Chapter 2 (FUELS & COMBUSTION) Flashcards
Which is not viscosity rating?
Entropy Degrees API
Percent excess air is the difference between the air actually supplied and the theoretically required divided by
the theoretically air supplied
What is the apparatus used in the analysis of combustible gases?
Calorimeter
The viscosity of most commercially available petroleum lubricating oil changes rapidly above
180 °F
When 1 mol carbon combines with 1 mol oxygen
1 mol carbon dioxide
What are the immediate undersirable products from the petroleum based lubricating oil when subjected to high pressure and temperature?
Gums, resins and acids
What kind of bonding do common gases that exist in free state as diatomic molecules experiences?
Covalent bonds
An Orsat’s apparatus is used for
volumetric analysis of the flue gas
A theorem that states that the total property of a mixture of ideal gases is the sum of the properties that the individual gases would have if each occupied the total mixture volume alone as the same temperature.
Gibbs Theorem
A small enough particles suspended in a fluid exhibit small random movements due to the statistical collision of fluid molecules on the particles. This motion is called
Brownian motion
When two or more light atoms have sufficient energy ( available only at high temperatures and velocities) to fuse together to form a heavier nucleus the process is called
fusion
What is the residue left after combustion of a fossil fuel?
Ash
What is formed during incomplete combustion of carbon in fuels?
Carbon monoxide
A gas produced by the combustion of fuel oil and cannot be found in the fuel gasses is:
hydrogen
Which of the following chemical reactions in which heat is absorbed?
Endothermic reaction
A chemical reaction in which heat is given off.
Exothermic reaction
The colorless, odorless mixture of nitrogen and oxygen, with traces of other gases water vapor and same impurities
Air
The transfer of air and air characteristics by horizontal motion is called
advection
Properties of non-reacting gas mixtures are given by :
volumetric weighting for molecular weight and density, and geometric weight for all other properties except entropy
The process was of separating two or more liquids by means of the difference in their boiling point
Fractional distillation
The gaseous products of combustion of a boiler which contains carbon dioxide, carbon monoxide, oxygen, nitrogen and water vapor is called
Flue gas
The substance whose burning with oxygen yields heat energy such as coal, petroleum and natural gas.
Fuel
Stoichiometric ratio is :
chemically correct air-fuel ratio by weight
A type of radiation consisting of singly charged particles that generate to intermediate distances
Beta radiation
The increase velocity past the throat is due to the rapid decrease in the:
fluid density
In an oxidation- reduction chemical reaction, all of the following occur except:
nuclear fusion
The residual oil left after the distillation of gasoline and kerosene from crude petroleum; yellow to brown oil used as a diesel fuel and for enriching water gas
Gas oil
A fuel gas obtained by the destructive distillation of soft coal is called
Coal gas
Removing of impurities from a gas by bubbling it through a liquid purifying agent is called
Gas scrubbing
During a fusion process, mass is lost and converted to energy according to:
Einstein’s law
A finely divided carbon deposit by the smoke or flame is called
Soot
Rare gases such as helium, argon, krypton, xenon and radon that are non- reactive are called
Inert gases
Kinematics and dynamic viscosity vary from each other only by a factor equal to the:
fluid density
The following properties are different for isomers of the same chemical compound except:
number of atoms in amole of each isomers
Atomic weights of the elements in the periodic table are not whole numbers because of
The existence of isotopes
The tendency of a pure compound to be composed of the same elements combined in a defined proportion by mass
The law of definite proportions
What is the effect of a catalyst in a chemical reaction?
lower the activation energy
The relationship between the concentration of products and reactants in a reversible chemical reaction given by
the equilibrium constant
What fuel gas obtained by the destructive distillation of soft coal?
Coal gas
The process of splitting the nucleus into smaller fragments
fission
The ash that us remover from the combustor after the fuel is burn is the
bottom ash
A mixture of hydrogen and carbon monoxide made by passing steam over hot coke
water gas
All of the following are true of non-stoichiometric reactions except
non- stoichiometric reactions are rare in the combustion process
Is the ratio of the volume at the end of heat addition to the volume at the start of heat addition
cut-off ration
Piston rings are made of
cast iron
Low power is due to
low injection pressure
A branch system of pipes to carry waste emissions away from the piston chambers of an internal combustion engine is called
Exhaust manifold
The type of filter where the filtering elements is replaceable
metal edge filter
When four events takes place in one revolution of a crankshaft of an engine, the engine is called
two stroke engine
Which of the following does not belong to the group
Time injection system
Specific heat capacity is an SI derived unit described as:
J/kg °K
A device whose primary function is to meter the flow of refrigerant to the evaporator
Thermostatic expansion valve
The internal combustion engines never works in
Rankine cycle
The general chemical formula for all hydrocarbons is CnHm. In different combinations of interest, as internal combustion engine fuel, n varies from:
1 to 26
The general chemical formula for all hydrocarbons is CnHm. In different combinations of interest, as internal combustion engine fuel, m varies from:
2 to 54
The general formula of a paraffin fuel is
CnH2n+2
Napthenes and olefins are types of hydrocarbons with chemical formula of
CnH2n
Which of the following types of hydrocarbons have chemical formula of CnH2n-2?
Diolefins
Which of the following types of hydrocarbons have chemical formula of CnH2n-4
Asphaltics
What is the chemical formula of an Aromatic type of hydrocarbon fuels?
CnH2n-6
At atmospheric condition, hydrocarbon molecules with a low number of carbon atoms, 1 to 4 are
Gases
Hydrocarbons with 5 to 15 carbon atoms are:
more or less volatile light oils
Hydrocarbons with 16 to 26 atoms are referred to as:
heavy oils
In a four stroke engine if a valve opens 25 ° before B.D. C. and close 10 ° after T.D.C. the valve should be
exhaust valve
In a hot wire anemometer the rate of heat loss from sensing elements is a function of:
velocity of flow
Sticking valves
valve springs of defective material
Detonation of pinging noise is due to:
late timing of fuel injection
The thermal efficiency of a dual cycle engine with fixed compression ratio and fixed quantity of heat and with increase in pressure ratio will:
increase
Scavenging efficiency of a four stroke diesel engine is:
between 95% and 100%
Volumetric efficiency of a well designed engine may be in the range of:
75 to 90 per cent
During idling in a compression ignition engine the air fuel ratio may be of the order:
30
Vapor lock is
complete or partial stoppage of fuel supply because of vaporization of fuel in supply system
Flash point of liquids is the temperature at which:
The fuel emits vapors at a rate which produces an inflammable mixture with air
The mean effective pressure of a diesel cycle having fixed compression ratio will increase if cut off ratio is
increased
Hot spots
are the spots where heavier functions of fuel are vaporized
Flash point for diesel fuel oil should be:
maximum 49 °C
Morse test is conducted on :
multi-cylinder engines
Prony brake is used for testing of:
small engines
Clog point of an oil refer to:
the temperature at which paraffin and waxes in oil start precipating
Otto cycle consists of
two isentropic and two constant volumes processed
Diesel cycle consists of:
two isentropic, one constant volume and one constant pressure processes
Which is not correct for calculating air standard efficiency?
Gases dissociate at higher temperatures
The king pin inclination is generally:
between 2 ° and 5 °
For balancing single cylinder engine a counter weight is added to:
Crank
To measure a clearance between the valve and tappet of an automobile engine we use a
feeler gauge
By supercharging:
thermal efficiency of the engine can be improved
Speedometer drive is generally taken from
front wheel
Odometer is:
an instrument used for distance measurement
Automobile radiator is filled with
soft water
The ignition coil acts as:
a step up transformer
The self starting motor for automobiles is a:
DC series motor
Starting motor current may be about
25 A
As a rule before the piston are removed, it is essential to remove the:
piston rings
Common causes for excessive oil consumption include:
high speed and worn engine
The device that is used for reducing the exhaust noise is called
muffler
The device that is used to measure the clearance between the valve and tappet of an internal combustion engine is measured by using:
feeler gauge
Which of the following instrument is used measuring specific gravity
Hydrometer
Exhaust gas leakage into a cooling system is most likely to occur because of defective:
cylinder head gasket
Clutch slippage with clutch is engaged is specially noticeable
during acceleration
To engage securely and prevent dragging the clearance between release bearing and release collar in a clutch is generally:
2-3 mm
Gudgeon pins are made of:
A. same material as that of piston
B. cast iron
C. hardened and ground steel
D. none of these
none of these
Latex is:
a milky juice of rubber
Cross wire grooves on tires
absorb shocks because of road unevenness
The diesel pump is designed to supply fuel
insufficient quantity in accordance with the engine speed
The fuel injected into a cylinder in Diesel engine, when the piston is:
approaching T.D.C. during compression stroke
In the cam, the distance between the base circle and the nose is known as
lift
Dirt or gum in fuel nozzle or jets can produce:
smoky black exhaust
Oil pan is attached:
to the bottom of the cylinder block
Excess oil consumption in engine may be because of :
any of the above
Wheel base of the vehicle is the:
distance between front and rear axles
The percent of heat released from fuel-air mixture, in an internal combustion engine which converted into useful work is roughly
20-25 per cent
The efficiency of hydraulic braking system is:
about 90 per cent of
The instrument that is used to check the state of charge of a battery is called a
hydrometer
When not in use, the self discharge of an automobile battery in dry weather is generally:
0.5 to 1%
A laminated glass on cracking:
sandwitched layer taps the fragments
Wax is applied on car body as:
any of the above
A spark voltage requires a voltage of:
220 V
The minimum cranking speed in petrol engine is
60-80 rpm
Which oil is more viscous?
SAE 80
Engine oil is generally changed after:
2500-6000 km
The most probable cause for uneven wear of tires for a truck is
any of the above
In a vehicle the most probable cause for hard steering may be:
any of the above
Poor compression in a two stroke engine cannot be because of :
leaky valves
The number of exhaust manifolds in a V-8 engine is:
two
The device for soothing out the power impulses from engine is known as:
fly wheel
The firing order in case of four cylinder in- line engines is generally
A. 1-2-4-3
B. 1-3-4-2
C. 1-4-3-2
either B or C
In case of four cylinder opposed cylinder engines, the firing order is
1-4-3-2
In a four stroke engine , for the combustion of one liter of fuel, the volume of air needed would be approximately
9-10 cu.m
Theoretically air needed for the combustion of one kg of fuel is:
14.5 kg
Which of the following is the cause of loss power?
Low injection pressure
A valve in the carburetor of an internal combustion engines which regulates the proportion of air gasoline vapors entering the cylinder
Choke valve
What device combines air and fuel for burning in cylinder?
Carburetor
A passive restraint device consisting of bags in front of the driver and passenger
Air bag
The heat exchanger used in an Ericsson cycle is:
recuperator
In stirling engine, the heat added during
isothermal process
In an Otto engine, the heat is added during
isometric process
Exhaust stroke of gasoline engine is also known as
scavenging
The mechanical efficiency of a device is the ratio of the
ideal energy input to the actual energy input
The smallest subdivision of an element that can take place in a chemical reaction is a/an
atom
The smallest subdivision of a compound that can exist in a natural state is a/an
molecule
Elements with different atomic weights but the same atomic number are:
isotopes
All of the following are characteristics of metals except:
tendency to form brittle solids
The following are all characteristics of nonmetals except
being reducing agents
Graduations in the properties of elements from one elements to the next are less pronounced in:
groups
All of the following are components of a chemical elements except:
ions
Which of the following is not a prefix used in naming isomers?
Bi
All of the following are types of chemical bonds except:
nuclear bonds
The equilibrium distance between elements in an ionic bond is function of all the following except:
atomic weight
Which of the following statements is not a characteristic of ionic compounds?
They are good electrical conductors in the solid phase
What kind of bonding do common gases that exist a free state as diatomic molecules experience?
Covalent bonds
Measure are diffuser’s ability to increase the pressure of the fluid is:
pressure recovery factor
A decrease in stagnation pressure will decrease the mass flux through the:
diverging nozzle
What is the main power generating plant that produces the most electricity per unit thermal energy in the fuel input and has the greatest surplus pf electricity for most cogeneration system?
Diesel engine
Air standard efficiency of a diesel engine depends on
compression ratio
What is meant by brake horsepower?
Actual horsepower delivered to the engine drive shaft
Average pressure on a surface when a changing pressure condition exist
mean effective pressure
What air pressure is needed for air starting a diesel engine?
250 psi
Mechanical energy of pressure transformed into energy of heat:
Enthalpy
Ignition of the air-fuel mixture in the intake of the exhaust manifold
Backfire
The total sulfur content in a diesel fuel must not exceed
0.5%
The color of lubricating oil:
does not indicate qualities
There are two broad types in the classification of lubricating oils, these are straight and
additives
Most commercially available petroleum lubricating oil deteriorates starting from operating temperature of:
200 °F
An Orsat apparatus is used for:
volumetric analysis of the flue gases
The indicator used to determine the anti-knock characteristics of gasoline
Octane number
Amount of heat liberated by the complete combustion of a unit weight or volume of duel is
heating value
Air the controls the rate of combustion in the combustion chamber is known as:
secondary air
Total sulfur content in a diesel fuel oil must not exceed
0.5%
Percentage of excess air is the difference between the air actually supplied and the theoretically required divided by:
theoretical air supplied
When fuel oil has a high viscosity then the fuel oil
will flow slowly through pipes
Engines using heavy fuels require heating of the fuel so that the viscosity at the injector is:
150 SSU or slightly higher
A gas produced by the combustion of fuel oil and cannot be found in the flue gases is:
hydrogen
Amount of heat liberated by the complete combustion oa a unit weight or volume of fuel is:
heating value
The products of complete combustion of hydrocarbons
Carbon dioxide and water
When the water in the products of combustion is in the vapor state, the heating value is:
lower heating value
At what temperature wherein an oil of any grade becomes cloudy and it freezes, thus its application is limited.
Cold point
Dry air can be approximately as__ % oxygen and ____% nitrogen by mole numbers
21% and 79%
When H2O in the products of combustion is in liquid form, the heating value is known as
higher heating value
Flow of fluids wherein its particles do not have definite paths and the paths of the individual and distinct particles cross one another is:
turbulent flow
If the composition of hydrocarbon fuel is known, the ratio between the nitrogen and oxygen that is supplied in air is:
constant
The property of liquid in which they extend resistance to angular or shear deformation is:
Viscosity
A property of lubricating oil that measures the thickness of the oil and will help determine how long oil will floe at a given temperature is known as:
viscosity
the temperature at which lubricating will form a cloud
Cloud point
The ideal cycle based on the concept that the combustion process is both diesel and gasoline in the combination of heat transfer processes that is constant pressure and constant volume.
Dual cycle
The unit used for expressing API gravity is:
degrees
API gravity of water is :
10
Which of the following variety of coal has highest ash content?
Lignite
Which of the following is petroleum fuel?
Naphta
Diesel engjne fuels are rated by:
cetane number
Which of the following needs to be filtered in a diesel engine?
Air, diesel oil and lubricating oil
ASTM coal classification is bases on:
proximate analysis
The minimum amount of air required for a complete combustion of fuel is called
theoretical air
