Understanding Diesel Engine Performance

A diesel engine is an intermittent-combustion piston-cylinder machine that operates either on a two-stroke or four-stroke cycle. These engines are typically constructed based on compression ratios wherein air is compressed at reasonably high temperatures to ignite the fuel, i.e., diesel injected into the cylinder. This combustion process causes an expansion that activates and actuates the piston. Chemical energy stored in the fuel is converted into mechanical energy resulting in power to create motion.

What Does Diesel Engine Performance Rely On?

The efficiency of diesel engines relies on the precision of the fuel injection system, which must be perfect, depending on the use and application of the engine. That is the main reason why specific application diesel engines differ from each other. It is the same with the power requirements, per application.

For the common purpose of understanding, diesel engines are generally categorised into small, medium and large, depending on the power requirement. These then get further specified into cylinder-wise classification. The classifications are based on size – small, medium, and large.

• Small engines are used in automobiles, light trucks, decentralised agricultural applications, smaller stationary power generators, and small-size mechanical drives.
• Medium ones for many heavy-duty trucks and V8 / V12 engines, with direct injection turbo-charges and aftercooled.
• Large diesel engines generally have power ratings ahead of 750 kWatts and are very used explicitly for marine propulsion, locomotion, and industrial mechanical drive applications.

These types of engines can also have the capability to operate at a low 500 rpm in supercritical cases.

Does Regular Maintenance Affect Diesel Engine Performance?

Maintenance and periodic servicing of diesel engines are incredibly critical for efficient operations at all times. It is essential to check the performance of an operating diesel engine at fixed intervals so that servicing the engine in case of bad working conditions for fault resolution becomes easier and less time-consuming.

Historically, the performance of diesel engines was always based on time-based data logging, assessment of the data, and manual scrutiny of the engine. However, with technology and the introduction of auto-sensor devices, actual working data can be logged via automatic monitoring systems directly connected to the overall maintenance system. This way, the engine can be kept at an optimum operating level.

In the case of marine propulsion applications (besides just the day-to-day engine parameter), monitoring, engine timing, compression pressure, cylinder detail, and the balance and loading needs to be monitored in a real-time situation to ensure optimum efficiency level of the engine.

In case of a defect in any functional component or assembly part of the engine, it becomes vital to ensure that the right marine diesel engine parts are sourced and replaced.

There have been instances where the old method for checking diesel performance was used as the alternate method in specific emergencies. This, however, is opted for only when the online monitoring system fails or there is a non-availability of spare parts required for rectification.

Few critical assessments of diesel engine operation:

• Transmission balance monitoring
• Spectroscopy
• Shock monitoring of the bearings
• Vibration monitoring
• Piston ring condition monitoring
• Lubrication oil pressure and level checking
• Coolant level monitoring
• Winding temperature control
• Fire Valve operating condition evaluation

To overcome sudden operational situations, most onboard marine application maintenance teams ensure carrying an inventory of critical marine diesel engine parts at all times. This could be time or condition-based. Diesel engine designs have been through many engineering and operational technology evolutions. Over the last many decades, there have been significant innovative developments in diesel engine design. This gives these engines an unparalleled mechanical advantage. The combustion method, the fuel injection process system and the ignition method in a diesel engine set it apart from gasoline-based engines.

What Are The Advantages Of Diesel Engines?

Diesel as a fuel has an economic advantage over the commonly used gasoline fuel. With the average fuel economy norms and standards being looked at (in many geographical regions where higher-capacity power is required for driving the application), more and more OEM manufacturers prefer diesel power plants in their equipment. Some areas are marine propulsion application, heavy-duty cargo carrying, trucking or large power generation application, and more.

Very high cylinder pressure, long strokes, and high boost levels in the diesel engine create the required torque, which is why these engines are built with heavy-duty components and parts. All this enables the diesel engines to withstand tremendous real-time stresses imposed on them during their application in the field. Diesel engines generally see longevity which other engines cannot.

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