Dual Fuel Engine Fundamentals

Questions and Answers

What is a Dual Fuel Engine?

An engine that can operate on two different types of fuel, often diesel and gas.

What are the typical engine speeds?

Low-Speed: 100-300 RPM

Medium-Speed: 300-1200 RPM

High-Speed: 1200-3000 RPM+

All of the above (correct)

How is an engine numbered?

Typically based on design, type, and size, e.g., manufacturer model codes.

Describe a heat engine and provide an example.

Converts heat into mechanical energy; example: internal combustion engine. Signup and view all the answers

What air standard cycle is often used in modern diesel engines?

The Diesel cycle (constant pressure combustion). Signup and view all the answers

What are the stages in the Diesel cycle?

Compression Signup and view all the answers

What is indicated power in an engine?

Power developed inside the engine cylinder. Signup and view all the answers

What is brake power?

Actual power available at the engine shaft. Signup and view all the answers

What is parasitic load?

Power consumed by engine components. Signup and view all the answers

What is a stoichiometric mixture?

Ideal fuel-air ratio for complete combustion. Signup and view all the answers

How can a combustion engine be described?

By its cycle (2-stroke or 4-stroke) or by its fuel type (gasoline or diesel). Signup and view all the answers

Petrol can be used in a compression ignition (CI) engine.

False Signup and view all the answers

Describe a 4-stroke engine cycle.

Intake, Compression, Power, Exhaust. Signup and view all the answers

Which stroke produces power in a 4-stroke engine?

The Power Stroke. Signup and view all the answers

How many revolutions of the crankshaft occur per power stroke in a 4-stroke engine?

2 revolutions. Signup and view all the answers

How many revolutions of the crankshaft occur per power stroke in a 2-stroke engine?

1 revolution. Signup and view all the answers

Describe a 2-stroke engine cycle.

Combines intake and compression into one stroke; power and exhaust into another. Signup and view all the answers

What is scavenging?

The process of removing exhaust gases and bringing in fresh air. Signup and view all the answers

What are methods of scavenging?

All of the above Signup and view all the answers

What are the four most significant pollutants in engine emissions?

NOx Signup and view all the answers

What potential hazards are associated with NOx?

Respiratory issues, smog. Signup and view all the answers

What potential hazards are associated with CO?

Poisonous gas. Signup and view all the answers

What potential hazards are associated with HC?

Contributes to smog. Signup and view all the answers

What potential hazards are associated with PM?

Respiratory and health issues. Signup and view all the answers

What is valve overlap?

The period when both intake and exhaust valves are open. Signup and view all the answers

What is the purpose of a bedplate in engine design?

Provides a stable foundation. Signup and view all the answers

What materials are typically used for chocks?

Rubber Signup and view all the answers

The dry sump system is simpler than the wet sump system.

False Signup and view all the answers

What are types of bearings used in engines?

Rolling-Element Bearings Signup and view all the answers

What materials are used for plain bearings?

Typically bronze or aluminum alloys. Signup and view all the answers

Why are plain bearings split in half?

Easier to install and replace. Signup and view all the answers

Why is the plain bearing larger on the bottom half?

Accommodates larger forces and better alignment. Signup and view all the answers

What is the purpose of a piston skirt?

Helps in maintaining piston alignment and reduces wear. Signup and view all the answers

What is the function of a garter spring?

Keeps piston rings in place. Signup and view all the answers

What are the types of piston rings and their functions?

Oil Control Rings Signup and view all the answers

What are the types of cylinder liners?

Dry Liners Signup and view all the answers

Study Notes

Dual Fuel Engine

Operates on two fuel types, typically diesel and gas.

Typical Engine Speeds

Low-Speed: 100-300 RPM
Medium-Speed: 300-1200 RPM
High-Speed: 1200-3000 RPM+

Typical Strokes and Bores

Low-Speed: Long stroke and large bore
Medium-Speed: Moderate stroke and bore
High-Speed: Short stroke and small bore

Engine Numbering

Based on design, type, and size, often represented through manufacturer model codes.

Heat Engine Description

Converts heat into mechanical energy; an example is an internal combustion engine.

Air Standard Cycle in Diesel Engines

Utilizes the Diesel cycle with constant pressure combustion.

Diesel Cycle Stages

Stages include Intake, Compression, Power, and Exhaust.

Indicated Power vs. Brake Power

Indicated Power: Power generated within the engine cylinder.
Brake Power: Actual power delivered at the engine shaft.

Parasitic Load

Power consumed by engine components, e.g., alternator and water pump.

Stoichiometric Mixture

The ideal fuel-air ratio for complete combustion, with gasoline at 14.7:1 and diesel at 14.5:1.

Combustion Engine Description

Described by its cycle (2-stroke or 4-stroke) or fuel type (gasoline or diesel).

Petrol in CI Engine

Compression Ignition (CI) engines require diesel due to its higher ignition temperature.

4-Stroke Engine Cycle

Comprised of Intake, Compression, Power, and Exhaust.

Power Stroke in 4-Stroke Engine

The Power Stroke is where actual power is produced.

Crankshaft Revolutions in 4-Stroke Engine

Requires 2 revolutions per power stroke; camshaft rotates at half the crankshaft speed.

Crankshaft Revolutions in 2-Stroke Engine

Requires just 1 revolution per power stroke; camshaft is not employed.

2-Stroke Engine Cycle

Combines intake and compression in one stroke and power and exhaust in another.

Scavenging

The removal of exhaust gases and introduction of fresh air into the engine.

Methods of Scavenging

Uniflow: Efficient but complex.
Crossflow: Simpler but offers less efficiency.
Loop Scavenging: Good performance with complexity.

Significant Pollutants in Engine Emissions

Four main pollutants: NOx, CO, HC, and PM.

Hazards of Engine Emissions Pollutants

NOx: Linked to respiratory issues and smog.
CO: Colorless and poisonous gas.
HC: Contributes to smog formation.
PM: Associated with respiratory and health complications.

Valve Overlap

Occurs when both intake and exhaust valves are open, improving engine performance.

Key Differences Between 2-Stroke and 4-Stroke Engines

2-Stroke: Simpler design, higher power-to-weight ratio.
4-Stroke: More efficient, but mechanically complex.

Engine Secured to the Ship

Stability and alignment provided through a solid framework.

Purpose of Bedplate

Serves as a stable foundation, typically made from steel or cast iron.

Materials for Chocks

Rubber: Effective damping but subject to wear.
Metal: Offers durability but can create noise.

Electrical Noise Reduction

Earthing the bedplate minimizes electrical noise and prevents corrosion.

Dry Sump vs. Wet Sump

Dry Sump: Offers better oil control but is more complex.
Wet Sump: Simpler system, potentially causes oil slosh.

Types of Bearings in Engines

Plain Bearings: Simple design suited for high loads.
Rolling-Element Bearings: Optimal for high-speed applications.

Materials for Plain Bearings

Typically crafted from bronze or aluminum alloys, featuring a smooth surface for reduced friction.

Split Plain Bearings

Designed in halves for easier installation and maintenance.

Plain Bearing Design

Larger on the bottom half to better support larger forces and enhance alignment.

Marine Palm

Device used to improve vibration management and alignment.

Oblique Conrod

Provides better load distribution and improves efficiency during engine operation.

Piston Skirt Purpose

Helps maintain piston alignment and minimizes wear on components.

Garter Spring Function

Keeps piston rings securely in position during operation.

Types of Piston Rings

Compression Rings: Seal the combustion chamber.
Oil Control Rings: Regulate oil consumption within the engine.

Types of Cylinder Liners

Wet Liners: Easy to replace.
Dry Liners: Provide enhanced cooling efficiency.

Purpose of Honing a Liner

Creates a smoother surface enhancing the sealing effectiveness and improving performance.

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Description

This quiz explores the dual fuel engine's operation on two types of fuel, such as diesel and gas. It covers typical engine speeds, strokes, and bore sizes, along with how these engines are numbered based on design and type. Test your knowledge on the mechanics and specifications of dual fuel engines.