Gujarat Technological UniversitySummer 2023 examination

GTU 3151909 Heat Transfer Summer 2023 Question Paper & PDF

B.E. · Mechanical Engineering · Semester 5 · Subject code 3151909
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Total
70 marks
To pass
23 marks (33%)
Duration
2.5 Hours 2:30 PM – 5:00 PM
Questions
5 with internal choice
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9 of 25 questions on this paper were also asked in other years. 4 more are types of question GTU sets again with new data. Each is marked below with the years it appeared.See all 19 repeated 3151909 questions, most asked first

Q.1

14 Marks
(a)
3 marks
Give difference between free and forced convection.
(b)
4 marks
Explain the terms thermal diffusivity and thermal contact resistance.
(c)
7 marksSame type asked in 2 of 4 papers

A mild steel tank of wall thickness 10 mm contains water at 90° C. The thermal conductivity of mild steel is 50 W/m°C , and the heat transfer coefficient for inside and outside of the tank area are 2800 and 11 W/m² °C, respectively. If the atmospheric temperature is 20°C , calculate

i)The rate of heat loss per m² of the tank surface area.
ii)The temperature of the outside surface tank.

Also asked in Summer 2026 Q2c, Summer 2026 Q2c OR

Q.2

14 Marks
(a)
3 marksSame type asked in 2 of 4 papers

A spherical shaped vessel of 1.2 m diameter is 100 mm thick. Find the rate of heat leakage, if the temperature difference between the inner and outer surfaces is 200° C. Thermal conductivity of material is 0.3 kJ /mh°C.

Also asked in Summer 2026 Q2c, Summer 2026 Q2c OR

(b)
4 marks
Write the general three dimensional heat conduction equation in
i)Cylindrical coordinates
ii)Spherical coordinates
(c)
7 marksSame type asked in 2 of 4 papers

A 12 cm diameter long bar initially at a uniform temperature of 40°C is placed in a medium at 650°C with a convective co efficient of 22 W/m²K. Calculate the time required for the bar to reach 255°C. Take k = 20W/mK, ρ = 580 kg/m³ and c = 1050 J/kg K.

Also asked in Winter 2024 Q5c

(c)
7 marksSame type asked in 3 of 4 papers

A motor body is 360 mm in diameter (outside) and 240 mm long. Its surface temperature should not exceed 55°C when dissipating 340 W. Longitudinal fins of 15 mm thickness and 40 mm height are proposed. The convection coefficient is 40W/m² °C. Determine the number of fins required. Atmospheric temperature is 30°C. Take thermal conductivity = 40 W/m°C.

Also asked in Summer 2026 Q3c OR, Winter 2024 Q2c OR

Q.3

14 Marks
(a)
3 marks
Explain Displacement thickness, Momentum thickness and Energy thickness.
(b)
4 marksAsked in 2 of 4 papers

Differentiate between steady state and transient heat conduction and give some examples of unsteady state heat conduction.

Also asked in Summer 2025 Q1a

(c)
7 marksAsked in 3 of 4 papers
For natural convection heat transfer, show that Nu = C (Prn , Grm).

Also asked in Summer 2026 Q3c, Winter 2024 Q3c OR

(a)
3 marks

Define radiation. State the range of wavelengths for ultraviolet, visible and thermal radiations.

(b)
4 marks
Discuss the significance of Prandtl, Nusselt and Stanton numbers in convection.
(c)
7 marksAsked in 3 of 4 papers

Define and discuss velocity boundary layer and thermal boundary layer over a flat plate. Show the thickness of thee layers for different Prandtl numbers.

Also asked in Summer 2026 Q2a, Summer 2025 Q5a OR

Q.4

14 Marks
(a)
3 marks
Explain the terms absorptivity, reflectivity and transmissivity of radiant energy.
(b)
4 marks

The filament of a 75 W light bulb may be considered as a black body radiating into a black enclosure at 70° C. the filament diameter is 0.10 mm and length is 5 cm. Considering the radiation, determine the filament temperature .

(c)
7 marks
State and prove Kirchhoff’s law.
(a)
3 marks
Calculate the shape factor for cylindrical cavity shown in Fig. 1 with respect to itself.
GTU Heat Transfer (3151909) Summer 2023 Question 4 OR (a) Diagram
(b)
4 marksAsked in 4 of 4 papers
Define Heat exchanger. Give classification of heat exchangers.

Also asked in Summer 2026 Q5b, Summer 2025 Q2b, Winter 2024 Q4c OR

(c)
7 marksAsked in 2 of 4 papers

Define intensity of radiation and show that for a unit surface the intensity of normal radiation is 1/π times the total emissive power.

Also asked in Summer 2026 Q4c OR

Q.5

14 Marks
(a)
3 marksAsked in 2 of 4 papers

What do you understand by fouling factor in case of heat exchanger? List the causes of fouling.

Also asked in Summer 2025 Q5b OR

(b)
4 marksAsked in 2 of 4 papers
Define and explain types of condensation.

Also asked in Summer 2026 Q5a

(c)
7 marksAsked in 3 of 4 papers
What is boiling? Explain different regimes of boiling.

Also asked in Summer 2026 Q5a OR, Winter 2024 Q3c

(a)
3 marks

What do you understand by TEMA charts? How are they useful in the design of multi-pass heat exchangers.

(b)
4 marks
Differentiate between pool boiling and forced convection boiling.
(c)
7 marksAsked in 2 of 4 papers
Derive LMTD formula for counter flow heat exchanger. ________________

Also asked in Winter 2024 Q1c

More Heat Transfer papers

Questions repeat across sessions. Working through two or three papers shows you which topics GTU asks most.

Summer 202670 marks · 5 questions · Solved
Winter 202570 marks · 5 questions
Summer 202570 marks · 5 questions
Winter 202470 marks · 5 questions

Other Semester 5 subjects

BE Mechanical

2151902
Theory of Machines
2151903
Fluid Power Engineering
2151908
Control Engineering
2151909
Heat Transfer

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About this paper

Official Gujarat Technological University (GTU) examination paper for Heat Transfer (Summer 2023, B.E. · Mechanical Engineering, Sem 5). 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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