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Most Important Factors in Engine Design

Date:2014-07-18     Views:764
Two most important factors in engine design,
Mechanical strength of engine parts and the other is consumption analysis. 
The Strength of mechanical parts determines engines reliability and safety.
It is the equivalent to a human’s skeleton,
If the skeleton is strong, human body will be strong and long lasting.
Engine combustion similar as a human’s digestive system
The fuel is similar as the food.
When food enters into the body, it provides the energy to burn
The engines working mechanism is the same,
if fuel is deliverd in a calculated burst
If the the fuel combustion rate will be low,
The thermal efficiency is high,
If exhaust gas temperature is low,

Then engine will be working at its best , and be more reliable with the  best efficiency.

When we talk about combustion analysis, we have to mention two parameters,
One is Air/Fuel ratio,
The other is excess air coefficient, (we also call as BMEP parameter).
Air-Fuel ratio, refers is the mass ratio of air to fuel present in an internal combustion engine.
Air-Fuel ratio is important for an engine exhaust gas flow, engine performance, and engine’s economy.
For different fuel, the ratio is different, as for gas the ratio is 14.7, for diesel the ratio is 14.3.
When air-fuel ratio is larger than theoretical value it’s called lean mix gas,
This means more gas and less oil,
In this procedure combustion will be at its best.
Very low fuel consumption, means low pollution,
But the output power will be less. 
When the ratio is smaller than theoretical value, we call it rich gas mixture.
This means less gas with more oil,
In this procedure power range is large,
The combustion ratio not good, but the oil combustion is high, and pollution will increase  .
According to the actual amount air to theoretical air, we call as excess air ratio; we usually use a 入 to represent it.
If a gas engine supplies fuel as the theoretical air ratio, we will find that there is very big difference
Between the actual situation and best situation
There are also big difference between exhaust gas temperature, and the output of power, and also fuel consumption.
Many years’ study in field tells us that, if the theoretical ratio is 14.7:1, then the gas generator output power is about 13-14kW/L exhaust gas output.
If we increase this ratio to 23.5:1, then the output power is about 18kW/L exhaust gas.
If we increase the ratio to 25.8:1, then the output power is about 22-23kW/L exhaust gas.
There are three engine rated power, standby power, prime power, and continuous output power (COP). For a power station, most manufacturer use continuous output power (COP).
When an engine use COP as standard state, So far, the world-class manufacturer use BMEP as an important generator parameter.
Normally the standby power BMEP is 25-26bar, prime power BMEP is 22-24bar, and COP BMEP is 18-19bar.
If the engine BMEP value is too high, though the rated power will increase dramatically, but it means the reliability will be significantly reduced.
So far, the best gas engine company in the world, their COP BMEP is between 18-19bar.
At this point, in fact, it’s the highest mechanical parts of a diesel engine.
In other words, if your gas engine COP BMEP is 22-23bar, then the gas engine reach the world class level, you only need to solve the gas engine mechanical design problems , and the fuel combustion has reach the high level.
Googol gas engines adopt the world top brand German MOTOR combustion solutions,
we use German Heinzmann speed governor, so our gas engine BMEP is 22-23bar.
Googol  have reached the world class level. Nowadays,
Only GE Jenbacher, Germany MWM, and Spain’s Guascor successfully reach their gas engines at highest level.