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Gujarat Technological UniversityWinter 2025 Examination

GTU 3110006 Basic Mechanical Engineering (BME) Winter 2025 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)
Give classification of Cochran boiler and Lancashire boiler.
3 Marks
(b)
Write a short note on CNG as a fuel.
4 Marks
(c)
iThe absolute pressure in a compressed air tank is 200 kPa. What is the gauge pressure in the tank if atmospheric pressure is 1.01 bar?
iiThe temperature of a system rises by 130°C during a heating process. Express this rise in temperature in kelvins.
iiiA 4-kW resistance heater in a water heater runs for 3 hours to raise the water temperature to the desired level. Determine the amount of electric energy used in both kWh and kJ.
7 Marks

Question 2

14 MarksMedium
(a)
State the function of any three mountings in boilers.
3 Marks
(b)
Classify engineering materials.
4 Marks
(c)
04 kg of gas is expanded isentropically from 10 bar and 340oC to 1 bar. It is then heated at constant volume to 3 bar and 340 oC and then finally it is compressed isothermally until the initial pressure of 10 bar is attained. Draw the p-V diagram for these processes and find the value of the adiabatic index γ. Take Cp = 1.005 kJ/kgK.
7 Marks
OR OPTION
(c)

A gas expands from 450 kPa and 130 litres to 150 kPa and 260 litres. The decrease in enthalpy during the process is 55 kJ. Taking Cv = 718 J/kgK, determine (i) change in internal energy, (ii) value of Cp, and (iii) value of R.

7 Marks

Question 3

14 MarksMedium
(a)
What is a rigid coupling? What are its types?
3 Marks
(b)

Draw a schematic diagram of the vapor compression refrigeration system. Where is the condenser located in a split air-conditioner?

4 Marks
(c)

A rigid tank contains 10 kg of water at 90°C. If 8 kg of the water is in the liquid form and the rest is in the vapor form, determine (a) the pressure in the tank and (b) the volume of the tank.

7 Marks
OR OPTION
(a)

What is a friction clutch? What are its types? 03 Page 1 of

2 Marks
(b)

What is the difference between the working principle of vapor compression and vapor absorption refrigeration system?

4 Marks
(c)

Find the dryness fraction of steam supplied in a combined separating-and-throttling calorimeter from following data: initial pressure = 10 bar, final pressure = 1 bar, water separated = 1.5 kg, steam discharged from throttling calorimeter = 20 kg, temperature of steam after throttling = 120oC. Take specific heat of superheated steam as 2.1 kJ/kg K.

7 Marks

Question 4

14 MarksMedium
(a)
Find the incorrect statements from the following and correct them.
  • Rigid flange coupling is used when axes of shafts are parallel but not in alignment.
  • Pin type flexible coupling is used where angular misalignment is more.
  • Universal coupling requires proper alignment of shaft axes.
  • Oldham’s coupling is for small angular misalignment.
3 Marks
(b)
Describe main parts of a centrifugal pump in short.
4 Marks
(c)

A Diesel engine has a compression ratio of 15 and heat addition at constant pressure takes place 6% of the stroke. Find the air standard efficiency of the engine.

7 Marks
OR OPTION
(a)
Draw a labeled diagram of a simple band brake.
3 Marks
(b)
Explain any one type of rotary pumps with figure.
4 Marks
(c)

In an air standard Otto cycle, the upper and lower limits of absolute temperatures are T3 and T1 respectively. Show that for maximum work, the ratio of compression should have the value .

7 Marks

Question 5

14 MarksMedium
(a)
Which mechanical drive will you suggest in each of the following different situations:
  • When there is less space available.
  • Where ‘slip’ is permitted.
  • When high velocity ratio is required.
3 Marks
(b)

What is isothermal efficiency, clearance ratio, and volumetric efficiency of a compressor?

4 Marks
(c)

Distinguish between petrol engine and diesel engine. Use the following points: cycle of operation, compression ratio, fuel ignition, governing, engine speed, thermal efficiency, engine weight.

7 Marks
OR OPTION
(a)
State three disadvantages of using gear drives.
3 Marks
(b)
Give classification of air compressors.
4 Marks
(c)
The following data refer to a test on I.C. engine:

Indicated power = 42 kW, frictional power = 7 kW, engine speed = 1800 rpm, specific fuel consumption per B.P. = 0.30 kg/kWh, calorific value of fuel used = 43000 kJ/kg. Calculate: (i) mechanical efficiency, (ii) brake thermal efficiency, and

iiiindicated thermal efficiency. Page 2 of
2 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 2025, 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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