(SEM IV) THEORY EXAMINATION 2024-25 APPLIED THERMODYNAMICS

This document contains the complete B.Tech (Semester IV) Theory Examination 2024–25 question paper for Applied Thermodynamics (BME401). The paper consists of two printed pages, carries 70 marks, and evaluates a student’s understanding of thermodynamic cycles, steam power plants, IC engines, turbines, nozzles, combustion, gas turbine cycles, boilers, condensers, and jet propulsion systems.
 

Section A – Short Theoretical Questions (14 Marks)

Section A contains seven 2-mark questions, each targeting fundamental thermodynamic concepts (Page 1):

Otto vs. Diesel cycle differences

Effect of superheating on Rankine cycle efficiency

Definitions of HHV (Higher Heating Value) & LHV (Lower Heating Value)

Two boiler mountings & two boiler accessories

Meaning of choked flow in nozzles

Impulse vs. Reaction turbines

Advantages of regenerator in gas turbine cycle

These short questions test conceptual clarity on cycles, steam systems, and turbine principles.

Section B – Numerical & Descriptive Questions (21 Marks)

Students must attempt any three out of the five questions.

Rope Brake Dynamometer (IC Engine Performance)

Given pulley diameter, rope diameter, brake load, fuel consumption & calorific value — calculate:

Brake Specific Fuel Consumption (BSFC)

Brake Thermal Efficiency

Ideal Steam Turbine Cycle

Steam expands from 20 bar, 360°C to 0.08 bar, followed by condensation → pump → boiler.
Calculate:

Net work per kg of steam

Cycle efficiency (ideal Rankine cycle)

Surface Condenser

Explanation with neat diagram + effect of air leakage on condenser vacuum & efficiency.

Convergent Nozzle

Derivation of maximum mass flow rate per unit area + definition of nozzle efficiency.

Turbojet Engine

Working with a neat labeled diagram.

These questions check analytical ability, numerical application & thermodynamic reasoning.

Section C – Long, Higher-Order Questions (35 Marks)

Attempts are made one part from each question (Q3–Q7). These questions require deeper understanding, derivations, or complex numericals.

Q3 – Diesel Cycle Efficiency / Turbocharger

Given compression ratio r = 16 and cut-off ratio ρ = 2.5, calculate thermal efficiency of Diesel cycle
OR

Explain turbocharger with diagram and differentiate it from supercharger.

Q4 – Combustion of Alcohol / Flame Temperature

For C₂H₆O, compute:

Stoichiometric air–fuel ratio

Composition of combustion products per kg of fuel
OR

Derive expression for adiabatic flame temperature at constant pressure.

Q5 – Boiler Draught / Boiler Components

Given chimney height (30 m), draught required (12 mm WC), ambient temperature (27°C), air requirement (20 kg/kg fuel) — determine minimum exit gas temperature
OR

Working of feed water heater & superheater and impact on boiler efficiency.

Q6 – Impulse Turbine Velocity Diagram / Turbine Numerical

Draw velocity diagram for single stage impulse turbine and derive:

Work done

Blade efficiency
OR

Numerical involving nozzle efficiency, velocity coefficients, blade speed ratio, blade angles, power developed, thrust, etc.

Q7 – Brayton Cycle / Turboprop Engine

Air enters compressor at 101.325 kPa, 27°C, pressure ratio = 6, WT = 2.5 WC → calculate:

Maximum temperature in cycle

Cycle efficiency
OR

Working of turboprop engine with diagram + difference from turbojet.

Summary

The Applied Thermodynamics (BME401) exam paper covers:

Otto, Diesel, Rankine & Brayton cycles

Superheating, regeneration & turbine expansion

IC engine performance (BSFC, efficiency)

Steam turbines & condensers

Boilers, mountings, accessories & draught

Nozzles & choked flow

Turbojet, turboprop, turbocharger & supercharger systems

Combustion calculations

Velocity diagrams & turbine performance

Gas turbine cycle analysis

This exam paper is a complete resource for mechanical engineering students studying the conversion of heat into work and the performance of power-producing devices.