PIPE Elements 2

Improving the efficiency of an air-standard Otto cycle engine depends chiefly on
a. increasing the compression ratio
b. increasing the temperature and pressure
c. decreasing density
d. increasing specific

Increasing the piston diameter or piston stroke of Otto cycle engine will
a. decrease the efficiency of the engine
b. increase the efficiency of the engine
c. increase the work
d. decrease the work

The work output per cycle also depends strongly on the compression ratio as well as the
a. bore of the engine
b. isentropic compression
c. isentropic expansion
d. volumetric displacement of the engine

The mean effective pressure of Otto cycle can be increased by increasing the heat transfer into the engine per cycle or by
a. decreasing volumetric expansion
b. increasing the volumetric efficiency
c. increasing pressure ratio
d. decreasing pressure ratio

_______the engine in Otto cycle can increase the power of the cycle but not to increase efficiency
a. Discharging
b. Charging
c. Supercharging
d. Scavenging

A________ is used in aircraft engines and some automotive engine. In this method a turbine driven by the exhaust gases is used to provide power to compressor or blower at the inlet.
a. discharging
b. turbocharging
c. supercharging
d. scavenging

The practical disadvantage of supercharging is that the pressure P3 will be greater in the supercharge engine resulting in
a. choking
b. knocking
c. trickiting
d. blocking

Most supercharged of turbo-charged engines use fuel injection of gasoline directly to
a. heat exchanger
b. furnace
c. recuperator
d. combustion chamber

The ideal cycles are
a. externally reversible
b. internally reversible
c. externally irreversible
d. internally irreversible

The thermal efficiency of an ideal cycle is less than that of a totally reversible cycle operating between
a. temperature decrease
b. temperature limits
c. temperature increase
d. none of these

The only devices where the changes in kinetic energy are significant are the
a. compressor
b. pumps
c. nozzles and diffusers
d. none of these

The T-S diagram is useful in the analysis of
a. actual power cycles
b. ideal power cycles
c. combined power cycles
d. none of these

Equations pertaining to steady flow systems should be used in the analysis of
a. Carnot cycle
b. Otto cycle
c. Brayton cycle
d. Rankine cycle

Equations pertaining to closed systems should be used in the analysis of
a. Otto cycle
b. Brayton cycle
c. Absorption system
d. Stirling cycle

The carnot cycle is a function of the
a. absolute temperature
b. limit temperature
c. critical temperature
d. sink and source temperature

Thermal efficiency of Carnot cycle increases with______at which heat is added to the system or with a decrease in the average temperature at which heat is rejected from the system
a. a constant average temperature
b. an increase in average temperature
c. a decrease in average temperature
d. none of these

Spark-ignition automobile engines diesel engines and the conventional gas turbines are devices which operate on______. They are also internal combustion engines.
a. steam cycles
b. gas cycles
c. heat cycles
d. none of these

Another assumption which is often utilized to simplify the analysis of air standard assumptions is that air has ______whose values are determined at room temperature (25C)
a. variable specific heat
b. all of these
c. thermal specific heat
d. constant specific heat

A cycle for which the air-standard assumptions are applicable is frequently referred as
a. gas standard cycle
b. adiabatic cycle
c. reversible cycle
d. air standard cycle

_________ basically a piston-cylinder device.
a. centrifugal engine
b. steam engine
c. moving engine
d. reciprocating engine

_________is the position of the piston when it forms the smallest volume in the cylinder.
a. middle dead center
b. Top dead center
c. bottom dead center
d. approach dead center

_________is the position of the piston when it forms the largest volume in the cylinder.
a. middle dead center
b. Top dead center
c. bottom dead center
d. approach dead center

The distance between TDC and BDC in which the piston can travel is the
a. right extreme position
b. displacement stroke
c. stroke of the engine
d. swept stroke

The air or air-fuel mixture is drawn into the cylinder through the
a. intake valve
b. exhaust valve
c. intake pump
d. jet pump

The combustion products are expelled from the cylinder through the
a. intake valve
b. exhaust manifold
c. exhaust valve
d. none of these

The minimum volume formed in the cylinder when the piston is at TDC is called the
a. compression
b. expansion valve
c. volume change
d. clearance volume

The volume displaced by the piston as it moves between TDC and BDC is called
a. free mixture
b. clearance volume
c. piston discharge
d. displacement volume

The ratio of the maximum volume formed in the cylinder to the minimum volume is called the ______of the engine
a. expansion ratio
b. cut-off ratio
c. intake volume ratio
d. compression ratio

Compression ratio is a
a. pressure ratio
b. temperature ratio
c. entropy ratio
d. volume ratio

_______is the fictitious pressure which if it acted on the piston during the entire power stroke, would produce the same amount of net work as that produced during the actual cycle is called

Reciprocating engines are classified as a
a. spark ignition engines or compression ignition engines
b. spark ignition engines
c. compression ignition engines
d. heat engines

in spark ignition engine the combustion of the air-fuel mixture is initiated by a
a. carburator
b. injector
c. feed pump
d. spark plug

In compression-engine the combustion of air-fuel mixture is self-ignited as a result of compressing the mixture above its
a. self developed temperature
b. mixing temperature
c. self feed temperature
d. self ignition temperature

_________ the piston executes four complete strokes (two mechanical cycles) within the cylinder and crankshaft completes 2 revolutions for each thermodynamic cycles
a. one stroke internal combustion engine
b. two stroke internal combustion
c. three stroke internal combustion engine
d. four stroke internal combustion engine

Shortly before the piston reaches its highest position

In four stroke cycle the useful output is done during the
a. exhaust stroke
b. expansion or compression stroke
c. intake stroke
d. heat stroke

The pressure in the cylinder is ______ during the exhaust stroke and slightly below during intake stroke
a. slightly above
b. slightly below
c. is atmospheric
d. approaches infinity

Two stroke engines are generally _____than four-stroke engines because of isentropic expulsion of the exhaust gases and partial expulsion of fresh air-fuel mixture with the exhaust gases
a. less efficient
b. more efficient
c. generally more efficient
d. critically efficient

Two stroke engines has ________ compares to four stroke engine
a. less power
b. more power
c. less efficient
d. more efficient

The thermal efficiency of an ideal Otto cycle depends_________of the working fluid
a. the pressure ratio of the engine and the specific heat ratio
b. the temperature ratio of the engine and the specific heat ratio
c. the moles ratio of the engine and the the specific heat ratio
d. the compression ratio of the engine and specific ratio

The thermal efficiency of Otto cycle increases as the compression ratio.
a. increases
b. decrease
c. remains constant
d. none of these

Typical compression ratio of Otto cycle is
a. 6.0
b. 7.0
c. 8.0
d. 9.0

The premature ignition of the fuel is called
a. super ignition
b. autoignition
c. ignition delay
d. pre-ignition

Autoignition in spark-ignition engine can ______to the engine
a. explode
b. cause drastic change
c. cause damage
d. cause separation

_____has been added to gasoline because it is the cheapest method of raising the octane rating.
a. tetraethyl lead
b. unleaded
c. super leaded
d. blaze

is a measure of the engine knock resistance of fuel
a. Ucrain
b. Anti knock rating
c. octane rating
d. saybolt rating

leaded gasoline engine has
a. best effect
b. produce double effect
c. undesirable side effect
d. none of these

most cars have been designed to use unleaded gasoline and the compression ratio had to be lowered to avoid
a. infinite revolution
b. zagging knocking
c. super knock
d. engine knock

The thermal efficiency of car engines has been decreased somewhat as a result
a. increased compression ratio
b. decreased compression ratio
c. dead weight ratio
d. zero clearance

The second parameter affecting the thermal efficiency of an ideal Otto cycle is the
a. density
b. air condition
c. specific heat ratio
d. compression ratio

Using monatic gas the thermal efficiency of Otto cycle
a. increases
b. decreases
c. remains constant
d. none of these

The thermal efficiency of actual spark-ignition engines range feom about
a. 25 to 30%
b. 30 to 35%
c. 35% to 40%
d. 40 to 50%

The diesel engine is the ideal for CI(compression ignition) is
a. reciprocating engine
b. combustion engine
c. external engine
d. two way engine

Invented diesel engine is ________in the 1890
a. Rudolph Hitler
b. Ronnie Diesel
c. Rodel Diesel
d. Rudolph Diesel

If the density of air increases its ______ will increase
a. temperature
b. specific volume
c. entropy
d. pressure

The difference between enthalpy and work flow is
a. internal work
b. internal energy
c. specific heat
d. kinetic energy

At critical point of TS diagram in Rankine cycle

The fuel used in diesel is ___than in the fuel used in gasoline engine
a. less expensive
b. more expensive
c. P10 more
d. none of these

The fuel injection process in diesel engines starts when the piston_____ and continuous during the first part of power stroke
a. and of BDC
b. becore TDC
c. approaches BDC
d. approaches TDC

In diesel engine

The Otto and Diesel cycle differs during
a. expansion process
b. intake process
c. exhaust process
d. combustion process

A measure of performance for any power cycle is its
a. back work ratio
b. thermal efficiency
c. autoignition efficiency
d. none of these

Is the ratio of cylinder volumes after and before the combustion process
a. expansion ratio
b. back work ratio
c. cut-off ratio
d. compression ratio

The thermal efficiency of Otto cycle is always ______ the thermal efficiency of Diesel cycle when both operates in the same compression ratio
a. greater than
b. less than
c. equal
d. none of these

If the cutoff ratio decreases

If the cutoff ratio is unity

The diesel engines also burn the fuel more completely since they usually operate ____than spark ignition engines
a. higher revolutions per minute
b. medium speed
c. lower revolutions per minute
d. none of these

Thermal efficiencies of diesel engines range from about
a. 30 to 45%
b. 65 to 89%
c. 50 to 55%
d. 35 to 40%

The______of diesel engines make them the clear choice in applications requiring relatively large amounts of power

A diesel engine can be built as much as __________at 122 rpm
a. 20

A better approach would be to model the combustion process in both gasoline and diesel engines as a combination of two heat transfer process. This process is known as
a. gas cycle
b. Otto cycle
c. Diesel cycle
d. Dual cycle

In dual cycle

Is the process during which heat is transferred to a thermal energy storage device
a. adiabatic
b. regeneration
c. recuperation
d. isentropication

The regenerator is a device that borrows ____ from the working fluid during one part of the cycle and pays it back during another part of the cycle
a. heat
b. energy
c. work
d. none of these

In stirling cycle

In Ericsson cycle

Invented Stirling engine is _____. It is very heavy and complicated
a. Robert Deniro
b. Robert Boyle
c. Robert Sreri
d. Robert Sterling

Both the Stirling and Ericsaon cycles are totally reversible as is the
a. Carnot cycle
b. Otto cycle
c. Diesel cycle
d. Gas turbine cycle

_________have the same efficiency when operating the same temperature limits.
a. Stirling and gas turbines
b. Carnot and Otto cycles
c. Stirling

Both the Stirling and Ericsson cycles are
a. internal combustion engines
b. external combustion engines
c. Otto engine
d. Stirling engine

Are two gases commonly employed in Stirling and Ericsson cycles
a. Hydrogen and Helium
b. Water and Brine
c. Salt and water
d. Oxygen and Nitrogen

Advantage of Stirling and Ericsson cycle
a. can use variety of fuels as a source of energy
b. There is more time for combustion
c. They operate on closed cycles
d. all of these

In Stirling cycle

Brayton cycle is invented by
a. George Bragat
b. George Smith
c. George turbine
d. George brayton

Gas turbines usually operates on an
a. closed cycle
b. open cycle
c. controllable cycle
d. none of these

in gas turbine the gas is expanded to the
a. vacuum pressure
b. negative pressure
c. gage pressure
d. atmospheric pressure

Brayton cycle is made up of ________internally reversible process
a. one
b. two
c. three
d. four

In brayton cycle

The thermal efficiency on an ideal Brayton cycle depends on
a. pressure ratio of the gas turbine and specific volume ratio
b. temperature ratio of the gas turbine and specific heat ratio
c. pressure ratio of the gas turbine and isentropic process
d. pressure ratio of the gas turbine and specific heat ratio

The highest temperature of Gas turbine cycle occurs at the end of
a. expansion process
b. compression process
c. combustion process
d. extraction process

For a fixed turbine inlet temperature

In most common design of Gas turbine

In gas turbines