About this previous year paper
This document is a B.Tech (Semester IV) Theory Examination Question Paper for the subject BME401 – Applied Thermodynamics, conducted in the academic session 2023–2024.
It is a 3-hour, 70-mark examination designed to assess a student’s knowledge of internal combustion engines, power cycles, boilers, condensers, turbines, gas turbine cycles, combustion, heat transfer in power plants, and steam nozzle/steam turbine calculations.
The question paper is divided into three sections—A, B, and C—covering conceptual theory, comparative analysis, numerical problems, and cycle-based calculations.
SECTION A – Short Answer Questions (14 Marks)
Seven short 2-mark questions that test fundamental thermodynamics knowledge:
Difference between S.I. engine and C.I. engine
Limitations of Carnot vapour cycle
Meaning of endothermic & exothermic reactions
Function of air pre-heater in a boiler
Difference between surface condenser and jet condenser
Factors affecting nozzle efficiency
Meaning of stage efficiency
These questions test conceptual understanding of power plants, IC engines, and thermal equipment.
SECTION B – Descriptive / Comparative / Derivation Questions (21 Marks)
Students must attempt any three:
a. Otto Cycle Efficiency Derivation
Derive the expression for air-standard efficiency of the Otto cycle.
b. Regenerative vs Rankine Cycle
Compare performance and efficiency of a Regenerative Rankine cycle with a simple Rankine cycle.
c. Condensers in Power Plants
Discuss different types of condensers and their key features.
d. Maximum Blade Efficiency in Impulse Turbine
Condition for maximum blade efficiency and how it varies with blade speed to steam velocity ratio.
e. Purpose of Reheat in Gas Turbine Cycle
Explain how reheating affects specific work and thermal efficiency.
This section checks derivation skills, analytical reasoning, and knowledge of thermal cycles.
SECTION C – Numerical & Cycle-Based Problems (35 Marks Total)
Each question contains two options, and the student must attempt one part from each.
3. SI Engine Cycle / Turbocharger Principle (7 Marks)
Option 3(a)
A large numerical problem on a 4-stroke SI engine involving:
Compression ratio = 6 Swept volume = 0.15 m³
Initial P = 98 kPa, T = 60°C Heat added = 150 kJ/kg
Find P, V, T at all points, entropy change, work done, efficiency, mean effective pressure
Draw T-S diagram
Option 3(b)
Explain operation & performance benefits of a turbocharger.
4. Rankine Cycle / Combustion Analysis (7 Marks)
Option 4(a)
Rankine cycle with steam entering turbine at:
40 bar, 350°C → expands to 0.05 bar
Compute network output per kg steam, cycle efficiency, pump work
Draw T-S diagram
Option 4(b)
Orsat analysis for diesel combustion:
Given CO₂ = 7.2%, O₂ = 10.8%, rest N₂ Determine air-fuel ratio and excess air %
5. Boiler Draught / Condenser Air Leakage (7 Marks)
Option 5(a)
Artificial draught boiler with:
Gas exit = 150°C Chimney height = 60 m
Gas temp inside = 300°C Air temp = 17°C
Air requirement = 19 kg/kg fuel CV = 32604 kJ/kg
Compute:
Draught in mm of water Chimney efficiency
Extra heat lost in flue gases
Option 5(b)
Air leakage into steam condenser:
Steam = 35°C → condensate = 34°C Air removed at 33°C
Air leak: 3 kg/hr Determine air volumes handled by pumps
6. Impulse Turbine / Nozzle Flow (7 Marks)
Option 6(a)
Single-stage impulse turbine with:
Isentropic drop = 200 kJ/kg Nozzle efficiency = 96%
Nozzle angle = 15° Blade velocity coefficient = 0.96
Speed ratio = 0.5 Mass flow = 20 kg/s
Inlet steam velocity = 50 m/s
Find:
Blade angles Blade efficiency
Power developed Axial thrust
Option 6(b)
Isentropic nozzle flow:
Inlet: 10 bar, 500°C Exit: 6 bar
Exit area = 20 cm²
Compute mass flow rate and show process on h-s diagram.
7. Gas Turbine / Turbojet Comparison (7 Marks)
Option 7(a)
Gas turbine:
Inlet air = 1 bar, 300 K Compression ratio = 6.2
Compressor efficiency = 88% Fuel CV = 44186 kJ/kg
f/a ratio = 0.017 Turbine internal efficiency = 90%
Compute:
Compressor work Turbine work
Thermal efficiency
Option 7(b)
Compare turbojet engines with other jet propulsion systems.
📄 Overall Purpose of the Document
This exam paper assesses comprehensive thermodynamic competency, including:
IC engine cycles (Otto, SI engine cycle)
Gas turbine cycles, reheat, turbochargers
Steam power plant cycles (Rankine, regenerative)
Boiler equipment (air pre-heaters, chimneys, draught calculations)
Steam turbines (impulse stage, blade efficiency)
Nozzle flow thermodynamics
Combustion analysis (Orsat method)
Condenser performance and air leakage
Entropy, heat transfer, and cycle efficiencies
This evaluation combines theory, derivations, numerical problems, and thermodynamic cycle diagrams, ensuring a complete assessment of applied thermodynamics.