75% alcohol is composed of 75% ethanol and 25% water. It is generally used as medical alcohol and is a regular household medical product during the epidemic.
Because alcohol can be ignited at a concentration of more than 60%, if you just watch the alcohol burning, chemical energy is converted into heat energy, and you can really add some to the engine. Anyway, gasoline is also burned, and alcohol is also burned. They all burn and expand to do work. Why can’t gasoline do it, and alcohol can’t do it. After all, alcohol is also environmentally friendly. It has no taste when it is burned, and it is no problem to make hot pot.
And the country has also introduced fuel with alcohol, ethanol gasoline or something.
Like the picture above, E10 represents 10% ethanol, but E10 also represents 90% gasoline, both of which are basically water-free ……
Then why use ethanol gasoline, because ethanol combustion can reduce emissions. The original 100% gasoline combustion produces 100% nitrogen, oxygen, and hydrocarbon pollutants. And with 10% of the fuel, you can immediately reduce pollution by 10%.
Although the calorific value of ethanol is 26.75MJ/KG and that of gasoline is 46MJ/KG, the calorific value of ethanol is about 60% of that of gasoline. However, the overall thermal efficiency of the engine is only about 30%, so the use of 10% ethanol will have a weaker impact on the output power of the engine by about 1% to 2%.
But that is also adding ethanol (without water) + gasoline (with water less than 0.8%), because the engine itself is afraid of water.
Even the service life of ethanol gasoline is much shorter than that of pure gasoline, because alcohol, an organic solvent , has good water absorption , which means that alcohol gasoline must be used as soon as possible, because it is not used, absorbs water, and there is too much water in the fuel. , it will cause damage to the fuel engine. Generally, we now add alcohol gasoline, such as gasoline with 15% alcohol concentration, and the ordinary engines used are generally used up within 30 days. If the local humidity is high, it should be used up within two to three weeks.
If a little bit of water keeps the engine high temperature (the engine operates normally, the temperature of the parts is kept at about 90 degrees Celsius, and the temperature of the combustion chamber is thousands of degrees Celsius), it can evaporate the tiny water vapor, and it will not have too much impact on the engine.
If there is too much water, if it is 25% water in the fuel, this is a heavy weight that a normal fuel engine cannot handle. If there is more water, the engine will basically be useless.
One is that water will cause the combustible mixture to not be fully burned, the power of the car will become weak, the response will be slow, and the carbon deposition will increase. There is too much water to a certain extent, and even the spark plug cannot be fired, and the engine cannot be started when the engine is turned off.
After several car owners in Hanzhong, Shaanxi Province, refueled at a local gas station, the car broke down and broke down on the side of the road before they drove far. The gasoline drawn from the fuel tank was obviously stratified, and there was sedimentary turbidity, and the owners immediately called the police. On May 21, the inspection report issued by the Shaanxi Provincial Energy Quality Supervision and Inspection Institute showed that the moisture of gasoline samples at the gas station involved accounted for 88% of the oil. At present, the gas station involved has been investigated by the local police on suspicion of selling fake and shoddy products, and the relevant personnel of the gas station are under control.
Another too much water will pollute the oil, make the oil emulsification, dilute the viscosity of the oil, and greatly reduce the lubricating, cooling and cleaning effects of the oil, and finally damage the engine.
In fact, alcohols such as alcohol are mixed with gasoline and used as fuel, and there are also many researches and commercializations in China. For details, please refer to my answer below.
In addition, can this kind of fuel with high water content really not be used in car engines?
The answer is really usable. A large amount of fuel is mixed with water as an energy-saving technology. A lot of research and even commercialization have been done as early as the last century, but water cannot be added directly in this way.
At the first annual meeting of the International Combustion Association held in July 1981, fuel emulsion mixed with water combustion was listed as one of the three major combustion energy-saving measures.
Of course, this kind of fuel mixed with water is not simply adding water to the fuel, but adding emulsifiers , catalysts and other additives to mix the oil and water through mechanical, ultrasonic and other methods to generate emulsified liquid fuel.
In 1999, the French Elf Oil Company developed a stable mixed emulsified fuel oil (water and gasoline/diesel are mixed, the proportion of water is about 10%-20%), Aquazole emulsified fuel oil . Through experiments on diesel engines, NOX emissions were reduced by 30%, soot was reduced by 50%, and the overall structure of the engine did not require major changes. The ” A-55 “ developed by Caterpillar in the United States (one of the largest diesel engine manufacturers in the world) is mixed with more than 30% water in gasoline , and the fuel saving rate is between 12% and 16%.
In China, related research and promotion began at the end of the last century. HF fuel oil emulsification technology was included in the “National Torch Program Project” in 2004, and was included in the “National Torch Program Key Project” in 2005 . and other large enterprises for testing.
HF fuel oil emulsification technology refers to mixing 70% to 80% of heavy oil and diesel with 20% to 30% of chemical liquid soft water , adding a certain proportion of energy-saving additives such as emulsification, strong catalysis, combustion support, etc., after scientific blending and technological reaction Finally, a new type of fuel oil with the same performance as ordinary heavy oil and diesel is formed, which can be normally and stably used in industry and civil use in society. The combustion products are non-polluting, non-corrosive and non-toxic.
Briefly explain the principle of fuel water emulsification.
This is also the micro-explosion of the physical phenomenon of the emulsion discovered by the former Soviet Union BM Ivanov scientists in the early 20th century:
Water-in-oil molecular group, oil is the continuous phase, and water is the dispersed phase. Under the action of the fuel injector, the water is dispersed in the oil as tiny particles (emulsified oil mist, one-time atomization ). Because the boiling point of water (100°C) is lower than the boiling point of fuel (above 130°C), when the temperature of the cylinder rises sharply, the water particles first boil and gasify, resulting in gasification and expansion, and the volume increases by 1500 times in one ten thousandth of a second. The oil film wrapped by the water is explosively dispersed (micro-explosion), and the oil mist becomes finer particles (secondary atomization) .
The tiny oil droplets after the secondary atomization are easier to burn, and their combustion surface is about 104 times larger than that of pure fuel oil, and the shock wave generated by the micro-explosion phenomenon can make the fuel vapor more evenly distributed in the combustion chamber, speeding up the combustion speed. It reduces the phenomenon of post-combustion, avoids the pyrolysis and cracking of the local high temperature in the combustion zone , makes the fuel burn more fully, reduces the emission of harmful substances, and improves the fuel economy. In addition, the cooling effect of water droplet gasification and the dilution effect of water vapor as an inert gas can effectively resist explosion and improve the inflation efficiency .
Because water and oil are immiscible, a special emulsification method is required to form a stable fuel oil mixed with water emulsion and to ensure the size, uniformity and stability of the water-in-oil particle size.
In the last century, the state introduced No. 66 gasoline mixed with 13%-15% water, No. 70 gasoline mixed with 10% water, and 1% emulsifier (the latter No. 70 gasoline was replaced by No. 90 gasoline in 1997).
Therefore, it is also feasible to add water to the fuel, but do not directly add tens of percent of water to the fuel, and pour it into the engine without any treatment, then the engine will also be overwhelmed.
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Source: Zhihu www.zhihu.com
Author: Will.liu
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