Energy substance of a usual diesel fuel is 42 MJ kg-1 . Flash point is temperature at which the liquid has to be heated for vapour to type a combustible mixture by air at atmospheric pressure. As flash point in diesel fuel is as a minimum 55°C, this makes it safer fuel to store than also petrol or kerosene. Flash point of kerosene is 30°C.
It engine runs on fuel by also low a cetane number, there will be diesel knock. Diesel knock is caused by too quickly combustion and is effect of a long ignition holdup time, as during this period fuel is inject and mixes by air to form a prepared combustible mixture. Ignition occurs just after pressure and temperature contain been over certain limits for enough time, and fuels by high cetane numbers are those that self-ignite eagerly.
It is predictable that fuels by high cetane numbers contain low octane numbers and vice- versa. Ignition wait is most marked at low speeds because of reduced temperature and pressure through compression. For cold starting is generally remedied through if a ability on injector pump to inject excess fuel.
Diesel fuel have 1 2 to 22 carbon atoms. They might be of higher molecular mass works (for example cetane C16 H34) that possible solid at room temperature if they were not mix by other hydrocarbons. Therefore, when diesel fuel is chilled a point will be reach at which higher molecular mass components will start to solidify and form a waxy precipitate. This can be use in anti-waxing additives to modify shape of wax crystals. Additives in diesel fuel to get better the cetane number are referred to as ignition accelerators.