16. How air conditioners work in cars?
Ans:
Air conditioners are based on the
principles of evaporation and condensation and then compression and expansion.
The hot air of the car is removed by the process of evaporation and then the
condensation of the evaporated air takes places which is then further
compressed by the compressor and then finally expanded to us in the form of cold
breeze. Somehow, Air conditioning reduces the average of the car, as the energy
is required to remove the hot air and then compression and expansion.
17. How does the thermostat work?
Ans:
When the engine is too cold the
thermostat closes the main valve, thus stopping the flow to the radiator. When
the engine is too hot, it opens the main valve for normal circulation through
the radiator.
18. Definition of Octane number & Cetane number?
Octane No.- Octane number is
defined as the percentage, by volume, of iso octane in the mixture of iso
octane and h-heptane. It is the measure of rating of SI engine. Cetane No.-
Cetane number is defined as the percentage, by volume, of n-cetane in the
mixture of n-cetane and alpha methyl naphthalene. It is the measure of rating
of CI engine.
19. What is the formula for calculating BHP IN SI UNITS?
Ans:
Boiler horse power (BHP) is a
power unit used for measuring the power output of boilers, widely used in the
past, but now confined to North America . The
boiler horsepower conversion formula is as follows.
1 Boiler Horsepower = 9,809.5
Watts
20. Explain different between two stroke engine four stroke engine?
Ans:
In a two stroke engine, for every
two rotations of the crank shaft there will be one power stroke. Hence during compression
stroke, fuel will be drawn in to the crank case (suction) and during power
stroke, burnt fuel will be thrown out through transfer ports (exhaust). In a
four stroke engine, for every four rotations of the crank shaft there will be
one power stroke. Here, suction, compression, power & exhaust strokes are separate
as there will be inlet and exhaust valves.
21. Explain the basic difference between BS2 and BS3 engine?
Ans:
The basic difference of BS2 and
BS3 engines is the presence of catalytic converter. Catalytic converter is
present in BS3 engine which helps in reducing the formation of HC and CO. While
in BS2 engine, no catalytic converter is present which forms HC and CO. Thus in
BS3 engine there is no emission of harmful CO and HC. The full form of BS is
bharat stage, which is a standard of emission in India .
22. What is the use of hydrogen in automobile?
Ans:
Low emissions. Essentially no CO
or HC in the exhaust as there is no carbon in the fuel. Most exhaust would be
H2O and N2 Fuel availability. There are a number of different ways of making
hydrogen, including electrolysis of water.
23. What are three methods of heat transfer?
Ans:
Three methods of heat transfer
are conduction, convection and radiation. Conduction: The transfer of energy by
collisions between the atoms and molecules in a material. Convection: Transfers
heat when particles move between objects or areas that differ in temperature.
Radiation: The transfer of energy by waves.
24. What is clutch drag?
Ans:
When the clutch is not
disengaging fully and provides some difficulty in changing the gears then this
defect is called clutch drag.
25. What is DTSI? Why this technology is used in motor bikes?
Ans:
DTSI stands for Digital Twin Spark Ignition. This is used to get better
combustion in the combustion chamber. In this technique double spark plugs are
used to obtain better combustion of fuel in cylinder head. Through this
technique fuel is ignited properly. Moreover it provides better efficiency and
it is economical in fuel consumption.
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