environ. |
utilisation of calorific value Calorific value is the heat per unit mass produced by complete combustion of a given substance. Calorific values are used to express the energy values of fuels; usually these are expressed in megajoules per kilogram. They are also used to measure the energy content of foodstuffs; i.e. the energy produced when the food is oxidized in the body. The units here are kilojoules per gram. Calorific values are measured using a bomb calorimeter (apparatus consisting of a strong container in which the sample is sealed with excess oxygen and ignited electrically. The heat of combustion at constant volume can be calculated from the resulting rise in temperature) (热值是某一物质每单位质量完全燃烧所产生的热量。热值是用来表示燃料的能量值,通常是用每千克兆焦耳来表示。它们也可用来测量食品的能量值,即当食物在体内氧化所产生的能源,这里的单位是每克千焦。热值使用爆炸量热器(仪器有强大的容器,样品是用过量氧气密封而成,以电动方式点燃,导致的温度上升可计算出定容燃烧热量)来测量。) |