Marine Engine Diagram
The main motor must perform satisfactorily and give the rated energy within rated RPM within thin but allowable restrictions of heat and force along with proper specific fuel oil usage.
OVERALL PERFORMANCE CURVES
During the test bed or shop test the overall performance curves for the engine are plotted. The overall performance curves would be the graphs various parameters on x-axis plotted against engine power or load regarding the y-axis. These various plotted curves tend to be below:
- Engine RPM vs. Load: This curve helps in ascertaining whether main motor is overloaded or otherwise not. A greater power generated at less RPM indicates an over loaded primary engine.
- Mean effective stress vs. burden: Mean efficient stress is used to determine horse power thus these two values should co-relate. In the event they don’t after that there may be some mistake in calculation or instrumentation.
- Maximum pressure vs. Load: This bend helps in understanding the condition of gas shot gear, injection timing plus the compression when you look at the cylinder an such like.
- Compression stress vs. Load: This curve suggests the healthiness of the components keeping compression like piston, piston bands and fatigue valves.
- Scavenge environment stress vs. Load: this implies the condition of the turbocharger and connected equipment.
- Exhaust fuel temperature in receiver vs. Load: this implies the enthalpy regarding the exhaust gas prior to entry in turbocharger. This value compared to the value following the turbocharger provides heat fall across the turbocharger, is an indication of turbocharger effectiveness.
- Exhaust fuel temperature after fatigue device vs. Load: This bend sheds light in the burning, gas injection, timing and compression an such like. A greater heat could be triggered as a result of after burning.
- Exhaust gas heat after turbocharger vs. Load: This bend is extremely of good use as it shows the enthalpy grabbed from the fatigue because of the turbocharger thus its problem. In case the receiver heat is at range nevertheless outlet temperature is greater it could indicate fouling regarding the turbocharger thus the associated reduced scavenge atmosphere pressure and high exhaust gasoline temperature.
- Total extra environment ratio vs. Load: This curve is hardly employed by ship staff and it is ideal for design designers. This curve sheds light on scavenging and the turbocharger ability and condition. It reveals that given that energy increases the extra atmosphere decreases as a result of usage.
- Specific gas oil consumption vs. Load: This curve helps counter check whether the engine is consuming gasoline oil properly according to force.
There could be other variables detailed depending on manufacturer. An average performance curve for a slow speed two-stroke marine diesel engine is given below.
Economical Fuel Usage
The key engine will run economically if the engine is well maintained and it is run at rated financial score where certain gas Oil Consumption could be the the very least. An engine is reported to be performing really or well maintained if it could be safely run on rated RPM during the rated load. For instance if an engine is having a continuous solution rating of 15000 BHP at 104 RPM but cannot achieve the rated RPM and is developing 15000 BHP prematurely at 98 RPM, there is certainly a loss of ship’s rate and a subsequent rate claim. Additionally tells there is an issue, the ship cannot provide rate, it's over consuming gas which the engine is over filled. It points to either hull fouling, damaged propeller or defective prime mover an such like.
In such cases the careful research of the sea trial data, motor store trial data therefore the performance curves will help to determine the reason for the issue.
For difficulty shooting initially the key motor overall performance must be taken on a beneficial climate day whenever motor load is steady. The primary motor must certanly be set you back its ranked energy. Thereafter the data discovered should be extremely imposed on the performance curves.
After superimposing the measured parameters regarding overall performance curves, we started to know perhaps the variables tend to be normal or irregular. A total research of this parameters allows us to to pin point the issue. An example of the overall performance data superimposed regarding the performance bend is given below.
From above diagram listed here points are inferred:
- At 75per cent MCR the RPM attained is leaner that the ocean test.
- The common optimum cylinder stress P max is leaner compared to sea trial.
- The compression force P comp is practically just like ocean trial verifying the running gear like piston, piston rings and exhaust valves tend to be okay.
- The scavenge force is virtually regular suggesting that turbocharger is in satisfactory problem and the enthalpy associated with fatigue gas exceeds typical because of this RPM.
- Exhaust conditions are typical increased suggesting irregular combustion, after burning up or change of timing. It may in addition suggest defective gasoline injection gear.
The aforementioned instance will comprehend the usage of performance curves for a ship’s professional. Following the main engine performance is taken and plotted in the original overall performance curves through the ocean test information, the difficulty are found out and SFOC restored on track values. This way at any phase throughout the entire life of this ship, we are able to understand why this woman is not doing centered on plotting her variables on the overall performance curves.