Mechanical engineering applies principles of physics and materials science to design, manufacture and maintain mechanical systems. It involves the use of heat and mechanical power. Mechatronics refers to the integration of mechanical systems with electronics using precision engineering, control theory, computer science and more to design smart products and systems. The Carnot, Otto and Diesel cycles represent the most efficient and ideal cycles for heat engines. The vapor compression refrigeration cycle exploits phase changes to transfer heat and cool spaces below the temperature of the surroundings.

1. BEL Mechanical Engineering Interview Questions
1.What is mechanical engineering?
Mechanical engineering is a discipline of engineering that applies the principles of physics and
materials science for analysis, design, manufacturing, and maintenance of mechanical systems. It is
the branch of engineering that involves the production and usage of heat and mechanical power for the
design, production, and operation of machines and tools
2.Explain mechatronics?
Mechatronics refers to the efficient and effective integration of mechanical systems and electronics. It is
a blend of mechanics and electronics, and has come to mean the synergistic use of:
precision engineering
control theory
computer science
mathematics
sensor technology, to design enhanced or "smart" products, processes and systems.
3. what are Carnot cycle, Otto cycle, and Diesel cycle?
Carnot cycle Represents
most efficient cycle that operates between two fixed temperatures TH and
TL
Otto Cycle Represents
ideal cycle for sparkignition
(SI) engines. Ex: Processes in 4stroke
engine
cycle
Diesel cycle Represents
ideal compression ignition (CI) engine. Almost similar to Otto cycle
4.Explain simple vapour compression cycle in refrigerator?
Compression refrigeration cycles in general take advantage of the idea that highly compressed fluids at
one temperature will tend to get colder when they are allowed to expand. If the pressure change is high
enough, then the compressed gas will be hotter than our source of cooling (outside air, for instance)
and the expanded gas will be cooler than our desired cold temperature. In this case, we can use it to
cool at a low temperature and reject the heat to a high temperature.
Vaporcompression
refrigeration cycles specifically have two additional advantages. First, they exploit
the large thermal energy required to change a liquid to a vapor so we can remove lots of heat out of our
airconditioned
space. Second, the isothermal nature of the vaporization allows extraction of heat
without raising the temperature of the working fluid to the temperature of whatever is being cooled.
5.Which compression is usually used in a/c?
Hermetically sealed reciprocating compressor .
Why don't CI engine need a spark?
The compression ratio is high enough to combust the diesel without the aid of sparkplugs
What is MPFI, TPFC system?
What are the law of thermodynamics and PMMs?
Which is your favourite car and why?
What is your favourite twowheeler
and why?

2. During intial startup,
exhaust smoke appears white. why?
What are the common automobile specification?
Define heat exchangers?
Define conduction, convection and radiation?
Explain concept of black body?
Describe the lubrication system in IC engines?
Can poisson's ratio be negative?
What is bending moment equation and torque equation?
What is crippling load and its equations?
What are principal stresses and strains?
What is Endurance limit?
Draft tube and its application?
What is six sigma?
Where does the future of mechanical engineering lie?
Differentiate between absolute and kinematics viscosity?
What is magnus efect?
Compare the constrctional details of a petrol and diesel engine?
Which gear is used to obtain maximum speed ratio?