- Date: 13/06/2025
- Type: Purely Technical
- Focus Area: Fluid Mechanics, Heat Transfer, Mass Transfer, Mechanical Design, Corrosion Science
- Additional: Some questions were also based on my final year project
🧪 Core Technical Questions Asked:
- Why is the pump not discharging fluid?
- Explained potential causes such as air lock, improper priming, clogged suction line, closed delivery valve, or insufficient NPSH.
- What is NPSH (Net Positive Suction Head)?
- Defined NPSH Available and NPSH Required
- Also discussed:
- What happens when the temperature of the liquid increases?
- ⇒ Vapor pressure increases → NPSHA decreases → higher risk of cavitation
- What is Cavitation?
- Formation and collapse of vapor bubbles in low-pressure zones of the pump
- Causes: Noise, vibration, pitting
- Prevention methods were also discussed.
- What is Osmosis and Reverse Osmosis (RO)?
- Osmosis: Natural movement of solvent from low to high solute concentration
- Reverse Osmosis: Applying pressure to reverse the natural process; used in water purification
- Types of Corrosion with Examples & Passivation
- Uniform, Galvanic, Crevice, Pitting, Intergranular, Stress corrosion cracking
- Passivation: Formation of protective oxide layer (e.g., stainless steel)
- Absorption Column Design:
- Discussed:
- Types of packings (Random, Structured)
- Concepts of NTU (Number of Transfer Units) and HTU (Height of Transfer Unit)
- Design considerations based on mass transfer efficiency
- Discussed:
- Difference Between Corrosion and Erosion:
| Parameter | Corrosion | Erosion |
|---|---|---|
| Cause | Electrochemical | Mechanical (abrasive) |
| Material Loss | Due to chemical reaction | Due to particle impact |
| Example | Rusting | Erosion in elbows of piping |
- Effect of Fouling in Heat Exchangers:
- Explained how fouling reduces overall heat transfer coefficient (U)
- Increases thermal resistance and causes pressure drop
- Flowmeters – Types and Working:
- Venturimeter
- Orifice meter
- Rotameter
- Magnetic and Ultrasonic flowmeters
- Flow Rate Measurement Using Venturimeter – Derivation:
- Derived equation using Bernoulli’s equation and Continuity principle
- Explained pressure difference and velocity relationship
📁 Project-Based Questions:
- Remaining questions were asked from my final year project, where I was expected to explain:
- Objective
- Design
- Working principle
- Challenges faced and solutions implemented