1. Cetane number.

十六烷值是評定柴油自燃性的指標。自燃型好壞，直接影響著柴油機燃燒過程的質(zhì)量和工作性能。柴油的十六烷值高，自燃性差，使柴油機運轉(zhuǎn)粗暴，并造成起動困難。但并不能說十六烷值越高越好。因為十六烷值太高，柴油機運轉(zhuǎn)粗暴，并造成起動困難。但并不能說十六烷值越高越好。因為十六烷值太高，柴油的穩(wěn)定性差，噴入燃燒室后，來不及與空氣充分混合就著火，使柴油在高溫下產(chǎn)生裂解分離出大量的游離碳，隨廢氣氣體排出，產(chǎn)生冒煙現(xiàn)象，造成燃料消耗增加。因此，要求具有適當(dāng)?shù)氖橹?，一般高速柴油機所用柴油的十六烷值為40-60.

Cetane number is an index to evaluate the spontaneous combustion of diesel. The quality of spontaneous combustion directly affects the quality and performance of diesel engine combustion process. Diesel fuel has high cetane number and poor spontaneous combustion, which makes the diesel engine run rough and makes it difficult to start. But it cannot be said that the higher the cetane number, the better. Because the cetane number is too high, the diesel engine runs rough and makes it difficult to start. But it cannot be said that the higher the cetane number, the better. Because the cetane number is too high and the stability of diesel is poor, it will catch fire before it is fully mixed with air after being injected into the combustion chamber, so that diesel will crack at high temperature and separate a large amount of free carbon, which will be discharged with exhaust gas, resulting in smoke, resulting in increased fuel consumption. Therefore, it is required to have an appropriate cetane number. Generally, the cetane number of diesel used in high-speed diesel engine is 40-60

2、餾程。

2. Distillation range.

柴油噴入汽缸是在激化以后再著火燃燒的，因此柴油的蒸發(fā)性好壞對柴油機燃燒過程有著重大影響。餾程表示柴油的蒸發(fā)性。餾程溫度低（即輕餾分燃料含量大），燃料與空氣能夠很好的混合，柴油機也容易起動。但輕餾分燃料容易過早地蒸發(fā)，造成同時燃燒的燃料過多，使柴油機工作粗暴。反之，重餾分燃料的黏度大，霧化不良，汽化緩慢，容易造成燃燒不完全而產(chǎn)生嚴重積炭現(xiàn)象。因此，要求柴油的輕、重餾分含量都不能過多，餾程范圍應(yīng)小。

Diesel injected into the cylinder is ignited and burned after intensification. Therefore, the evaporation of diesel has a significant impact on the combustion process of diesel engine. The distillation range indicates the evaporation of diesel oil. The distillation range temperature is low (i.e. the content of light fraction fuel is large), the fuel and air can be well mixed, and the diesel engine is easy to start. However, light fraction fuel is easy to evaporate prematurely, resulting in too much fuel burning at the same time, which makes the diesel engine work rough. On the contrary, heavy distillate fuel has high viscosity, poor atomization and slow vaporization, which is easy to cause incomplete combustion and serious carbon deposition. Therefore, it is required that the light and heavy fraction content of diesel oil should not be too much, and the distillation range should be small.

3、運動黏度。

3. Kinematic viscosity.

黏度表示柴油的流動性，黏度對燃油的霧化和燃料供給系統(tǒng)正常的工作有著密切關(guān)系，黏度過高，燃油在管路和濾清器內(nèi)流動阻力加大，噴霧惡化，燃燒不良。而黏度過低，使柴油系統(tǒng)內(nèi)的精密偶件潤滑條件惡化，加速零件磨損，并增加漏油量。黏度和穩(wěn)定有很大關(guān)系，溫度越低黏度越大，冬天柴油黏度會增大，甚至在管路中流動也有困難。故在低溫下使用時，應(yīng)進行適當(dāng)預(yù)熱。

Viscosity indicates the fluidity of diesel. Viscosity is closely related to the atomization of fuel and the normal operation of fuel supply system. The viscosity is too high, the flow resistance of fuel in the pipeline and filter increases, the spray worsens, and the combustion is bad. The low viscosity worsens the lubrication conditions of precision coupling parts in the diesel system, accelerates the wear of parts and increases the amount of oil leakage. Viscosity is closely related to stability. The lower the temperature, the greater the viscosity. In winter, the viscosity of diesel will increase, and even it is difficult to flow in the pipeline. Therefore, proper preheating shall be carried out when using at low temperature.

4、凝點

4. Freezing point

柴油的黏度隨溫度下降而增大，當(dāng)下降到某一溫度時，柴油中含有的高分碳氫化合物便產(chǎn)生結(jié)晶，使柴油失去流動性，此時溫度叫做凝固定（固定）。標準輕柴油的牌號就是根據(jù)固定而命名的，共分為10號、0號、-10號、-20號、-35號、-50號六種。如-10號輕柴油的凝點為-10℃。柴油的凝點高，在溫度低的環(huán)境下工作時，很容易引起油路和濾清器堵塞，產(chǎn)生供油不足，甚至中斷供油。因此，使用中必須根據(jù)環(huán)境溫度條件，選用適當(dāng)牌號的柴油。

The viscosity of diesel oil increases with the decrease of temperature. When it drops to a certain temperature, the high score hydrocarbons contained in diesel oil will crystallize, making diesel oil lose fluidity. At this time, the temperature is called coagulation fixation (fixation). The brand of standard light diesel oil is named according to the fixed, which is divided into six types: No. 10, No. 0, - No. 10, - No. 20, - No. 35 and No. 50. For example, the freezing point of - 10 light diesel oil is - 10 ℃. Diesel oil has high freezing point. When working in low temperature environment, it is easy to cause blockage of oil circuit and filter, resulting in insufficient oil supply and even interruption of oil supply. Therefore, diesel oil of appropriate brand must be selected according to ambient temperature conditions in use.