--- title: "Diesel components, lubricating and cooling functions" subject: "Power Plant Equipment" chapter: 5 key: "semester_7/power_plant_equipment:diesel-components-lube-cooling" source: https://www.bctengineer.com/q/semester_7/power_plant_equipment/diesel-components-lube-cooling site: BCT Engineering --- # Diesel components, lubricating and cooling functions Power Plant Equipment · Chapter 5: Diesel Power Plant - Asked in: 2078 Bhadra, 4+2+2 marks - Video: [Diesel Power Plant || working and layout || Diesel Engine](https://www.youtube.com/watch?v=ly9CI9nXaC8) — Aeran Classes - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/power_plant_equipment/diesel-components-lube-cooling - Whole chapter: https://www.bctengineer.com/md/semester_7/power_plant_equipment/chapter-5 ## Question Sketch the main components of diesel power plant. Write down the main function of lubricating system and cooling system in diesel engine power plant. ## Short answer Main components are engine, alternator, air intake, exhaust, fuel, cooling, lubrication, starting, and governing systems. Lubrication reduces friction and wear, cools moving parts, seals the piston rings, cleans contaminants, and prevents corrosion. Cooling removes about 25-35% of fuel heat to avoid overheating, thermal stress, and oil film breakdown. ## Answer A diesel power plant consists of a CI engine driving an alternator, together with auxiliary systems that supply fuel, air, cooling, lubrication and starting, and remove the exhaust. #### Main components (sketch) ```text Air filter -> Supercharger -+ v Fuel tank -> pump -> +--------------+ | DIESEL ENGINE|==> ALTERNATOR Air bottle --------> +--------------+ (starting) | | | Lube oil tank <---+ | +--> Silencer -> Stack filter, cooler v Jacket water -> Heat exch -> Cooling tower ``` 1. **Engine** – converts fuel energy to shaft work (2- or 4-stroke). 2. **Air intake system** – air filters, ducts and supercharger. 3. **Exhaust system** – exhaust manifold, silencer, stack; sometimes waste-heat boiler. 4. **Fuel system** – storage tank, day tank, filters, injection pump, injectors. 5. **Cooling system** – pumps, heat exchanger, cooling tower/radiator. 6. **Lubricating system** – oil tank, pump, filter, oil cooler. 7. **Starting system** – air compressor and air bottles (or battery motor). 8. **Governing system** – controls fuel supply to keep speed constant. #### Functions of the lubricating system - Reduces **friction and wear** between moving parts (piston and liner, bearings, gears) by keeping an oil film. - **Cools** the parts: oil carries heat away from bearings and piston crowns. - **Seals** the gap between piston rings and liner, preventing gas leakage. - **Cleans** the engine by carrying away carbon and metal particles to the filter. - Protects surfaces against **corrosion** and absorbs shocks in bearings. #### Functions of the cooling system - About 25–35 % of fuel heat goes into the cylinder walls, head and piston. The cooling system **removes this heat** so that metal temperatures stay within safe limits. - Prevents **thermal stresses**, cracking and distortion of cylinder head and liner. - Prevents breakdown of the **lubricating oil film** at high temperature, which would cause seizure. - Keeps the engine at a suitable working temperature for good combustion and efficiency (over-cooling is also avoided). ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What is the primary function of the lubricating system? A. Raise engine speed B. Reduce friction and wear by maintaining an oil film C. Compress the intake air D. Remove exhaust gas Answer: B. Oil film between piston and liner, bearings and gears reduces friction and wear. (Key point: Lubrication: reducing wear) 2. Roughly how much of the fuel heat does the cooling system remove from the cylinder walls, head and piston? A. 25-35% B. 5-8% C. 60-70% D. Nearly 100% Answer: A. About 25-35% of fuel heat goes into the engine structure and must be removed. (Key point: Heat removed by cooling) 3. What can happen if cooling fails and the oil film breaks down? A. The engine becomes more efficient B. Seizure C. The compression ratio drops D. Fuel burns cleaner Answer: B. High temperature destroys the oil film, causing seizure, and also causes thermal stress, cracking and distortion. (Key point: Consequence of poor cooling) 4. Why is over-cooling also avoided? A. It increases the exhaust temperature B. The engine needs a suitable working temperature for good combustion and efficiency C. It stops the lubricating pump D. It increases noise Answer: B. A suitable working temperature is needed for good combustion and efficiency. 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