Fuel gas is contrasted with liquid fuels and from solid fuels, though some fuel
gases are liquefied for storage or transport. While their gaseous nature can be advantageous,
avoiding the difficulty of transporting solid fuel and the dangers of spillage inherent in liquid
fuels, it can also be dangerous. It is possible for a fuel gas to be undetected and collect in certain
areas, leading to the risk of a gas explosion. For this reason, odorizers are added to most fuel

5. gases so that they may be detected by a distinct smell. The most common type of fuel gas in
current use is natural gas.
Biofuels
Biofuel can be broadly defined as solid, liquid, or gas fuel consisting of, or derived from
biomass. Biomass can also be used directly for heating or power—known as biomass fuel.
Biofuel can be produced from any carbon source that can be replenished rapidly e.g. plants.
Many different plants and plant-derived materials are used for biofuel manufacture. Perhaps the
earliest fuel employed by humans is wood. Evidence shows controlled fire was used up to 1.5
million years ago at Swartkrans, South Africa. It is unknown which hominid species first used
fire, as both Australopithecus and an early species of Homo were present at the sites. As a fuel,
wood has remained in use up until the present day, although it has been superseded for many
purposes by other sources. Wood has an energy density of 10–20 MJ/kg. Recently biofuels have
been developed for use in automotive transport (for example Bioethanol and Biodiesel), but there
is widespread public debate about how carbon efficient these fuels are.
Fossil fuels
Fossil fuels are hydrocarbons, primarily coal and petroleum (liquid petroleum or natural gas),
formed from the fossilized remains of ancient plants and animals by exposure to high heat and
pressure in the absence of oxygen in the Earth's crust over hundreds of millions of years.
Commonly, the term fossil fuel also includes hydrocarbon-containing natural resources that are
not derived entirely from biological sources, such as tar sands. These latter sources are properly
known as mineral fuels.
Fossil fuels contain high percentages of carbon and include coal, petroleum, and natural gas.
They range from volatile materials with low carbon:hydrogen ratios like methane, to liquid
petroleum to nonvolatile materials composed of almost pure carbon, like anthracite coal.
Methane can be found in hydrocarbon fields, alone, associated with oil, or in the form of
methane clathrates. Fossil fuels formed from the fossilized remains of dead plants .
by exposure
to heat and pressure in the Earth's crust over millions of years. This biogenic theory was first
introduced by German scholar Georg Agricola in 1556 and later by Mikhail Lomonosov in the
18th century.
It was estimated by the Energy Information Administration that in 2007 primary sources of
energy consisted of petroleum 36.0%, coal 27.4%, natural gas 23.0%, amounting to an 86.4%
share for fossil fuels in primary energy consumption in the world. Non-fossil sources in 2006

6. included hydroelectric 6.3%, nuclear 8.5%, and others (geothermal, solar, tidal, wind, wood,
waste) amounting to 0.9%. World energy consumption was growing about 2.3% per year.
Fossil fuels are non-renewable resources because they take millions of years to form, and
reserves are being depleted much faster than new ones are being made. The production and use
of fossil fuels raise environmental concerns. A global movement toward the generation of
renewable energy is therefore under way to help meet increased energy needs. The burning of
fossil fuels produces around 21.3 billion tonnes (21.3 gigatonnes) of carbon dioxide (CO2) per
year, but it is estimated that natural processes can only absorb about half of that amount, so there
is a net increase of 10.65 billion tonnes of atmospheric carbon dioxide per year (one tonne of
atmospheric carbon is equivalent to 44/12 or 3.7 tonnes of carbon dioxide). Carbon dioxide is
one of the greenhouse gases that enhances radiative forcing and contributes to global warming,
causing the average surface temperature of the Earth to rise in response, which the vast majority
of climate scientists agree will cause major adverse effects. Fuels are a source of energy.
Nuclear
Nuclear fuel is any material that is consumed to derive nuclear energy. Technically speaking this
definition includes all matter because any element under the right conditions will release nuclear
energy, the only materials that are commonly referred to as nuclear fuels though are those that
will produce energy without being placed under extreme duress. Nuclear fuel is a material that
can be 'burned' by nuclear fission or fusion to derive nuclear energy. Nuclear fuel can refer to the
fuel itself, or to physical objects (for example bundles composed of fuel rods) composed of the
fuel material, mixed with structural, neutron moderating, or neutron reflecting materials.
Most nuclear fuels contain heavy fissile elements that are capable of nuclear fission. When these
fuels are struck by neutrons, they are in turn capable of emitting neutrons when they break apart.
This makes possible a self-sustaining chain reaction that releases energy with a controlled rate in
a nuclear reactor or with a very rapid uncontrolled rate in a nuclear weapon. The most common
fissile nuclear fuels are uranium-235 (235
U) and plutonium-239 (239
Pu). The actions of mining,
refining, purifying, using, and ultimately disposing of nuclear fuel together make up the nuclear
fuel cycle. Not all types of nuclear fuels create power from nuclear fission. Plutonium-238 and
some other elements are used to produce small amounts of nuclear power by radioactive decay in
radioisotope thermoelectric generators and other types of atomic batteries. Also, light nuclides
such as tritium (3
H) can be used as fuel for nuclear fusion. Nuclear fuel has the highest energy
density of all practical fuel sources.
Fission
The most common type of nuclear fuel used by humans is heavy fissile elements that can be
made to undergo nuclear fission chain reactions in a nuclear fission reactor; nuclear fuel can

7. refer to the material or to physical objects (for example fuel bundles composed of fuel rods)
composed of the fuel material, perhaps mixed with structural, neutron moderating, or neutron
reflecting materials. The most common fissile nuclear fuels are 235
U and 239
Pu, and the actions of
mining, refining, purifying, using, and ultimately disposing of these elements together make up
the nuclear fuel cycle, which is important for its relevance to nuclear power generation and
nuclear weapons.
Fusion
Fuels that produce energy by the process of nuclear fusion are currently not utilized by man but
are the main source of fuel for stars. Fusion fuels tend to be light elements such as hydrogen
which will combine easily. Energy is required to start fusion by raising temperature so high all
materials would turn into plasma, and allow nuclei to collide and stick together with each other
before repelling due to electric charge. This process is called fusion and it can give out energy. In
stars that undergo nuclear fusion, fuel consists of atomic nuclei that can release energy by the
absorption of a proton or neutron. In most stars the fuel is provided by hydrogen, which can
combine together to form helium through the proton-proton chain reaction or by the CNO cycle.
When the hydrogen fuel is exhausted, nuclear fusion can continue with progressively heavier
elements, although the net energy released is lower because of the smaller difference in nuclear
binding energy. Once iron-56 or nickel-56 nuclei are produced, no further energy can be
obtained by nuclear fusion as these have the highest nuclear binding energies. The elements then
on use up energy instead of giving out when fused, and therefore fusion stops and the stars die.
In attempts by human, fusion are only carried out with hydrogen (isotope of 2 and 3) to form
helium-4 as this reaction gives out the most net energy. Electric confinement (ITER), inertial
confinement(heating by laser) and heating by strong electric currents are the popular methods
used. The power given out is enormonus as each kilogram of hydrogen can give out 0.41PJ. This
means that burning 0.7 tonne of hydrogen per second can power the world, replacing the millions
of tonnes of fossil fuels burnt and emission made by us each second. Unfortunately this clean
energy whose product would dissipate harmlessly as helium if leak happens, and also does not
emit any radiation or pollution, is not expected to contribute electricity to electricity networks
until 2040.
Analysis of Coal
Coal Analysis techniques are specific analytical methods designed to measure the particular
physical and chemical properties of coals. These methods are used primarily to determine the
suitability of coal for coking, power generation or for iron ore smelting in the manufacture of
steel.

8. Chemical properties of coal
Coal comes in four main types or ranks: lignite or brown coal, bituminous coal or black coal,
anthracite and graphite. Each type of coal has a certain set of physical parameters which are
mostly controlled by moisture, volatile content (in terms of aliphatic or aromatic hydrocarbons)
and carbon content.
Moisture
Moisture is an important property of coal, as all coals are mined wet. Groundwater and other
extraneous moisture is known as adventitious moisture and is readily evaporated. Moisture held
within the coal itself is known as inherent moisture and is analysed quantitatively. Moisture may
occur in four possible forms within coal:
• Surface moisture: water held on the surface of coal particles or macerals
• Hydroscopic moisture: water held by capillary action within the microfractures of the
coal
• Decomposition moisture: water held within the coal's decomposed organic compounds
• Mineral moisture: water which comprises part of the crystal structure of hydrous silicates
such as clays
Total moisture is analysed by loss of mass between an untreated sample and the sample once
analysed. This is achieved by any of the following methods;
1. Heating the coal with toluene
2. Drying in a minimum free-space oven at 150 °C (302 °F) within a nitrogen atmosphere
3. Drying in air at 100 to 105 °C (212 to 221 °F) and relative loss of mass determined
Methods 1 and 2 are suitable with low-rank coals but method 3 is only suitable for high-rank
coals as free air drying low-rank coals may promote oxidation. Inherent moisture is analysed
similarly, though it may be done in a vacuum.
Volatile matter
Volatile matter in coal refers to the components of coal, except for moisture, which are liberated
at high temperature in the absence of air. This is usually a mixture of short and long chain
hydrocarbons, aromatic hydrocarbons and some sulfur. The volatile matter of coal is determined
under rigidly controlled standards. In Australian and British laboratories this involves heating the
coal sample to 900 ± 5 °C (1650 ±10 °F) for 10 min.

9. Ash
Ash content of coal is the non-combustible residue left after coal is burnt. It represents the bulk
mineral matter after carbon, oxygen, sulfur and water (including from clays) has been driven off
during combustion. Analysis is fairly straight forward, with the coal thoroughly burnt and the ash
material expressed as a percentage of the original weight. It can also give an indication about the
quality of coal.
Fixed carbon
The fixed carbon content of the coal is the carbon found in the material which is left after volatile
materials are driven off. This differs from the ultimate carbon content of the coal because some
carbon is lost in hydrocarbons with the volatiles. Fixed carbon is used as an estimate of the
amount of coke that will be yielded from a sample of coal. Fixed carbon is determined by
removing the mass of volatiles determined by the volatility test, above, from the original mass of
the coal sample.
Chemical analysis
Coal is also assayed for oxygen content, hydrogen content and sulfur. Sulfur is also analysed to
determine whether it is a sulfide mineral or in a sulfate form. Sulfide content is determined by
measurement of iron content, as this will determine the amount of sulfur present as iron pyrite or
dissolution of the sulfates in hydrochloric acid with precipitation as barium sulfate. Carbonate
minerals are analysed similarly, by measurement of the amount of carbon dioxide emitted when
the coal is treated with hydrochloric acid. The carbonate content is necessary to determine the
combustible carbon content and incombustible (carbonate carbon) content. Chlorine, phosphorus
and iron are also determined to characterise the coal's suitability for steel manufacture.An
analysis of coal ash may also be carried out to determine not only the composition of coal ash,
but also to determine the levels at which trace elements occur in ash.
Physical and mechanical properties
Relative density
Relative density or specific gravity of the coal depends on the rank of the coal and degree of
mineral impurity. Knowledge of the density of each coal ply is necessary to determine the
properties of composites and blends. The density of the coal seam is necessary for conversion of
resources into reserves. Relative density is normally determined by the loss of a sample's weight
in water. This is best achieved using finely ground coal, as bulk samples are quite porous. To

10. determine in-place coal tonnages however, it is important to preserve the void space when
measuring the specific gravity.
Particle size distribution
The particle size distribution of milled coal depends partly on the rank of the coal, which
determines its brittleness, and on the handling, crushing and milling it has undergone. Generally
coal is utilised in furnaces and coking ovens at a certain size, so the crushability of the coal must
be determined and its behaviour quantified. It is necessary to know these data before coal is
mined, so that suitable crushing machinery can be designed to optimise the particle size for
transport and use.
Float-sink test
Coal plies and particles have different relative densities, determined by vitrinite content, rank,
ash value/mineral content and porosity. Coal is usually washed by passing it over a bath of liquid
of known density. This removes high-ash value particles and increases the saleability of the coal
as well as its energy content per unit volume. Thus, coals must be subjected to a float-sink test in
the laboratory, which will determine the optimum particle size for washing, the density of the
wash liquid required to remove the maximum ash value with the minimum work. Floatsink
testing is achieved on crushed and pulverised coal in a process similar to metallurgical testing on
metallic ore.
Abrasion testing
Abrasion is the property of the coal which describes its propensity and ability to wear away
machinery and undergo autonomous grinding. While carbonaceous matter in coal is relatively
soft, quartz and other mineral constituents in coal are quite abrasive. This is tested in a calibrated
mill, containing four blades of known mass. The coal is agitated in the mill for 12,000
revolutions at a rate of 1,500 revolutions per minute.(I.E 1500 revolution for 8 min.) The
abrasion index is determined by measuring the loss of mass of the four metal blades.
Special combustion tests
Aside from physical or chemical analyses to determine the handling and pollutant profile of a
coal, the energy output of a coal is determined using a bomb calorimeter which measures the
specific energy output of a coal during complete combustion. This is required particularly for
coals used in steam-raising.

11. Ash fusion test
The behaviour of the coal's ash residue at high temperature is a critical factor in selecting coals
for steam power generation. Most furnaces are designed to remove ash as a powdery residue.
Coal which has ash that fuses into a hard glassy slag known as clinker is usually unsatisfactory in
furnaces as it requires cleaning. However, furnaces can be designed to handle the clinker,
generally by removing it as a molten liquid. Ash fusion temperatures are determined by viewing
a moulded specimen of the coal ash through an observation window in a high-temperature
furnace. The ash, in the form of a cone, pyramid or cube, is heated steadily past 1000 °C to as
high a temperature as possible, preferably 1,600 °C (2,910 °F). The following temperatures are
recorded;
• Deformation temperature: This is reached when the corners of the mould first become
rounded
• Softening (sphere) temperature: This is reached when the top of the mould takes on a
spherical shape.
• Hemisphere temperature: This is reached when the entire mould takes on a hemisphere
shape
• Flow (fluid) temperature: This is reached when the molten ash collapses to a flattened
button on the furnace floor.
Crucible swelling index (free swelling index)
The simplest test to evaluate whether a coal is suitable for production of coke is the free swelling
index test. This involves heating a small sample of coal in a standardised crucible to around 800
degrees Celsius (1500 °F).
After heating for a specified time, or until all volatiles are driven off, a small coke button
remains in the crucible. The cross sectional profile of this coke button compared to a set of
standardised profiles determines the Free Swelling Index.
Determination of Calorific values
Heating value
The heating value (or energy value or calorific value) of a substance, usually a fuel or food (see
food energy), is the amount of heat released during the combustion of a specified amount of it.
The energy value is a characteristic for each substance. It is measured in units of energy per unit
of the substance, usually mass, such as: kJ/kg, kJ/mol, kcal/kg, Btu/lb. Heating value is
commonly determined by use of a bomb calorimeter.

12. Heating value unit conversions (for more visit Wolfram Alpha):
• kcal/kg = MJ/kg * 238.846
• Btu/lb = MJ/kg * 429.923
• Btu/lb = kcals * 1.8
The heat of combustion for fuels is expressed as the HHV, LHV, or GHV.
Higher heating value
The quantity known as higher heating value (HHV) (or gross energy or upper heating value or
gross calorific value (GCV) or higher calorific value (HCV)) is determined by bringing all the
products of combustion back to the original pre-combustion temperature, and in particular
condensing any vapor produced. Such measurements often use a standard temperature of 25°C.
This is the same as the thermodynamic heat of combustion since the enthalpy change for the
reaction assumes a common temperature of the compounds before and after combustion, in
which case the water produced by combustion is liquid.The higher heating value takes into
account the latent heat of vaporization of water in the combustion products, and is useful in
calculating heating values for fuels where condensation of the reaction products is practical (e.g.,
in a gas-fired boiler used for space heat). In other words, HHV assumes all the water component
is in liquid state at the end of combustion (in product of combustion) and that heat below 150°C
can be put to use.
Lower heating value
The quantity known as lower heating value (LHV) (net calorific value (NCV) or lower calorific
value (LCV)) is determined by subtracting the heat of vaporization of the water vapor from the
higher heating value. This treats any H2O formed as a vapor. The energy required to vaporize the
water therefore is not released as heat. LHV calculations assume that the water component of a
combustion process is in vapor state at the end of combustion, as opposed to the higher heating
value (HHV) (a.k.a. gross calorific value or gross CV) which assumes that all of the water in a
combustion process is in a liquid state after a combustion process. The LHV assumes that the
latent heat of vaporization of water in the fuel and the reaction products is not recovered. It is
useful in comparing fuels where condensation of the combustion products is impractical, or heat
at a temperature below 150°C cannot be put to use. The above is but one definition of lower
heating value adopted by the American Petroleum Institute (API) and uses a reference
temperature of 60°F (15.56°C). Another definition, used by Gas Processors Suppliers
Association (GPSA) and originally used by API (data collected for API research project 44), is
the enthalpy of all combustion products minus the enthalpy of the fuel at the reference

13. temperature (API research project 44 used 25°C. GPSA currently uses 60°F), minus the enthalpy
of the stoichiometric oxygen (O2) at the reference temperature, minus the heat of vaporization of
the vapor content of the combustion products. The distinction between the two is that this second
definition assumes that the combustion products are all returned to the reference temperature and
the heat content from the condensing vapor is considered not to be useful. This is more easily
calculated from the higher heating value than when using the preceding definition and will in
fact give a slightly different answer.
Gross heating value
• Gross heating value (see AR) accounts for water in the exhaust leaving as vapor, and
includes liquid water in the fuel prior to combustion. This value is important for fuels like
wood or coal, which will usually contain some amount of water prior to burning.
• Note that GPSA 12th Edition states that the Gross Heating Value of a gas is equivalent to
Higher Heating Value. This suggests that there may be different standards in play. The
use of the term Gross normally describes a larger value than the Net, which usually
describes a smaller value. GPSA is consistent with this, and equates the Gross Heating
Value to the higher heating value (for a gas - so probably with no liquid water present),
and the Net Heating Value to the lower heating value.
Measuring heating values
The higher heating value is experimentally determined in a bomb calorimeter. The combustion of
a stoichiometric mixture of fuel and oxidizer (e.g., two moles of hydrogen and one mole of
oxygen) in a steel container at 25° is initiated by an ignition device and the reactions allowed to
complete. When hydrogen and oxygen react during combustion, water vapor is produced. The
vessel and its contents are then cooled to the original 25°C and the higher heating value is
determined as the heat released between identical initial and final temperatures. When the lower
heating value (LHV) is determined, cooling is stopped at 150°C and the reaction heat is only
partially recovered. The limit of 150°C is an arbitrary choice.
Relation between heating values
The difference between the two heating values depends on the chemical composition of the fuel.
In the case of pure carbon or carbon monoxide, the two heating values are almost identical, the
difference being the sensible heat content of carbon dioxide between 150°C and 25°C (sensible
heat exchange causes a change of temperature. In contrast, latent heat is added or subtracted for
phase transitions at constant temperature. Examples: heat of vaporization or heat of fusion). For
hydrogen the difference is much more significant as it includes the sensible heat of water vapor
between 150°C and 100°C, the latent heat of condensation at 100°C, and the sensible heat of the

14. condensed water between 100°C and 25°C. All in all, the higher heating value of hydrogen is
18.2% above its lower heating value (142 MJ/kg vs. 120 MJ/kg). For hydrocarbons the
difference depends on the hydrogen content of the fuel. For gasoline and diesel the higher
heating value exceeds the lower heating value by about 10% and 7% respectively, and for natural
gas about 11%.
A common method of relating HHV to LHV is:
HHV = LHV + hv x (nH2O,out/nfuel,in)
where hv is the heat of vaporization of water, nH2O,out is the moles of water vaporized and nfuel,in
is the number of moles of fuel combusted.
Most applications that burn fuel produce water vapor, which is unused and thus wastes its heat
content. In such applications, the lower heating value is generally used to give a 'benchmark' for
the process; however, for true energy calculations the higher heating value is correct. This is
particularly relevant for natural gas, whose high hydrogen content produces much water. The
gross energy value is relevant for gas burned in condensing boilers and power plants with flue-
gas condensation that condense the water vapor produced by combustion, recovering heat which
would otherwise be wasted.
Biogas
Biogas consists of about 2/3 methane (CH4), 1/3 carbon dioxide (CO2) a little hydrogen sulphide
(H2S) and a little hydrogen (H2). It is created by the decomposition of manure and other forms
of organic waste from industry or households in anaerobic (that is oxygen free) tanks where it is
heated. In the reactor a biological decomposition takes place where the bacteria are producing
biogas. The biomass stays in the reactor for about 2-3 weeks. Biogas can be used for production
of heat and electricity. Biogas is created naturally by the decomposition of organic matter; one
example in the natural world is from moors where marsh gas is created. It is possible to use
about 65% of the energy available in biogas:
30% for electricity, 35% for heat This process has a loss of about 35%:
20% for the heating of the biomass 15% engine loss In principle any kind of organic material can
be transformed for biogas. But if the biogas plant is supposed to be profitable with the current
energy prices there should be used; manure (slurry) from the agriculture, sludge from cleaning of
waste water, plants and waste from the food industry. Manure is the main ingredient – waste is
an additive that increases the production. Pure waste material produces too much gas and thereby
foam which destroys the gas (it has to be separated first). There are two kinds of different biogas
plants in Denmark: common plants and farm plants. Common plants receive manure from
industry and households. In Denmark the first common plant was inaugurated in 1984 and today
there are 20 common plants. The gas that these plants produce can be sold to local CHP units

15. that generate electricity and heat. A farm plant uses only waste material from a single farm, but
also uses manure as material. In Denmark the first farm plants were build after the energy crisis
in the 1970ies, today there are about 60 plants running or under construction.
Biomass
In recent years, environmentalists and policymakers have struggled to evaluate the merits of
various biomass resources. This has posed an enormous challenge, in part, because biomass
brings together a host of environmental disciplines, including air, water, land-use, climate, and
energy. Since few people have expertise in all of these areas, the full range of environmental
impacts – both positive and negative – are not as readily apparent for biomass as they are for
solar, wind, or traditional fossil resources. As a result, environmental groups, large and small,
approach the topic of biomass with exceeding caution despite the fact that biomass has the
potential to be one of the few carbon-neutral and renewable energy resources that is available on
demand and has large-scale, commercially viable applications.
Biomass electricity generation, or biopower, is a multi-stage process that converts non-fossil
fuel-derived organic material into electricity. Biomass can also be used to produce fuels –
biofuels – that can be used in vehicles. Because the vegetation that is the base for all biomass can
be regrown, biopower and biofuels can be renewable. This means that biopower and biofuels can
help reduce our dependency on fossil fuels and nuclear power. If the biomass is regrown, then it
will sequester all of the carbon dioxide released when the biomass is burned. This means that
biopower and biofuels can help reduce the risks of climate change. Furthermore, since biomass
can be stored and burned when needed, biopower can be available on demand, unlike wind and
solar which are only available when the wind blows and the sun shines. A 1997 Energy
Innovations report from a group of environmental organizations forecasts that by 2030 with
proper incentives, biomass could provide more than half of all renewable energy in our economy
and over 15% of all our energy needs. However, in order for the United States to reduce its
greenhouse gas emissions and create a sustainable energy industry, biomass companies must
substantially increase their market share of electric generation. Unfortunately, the biomass
industry operates under a dark cloud that seriously impairs its ability to meet this challenge. This
is due, in large part, to the poor environmental record of the incineration of municipal solid waste
(MSW), a highly suspect category of materials that can be laced with deadly toxins that are
emitted into the air when burned. Unfortunately, MSW is often considered to be a form of
biomass, a cause of great concern for environmental and public health interests who would prefer
to focus the developmental potential of this technology on the many clean and renewable organic
alternatives. In addition, the negative environmental impacts of factory farms, poor forest
management, and large-scale agribusiness have compounded the pessimism surrounding
America’s biomass industry. Biomass developers have done little to alleviate this problem, as
many fail to adequately distinguish sustainable projects from their toxic siblings.

16. Cement and its application
Cement in general, adhesive substances of all kinds, but, in a narrower sense, the binding
materials used in building and civil engineering construction. Cements of this kind are finely
ground powders that, when mixed with water, set to a hard mass. Setting and hardening result
from hydration, which is a chemical combination of the cement compounds with water that
yields submicroscopic crystals or a gel-like material with a high surface area. Because of their
hydrating properties, constructional cements, which will even set and harden under water, are
often called hydraulic cements. The most important of these is.
Applications of cement
Cements may be used alone (i.e., “neat,” as grouting materials), but the normal use is in mortar
and concrete in which the cement is mixed with inert material known as aggregate. Mortar is
cement mixed with sand or crushed stone that must be less than approximately 5 mm (3
/16 inch)
in size. Concrete is a mixture of cement, sand or other fine aggregate, and a coarse aggregate that
for most purposes is up to 19 to 25 mm (3
/4 to 1 inch) in size, but the coarse aggregate may also
be as large as 150 mm (6 inches) when concrete is placed in large masses such as dams. Mortars
are used for binding bricks, blocks, and stone in walls or as surface renderings. Concrete is used
for a large variety of constructional purposes. Mixtures of soil and portland cement are used as a
base for roads. Portland cement also is used in the manufacture of bricks, tiles, shingles, pipes,
beams, railroad ties, and various extruded products. The products are prefabricated in factories
and supplied ready for installation. Because concrete is the most widely used of all construction
materials in the world today, the manufacture of cement is widespread. Each year almost one ton
of concrete is poured per capita in the developed countries.
Plaster of paris
Plaster is a building material used for coating walls and ceilings. Plaster is manufactured as a dry
powder and is mixed with water to form a paste when used. The reaction with water liberates
heat through crystallization and the hydrated plaster then hardens. Plaster can be relatively easily
worked with metal tools or even sandpaper. These characteristics make plaster suitable for a
finishing, rather than a load-bearing material. The term plaster can refer to gypsum plaster (also
known as plaster of Paris), lime plaster, or cement plaster.
Gypsum plaster, or plaster of Paris, is produced by heating gypsum to about 300 °F (150 °C):
4CaSO4·4H2O + Heat → 4CaSO4·H2O + 3H2O (released as steam)
When the dry plaster powder is mixed with water, it re-forms into gypsum. The setting of
unmodified plaster starts about 10 minutes after mixing and is complete in about 45 minutes; but

17. not fully set for 72 hours.[3]
If plaster or gypsum is heated above 392°F (200°C), anhydrite is
formed, which will also re-form as gypsum if mixed with water.
A large gypsum deposit at Montmartre in Paris led "calcined gypsum" (roasted gypsum or
gypsum plaster) to be commonly known as "plaster of Paris". Plasterers often use gypsum to
simulate the appearance of surfaces of wood, stone, or metal, on movie and theatrical sets for
example. Nowadays, theatrical plasterers often use expanded polystyrene, although the job title
remains unchanged. Plaster of Paris can be used to impregnate gauze bandages to make a
sculpting material called modroc. It is used similarly to clay, as it is easily shaped when wet, yet
sets into a resilient and lightweight structure. This is the material that was (and sometimes still
is) used to make classic plaster orthopedic casts to protect limbs with broken bones, the medical
use having been partly inspired by the artistic use (see orthopedic cast). Set modroc is an early
example of a composite material.
Lubricant
The substance used between contact surfaces of moving parts to reduce friction and to dissipate
heat is termed as lubricant. A lubricant may be oil, grease, graphite, or any substance—gas,
liquid, semisolid, or solid—that permits free action of mechanical devices and prevents damage
by abrasion and “seizing” of metal or other components through unequal expansion caused by
heat. In machining processes (e.g. UNICORN automotive lubs) lubricants may also function as
coolants to forestall heat-caused deformities.
Types of Lubricants
UNICORN brand Lubricants can be classified into four main types:
v Automotive Lubricants
v Marine Lubricants
v Industrial Lubricants and
v Specialty Products
In today’s world, most lubricants are derived from mineral oils, such as petroleum and shale oil,
which can be distilled and condensed without decomposition. Synthetic lubricants, like
UNICORN Ultrasynt Brand lubricants are of great value in automotive applications involving
extreme temperatures. In certain types of high-speed machinery films of gas under pressure have
been successfully used as lubricants.

18. Application of UNICORN Brand Lubricants
For the increasingly varied modern industrial requirements, UNICORN offers a wide range of
selection for lubricants, differing widely in viscosity, specific gravity, vapor pressure, boiling
point, and other properties. UNICORN brand lubricants efficiently replace dry friction with
either thin-film or fluid-film friction, depending on the load, speed, or intermittent action of the
moving parts. Thin-film lubrication, in which there is some contact between the moving parts,
usually is specified where heavy loads are a factor. In the case of our fluid or thick-film
lubrication, a pressure film is formed between moving surfaces and keeps them completely apart.
But this type of lubrication cannot easily be maintained in high-speed machinery and therefore is
recommended for use where reciprocating or oscillating conditions are moderate. Application
method is highly significant for efficient operation of machinery. For most machinery, different
methods of lubrication and types of lubricants must be employed for different parts. For
example, in an automobile the chassis is lubricated with grease, the manual transmission and
rear-axle housings are filled with heavy oil, the automatic transmission is lubricated with a
special-grade light oil, wheel bearings are packed with a grease that has a thickener composed of
long fibers, and the crankcase oil that lubricates engine parts is a lightweight, free-flowing oil.
Grease lubricants are semisolid and have several important advantages: They resist being
squeezed out, they are useful under heavy load conditions and in inaccessible parts where the
supply of lubricant cannot easily be renewed, and they tend to form a crust that prevents the
entry of dirt or grit between contact surfaces. It may be applied in various ways: by packing
enclosed parts with it, by pressing it onto moving parts from an adjacent well, by forcing it
through grease cups by a spring device, and by pumping it through pressure guns. Solid
lubricants are especially useful at high and low temperatures, in high vacuums, and in other
applications where oil is not suitable; common solid lubricants are graphite and molybdenum
disulfide.
Corrosion
Corrosion is a general term used to describe various interactions between a material and its
environment leading to degradation in the material properties.
• Interaction with ambient oxygen can cause the formation of oxide layers via diffusion
controlled growth. These may passivate the material against further oxidation.
• In a wet environment, aqueous corrosion can occur due to electrochemical processes
which depend upon metal ion transport and reaction. Gradients of metallic and
electrolytic ion concentrations, temperature, ambient pressure, and the presence of other
metals, bacteria, or active cells, all influence the corrosion rate.
• Electric fields applied to corroding systems can accelerate or inhibit the rate of corrosion
or material deposition. Galvanic corrosion between different metals in an aqueous

19. environment is due to the electric field arising from the different electrode potential of the
two materials. External fields may enhance or supress this corrosion.
• In all of these reactions, electron and ionic transport occurs. The following sections will
be concerned with these processes and the effect of conditions on the corrosion rates.