Why Can't Gasoline Generators be Directly Compressed Fired?

atomization quality into the cylinder at a certain pressure for a certain period of time according to a certain injection pattern, and mix and burn it quickly and well with compressed air. However, the starting of a gasoline generator requires the use of a spark plug for ignition. In fact, many gasoline generator sets are currently equipped with direct injection gasoline engines, which can also inject gasoline directly into the cylinder. So why can't gasoline engines be directly compressed and ignited like diesel engines? This article will provide you with a detailed analysis of Dingbo Power from the following aspects.

1. Is gasoline easier to ignite?

To answer this question, we first need to understand a professional term - "flash point". Flash point is the lowest temperature at which a liquid vaporizes and ignites using a certain ignition source under specified test conditions. The flash point of gasoline can be less than 28 ℃, while the flash point of light diesel is between 45-120 ℃. Oil products with a flash point below 61 ℃ are flammable. It is difficult to ignite diesel with an open flame because the temperature at 20 ℃ is much lower than the flash point of diesel. At this time, diesel is still stable and has not evaporated, making it difficult to ignite!

Diesel is not as volatile as gasoline and only has a surface layer in contact with air. However, gasoline is highly volatile and produces gasoline vapor that mixes well with air, making it easier to ignite.

2. Low self ignition point makes compression ignition easier

The self ignition point refers to the temperature at which combustible materials undergo spontaneous combustion in the presence of oxygen. The self ignition point of diesel is only 220 ℃, while that of gasoline is 427 ℃. The high temperature generated by the compressed air of the piston can reach the self ignition point of diesel, but cannot reach the self ignition point of gasoline. Therefore, diesel engines can use compression ignition, while gasoline engines can only be ignited by spark plugs.

3. The combustion characteristics of diesel and gasoline are different

Gasoline engines use "pre mixed" fuel, which means that the mixture that needs to be burned during the power stroke is ready before ignition, and only needs to be ignited by the spark plug when the ignition timing is right.

Because the ignition timing usually occurs near the top dead center of the piston, at which point the piston will have a directional movement. Therefore, it can be seen that the combustion space is constant for a short period of time, and the mixture quickly completes the combustion expansion work at this moment. This is the Otto cycle of "constant volume heating"!

The diesel engine starts injecting fuel into the cylinder when the temperature inside the cylinder is higher than its self ignition point when the piston is close to the top dead center. The atomized diesel enters the cylinder and mixes with air. As the temperature reaches the self ignition point, the diesel begins to burn. Due to the slow combustion speed of diesel, the diesel that needs to be burned in one operation will not be sprayed out in an instant, but will continue to be injected into the cylinder. As a result, the cylinder continues to burn while continuously injecting fuel, and the injected oil continues to mix with air and be ignited. The expanded air continues to push the piston, which is the constant pressure heating Diesel cycle.

Some users cannot help but ask: why can't we make the compression ratio of gasoline engines higher and inject fuel at the compression top dead center like diesel engines? A professional technician from Dingbo Electric Power stated that this is mainly because the combustion speed of gasoline is too fast, and the combustion process is uncontrollable, making it difficult to make the engine smooth and soft. The physical properties of the two types of oil determine that they are treated differently.

Through the above introduction, I believe you have understood why gasoline generators cannot be directly compressed and ignited like diesel generators, right? In addition to the differences in combustion systems, there are many differences between diesel generators and gasoline generators. Currently, the most suitable backup power source is the diesel generator set. If you are struggling with which type of generator to buy between the two, please feel free to call us for consultation. We will customize a reasonable backup power solution for you according to your requirements.