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Gujarat Technological UniversityWinter 2023 Examination

GTU 3110006 Basic Mechanical Engineering (BME) Winter 2023 Paper Solution & PDF

B.E. · Common Engineering · Semester 1 · Subject Code: 3110006
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Total Marks70 MarksExternal theory exam
Passing Marks23 Marks33% minimum cutoff
Exam Duration2.5 Hours2:30 PM – 5:00 PM
Paper Structure5 QuestionsWith internal OR choices
Jump toQ1Q2Q3Q4Q5

Question 1

14 MarksMedium
(a)

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

3 Marks
(b)
Explain advantages and disadvantages of wind energy.
4 Marks
(c)
iFill in the blanks: 1 bar = ______ Pa = _____ kPa = _____ MPa 1 atm = ________ bar
iiWrite the equation of 1st law of thermodynamics for a stationary closed system.
iiiDetermine 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.)
7 Marks

Question 2

14 MarksMedium
(a)
State the function of the following in boilers:

Economizer, air preheater, superheater.

3 Marks
(b)
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.
4 Marks
(c)

A gas 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 K and cp = 1.005 kJ/kg K.

7 Marks
OR OPTION
(c)

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.

7 Marks

Question 3

14 MarksMedium
(a)
Classify clutches.
3 Marks
(b)
Draw a schematic diagram of the vapor absorption refrigeration system.
4 Marks
(c)

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

i200 0.6
ii124 1835.2
7 Marks
OR OPTION
(a)
Draw a labeled diagram of a shoe brake used in automobiles.
3 Marks
(b)
Draw a self-explanatory diagram of window room air-conditioner.
4 Marks
(c)

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.

7 Marks

Question 4

14 MarksMedium
(a)
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

3 Marks
(b)
Compare centrifugal pumps v/s reciprocation pumps.
4 Marks
(c)

Consider a steam power plant operating on the simple ideal Rankine cycle. Steam enters the turbine at 3 MPa and 350°C and 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.)

7 Marks
OR OPTION
(a)
Give the similarities and differences between a clutch and a brake.
3 Marks
(b)
Explain any one type of rotary pumps with figure.
4 Marks
(c)

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)

7 Marks

Question 5

14 MarksMedium
(a)
Draw a schematic diagram of the fast and loose pulley drive.
3 Marks
(b)
Give classification of air compressors.
4 Marks
(c)

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?

7 Marks
OR OPTION
(a)
Differentiate between a belt drive and a gear drive.
3 Marks
(b)

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

4 Marks
(c)

A petrol 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.

7 Marks
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About this Examination Paper & Attribution

Official Gujarat Technological University (GTU) examination paper and step-by-step solutions for Basic Mechanical Engineering (BME) (Winter 2023, B.E. · Common Engineering, Sem 1). Features complete 70-mark regular & remedial examination pattern, official marking distribution across all 5 questions, and direct 1-click official PDF download.

Transcribed for student exam preparation from Gujarat Technological University official examination archives. Questions, syllabus guidelines, and curriculum marking schemes remain the intellectual property of Gujarat Technological University.

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