Republic of the Philippines

University of Science and Technology of Southern Philippines

Junior Philippine Society of Mechanical Engineers

C.M. Recto Avenue, Lapasan, Cagayan de Oro City

Performance Innovative Task

ME37 – Combustion Engineering

Submitted by:
Dave Raphael A. Dumanat
BSME – 4A_F1

Submitted to:
Engr. Elmer N. Mantala
ME37 - Instructor
 I. Gas Mixtures

Nonreacting gas mixtures - A nonreacting gas mixture can Dividing each term of Eq. 12.5 by the total number of
be treated as a pure substance since it is usually a moles of mixture n and using Eq. 12.6
homogeneous mixture of different gases. The properties of
a gas mixture obviously depend on the properties of the
individual gases (called components or constituents) as
well as on the amount of. That is, the sum of the mole fractions of all the
Consider a closed system consisting of a gaseous mixture components in a mixture is equal to unity. The apparent
of two or more components. The composition of the (or average) molecular weight of the mixture, M, is
mixture can be described by giving the mass or the defined as the ratio of the total mass of the mixture, m, to
number of moles of each component present. The mass, the total number of moles of mixture, n
the number of moles, and the molecular weight of a
component 𝑖 are related by

The apparent molecular weight of the mixture can be

calculated as a mole-fraction average of the component
molecular weights

Where:
𝑚𝑖 = 𝑚𝑎𝑠𝑠(𝑘𝑔 𝑜𝑟 𝑙𝑏)
𝑛𝑖 = 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠 (𝑘𝑚𝑜𝑙 𝑙𝑏𝑚𝑜𝑙
Dalton’s Law
𝑀𝑖 = 𝑀𝑜𝑙𝑒𝑐𝑢𝑙𝑎𝑟 𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑐𝑜𝑚𝑝𝑜𝑛𝑒𝑛𝑡 𝑖
The Dalton model is consistent with the concept of an
ideal gas as being made up of molecules that exert
The relative amounts of the components present in the
negligible forces on one another and whose volume is
mixture can be specified in terms of mass fractions. The
negligible relative to the volume occupied by the gas. the
mass fraction mfi of component i is defined as
Dalton model assumes that each mixture component
behaves as an ideal gas as if it were alone at the
A listing of the mass fractions of the components of a
temperature T and volume V of the mixture. It follows
mixture is sometimes referred to as a gravimetric
from the Dalton model that the individual components
analysis.
would not exert the mixture pressure p but rather a partial
pressure.
Total pressure of an ideal gas mixture is equal to the sum
Dividing each term of Eq. 12.2 by the total mass of mixture
of the partial pressures of the constituent components,
m and using Eq. 12.3
That is
That is, the sum of the mass fractions of all the
components in a mixture is equal to unity.

Where:
P= the total pressure of the mixture
Pi = the partial pressure of species
The relative amounts of the components present in the
mixture also can be described in terms of mole fractions.
The mole fraction yi of component i is defined as

R = the universal gas constant = 8.314 kJ/k mol K

A listing of the mole fractions of the components of a

mixture may be called a molar analysis. An analysis of a Thus, the partial pressure of component i can be

mixture in terms of mole fractions is also called a evaluated in terms of its mole fraction yi and the mixture

volumetric analysis. pressure p

 Dividing Eq. 12.14 by the total volume V

Amagat’s Law
The underlying assumption of the Amagat model is that
each mixture component behaves as an ideal gas as if it Thus, the partial volume of component i also can be
existed separately at the pressure p and temperature T evaluated in terms of its mole fraction yi and the total
of the mixture. volume
The volume that ni moles of component i would occupy if
the component existed at p and T is called the partial
volume, Vi, of component i. As shown below, the sum of Since the sum of the mole fractions equals unity, this

the partial volumes equals the total volume. The partial becomes

volume can be evaluated using the

ideal gas equation of state

Finally, note that the Amagat model is a special case of

the additive volume model.
 EXAMPLES

Gas Mixtures

Deep-sea divers must use special gas mixtures in

their tanks, rather than compressed air, to avoid
serious problems, most notably a condition called
51.2
𝑛𝑂2 = = 1.60 𝑚𝑜𝑙
“the bends.” At depths of about 350 ft, divers are 32.00 𝑔/𝑚𝑜𝑙
subject to a pressure of approximately 10 atm. A
typical gas cylinder used for such depths contains B. We can now use the ideal gas law to
51.2 g of O2O2 and 326.4 g of He and has a calculate the partial pressure of each:
volume of 10.0 L. What is the partial pressure of
each gas at 20.00°C, and what is the total pressure 𝑛𝐻𝑒 𝑅𝑇
in the cylinder at this temperature? 𝑃𝐻𝑒 =
𝑉
𝑎𝑡𝑚. 𝐿
Given: masses of components, total volume, and 81.54 𝑚𝑜𝑙 𝑥 0.08206 𝑥293.15 𝐾
= 𝑚𝑜𝑙 .𝐾
temperature 10.0 𝐿
= 𝟏𝟗𝟔. 𝟐 𝒂𝒕𝒎
Asked for: partial pressures and total pressure

Strategy: 𝑛𝑜2 𝑅𝑇
𝑃𝑜2 =
𝑉
A. Calculate the number of moles of He and 𝑎𝑡𝑚. 𝐿
1.60 𝑚𝑜𝑙 𝑥 0.08206 𝑥293.15 𝐾
= 𝑚𝑜𝑙 .𝐾
O2 present.
10.0 𝐿
B. Use the ideal gas law to calculate the partial = 𝟑. 𝟖𝟓 𝒂𝒕𝒎
pressure of each gas. Then add together The total pressure is the sum of the two
the partial pressures to obtain the total partial pressures:
pressure of the gaseous mixture. 𝑃𝑡𝑜𝑡 = 𝑃𝐻𝑒 + 𝑃𝑜2 = (196.2 + 3.85)𝑎𝑡𝑚
= 𝟐𝟎𝟎. 𝟏 𝒂𝒕𝒎

Solution:

A. The number of moles of He is

326.4
𝑛𝐻𝑒 = = 81.54 𝑚𝑜𝑙
4.003 𝑔/𝑚𝑜𝑙
 II.Reacting Mixtures and Combustion

Introduction of Combustion Theoretical Air

When a chemical reaction occurs, the bonds within The minimum amount of air that supplies sufficient oxygen
molecules of the reactants are broken, and atoms and for the complete combustion of all the carbon, hydrogen,
electrons rearrange to form products. In combustion and sulfur present in the fuel is called the theoretical
reactions, rapid oxidation of combustible elements of the
fuel results in energy release as combustion products are
formed. The three major combustible chemical elements in
most common fuels are carbon, hydrogen, and sulfur. amount of air. For complete combustion with the
Combustion is complete when all the carbon present in the theoretical amount of air, the products consist of carbon
fuel is burned to carbon dioxide, all the hydrogen is burned dioxide, water, sulfur dioxide, the nitrogen accompanying
to water, all the sulfur is burned to sulfur dioxide, and all the oxygen in the air, and any nitrogen contained in the fuel.
other combustible elements are fully oxidized. When these No free oxygen appears in the products.
conditions are not fulfilled, combustion is incomplete.
In this chapter, we deal with combustion reactions Determining of Combustion Products
expressed by chemical equations Complete combustion is assumed from any given
of the form problems. For a hydrocarbon fuel, this means that the
only allowed products are CO2, H2O, and N2, with O2
also present when excess air is supplied. If the fuel is
or
specified and combustion is complete, the respective
amounts of the products can be determined by applying the
Fuels conservation of mass principle to the chemical equation.
A fuel is simply a combustible substance. In this chapter The procedure for obtaining the balanced reaction equation
emphasis is on hydrocarbon fuels, which contain hydrogen of an actual reaction where combustion is incomplete is not
and carbon. Sulfur and other chemical substances also may always so straightforward.
be present. Hydrocarbon fuels can exist as liquids, gases, Among several devices for measuring the composition
and solids. of products of combustion are the Orsat analyzer, gas
chromatograph, infrared analyzer, and flame ionization
Air-Fuel Ratio detector. Data from these devices can be used to
determine the mole fractions of the gaseous products of
The air–fuel ratio is simply the ratio of the amount of air in combustion. The analyses are often reported on a “dry”
a reaction to the amount of fuel. The ratio can be written on basis. In a dry product analysis, the mole fractions are
a molar basis (moles of air divided by moles of fuel) or on a given for all gaseous products except the water vapor.
mass basis (mass of air divided by mass of fuel). Since water is formed when hydrocarbon fuels are burned,
Conversion between these values is accomplished using the mole fraction of water vapor in the gaseous products of
the molecular weights of the air, Mair, and fuel, Mfuel, combustion can be significant. If the gaseous products of
Where: combustion are cooled at constant mixture pressure, the
̅̅̅̅
𝐴𝐹 = 𝐴𝑖𝑟 − 𝐹𝑢𝑒𝑙 𝑟𝑎𝑡𝑖𝑜 dew point temperature is reached when water vapor begins
𝐴𝐹 = 𝑟𝑎𝑡𝑖𝑜 𝑜𝑛 𝑚𝑎𝑠𝑠 𝑏𝑎𝑠𝑖𝑠 to condense.
 III.Enthalpy Formation, Enthalpy of Combustion, and The First Law
The First Law of Thermodynamics
Enthalpy Formation
It specifies that energy is recollected. According to it, the
Enthalpy values can be assigned to compounds energy is never made nor extinguished but it can be altered.
for use in the study of reacting systems. The enthalpy of a The quantity of energy lost by a system will be an equal
compound at the standard state equals its enthalpy of measure of the quantity of energy absorbed by the
formation, symbolized h°f. The enthalpy of formation is environment during the energy alteration between the
the energy released or absorbed when the compound is system and the environment. When the system employs
formed from its elements, the compound and elements all energy from the environment, then it is referred to as
being at Tref and pref. The enthalpy of formation is usually endothermic. Similarly, when the system wastes energy to
determined by application of procedures from statistical the environment then it is referred to as exothermic.
thermodynamics using observed spectroscopic data. The first law applied to a combustion process in a control
The enthalpy of formation also can be found in volume is
principle by measuring the heat transfer in a reaction in
which the compound is formed from the elements. 𝑄 = 𝐻𝑃 – 𝐻𝑅
Where:
Example
𝐻𝑃 = 𝑒𝑛𝑡ℎ𝑎𝑙𝑝𝑦 𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑠 𝑜𝑓 𝑐𝑜𝑚𝑏𝑢𝑠𝑡𝑖𝑜𝑛 𝑡ℎ𝑎𝑡 𝑙𝑒𝑎𝑣𝑒𝑠
One half mole of gaseous hydrogen H2(g) reacts with one
𝐻𝑅 = 𝑒𝑛𝑡ℎ𝑎𝑙𝑝𝑦 𝑜𝑓 𝑟𝑒𝑎𝑐𝑡𝑎𝑛𝑡𝑠 𝑡ℎ𝑎𝑡 𝑙𝑒𝑎𝑣𝑒𝑠 𝑒𝑛𝑡𝑒𝑟𝑠
half mole of gaseous chlorine Cl2(g) to produce one mole
of gaseous hydrogen chloride HCl(g) with the enthalpy of For any reaction the first law, can be applied to a control

formation of − 92.30 kJ. volume. If the reactants and products consist of several

Show the creation of carbon dioxide from methane with components, the first law is, neglecting kinetic and

the enthalpy of formation values as in Figure (1). potential energy changes.

Where NI represents the number of moles of substance i.

The work is often zero, but no in, for example, a
combustion turbine.
If combustion occurs in a rigid chamber, for example, a
bomb calorimeter, the first law is

Enthalpy Combustion where we have used enthalpy since the h°f. values are
Enthalpy of combustion denotes the change in enthalpy tabulated. Since the volume of any liquid or solid is
experienced when one mole of an element is heated in negligible compared to the volume of the gases, we write
excess amount of oxygen under the standard conditions. It
is related to the combustion of the element throughout the
process. It is symbolized by Δ Hc.
if 𝑁𝑝𝑟𝑜𝑑 = 𝑁𝑟𝑒𝑎𝑐𝑡 then Q for the rigid volume is equal to Q
The enthalpy of combustion ̅̅̅̅̅
𝒉𝑹𝑷 is defined as the
for the control volume for the isothermal process.
difference between the enthalpy of the products and the
In above relations we employ one of the following methods
enthalpy of the reactants when complete combustion
to (ℎ̅ − ℎ°
̅)
occurs at a given temperature and pressure. That is where
the n’s correspond to the respective coefficients of the
Table B-7 Enthalpy of Combustion and Enthalpy of
reaction equation giving the moles of reactants and Vaporization (Appendices)
products per mole of fuel.
Adiabatic Flame Temperature

In the absence of work Wcv and appreciable kinetic

and potential energy effects, the energy liberated on
combustion is transferred from the reactor in two
ways only: by energy accompanying the exiting
combustion products and by heat transfer to the procedure, let us suppose that the combustion air
surroundings. The smaller the heat transfer, the and the combustion products each form ideal gas
greater the energy carried out with the combustion mixtures.
products and thus the greater the temperature of the
products. The temperature that would be achieved by Then, with the other assumptions stated previously,
the products in the limit of adiabatic operation of the the energy rate balance on a per mole of fuel basis,
reactor is called the adiabatic flame temperature or Eq. 13.12b, reduces to the form hP - hR—that is
adiabatic combustion temperature.
The adiabatic flame temperature can be
where i denotes the incoming fuel and air streams
determined by use of the conservation of mass and
and e the exiting combustion products. With this
conservation of energy principles. To illustrate the
expression, the adiabatic flame temperature can be
determined using table data or computer software,
as follows.

The n’s are obtained on a per mole of fuel basis from

the balanced chemical reaction equation.
 EXAMPLES

In this problem we wish to develop the combustion equation and determine the air-fuel ratio for the complete
combustion of n-Butane (C4H10) with a) theoretical air, and b) 50% excess air.
 IV.Handling of Gaseous Fuels

Gaseous fuel
Composition (% vol)
-it is obtained either naturally or by the treatment of
CH4 92
solid or liquid fuel. Among the naturally occurring
other HC 5
gaseous fuels, natural gas and liquefied
inert gases 3
petroleum gas are most important
Density (kg/m3) 0.7
Gross calorific value 41
Types of Gaseous Fuels
(MJ/m3)

Natural gas is a gaseous fuel which is obtained from

This gas was produced by a cyclic process where the
deposits in sedimentary rock formations which are
reacting bed was alternately blown with air and
also sources of oil.
steam- the former exhibiting an exothermic, and the
• It is then distributed in a high-pressure
latter an endothermic, reaction.
mains system.
A typical town gas produced by this process has the
• Pressure losses are made up by
following properties:
intermediate booster stations and the
Composition (% vol)
pressure is dropped to around 2500 Pa in
H2 48
governor installations where gas is taken
CO 5
from the mains and enters local distribution
CH4 34
networks.
CO2 13
• The initial processing, compression and
heating at governor installations uses the
Density (kg/m3) 0.6
gas as an energy source.
Gross calorific value 20.2
• The energy overhead of the winning and
(MJ/m3)
distribution of a natural gas is about 6% of
the extracted calorific value. Further reaction to methane is promoted by a nickel
catalyst at temperatures of about 250-350℃:

The characteristics of a typical natural gas are:

CO + 3H2 → CH4+ H2O

Coal gas - The gas was produced by heating the The sulfur present in the coal can be removed by the
raw coal in the absence of air to drive off the volatile presence of limestone as follows:
products.This was essentially a two-stage process,
with the carbon in the coal being initially oxidized to H2 + S → H2S
carbon dioxide, followed by a reduction to carbon H2S + CaCO3 → CaS +H2O +CO2
monoxide:
LPG (Liquefied Petroleum Gas) - is a petroleum-
derived product distributed and stored as a liquid in
C + O2 → CO2
pressurized containers. LPG fuels have slightly
CO2 + C → 2CO
variable properties, but they are generally based on
propane (C3H8) or the less volatile butane (C4H10).
Compared to the gaseous fuel described above,
commercial propane and butane have higher calorific
values (on a volumetric basis) and higher densities.
Both these fuels are heavier than air, which can have
a bearing on safety precautions in some
circumstances.

Typical properties of industrial LPG are given below:

Typical values for some gaseous fuels are:
Gas Propane Butane
Density 1.7-1.9 2.3-2.5 Fuel Lower Upper
(kg/m3) Explosion Explosion Limit
Gross calorific 96 122 Limit (LEL) (UEL) %
value (MJ/m3) %
Boiling point -45 0 Methane 5 15
(℃ at 1 bar) Propane 2 10
Hydrogen 4 74
Flammability Limits Carbon 13 74
• Gaseous fuels are capable of being fully monoxide
mixed (i.e. at a molecular level) with the
combustion air. Type of Gas Burners
• However, not all mixtures of fuel and air are
capable of supporting, or propagating, a Diffusion Burners
flame. • The fuel issues from a jet into the
• When the energy transfer from the initial surrounding air and the flame burns by
control volume is insufficient to propagate a diffusion of this air into the gas envelope.
flame, the mixture will be nonflammable. • A diffusion flame from a hydrocarbon fuel
• Flammability limits can be experimentally has a yellow color as a result of radiation
determined to a high degree of repeatability from the carbon particles which are formed
in an apparatus developed by the US within the flame.
Bureau of Mines. • The flame can have laminar characteristics
• The apparatus consists of a flame tube with or it may be turbulent if the Reynolds
ignition electrodes near to its lower end number at the nozzle of the burner is
greater than 2,000.

Premixed Burners

• The vast majority of practical gaseous

burners mix the air and fuel before they
pass through a jet into the combustion
zone.

• In the simplest burners, such as those that

are used in domestic cookers and boilers,
• The limits are affected by temperature and
the buoyancy force generated by the hot
pressure but the values are usually quoted
gases is used to overcome the resistance of
as volume percentages at atmospheric
the equipment.
pressure and 25℃.
• However, in larger installations the gas gas from the wellhead to the processing
supply pressure is boosted and the air is plant.
supplied by a fan.
• Intrastate/interstate pipeline system --
• The principle is illustrated by the flame from Pipelines can be classified as intrastate or
a Bunsen burner with the air hole open interstate. Their technical and operational
characteristics are substantially similar, and
The gas and air are mixed between the fuel they both have the same goal: to
jet and the burner jet, usually with all the air transport natural gas from the processing
required for complete combustion. plant to the centers of its consumption
• Distribution pipeline system -the
Three Types of Pipelines along the
distribution pipeline system has the
Transportation Route:
purpose of delivering gas to the end-
• Gathering pipeline system - the consumers.
gathering system includes low pressure
small pipelines that transport raw natural
 V.Handling of Volatile Liquid Fuels

Liquid fuels are combustible or energy-generating • Position the fuel truck away from other
molecules that can be harnessed to create vehicles so it doesn’t interfere with their
mechanical energy, usually producing kinetic movements.
energy; they also must take the shape of their
Homeowners Use Liquid Fuels for:
container.
• Vehicles
It is the fumes of liquid fuels that are
• Equipment
flammable instead of the fluid.
• Heating
Most liquid fuels in widespread use are
derived from fossil fuels; however, there are several
Liquid Fuels Hazards
types, such as hydrogen fuel (for automotive uses),
ethanol, and biodiesel, which are also categorized as • Leaks and spills can pollute water, soil and
a liquid fuel. Many liquid fuels play a primary role in air.
transportation and the economy • Contaminated water and soil can be costly
to cleanup

Underground Fuel Tanks

• Locate fuel storage tanks more than 150

feet from a well, spring, cistern, sinkhole or
surface water.

STORING AND HANDLING FUEL • Replace underground tanks that are more
thank 15 years old because they are at high
• Don’t store more fuel than the minimum amount
risk for leaks.
needed.
• Buy the tanks that offer corrosion protection
• Use approved containers, away from heat sources • Test the tank frequently for “tightness” and
and in well-ventilated areas. account for use monthly.

• Never attempt to siphon gasoline with your mouth –

doing so could be deadly. Avoiding Spills

• Refrain from prolonged skin contact with fuel, avoid Most spills are caused by overfilling. To avoid
breathing in fuel fumes or vapors, and remove any overfilling, you should:
clothing that comes in contact with fuel
• Always supervise fuel transfers
RECEIVING FUEL • Use automatic shutoff devices if available.
• Install a fill level indicator or vent whistle.
• When your workplace is receiving fuel from a delivery
• Construct a concrete containment dike.
truck:

• Don’t allow smoking near fuel trucks, as vapors may

Supports tanks well.
ignite.
• Place on a solid, stable base
• Have spill kits handy in the event of a spill.
• Construct footing of brick, cinder block or
• Keep fuel caps closed, except during filling and concrete.
gauging, to avoid the release of vapors.
Protect tanks from damage. the neck. These flasks should always be
kept behind protective shields while in use.
• Don’t store objects around, over or under a tank
• Liquefied gases, because of their extremely
• Enclose in a structure or install posts or other
low temperature, will “burn” the skin like hot
barriers around the tank.
liquids. Never permit liquefied gases to
come into contact with the skin or allow
Abandoned Tanks
liquid oxygen or liquid nitrogen to soak
Consult a previous owner or neighbor if you’re not clothing. Serious burns may result from
sure where the tank is located. careless handling
• When personnel are handling liquefied
Remove unused tanks because:
gases, they are advised to protect
• They may pose risk to health and the themselves by wearing goggles or face
environment. shields and leather gloves large enough to
• They can cost you money allow quick removal. Rubber aprons and
Check for leaks after the tank is removed. high-topped shoes worn with trouser legs
outside the tops are also desirable.
Portable Fuel Containers
• Liquid oxygen must never be poured upon

• Buy fuel in small quantities. clothing, fabrics, rags, waste or other

• Store in original or UL approved containers. readily combustible materials, nor the

• Check containers and machinery often for gaseous oxygen arising from liquid oxygen

leaks be allowed to penetrate clothing.

• Store containers in a secure, well- Combustible substances in the presence of

ventilated, unattached garage or shed away oxygen are highly flammable. A spark can

from the house. start a serious fire and may cause serious
personal injury.

Liquified Gas Safety Precautions: Handling • Liquid oxygen should never be poured or
demonstrated in close proximity to a source
• Personnel handling liquefied gases should of ignition. A spark coming into contact with
be thoroughly instructed as to the nature of a combustible material in an oxygen-
the materials. Training is essential to enriched atmosphere can burst into flames
minimize accidental spilling. This is to and immediately cover the surface of the
prevent damage from the coldness of the combustible material.
liquid or from the fire hazard of the oxygen • When pouring liquefied gases from one
enriched air. container to another, the receiving
• Personnel handling liquefied gases should container should be cooled gradually to
be thoroughly instructed as to the nature of prevent thermal shock. The liquid should be
the materials. Training is essential to poured slowly to avoid spattering. The
minimize accidental spilling. This is to receiving vessel should always be vented to
prevent damage from the coldness of the the atmosphere and high concentrations of
liquid or from the fire hazard of the oxygen gaseous oxygen and/or nitrogen should not
enriched air. be allowed to collect.
• Small amounts of liquefied gases are
frequently handled in glass dewar flasks
which occasionally collapse, particularly if
the liquid oxygen is splashed on the joint at
 VI.Fuels Oil Handling System (FOHS)

Fuel oil (heavy industrial fuel oil) is a medium • In the unlikely event of a fire involving oil
viscosity product that is highly variable and often products, call the emergency Services
blended with lower boiling products. Fuel oil is a immediately. To extinguish a small fire, a
fraction obtained from petroleum distillation, either as foam, dry powder or CO2 extinguisher or
a distillate or a residue at the Oil refinery. It is earth/sand can be used.
commonly used for burning in furnaces, boilers,
• DO NOT USE WATER ON AN OIL FIRE
stoves and lanterns to generate heat.
AS IT WILL CAUSE THE FIRE TO
Benefits of using Fuel Oil SPREAD

• Safe and Secure – Fuel oil is not explosive OIL STORAGE

and can only be ignited when using a
• Oil products should be stored in a soundly
specific system. This means it can be
constructed tank, designed specifically for
stored safely and used in boilers and
the purpose, and should be sited away from
furnaces without any safety issues.
any source of heat or potential ignition. A
• Economical – Depending on when you means, such as a drip-tray or bund, should
purchase fuel oil, you will probably find that ideally be provided, capable of containing
it is cheaper to use than gas and electricity. any oil that may leak or spill from the tank.
It’s also very efficient, which means you
• The tank should be clearly marked with the
won’t have to refill your tank as often as you
grade of oil required and the tank's total
might think.
capacity. An accurate gauge or dipstick
TYPES OF FUEL should be fitted to the tank to avoid
overfilling (a principal cause of spillages).
• Light diesel oil (LDO)
Water from rain or condensation should be
• High speed diesel oil (HSDO) removed from the tank regularly.

• Heavy furnace oil (HFO) • The tank and its associated equipment
should be examined carefully before and
• Low Sulphur heavy stock (LSHS)
after a delivery and if there is a problem,
Table 6.1 Specification for Light Diesel Oil such as a spillage or leakage, this must be
(LDO) notified to the oil supplier as soon as
possible.
Table 6.2 High Speed Diesel Oil - Normal
• In the event of a spillage or leakage, do not
HEALTH & SAFETY INFORMATION
smoke in the vicinity and do not try to
• These products are flammable but disperse the oil with water; under no
evaporate only slowly at ambient circumstances should a petroleum product
temperature and, in normal use, they do not be allowed to enter a drain or watercourse.
constitute a significant fire or health hazard.
Fuel Oil Handling System (FOHS)
• Never heat a container that has stored oil
• Unloading hose
without first ensuring that it is free of
residual oil and oil vapour. • Decanting and transfer facilities

• Pumping and heating unit

• Bulk storage tank, floating roof tanks with material of construction
of SS 316 / SS304 / Carbon steel.
• Day tank
A typical storage tank consists of
• Process utility piping.
• Electrical / steam heaters

• Flame and lightings arresters

• Breather valves

• Instrumentation (level and temperature)

• Thermal insulation

Unloading Skid

Used for unloading the fuel from tankers /

wagons through hoses

A typical unloading skid consists of

• Suction strainers

• Pumps with drives

• Instrumentation (pressure, temperature &

Transfer Skid
flow)
Used for transferring the fuel from storage tanks
• Interconnecting piping with valves mounted
to the day tanks
on a common base frame
A typical transfer skid consists of suction
strainers

• pumps with drives

• instrumentation (pressure, termperature &

flow)

• interconnecting piping with valves

Bulk Storage Tank

Designed to API 650 and IS 803 standards to

accommodate the Fuel Oil unloaded from
tankers / wagons. These can be vertical fixed /
 • inline heaters on the pump discharge line engine etc. at a required pressure, temperature &
mounted on a common base frame. flow rate.

A typical PHF unit consists of

Day Tanks • Inline Heater

Designed to accommodate the day’s • Instrumentation (pressure, temperature,

requirement of fuel and located near the utility flow, viscosity etc.)
point.
• Pressure regulating / control valves

The balance scope as described in the transfer skid.

Pumping & Heating (PHF) Unit

PHF unit is used to transfer the fuel from day tanks

to the utility point i.e. boiler firing, furnace firing,
 VII.Gas Cycle
Air-Standard Otto Cycle The thermal efficiency is the ratio of the net
The air-standard Otto cycle is an ideal cycle that work of the cycle to the heat added.
assumes heat addition occurs instantaneously while
the piston is at top dead center. The Otto cycle is
shown on the p–y and T–s diagrams of Fig. 9.3. The
cycle consists of four internally reversible processes
in series:
Process 1–2 is an isentropic compression of the air
as the piston moves from bottom dead center to top
Compression Ratio:
dead center.
rv = V1/V2
Process 2–3 is a constant-volume heat transfer to
When the Otto cycle is analyzed on a cold air
the air from an external source while the piston is at
standard basis, would be used for the isentropic
top dead center. This process is intended to
processes, respectively
represent the ignition of the fuel–air mixture and the
subsequent rapid burning.
Process 3–4 is an isentropic expansion (power
stroke).
Process 4–1 completes the cycle by a constant-
volume process in which heat is rejected from the air
while the piston is at bottom dead center. where k is the specific heat ratio, k = cp/cv.

Air-Standard Diesel Cycle

The air-standard Diesel cycle is an ideal cycle that
assumes heat addition occurs during a constant-
pressure process that starts with the piston at top
dead center. The Diesel cycle is shown on p–y and
T–s diagrams.

Process 1–2 is an isentropic compression of the air

as the piston moves from bottom dead center to top
Figure 7.1 p–v and T–s diagrams of the air-standard
dead center.
Otto cycle.
Process 2–3 is a constant-volume heat transfer to
Cycle Analysis the air from an external source while the piston is at
Expressions for these energy transfers are obtained top dead center. This process is intended to
by reducing the closed system energy balance represent the ignition of the fuel–air mixture and the
assuming that changes in kinetic and potential subsequent rapid burning.
energy can be ignored. The results are Process 3–4 is an isentropic expansion (power
stroke). Constant Volume
Process 4–1 in which heat is rejected from the air
while the piston is at bottom dead center. This
process replaces the exhaust and intake processes
of the actual engine.
 Cycle Analysis

Figure 7.3 p–v and T–s diagrams of the air-

Figure 7.2 p–v and T–s diagrams of the air- standard Dual cycle.

standard Diesel cycle.

Compression Ratio: During the isentropic compression process 1–2

rc = V3/V2 there is no heat transfer, and the work is

In a cold air-standard analysis, the appropriate

expression for evaluating T2 is provided by

As for the corresponding process of the Otto cycle,

in the constant-volume portion of the heat addition
process, Process 2–3, there is no work, and the
heat transfer is

The thermal efficiency of the Diesel cycle increases

with increasing compression ratio. This can be In the constant-pressure portion of the heat addition
process, Process 3–4, there is both work and heat
brought out simply using a cold air-standard analysis.
transfer, as for the corresponding process of the
On a cold air-standard basis, the thermal efficiency Diesel cycle
of the Diesel cycle can be expressed as

During the isentropic expansion process 4–5 there

is no heat transfer, and the work is

Air-Standard Dual Cycle

The pressure–volume diagrams of actual internal
combustion engines are not described well by the Finally, the constant-volume heat rejection process

Otto and Diesel cycles. An air-standard cycle that 5–1 that completes the cycle involves heat transfer

can be made to approximate the pressure variations but no work

more closely is the air-standard dual cycle.

Process 1–2 is an isentropic compression. The
heat addition occurs in two steps. Pressure Ratio:
Process 2–3 is a constant volume heat addition rp = P3/P2
Process 3–4 is a constant-pressure heat addition. It On a cold air-standard basis, the thermal efficiency
also makes up the first part of the power stroke. of the Dual cycle can be expressed as
Process 4–5 is an isentropic expansion and the
remainder of the power stroke.
Process 5–1 the cycle is completed by a constant-
volume heat rejection process.
Gas Turbine Power Plants

Gas turbine power plants may operate on either an

open or closed basis. The open mode pictured in Fig.
9.8a is more common. This is an engine in which
atmospheric air is continuously drawn into the
compressor, where it is compressed to a high
The heat rejected per unit of mass is
where Qout is positive in value.

Figure 7.4 Simple gas turbine. (a) Open to the

atmosphere. (b) Closed.

Air-Standard Brayton Cycle

A simplified representation of the states visited by the

air in such a cycle can be devised by regarding the
turbine exhaust air as restored to the compressor
The thermal efficiency of the cycle
inlet state by passing through a heat exchanger
where heat rejection to the surroundings occurs. The
cycle that results with this further idealization is
called the air-standard Brayton cycle.
The back work ratio for the cycle is

Figure 7.5 Air-standard gas turbine cycle.

The symbol Wc denotes work input and takes on a
positive value. The heat added to the cycle per unit
of mass is
 EXAMPLES

Otto Cycle

A spark ignition engine is proposed to have a compression ratio of 10 while operating with a low temperature of
200°C and a low pressure of 200 kPa. If the work output is to be 1000 kJ/kg, calculate the maximum possible
thermal efficiency and compare with that of a Carnot cycle. Also, calculate the MEP. The Otto cycle provides the
model for this engine. The maximum possible thermal efficiency for the engine would be

Diesel Cycle

A diesel cycle, with a compression ratio of 18 operates on air with a low pressure of 200 kPa and a low
temperature 200°C. if the work output is 1000 kJ/kg, determine the thermal efficiency and the MEP. Also,
compare with the efficiency of an Otto cycle operating with same maximum pressure. The cut-off ratio rc is found
first. We have
Dual Cycle

A dual cycle, which operates on air with a compression ratio of 16, has a low pressure of 200 kPa ad low
temperature of 200°C. If the cut-off ratio is 2 and the pressure ratio is 1.3, calculate the thermal efficiency, the
heat input, the work out, and the MEP.
 VIII.Performance Parameters
Engine performance is an indication of the degree of The power developed by an engine and
success of the engine performs its assigned tasks, measured at the output shaft is called the brake
i.e. the conversion of the chemical energy contained power (bp) and is given by
in the fuel into the useful mechanical work. The
2𝜋𝑁𝑇
performance of an engine is evaluated on the basis 𝑏𝑝 =
60
of the following:
where, T is torque (N-m) and N is the rotational
a. Specific Fuel Consumption
speed (rpm)
b. Brake Mean Effective Pressure
c. Specific Power Output Indicated Power
d. Specific Weight
It is the power developed in the cylinder and
e. Exhaust Smoke and Other Emissions
For the evaluation of an engine performance few thus, forms the basis of evaluation of
combustion efficiency or the heat release in the
more parameters are choses and the effect of
cylinder,
various operating conditions, design concepts and
modifications on theses parameters are studied. The 𝑃𝑖𝑚 𝐿𝐴𝑁𝐾
𝐼𝑃 =
basic performance parameters are the following: 60

a. Power and Mechanical Efficiency Where,

b. Mean Effective Pressure and Torque
𝑃𝑖𝑚 = 𝑀𝑒𝑎𝑛 𝑒𝑓𝑓𝑒𝑐𝑡𝑖𝑣𝑒 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒, 𝑁/𝑚2
c. Specific Output
d. Volumetric Efficiency 𝐿 = 𝑙𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑡ℎ𝑒 𝑠𝑡𝑟𝑜𝑘𝑒, 𝑚
e. Fuel-Air Ratio
𝐴 = 𝑎𝑟𝑒𝑎 𝑜𝑓 𝑡ℎ𝑒 𝑝𝑖𝑠𝑡𝑜𝑛, 𝑚2
f. Specific Fuel Consumption
g. Thermal Efficiency and Heat Balance 𝑁 = 𝑟𝑜𝑡𝑎𝑡𝑖𝑜𝑛𝑎𝑙 𝑠𝑝𝑒𝑒𝑑 𝑜𝑓 𝑡ℎ𝑒 𝑒𝑛𝑔𝑖𝑛𝑒, 𝑟𝑝𝑚
h. Exhaust Smoke and Other Emissions
𝑘 = 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑐𝑦𝑙𝑖𝑛𝑑𝑒𝑟𝑠
i. Specific Weight
𝑏𝑝
𝑀𝑒𝑐ℎ𝑎𝑛𝑖𝑐𝑎 𝐸𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 =
𝑖𝑝
Power and Mechanical Efficiency
Friction Power, fp = ip – bp
The main purpose of running an engine is to obtain
mechanical power. 𝑏𝑝
𝑀𝑒𝑐ℎ𝑎𝑛𝑖𝑐𝑎𝑙 𝐸𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 =
𝑏𝑝 − 𝑓𝑝
• Power is defined as the rate of doing work
Mean Effective Pressure and Torque
and is equal to the product of force and
linear velocity or the product of torque and It is defined as hypothetical/average pressure
angular velocity. which is assumed to be active on the piston
• Thus, the measurement of power involves throughout the power stroke, therefore,
the measurement of force (or torque) as
𝑃𝑖𝑚 𝐿𝐴𝑁𝐾
well as speed. The force or torque is 𝑃𝑖𝑚 =
60
measure with the help of a dynamometer
and the speed by a tachometer. Where,

𝑃𝑖𝑚 = 𝑀𝑒𝑎𝑛 𝑒𝑓𝑓𝑒𝑐𝑡𝑖𝑣𝑒 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒, 𝑁/𝑚2

𝐿 = 𝑙𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑡ℎ𝑒 𝑠𝑡𝑟𝑜𝑘𝑒, 𝑚

 𝐴 = 𝑎𝑟𝑒𝑎 𝑜𝑓 𝑡ℎ𝑒 𝑝𝑖𝑠𝑡𝑜𝑛, 𝑚2 𝑅𝑒𝑙𝑎𝑡𝑖𝑣𝑒 𝑓𝑢𝑒𝑙 − 𝑎𝑖𝑟 𝑟𝑎𝑡𝑖𝑜, 𝐹𝑟
𝐴𝑐𝑡𝑢𝑒𝑙 𝑓𝑢𝑒𝑙 − 𝐴𝑖𝑟 𝑟𝑎𝑡𝑖𝑜
𝑁 = 𝑟𝑜𝑡𝑎𝑡𝑖𝑜𝑛𝑎𝑙 𝑠𝑝𝑒𝑒𝑑 𝑜𝑓 𝑡ℎ𝑒 𝑒𝑛𝑔𝑖𝑛𝑒, 𝑟𝑝𝑚 =
𝑆𝑡𝑜𝑖𝑐ℎ𝑖𝑜𝑚𝑒𝑡𝑟𝑖𝑐 𝑓𝑢𝑒𝑙 − 𝐴𝑖𝑟 𝑟𝑎𝑡𝑖𝑜

𝑘 = 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑐𝑦𝑙𝑖𝑛𝑑𝑒𝑟𝑠 Brake Specific Fuel Consumption

Specific fuel consumption is defined as the amount
Friction mean effective (fmap) of fuel consumed for each unit of brake power
developed per hour. It is clear indication of the
𝑓𝑚𝑎𝑝 = 𝑖𝑚𝑒𝑝 − 𝑏𝑚𝑒𝑝
efficiency with which the engine develops power from
Where: fuel.
𝐵𝑟𝑎𝑘𝑒 𝑠𝑝𝑒𝑐𝑖𝑓𝑖𝑐 𝑓𝑢𝑒𝑙 𝑐𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 (𝑏𝑠𝑓𝑐)
imep = indicated mean effective pressure
𝐴𝑐𝑡𝑢𝑎𝑙 − 𝑅𝑎𝑡𝑖𝑜
=
bmep = brake mean effective pressure 𝑆𝑡𝑜𝑖𝑐ℎ𝑖𝑜𝑚𝑒𝑡𝑟𝑖𝑐 𝑓𝑢𝑒𝑙 − 𝐴𝑖𝑟 𝑟𝑎𝑡𝑖𝑜

Specific Output
Thermal Efficiency and Heat Balance
Specific output of an engine is defined as the It is defined as the ratio of the output to that of the
brake power (output) per unit of piston chemical energy input in the form of fuel supply. It
displacement and is given by, mat be based on brake or indicated output, it is the
true indication of the efficiency with which in the
𝑏𝑝
𝑆𝑝𝑒𝑐𝑖𝑓𝑖𝑐 𝑜𝑢𝑡𝑝𝑢𝑡 = chemical energy of fuel (input) is converted into
𝐴𝑥𝐿
mechanical work.
= 𝐶𝑜𝑛𝑠𝑡𝑎𝑛𝑡 𝑥 𝑏𝑚𝑒𝑝 𝑥 𝑟𝑝𝑚
𝑏𝑝
𝐵𝑟𝑎𝑘𝑒 𝑡ℎ𝑒𝑟𝑚𝑎𝑙 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 =
Volumetric Efficiency 𝑚𝑓 𝑥 𝐶𝑣
𝑘𝐽
Where, 𝐶𝑣 𝐶𝑎𝑙𝑜𝑟𝑖𝑓𝑖𝑐 𝑣𝑎𝑙𝑢𝑒 𝑜𝑓 𝑓𝑢𝑒𝑙,
It is an indication of the measure of the degree 𝑘𝑔

to which the engine fills its swept volume. It is 𝑚𝑓 = 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑓𝑢𝑒𝑙 𝑠𝑢𝑝𝑝𝑙𝑖𝑒𝑑, 𝑘𝑔/𝑠𝑒𝑐
defined as the ratio of the mass of air inducted
into the engine cylinder during the suction stroke Stirling Cycle
to the stroke to the mass of the air It is a thermodynamic cycle consists of two
corresponding to the swept volume of the engine isothermal and two isochoric processes. Heat
at atmospheric pressure and temperature. rejection and heat addition takes place at constant
temperature.
Volumetric Efficiency,

𝑛𝑣
𝑀𝑎𝑠𝑠 𝑜𝑓 𝑐ℎ𝑎𝑟𝑔𝑒𝑑 𝑎𝑐𝑡𝑢𝑎𝑙𝑙𝑦 𝑠𝑢𝑐𝑘𝑒𝑑
=
𝑚𝑎𝑠𝑠 𝑜𝑓 𝑐ℎ𝑎𝑟𝑔𝑒 𝑐𝑜𝑟𝑟𝑒𝑠𝑝𝑜𝑛𝑑𝑖𝑛𝑔 𝑡𝑜 𝑡ℎ𝑒 𝑐𝑦𝑙𝑢𝑛𝑑𝑒𝑟 𝑖𝑛𝑡𝑎𝑘𝑒 𝑃 𝑎𝑛𝑑 𝑇 𝑐𝑜𝑛𝑑𝑖𝑡𝑖𝑜𝑛𝑠

Fuel-Air Ratio (F/A)

It is the ratio of the mass of fuel to the mass of air in
the fuel-air mixture. It is reciprocal of fuel-air ratio.
Fuel-air ratio of the mixture affects the combustion
phenomenon in that it determines the flame
propagation velocity, the heat release in the
combustion chamber, the maximum temperature
and the completeness of combustion. Where,

1-2: Isothermal compression

2-3: Constant volume cooling

3-4: Isothermal expansion Work done = heat supplied – heat rejected

4-1: Contant volume heating Thermal efficiency can be given by the equation

From the p-V and T-s diagram of stirling cycle it is

clear that the amount of heat addition and heat

rejection during constant volume is same.

Heat supplied = Work done during isothermal

expansion

Heat rejected by the air during isothermal

compression
 EXAMPLES

Stirling Cycle
A Stirling cycle operates on air with a compression ratio of 10. If the low pressure is 30 psia, the low temperature
is 200°F, and the high temperature is 1000°F, calculate the work output and heat input.

Performance of CI Engine
Find the air-fuel ratio of a 4-stroke, 1 cylinder, air cooled engine with fuel consumption time for 10 cc as 20.0 sec. and air
consumption time for 0.1 m3 as 16.3 sec. The load is 16 kg at speed of 3000 rpm. Also find brake specific fuel consumption
in g/kWh and thermal brake efficiency. Assume the density of air as 1.175 kg/m3 and specific gravity of fuel to be 0.7. The
lower heating value of fuel is 44 MJ/kg and the dynamometer constant is 5000.
REFERENCE

Moran, M., Moran, M., Shapiro, H., Boettner, D., & Bailey, M. Fundamentals of
engineering thermodynamics.
Kaushik, S., Tyagi, S., & Kumar, P. (2017). Finite Time Thermodynamics of Power
and Refrigeration Cycles. New York: Springer.
Cengel, Y., & Boles, M. (2015). Thermodynamics. New York: McGraw-Hill
Education.
10.6: Gas Mixtures and Partial Pressures. (2019). Retrieved from
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10.6: Gas Mixtures and Partial Pressures. (2019). Retrieved from
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10.6: Gas Mixtures and Partial Pressures. (2019). Retrieved from
https://chem.libretexts.org/Bookshelves/General_Chemistry/Map%3A_Chemis
try_-
_The_Central_Science_(Brown_et_al.)/10%3A_Gases/10.6%3A_Gas_Mixtur
es_and_Partial_Pressures