Thermal Engineering Interview Questions

01-interview-interview questions-placement paper-interview questions and answers-interview tips-interview skills-interview preparation-Job-Interview-Questions

  • A bearing is designated as 6205 , what is it’s bore diameter?
  • advantages and disadvantages of using LPG in car?
  • All Rector or Exchanger have spherical/hemispherical end Why?
  • Compare Brayton and Otto cycle.
  • current rating of a 3 phase DG set is 20 Amps, but what will be the per phase current for single phase supply.
  • Define Overall Heat transfer coefficient.
  • Does Is 2062 Specifies Only Seamless Pipes Or ERW Pipe Is Also Covered Under Is 2062
  • During Steam Blowing Of Pipe Line, A Bluish Color Conical Pattern Is Observed At The End Of?
  • even though LPG is economical than petrol,why we are not promoting LPG usage?
  • explain bearing nomenclature with example.
  • Explain Why Nozzles are made convergent and Divergent?
  • Function of clutch
  • How a Diesel Engine Works in Generators?Explain with Labeled Diagram.
  • how can you increase the efficiency of power plant without changing in effort?
  • how gravity filling machine is designed
  • How hydraulic power steering @ clutch works please explain?
  • how much efficiency loss will took place in a steam turbine due to low vacuum
  • how to calculate the speed of conveyer in meter per minute
  • How to convert from HP to BHP or CC to BHP please explain?
  • How to find rating of Chiller a.c. plant i.e. how to calculate the a.c. load of an area, feed by Chiller ?
  • How to measure sound level of engine of tractor?
  • how turbo charger works?
  • If I want to set a power plant in desert of ‘Rajasthan’ and I have option of steam and gas power plant. Which plant I should set up?
  • if the blade height is increased,then how it increases the specific speed of centrifugal pump?
  • if you have to give support in 1 km long bridge,where you will give it & how many?
  • In a Waste heat recovery boiler feed control valve is after the economizer where as in auxiliary boiler feed control valve is given before the economizer.why?
  • In auto mobile industry for any type of vehicle how can we differentiate 2 stroke and 4 stroke engine….
  • In hydraulic clutch mechanism can i adjust clutch play? if it is possible please explain ?
  • increase in unit speed increases the discharge of impulse turbine how?
  • Name fuels used in nuclear power plant?
  • On what property u can distinguish material as brittle or ductile?
  • On what thermodynamic cycle nuclear power plant works?
  • Pipe. What’s The Concept Behind It?
  • Purpose of centrifugal pump casing wear ring and impeller wear ring what is back plate in centrifugal pumps and its purpose?
  • Suppose a steel bar of cross sectional area A is subjected to load P at one end and 2P at the other end ,what will be the induced
  • what are engines that use carburetor and that use inductor ? difference between them
  • What are the conditions considered while evaluating MARGIN OF SAFETY for newly designed mechanical components….? or
  • what are the types of welding machine?
  • What are your significant functional achievements in the present company? How did they contribute to the total process
  • What does a pump develops? Flow or Pressure. Give the Answer with Proper Logic.
  • what for orifice using in liquid flow line
  • what is bearing? how many types of bearing
  • What is difference between sand blasting and grit blasting ? What is its purpose and how is it done ?
  • what is drive speed & what is driven speed
  • What is Dry Bulb Temperature and Wet Bulb temperature?
  • what is electronically operated pneumatic valves? give one example
  • What is FEED?
  • what is friction?
  • what is gear ratio & how it can calculate
  • what is gyroscopic & gyroscopic effect?
  • What is mean by Resistance welding
  • What Is Mean By Ss-314(Stainless Steel Pipe Grade)?
  • what is pulverization
  • what is requirement of bottle filling machine
  • What is Solution Annealing? kindly explain its process in brief.
  • what is the basic need for designing the bottle filling machines
  • What is the critical speed. Compare the critical speed of hollow shaft and solid shaft.
  • What is the definition of mechanical
  • What Is The Difference Between Rated Speed And Economic Speed?
  • What Is The Difference In Is2062 And Is1239
  • what is the difference between construction of reaction turbine and impulse turbine
  • what is the difference between Torque and Power ( layman Idea)?
  • what is the manufacturing process for impellers of closed, semi open and open type?
  • What is the principle of operation of simple jet propulsion system?
  • what is the relationship between cop and hp(horse power) of compressor?
  • what is the thermodynamics?
  • what is the use of vanadium (non metal) ?
  • What is thermodynamics?
  • what is unit Ps ?
  • what’s the difference between front and rear wheel drive?on what basis we choose the type of drive?
  • what’s the range of poisson’s ratio of a stable material??
  • when a solid shaft is subjected to tension its linear dimension changes equally as its lateral dimension,then what will be its poisson’s
  • Whether ductile material can fail in brittle manner? WHEN?
  • which engine is more suitable over all. petrol engine, diesel engine . what are their differences
  • Who are the leaders among expansion valve manufacturers? what are the recent developments in the expansion valve industry, used in refrigeration and air-conditioning?
  • Why Air Conditioner capacity measured in Ton. Like 1.5ton
  • why as atmospheric pressure increases,boiling point also increases?
  • why de-super heater tubes are bend in shape
  • why diesel engine does not have spark plug like petrol engine, how ever petrol is better fuel than diesel?
  • why does cycle rim don’t bend even in heavy loads?
  • Why green curtains are used in hospital?
  • why petrol engine gives more power than diesel engine even though diesel engine has high compression ratio?
  • why petrol engines have more power than diesel engines of same capacity?
  • why the back wheel of tractor is bigger than front wheel?
  • why the path of a satellite is always elliptical with earth not at the centre of the ellipse?
  • Why tires are manufactured in black colour?
  • why we cant measure absolute entropy directly,but the change we can?
  • why we express the unit of torque in Nm.even though it can be expressed as Joule ( J )?
  • why we have to know the specific frequency of any equipment? does anybody know about specific frequency ?
  • Will anybody tell me about types and numbers of sensors in Toyota corolla GLI, Honda civic and Suzuki Cultus VXRI?
  • Write down the expression for air standard efficiency of diesel cycle?
  • You have to design a machine component. For what type of failure (ductile or brittle) you will design?
  • Latest Mechanical Engineering Interview Questions with Answers

    01-interview-interview questions-placement paper-interview questions and answers-mechanical interview tips-interview skills-interview preparation

    1. A Bearing is designated as 6205 , what is it’s bore diameter?

    Bore diameter is equal to : last two digit multiplied by 5.
    In case of 6205 , the bore diameter =05 x 5 = 5 x 5 =25 mm

    1.The third and fourth digits indicate the bore size in millimeters. Except for                  0 through 3, the bore size is simply five times the third and fourth digits together. 0 through 3, however, are different:
    00 10mm
    01 12mm
    02 15mm
    03 17mm
    2.Bearing number starts from a number means it is a metric series bearing.
    3.Type 6, “single-row deep groove”, is perhaps the most common type of bearing.
    4.The second digit is the series reflects the robustness of the bearing.
    In 6205 ….>second digit is 2 and it is a light series.

    2. Advantages and Disadvantages of using  LPG in car?


    1. Complete combustion

    2. Fuel saving

    3. Homogenous combustion


    1. As complete combustion is occurring ,more heat liberated,not advised for long journey, engine will be over heated

    2. Installation is difficult

    3.  Reduce engine life efficiency

    3. All Reactor or Exchanger have Spherical/Hemispherical end Why?

    Its in order to reduce the internal stress of the working substance.

    For eg., If Water Vapour Dry is the working substance in the reactor or boiler and if the ends are square, at the corners there are possibilities of pressure shoot up and also possibility of more pressure concentration at those points. in order to avoid that, Spherical/Hemispherical Vessels are used. Spherical head is the only remaining option because it is stronger.

    One more place where Spherical vessels are used for storage is LPG Storage Containers

    4. Compare Brayton and Otto cycle.

    The heat addition and rejection processes in Otto cycle are of constant volume, whereas in Brayton cycle, they are of constant pressure.

    -Otto cycle is the ideal cycle for spark ignition engines.
    -Brayton cycle is the ideal cycle for gas power turbines.

    5. Current rating of a 3 phase DG set is 20 Amps, but what will be the per phase current for single phase supply.

    Amps means product of voltage and current. For 3 phase generator, its Amps = (1.732 X (Line Voltage) X Current)/1000.

    substitute the value and you get the answer.

    6. Define Overall Heat transfer coefficient.

    The overall heat transfer coefficient U is a measure of the overall ability of a series of conductive and convective barriers to transfer heat. It is commonly applied to the calculation of heat transfer in heat exchangers, but can be applied equally well to other problems.

    1 / U A = 1 / h1 A1 + dxw / k A + 1 / h2 A2         (1)


    U = the overall heat transfer coefficient (W/m2K)

    A = the contact area for each fluid side (m2)

    k = the thermal conductivity of the material (W/mK)

    h = the individual convection heat transfer coefficient for each fluid (W/m2K)

    dxw = the wall thickness (m)

    The thermal conductivity – k – for some typical materials: .

    • Polypropylene PP – 0.12 W/mK
    • Stainless steel – 21 W/mK
    • Aluminum – 221 W/mK

    7. Does Is 2062 Specifies Only Seamless Pipes Or ERW Pipe Is Also Covered Under Is 2062

    IS:2062 Steel is a hot rolled structural steel that comes in three grades- low, medium and high tensile strengths. So it’s only applied for Seamless pipe.

    ERW (Electric Resistance Welding) pipe is manufactured by rolling metal and then welding it longitudinally across its length. Seamless pipe is manufactured by extruding the metal to the desired length, hence ERW pipe has a welded joint in its cross-section, while seamless pipe does not have any joint in its cross-section through-out its length.

    8. During Steam Blowing of Pipe Line, A Bluish Color Conical Pattern Is Observed At The End. Why?

    Flames are blue because of the molecules that are produced during combustion. CH and C2 radicals give off light in the green to blue region of the visible spectrum.

    Fire needs oxygen to burn, and since the bottom of a flame does not get much oxygen, it is the hottest spot in the flame and is blue in color.

    9. Even though LPG is economical than petrol,why we are not promoting LPG usage?

    Because it’s not an alternating source.

    Its exhaust emissions contain a large number of harmful substances, these substances emitted to the atmosphere, in a free state, ready for human and biological absorption affected by .

    LPG does not have as many BTUs per gallon as petrol. That means an engine running on LPG will not have as much power as the same engine running on petrol.