Diesel Power Plant (Theories and Elements)

Vocabulary flashcards covering key concepts, components, and principles from the Diesel Power Plant lecture notes.

Internal Combustion Engine (ICE)

An engine in which fuels burn inside the engine; the products of combustion form the working fluid that generates mechanical power.

Diesel Engine (Direct Injection)

An IC engine with no spark plug; air is taken in, compressed, and fuel is injected directly into the combustion chamber, igniting by the heat of the compressed air.

Direct Injection

Fuel is injected directly into the combustion chamber rather than into the intake port.

Gas Turbine

A turbine powered by combustion occurring in a separate chamber, with hot working fluid admitted to the turbine.

Five Functions of the Fuel System

Deliver fuel from storage to injector, raise fuel pressure to atomization level, measure/control the amount of fuel per cycle, control injection timing, and spray fuel into the cylinder in atomized form.

Lubrication System

System that reduces friction, seals spaces, cleans surfaces, absorbs shock, cools parts, and helps keep gases sealed in the cylinder; lubricant consumption is about 1% of fuel use.

Wet Sump Lubrication

Liquid lubricants are stored in a sump inside the engine.

Dry Sump Lubrication

Lubricant is stored in a separate sump outside the engine (dry sump system).

Semi-solid Lubricants (Mist)

Lubricants in a semi-solid form (greases) made from mineral oils and fatty oils.

Liquid Lubricants

Lubricants that are liquids; main types are mineral oils and fatty oils.

Solid Lubricants

Solid lubricants such as graphite, white lead, and mica.

Air Intake System

System delivering fresh air through filters to the engine; large diesel engines require about 0.076–0.114 m3/min per kW; paths include the intake manifold, scavenging pump inlet, and/or supercharger inlet.

Air Intake Precautions

Do not locate intakes inside the engine room; avoid confined spaces and too-small or very long ducts; filters should be accessible and not located near the roof due to vibrations.

Supercharging

Raising the volumetric efficiency by increasing the charge density to boost power without increasing engine size or RPM.

Supercharger

A device driven by the engine that compresses incoming air to increase its density.

Advantages of Supercharging

Power increase (mean effective pressure up 30–50%), better fuel economy, higher mechanical efficiency, reduced ignition lag and smoother operation, and improved volumetric efficiency.

Exhaust System

Discharges engine exhaust to the atmosphere; designs aim to reduce noise, limit air pollution at breathing level, minimize pressure loss, isolate vibrations, and allow heat extraction for heating if needed.

Exhaust Temperature

Exhaust gases can be around 400°C under full load; heat recovery from exhaust and jacket water can raise overall thermal efficiency, sometimes to about 80%.

Heat Recovery

Recover heat from exhaust gases and jacket water to heat oil/buildings or provide low-pressure steam, improving overall efficiency (up to ~80%).

Cooling System

System to prevent overheating; peak gas temperatures in the cylinder can reach ~2500 K; cooling keeps cylinder head and components within safe temperatures.

Cooling System Types

Open cooling, natural circulation, forced circulation, and evaporation cooling; air cooling is used in small engines while large diesel engines are liquid cooled.

Temperature Limits in Cooling

Water-cooled engines: target cylinder-head temperatures ≈400°C (cast iron) and ≈300°C (aluminum); air-cooled: ≈270°C and ≈200°C respectively.

Oil Temperature Limit

Gas-side surface temperature of the cylinder wall is typically limited to about 160–180°C to protect the lubricating oil.

Piston Seizure

Seizure due to overheating caused by lubrication failure or excessive temperatures.

Open/Natural/Forced/Evaporation Cooling

Different cooling methods for diesel engines: open cooling, natural circulation (thermo-system), forced circulation, and evaporation cooling.

Fuel Cost Comparison

Fuel costs per kW produced by diesel plants are typically 30–50% lower than those for gas engines.

Engine Life Hours (Diesel vs Gas)

1800 rpm water-cooled diesel units typically run 12,000–30,000 hours between major maintenance; gas units run 6,000–10,000 hours because they are built on lighter-duty blocks.

Applications of Diesel Power Plant

Suitable for mobile power generation, standby power for continuity (e.g., hospital, telephone exchanges), and peak-load/industrial use in smaller capacities (roughly 100–5000 HP).