1. Cetane number.

十六烷值是评定柴油自燃性的指标。自燃型好坏，直接影响着柴油机燃烧过程的质量和工作性能。柴油的十六烷值高，自燃性差，使柴油机运转粗暴，并造成起动困难。但并不能说十六烷值越高越好。因为十六烷值太高，柴油机运转粗暴，并造成起动困难。但并不能说十六烷值越高越好。因为十六烷值太高，柴油的稳定性差，喷入燃烧室后，来不及与空气充分混合就着火，使柴油在高温下产生裂解分离出大量的游离碳，随废气气体排出，产生冒烟现象，造成燃料消耗增加。因此，要求具有适当的十六烷值，一般高速柴油机所用柴油的十六烷值为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、馏程。

2. Distillation range.

柴油喷入汽缸是在激化以后再着火燃烧的，因此柴油的蒸发性好坏对柴油机燃烧过程有着重大影响。馏程表示柴油的蒸发性。馏程温度低（即轻馏分燃料含量大），燃料与空气能够很好的混合，柴油机也容易起动。但轻馏分燃料容易过早地蒸发，造成同时燃烧的燃料过多，使柴油机工作粗暴。反之，重馏分燃料的黏度大，雾化不良，汽化缓慢，容易造成燃烧不完全而产生严重积炭现象。因此，要求柴油的轻、重馏分含量都不能过多，馏程范围应小。

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、运动黏度。

3. Kinematic viscosity.

黏度表示柴油的流动性，黏度对燃油的雾化和燃料供给系统正常的工作有着密切关系，黏度过高，燃油在管路和滤清器内流动阻力加大，喷雾恶化，燃烧不良。而黏度过低，使柴油系统内的精密偶件润滑条件恶化，加速零件磨损，并增加漏油量。黏度和稳定有很大关系，温度越低黏度越大，冬天柴油黏度会增大，甚至在管路中流动也有困难。故在低温下使用时，应进行适当预热。

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、凝点

4. Freezing point

柴油的黏度随温度下降而增大，当下降到某一温度时，柴油中含有的高分碳氢化合物便产生结晶，使柴油失去流动性，此时温度叫做凝固定（固定）。标准轻柴油的牌号就是根据固定而命名的，共分为10号、0号、-10号、-20号、-35号、-50号六种。如-10号轻柴油的凝点为-10℃。柴油的凝点高，在温度低的环境下工作时，很容易引起油路和滤清器堵塞，产生供油不足，甚至中断供油。因此，使用中必须根据环境温度条件，选用适当牌号的柴油。

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.