Basic Mechanical Engineering — Winter 2023

What do you mean by ‘boiler mountings’ and ‘boiler accessories? Write three examples of them.

Explain advantages and disadvantages of wind energy.

i. Fill in the blanks: 1 bar = ______ Pa = _____ kPa = _____ MPa 1 atm = ________ bar ii. Write the equation of 1st law of thermodynamics for a stationary closed system. iii. Determine the power required to accelerate a 900-kg car from rest to a velocity of 80 km/h in 20 sec on a horizontal road. (Neglect friction, rolling resistance, air drag, etc.)

State the function of the following in boilers: Economizer, air preheater, superheater.

The gauge pressure of an automobile tire is measured to be 210 kPa before a trip and 220 kPa after the trip at a location where the atmospheric pressure is 95 kPa. Assuming the volume of the tire remains constant and the air temperature before the trip is 25°C, determine air temperature in the tire after the trip. Convert this change in temperature into percentage change.

Provide meaning of the following statements regarding cast iron material: 1) It is brittle and has low ductility. 2) It has high compressive strength but low tensile strength. 3) It has excellent castability. 4) It has poor formability.

Agas whose pressure, volume, and temperature are 2.75 bar, 0.09 m3, and 185oC respectively has the state changed at constant pressure until its temperature becomes 15oC. Calculate (i) the heat transferred, and (ii) the work done. Take R = 0.29 kJ/kg Kand c = 1.005 kJ/kg K. p

200 0.6 (ii) 124 1835.21

Draw a labeled diagram of a shoe brake used in automobiles.

Draw a self-explanatory diagram of window room air-conditioner.

Draw a neat, labeled diagram of barrel calorimeter. Write the equation used for this calorimeter for finding dryness fraction and state what each term in it indicates.

Classify clutches.

Draw a schematic diagram of the vapor absorption refrigeration system.

Determine the missing properties and the phase descriptions in the following table for water. Use steam tables and write necessary explanations. T, oC P, kPa h, kJ/kg x Phase description

Match the following: Rigid flange coupling Axis of shafts are parallel but not in alignment Pin type flexible coupling Where angular misalignment is more Universal coupling Requires proper alignment of shaft axes Oldham’s coupling For small angular misalignment

Compare centrifugal pumps v/s reciprocation pumps.

Consider a steam power plant operating on the simple ideal Rankine cycle. Steam enters the turbine at 3 MPa and 350°Cand is condensed in the condenser at a pressure of 74 kPa. Draw the T-s diagram and determine the thermal efficiency of this cycle. (Do not neglect the pump work.)

Give the similarities and differences between a clutch and a brake.

Explain any one type of rotary pumps with figure.

Derive, using P-v diagram, the equation to find air standard efficiency of Otto cycle. Use the formula you derived to find which gas from the following will give maximum efficiency for the same compression ratio: exhaust gas (γ=1.3), air, and monatomic gas (γ=1.67)

Draw a schematic diagram of the fast and loose pulley drive.

Give classification of air compressors.

A 4-stroke 6-cylinder IC engine has a stroke volume of 1.75 liters and is operating at a mean effective pressure of 6 bar. At what crankshaft rpm will the engine develop 35 hp? (Take 1 hp = 736 watts) What is the function of a carburetor and a fuel injector in an IC engine?

Differentiate between a belt drive and a gear drive.

Define with regard to compressors: double-acting compressor, multistage compressor, displacement (swept) volume, pressure ratio.

Apetrol engine has a compression ratio of 6 and develops 15 kW. Its brake thermal efficiency is half of its air standard efficiency. Find the fuel consumption. Take calorific value of petrol as 41500 kJ/kg. Why are more two-wheeler automobiles made with a 4-stroke engine instead of a 2-stroke engine? Give three technical reasons for this.