INSIGHT: Engine Performance is Key to Emissions Abatement

Matthias Winkler is managing director of CMT. Image Credit: CMT

There is an opportunity to create greater value from diesel engine condition monitoring that is currently being missed.

While comprehensive vessel and fleet performance monitoring systems typically include the ability to plug-in diesel engine performance monitoring tools, the resultant data is not being used to optimum effect.

As a result, ship managers are not getting a complete picture of what is causing their vessels to burn more fuel.

Indeed, many superintendents are leaving engine performance monitoring to onboard teams without offering them the support that cloud-based monitoring systems can provide. The result is increased fuel costs and increased CO2 emissions.

The concept of evaluating diesel engine performance by measuring changes in cylinder pressure
throughout a combustion cycle has been around since James Watt optimized the efficiency of the steam engine back in 1765, and today most vessels with two or four-stroke engines have modern equipment onboard to do it.

Typically, measurements are taken just once a month. Despite this low frequency, modern engine monitoring tools, such as our CMT PREMET® range can help engineers balance cylinder load, optimise injection timing and detect worn or damaged components.

This helps extend engine life, reduce the maintenance spend and meet decarbonisation requirements, NOx and soot emissions. It also helps reduce specific fuel oil consumption (SFOC). For each degree that ignition is retarded, incomplete combustion results in an SFOC increase of more than 2%.

A two-stroke engine may have combustion cycles of 60 rpm, or one cycle per second, while a four-stroke engine typically runs at around 1,000 rpm, so to measure compression at this scale
requires high-quality sensors and sophisticated analysis.

For instance, with conventional monitoring systems, the angle of the crankshaft is often estimated, but its precise measurement from the flywheel enables better understanding of the performance of each individual cylinder. If the compression pressure of one cylinder is lower than the others, it could mean that there is just a partially blocked injection valve, that the piston rings need to be replaced, or that pressure is being lost through the exhaust gas valve.

These possibilities cannot be detected if a software correction which is used instead of a direct crank angle measurement, and they can have a significant impact on combustion performance and therefore fuel consumption.

A CMT acoustic sensor can also be used to monitor the signature of a diesel engine's fuel injection process. This can detect problems with injectors, nozzles, and pumps. If an atomiser is worn, the fuel droplets may be too big to burn efficiently, or if the injection valve is not closing accurately then fuel can enter the combustion chamber at the incorrect time.

If there is a problem with the fuel pump, it may not be generating enough pressure, or the timing is wrong and it starts too early or two late.

Atomisation and fuel injection timing are among the most important variables in the combustion process and correlate directly with the amount of fuel consumed. If not detected in time, less than perfect atomisation can also lead to critical component damage. And if combustion is incomplete, the unburnt hydrocarbons in the exhaust gas can harm the environment.

Our PREMET range of engine performance tools automatically analyse measurements from each piston cylinder against a set of 22 parameters, such as rpm, fuel injection, compression pressures, and angles. The software can create (top dead centre) TDC graphs, combustion and decomposition curves and p-V diagrams to help engineers and ship managers optimise the performance of their diesel engines.

Trend analysis can help to detect worn parts or incorrect adjustment, and to help avoid unexpected failure, the software also provides alerts and recommended actions to optimise engine performance.

Measurements from high-precision devices can give the trained eye an impression of the condition of engine and fuel supply system components. Nevertheless, software analysis and visual representations offer the whole team the ability to act on concerns and communicate with specialists.

Having the capability to integrate accurate data and analytical power into cloud-based digital systems, such as the PREMET Cloud solution, enables managers, superintendents, and onboard engineers to compare sister engines or sister vessels, view historical trends, compare engine performance to shop or sea trials, and to get expert OEM opinion on any anomalies detected.

Sophisticated engine monitoring systems also protect against costly downtime by facilitating the implementation of predictive maintenance strategies. Major defects can be easily detected before they result in catastrophic failure.

Adding the ability to integrate data and functionality with other cloud-based ship performance tools brings further benefits. If paired with holistic vessel and fleet monitoring systems, the supplementary data required for accurate analysis of engine performance, such as exhaust gas temperature, fuel pump index and turbocharger speed, are already recorded.

This reduces the amount of data entry required by onboard engineers. They are already expected to be experts in mechanical engineering, electrical engineering, chemistry, and vibration, and as crew numbers generally are declining, these systems can ease the added burden of them also being required to be paperwork experts.

This is modern-day optimisation in action: matching human expertise, wherever it's physically located, with digital analysis to achieve the best and most timely outcomes in a complex, technological and physical environment. And an optimised ship is the sum of an increasing number of parts. There's no one single decarbonisation solution, particularly for existing vessels, so more systems will be added that can have a direct impact on engine performance including clean technologies such as air lubrication or sails. As complexity increases, so must the efficient use of time and resources.

James Watt invented an engine performance monitoring tool because he recognised its value as he developed is revolutionary technology. Today, engine management is crucial to reducing harmful emissions in line with social and regulatory mandates, and the best place to start is at the source: the combustion process itself.