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Questions and Answers
Which of the following best defines the term 'microbe'?
Which of the following best defines the term 'microbe'?
What are the essential survival needs of microbes?
What are the essential survival needs of microbes?
What is a common problem that diesel engine performance can face due to microbial infestation?
What is a common problem that diesel engine performance can face due to microbial infestation?
Which of the following factors could lead to contamination of diesel engine lubricating oil with water?
Which of the following factors could lead to contamination of diesel engine lubricating oil with water?
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Which of the following describes a significant problem caused by water contamination in engine oil?
Which of the following describes a significant problem caused by water contamination in engine oil?
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What is the primary purpose of atomisation in fuel combustion?
What is the primary purpose of atomisation in fuel combustion?
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Which factor is NOT typically considered when discussing the penetration of fuel?
Which factor is NOT typically considered when discussing the penetration of fuel?
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What is generally the main advantage of a vee type engine over in line engines?
What is generally the main advantage of a vee type engine over in line engines?
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Which component of a turbocharger is responsible for converting kinetic energy from the exhaust into usable energy for the engine?
Which component of a turbocharger is responsible for converting kinetic energy from the exhaust into usable energy for the engine?
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Why are relief valves often fitted in diesel engine crankcases?
Why are relief valves often fitted in diesel engine crankcases?
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What is the function of the diffuser in a turbocharger?
What is the function of the diffuser in a turbocharger?
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Which of the following conditions may not cause crankcase relief valves to operate?
Which of the following conditions may not cause crankcase relief valves to operate?
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What does a higher compression ratio generally indicate in a diesel engine?
What does a higher compression ratio generally indicate in a diesel engine?
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Study Notes
Combustion of Fuel
- Atomization: Breaking down liquid fuel into fine droplets, increases surface area for faster combustion.
- Penetration: The distance fuel droplets travel within combustion chamber, aiming for efficient mixing with air.
- Compression Ratio: The ratio of volume in the cylinder before compression to the volume after compression. Higher ratios lead to higher temperatures for easier ignition.
Factors Influencing Atomization, Penetration, and Compression Ratio
- Fuel properties like viscosity and volatility
- Injection system pressure and timing
- Engine design and cylinder geometry
Turbocharger Components
- Volute Casing: Directs exhaust gas flow into the turbine wheel, ensuring efficient energy transfer.
- Diffuser: Slows down the air after passing through the centrifugal compressor, increasing pressure for intake.
- Nozzle Ring: Controls the amount of exhaust gas entering the turbine, regulating turbocharger speed and boost pressure.
Engine Types
- In-line Engine: Cylinders are arranged in a single row, providing a simple design and ease of maintenance.
- Vee Engine: Cylinders are arranged in two banks at an angle, leading to more compact designs with potential for higher power output.
Advantages of Vee Engines
- Compact Size: Takes up less space than in-line engines, critical for smaller vessels
- Improved Balance: V-shaped design contributes to smoother operation
Crankcases
- Relief Valves: Release excessive pressure build-up within the crankcase, preventing damage to components.
Circumstances Causing Crankcase Relief Valve Operation
- Overpressure due to leaks in the cooling system
- Excessive blow-by from worn piston rings
- Air ingress due to faulty seals
- Excessive crankcase ventilation
Safety Detection System
- Pressure Gauge: Monitors crankcase pressure, alerting the operator to potential issues.
Microbial Infestation
- Microbes: Tiny organisms that can thrive in fuel tanks, causing problems in fuel systems.
- Microbe Survival Requirements: Moisture, nutrients, and suitable temperatures.
- Diesel Engine Problems: Fuel filter clogging, fuel line blockages, corrosion, and engine power loss.
- Identification: Visual inspection of fuel for discoloration or sediment, laboratory testing.
Distillate Fuel Oil Centrifugal Purifier
- Flow Direction: Dirty fuel enters the purifier and exits as clean fuel, while sludge and water are discharged separately.
- Key Components: Inlet, bowl, rotor, water outlet, sludge outlet.
Water Contamination in Lubricating Oil
- Sources: Leaking engine cooling system, condensation during cold starts, fuel washing during operation.
- Problems: Reduced lubrication, increased wear, corrosion, and foaming.
High Bearing Temperatures
- Causes: Insufficient oil flow, worn bearings, misalignment, lack of lubrication.
- Procedure: Reduce engine load, monitor temperature, investigate the cause, and repair as needed.
Pneumatically Operated Friction Clutches
- Oil Contamination: Reduces friction coefficient between pads, leading to slip and reduced engagement.
- Reduced Air Pressure: Weakens clutch engagement force, resulting in slip and potential component failure.
- Distorted Friction Pads: Compromises even engagement, leading to uneven wear and reduced performance.
- Angular Misalignment: Causes uneven pressure on pads, resulting in premature wear and reduced clutch life.
Reduction Gears
- Helical Teeth: Compared to spur gears, helical teeth provide smoother operation due to progressive engagement, reducing noise and vibration.
- Helical Tooth Advantages: Quiet operation, reduced vibration, and smoother running
- Helical Tooth Disadvantages: Requires more complex machining, potentially affecting gear efficiency.
- Double Helix: Compared to single helix, allows for higher torque transmission and a smaller gear size for the same ratio, but requires a more complex design.
- Double Helix Advantages: Higher torque capacity, reduced gear size.
- Double Helix Disadvantages: More complex design, potentially higher cost.
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Description
This quiz explores the principles of fuel combustion and the mechanics of turbocharger components. It covers atomization, penetration, compression ratio, and the factors that influence these processes. Test your understanding of these critical engineering concepts.
