Marine diesel engine MAN B&W MC/ME Engine- Construction and Principle

Summary

This video explains the operation of a diesel engine in marine applications, highlighting key components like pistons, crankshafts, and turbochargers. It details the combustion cycle, pressure and temperature management, and the importance of efficient cooling to prevent overheating. The video also introduces the Performance Monitoring Instrumentation (PMI) system, which helps optimize engine performance by accurately tracking cylinder pressures and crankshaft positions. The combination of advanced cooling systems and precise pressure management ensures the engine runs efficiently under high thermal stress.

Takeaways

• 😀 The diesel engine is essential for powering most of the world's shipping, offering efficient performance when properly maintained.
• 😀 Engine components like pistons, rods, crossheads, and crankshafts work together to convert thermal energy into mechanical energy.
• 😀 Powerful forces are at work in marine engines, requiring large, sturdy components to handle high pressures, including piston rings to ensure sealing.
• 😀 The crankshaft in some engines is made in two halves to facilitate manufacturing and installation, bolted together afterward.
• 😀 Two-stroke engines rely on turbocharged fresh air for the scavenge cycle, facilitating the efficient flow of air during compression and expansion.
• 😀 The engine’s power is largely determined by the pressure and volume relationship inside the cylinder during each stroke, visualized by the PV diagram.
• 😀 The PMI (Pressure Measurement Indicator) system is used to collect data for refining engine performance and maintaining cylinder load balance.
• 😀 The work done by the piston during compression and expansion is represented by the area under the respective curves in the indicator diagram.
• 😀 High temperatures during combustion can exceed the melting points of materials like lead, aluminum, and steel, but the metal surfaces do not reach these extremes.
• 😀 Efficient cooling is crucial to prevent overheating of engine components, achieved through oil and water cooling systems that maintain safe temperature limits.
• 😀 The heat transfer process involves micro boiling, where local boiling absorbs heat and prevents excessive wall temperatures, enabling the engine to perform optimally.

Q & A

What is the primary function of the diesel engine in shipping?

The diesel engine propels most of the tonnage of the world's shipping, providing maximum efficiency with minimal oil consumption when properly maintained.

What components are involved in the movement of the diesel engine's pistons?

The movement involves pistons, piston rods, crossheads, connecting rods, and the crankshaft, all working together to convert thermal energy into mechanical energy.

How are the forces from the piston transmitted to the engine frame?

The horizontal force from the piston is transmitted through the crosshead, which is supported by slide shoes that move along vertical surfaces on the engine frame.

Why is the piston fitted with piston rings?

The piston rings are used to provide sealing against high pressures within the engine and are installed using special tools to prevent permanent deformation.

What is the role of the turbocharger in a two-stroke diesel engine?

The turbocharger supplies fresh air into the engine by compressing air, which is then cooled and directed to the scavenge airspace around each cylinder.

What is the significance of the PV diagram in understanding engine performance?

The PV (pressure-volume) diagram illustrates the pressure sequence within the cylinder during the engine's cycle, helping to understand the relationship between pressure and volume during compression, combustion, and expansion.

What is the PMI system, and how does it improve engine performance?

The PMI (Pressure Measurement Indicator) system replaces traditional indicators, providing high-quality data collection to optimize engine performance by monitoring cylinder pressure and balancing load across cylinders.

How is the work done during the compression stroke calculated?

The work done during the compression stroke is calculated by multiplying the pressure acting on the piston by the change in volume, with the area below the compression curve representing the total work performed.

What factors contribute to the high temperatures inside the engine cylinders?

The high temperatures in the engine cylinders are a result of rapid combustion, with temperatures reaching the melting points of materials such as lead, aluminum, and cast iron.

How is cooling managed in a diesel engine to prevent overheating?

Cooling is achieved through a combination of oil circulated through the piston rod and water circulating through a cooling jacket around the cylinder, ensuring the temperature of the cylinder wall stays within safe limits.