油的发热量（Calorific value of oil）是指单位质量（或体积）的油在完全燃烧时所释放出的热量，是衡量油作为能源燃料品质的重要指标之一。它直接关系到油在燃烧过程中所能提供的能量多少，对于油的储存、运输、燃烧设备设计以及能源利用效率评估等都具有重要意义。

          The calorific value of oil refers to the amount of heat released when a unit mass (or volume) of oil is completely burned. It is one of the important indicators to measure the quality of oil as an energy fuel. It is directly related to the amount of energy that oil can provide during combustion, and is of great significance for the storage, transportation, design of combustion equipment, and evaluation of energy utilization efficiency of oil.

          不同种类的油，如原油、汽油、柴油、重油等，其发热量存在差异，这主要与它们的化学组成（如碳、氢等元素的含量比例）有关。通常情况下，油的发热量以兆焦 / 千克（MJ/kg）或千卡 / 千克（kcal/kg）为单位表示。

          Different types of oil, such as crude oil, gasoline, diesel oil, heavy oil, etc., have different calorific values, which are mainly related to their chemical composition (such as the proportion of elements like carbon and hydrogen). Usually, the calorific value of oil is expressed in megajoules per kilogram (MJ/kg) or kilocalories per kilogram (kcal/kg).