AKTU Applied Hermodynamics · Important Questions 2026Source: ryzenstudy.com PYQs
BME401 Applied Hermodynamics Important Questions 2026 (AKTU)
Repeat analysis + most-asked questions, unit-wise
What we did: built from all 5 AKTU Applied Hermodynamics papers (2021-22–2025-26): 114 questions grouped into 71 distinct questions, 22 of which were asked in more than one paper.
- of marks were repeat questions
- 50%
- of marks were repeat questions
- questions asked in 2+ papers
- 22
- questions asked in 2+ papers
- papers analysed (2021-22–2025-26)
- 5
- papers analysed (2021-22–2025-26)
- units, mapped to current syllabus
- 5
- units, mapped to current syllabus
How much of the paper repeats?
- Repeats are real: when we checked each newer BME401 paper against the papers before it, on average 50% of its marks were questions already asked in an earlier paper.
- 2023-24 paper: 68% of marks were repeats (11 of 16 repeated questions were in our top list).
- 2024-25 paper: 63% of marks were repeats (13 of 16 repeated questions were in our top list).
- 2025-26 paper: 18% of marks were repeats (2 of 4 repeated questions were in our top list).
- Topic weightage is a guide, not a guarantee: our Tier 1 + Tier 2 topics covered 58% of the next paper's marks — picking the same number of topics at random would have covered about 45%.
Across 10 subjects and 23 papers we tested, 43% of marks repeated earlier questions on average.
1.Unit-wise most-asked questions
Ranked by how many papers asked them, then by how recently. Click a paper to open it.
Unit 1:
13% of past marks| Question | Asked |
|---|---|
| Compare the performance of Superchargers and Turbochargers. | Asked 3× |
| State the difference between Otto and Diesel cycles | Asked 2× |
| Derive expression for efficiency of Otto cycle | Asked 2× |
| A four-stroke SI engine has the compression ratio of 6 and swept volume of 0.15 m3. Pressure and temperature at the beginning of compression are 98 kPa and 60°C. Determine the pressure, volume and temperatures at all salient points if heat supplied to it is 150 kJ/kg. Also find out entropy change, work done, efficiency and mean effective pressure of cycle assuming cp = 1 kJ/kg K, cv = 0.71 kJ/kg K. Also, plot the cycle on T-S diagram | Asked 2× |
Unit 2: Vapour Power cycles · Fuels and Combustion
22% of past marks| Question | Asked |
|---|---|
| In a steam turbine steam at 20 bar, 360°C is expanded to 0.08 bar. It then enters a condenser, where it is condensed to saturated liquid water. The pump feeds back the water into the boiler. Assume ideal processes, find per kg of steam the net work and the cycle efficiency | Asked 3× |
| The chemical formula for alcohol is C2H6O. Calculate the stoichiometric air/fuel ratio by mass and the percentage composition of the products of combustion per kg of C2H6O | Asked 3× |
| What is the effect of superheating on the efficiency of the Rankine cycle? | Asked 3× |
| Define "Lower Heating Value" (LHV) of a fuel. | Asked 2× |
Unit 3: Boilers · Condenser
19% of past marks| Question | Asked |
|---|---|
| Explain working of feed water heater and superheater in a boiler. How do they improve boiler efficiency? | Asked 4× |
| Name two boiler mountings and two accessories | Asked 3× |
| Define boiler draught. A boiler has chimney of 30 m height to produce natural draught of 12 mm of water column. Ambient air temperature is 27°C and boiler furnace requires 20 kg of air per kg of fuel for complete combustion. Determine minimum temperature of burnt gases leaving chimney | Asked 2× |
| What are the different types of condensers used in power plants, and what are their key features? | Asked 2× |
Unit 4: Steam and Gas Nozzles · Steam Turbines
29% of past marks| Question | Asked |
|---|---|
| the power developed in kW | Asked 3× |
| Draw a velocity diagram for a single-stage impulse turbine. Derive expressions for work done and blade efficiency | Asked 3× |
| Define "Nozzle Efficiency." | Asked 2× |
| Differentiate between impulse and reaction turbines | Asked 2× |
Unit 5: Gas Turbine · Jet Propulsion
16% of past marks| Question | Asked |
|---|---|
| What is the difference between a Turbojet and a Turboprop engine? | Asked 3× |
| Air enters the compressor of a gas turbine plant operating on Brayton cycle at 101.325 kPa, 27°C. The pressure ratio in the cycle is 6. Calculate the maximum temperature in the cycle and the cycle efficiency. Assume WT = 2.5 WC, where WT and WC are the turbine and the compressor work respectively. Take γ = 1.4 | Asked 2× |
| What is the purpose of reheat in a gas turbine cycle, and how does it affect thermal efficiency? | Asked 2× |
| A gas turbine unit receives air at 1 bar, 300 K and compresses it adiabatically to 6.2 bar. The compressor efficiency is 88%. The fuel has a heating value of 44186 kJ/kg and the fuel-air ratio is 0.017 kg fuel/kg of air. The turbine internal efficiency is 90%. Calculate the work of turbine and compressor per kg of air compressed and thermal efficiency. For products of combustion cp = 1.147 kJ/kg K, γ = 1.33 | Asked 2× |
2.Topic weightage: which topics carry the marks
Blue = Tier 1 + Tier 2 (topics that carried ~80% of past marks). Grey = the rest. It shows where marks have gone, not a promise of what comes next.
Impulse turbine velocity diagrams · U4
11.3% (cum 11%)
Nozzle flow and choking · U4
7.8% (cum 19%)
Mountings and accessories · U3
6.1% (cum 25%)
Superheat, reheat, regeneration · U2
5.6% (cum 31%)
Turbojet and turboprop · U5
5.4% (cum 36%)
Otto cycle · U1
5.4% (cum 42%)
Draught · U3
5.2% (cum 47%)
Rankine cycle basics · U2
5% (cum 52%)
Combustion and air requirement · U2
4.6% (cum 56%)
Staging, compounding, bleeding · U4
4% (cum 60%)
Intercooling, reheat, regeneration · U5
3.4% (cum 64%)
Turbocharger and supercharger · U1
3.1% (cum 67%)
Diesel cycle · U1
3.1% (cum 70%)
Condenser air leakage and performance · U3
2.9% (cum 73%)
Boiler types and working · U3
2.7% (cum 76%)
Gas turbine and Brayton cycle · U5
2.7% (cum 78%)
Condenser types and function · U3
2.5% (cum 81%)
Combined and binary cycles · U2
2% (cum 83%)
Rocket propulsion · U5
1.9% (cum 85%)
Efficiencies and actual cycle · U5
1.9% (cum 87%)
Shock waves and supersaturation · U4
1.8% (cum 88%)
Reaction turbine · U4
1.6% (cum 90%)
Adiabatic flame temperature · U2
1.5% (cum 92%)
Exergy analysis of vapour cycle · U2
1.4% (cum 93%)
Heating values · U2
1.3% (cum 94%)
Nozzle efficiency and friction · U4
1.3% (cum 96%)
Heat of formation and reaction · U2
1.1% (cum 97%)
Steam turbine types · U4
1.1% (cum 98%)
Otto vs Diesel comparison · U1
1% (cum 99%)
Jet propulsion performance · U5
1% (cum 100%)
Air-standard cycle basics · U1
0.4% (cum 100%)
| Topic | Papers | Share |
|---|---|---|
| Impulse turbine velocity diagrams · Unit 4 · Tier 1 | 4/5 | 11.3% |
| Nozzle flow and choking · Unit 4 · Tier 1 | 5/5 | 7.8% |
| Mountings and accessories · Unit 3 · Tier 1 | 5/5 | 6.1% |
| Superheat, reheat, regeneration · Unit 2 · Tier 1 | 4/5 | 5.6% |
| Turbojet and turboprop · Unit 5 · Tier 1 | 5/5 | 5.4% |
| Otto cycle · Unit 1 · Tier 1 | 4/5 | 5.4% |
| Draught · Unit 3 · Tier 1 | 5/5 | 5.2% |
| Rankine cycle basics · Unit 2 · Tier 1 | 4/5 | 5% |
| Combustion and air requirement · Unit 2 · Tier 2 | 4/5 | 4.6% |
| Staging, compounding, bleeding · Unit 4 · Tier 2 | 2/5 | 4% |
| Intercooling, reheat, regeneration · Unit 5 · Tier 2 | 3/5 | 3.4% |
| Turbocharger and supercharger · Unit 1 · Tier 2 | 3/5 | 3.1% |
| Diesel cycle · Unit 1 · Tier 2 | 2/5 | 3.1% |
| Condenser air leakage and performance · Unit 3 · Tier 2 | 3/5 | 2.9% |
| Boiler types and working · Unit 3 · Tier 2 | 1/5 | 2.7% |
| Gas turbine and Brayton cycle · Unit 5 · Tier 2 | 3/5 | 2.7% |
| Condenser types and function · Unit 3 · Tier 2 | 3/5 | 2.5% |
| Combined and binary cycles · Unit 2 · Tier 3 | 2/5 | 2% |
| Rocket propulsion · Unit 5 · Tier 3 | 2/5 | 1.9% |
| Efficiencies and actual cycle · Unit 5 · Tier 3 | 2/5 | 1.9% |
| Shock waves and supersaturation · Unit 4 · Tier 3 | 2/5 | 1.8% |
| Reaction turbine · Unit 4 · Tier 3 | 1/5 | 1.6% |
| Adiabatic flame temperature · Unit 2 · Tier 3 | 2/5 | 1.5% |
| Exergy analysis of vapour cycle · Unit 2 · Tier 3 | 1/5 | 1.4% |
| Heating values · Unit 2 · Tier 3 | 2/5 | 1.3% |
| Nozzle efficiency and friction · Unit 4 · Tier 3 | 2/5 | 1.3% |
| Heat of formation and reaction · Unit 2 · Tier 3 | 2/5 | 1.1% |
| Steam turbine types · Unit 4 · Tier 3 | 2/5 | 1.1% |
| Otto vs Diesel comparison · Unit 1 · Tier 3 | 2/5 | 1% |
| Jet propulsion performance · Unit 5 · Tier 3 | 1/5 | 1% |
| Air-standard cycle basics · Unit 1 · Tier 3 | 1/5 | 0.4% |
3.Paper pattern (2025-26)
| Section | Questions | Rule |
|---|---|---|
| A | 7 × 2 marks | Attempt all |
| B | 3 × 7 marks | Attempt any 3 |
| C | 5 × 7 marks | Attempt any 1 |
4.In the syllabus, never asked yet
Low priority, but read them once — a new paper can always start here.
- Dual cycle · U1
- Boiler efficiency and evaporation · U3
- Boiler trial and heat balance · U3
- Turbine losses and governing · U4
5.Study order
- 1Impulse turbine velocity diagrams (Unit 4, Tier 1)
- 2Nozzle flow and choking (Unit 4, Tier 1)
- 3Mountings and accessories (Unit 3, Tier 1)
- 4Superheat, reheat, regeneration (Unit 2, Tier 1)
- 5Turbojet and turboprop (Unit 5, Tier 1)
- 6Otto cycle (Unit 1, Tier 1)
- 7Draught (Unit 3, Tier 1)
- 8Rankine cycle basics (Unit 2, Tier 1)
- 9Combustion and air requirement (Unit 2, Tier 2)
- 10Staging, compounding, bleeding (Unit 4, Tier 2)
- 11Intercooling, reheat, regeneration (Unit 5, Tier 2)
- 12Turbocharger and supercharger (Unit 1, Tier 2)
- 13Diesel cycle (Unit 1, Tier 2)
- 14Condenser air leakage and performance (Unit 3, Tier 2)
- 15Boiler types and working (Unit 3, Tier 2)
- 16Gas turbine and Brayton cycle (Unit 5, Tier 2)
- 17Condenser types and function (Unit 3, Tier 2)
FAQ
Which units of BME401 carry the most marks?
Unit 4 (Steam and Gas Nozzles · Steam Turbines, 29% of past marks) and Unit 2 (Vapour Power cycles · Fuels and Combustion, 22% of past marks).
Do AKTU Applied Hermodynamics questions repeat?
Yes. On average 50% of the marks in each newer BME401 paper came from questions already asked in an earlier paper, and 22 questions have appeared in more than one paper.
How is this list made?
Every question from the 5 papers (2021-22–2025-26) was mapped to the current AKTU syllabus and grouped with the same question from other years. Questions are ranked by how many papers they appeared in, then by how recently.
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Note: this is based on past AKTU papers, not a guarantee. Questions are mapped to the current syllabus; topics that are no longer in the syllabus are left out.