Calories, kilocalories, joules, watts, standard coal – heat unit conversions

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Calorie (cal): The amount of heat absorbed or released when the temperature of 1 gram of water is raised or lowered by 1°C is defined as 1 calorie (cal)； Kilocalories (kcal): Kilocalories are also known as large calories. 1 large calorie (kcal) = 1000 calories (cal). Joules (J): A unit of measurement for work and energy; it is a unit of energy. Heat, as a form of energy, can certainly be measured in joules. Hence, there is what’s known as the mechanical equivalent of heat: 1 calorie (cal) = 4.1868 joules (J); 1 kilocalorie (kcal) = 4186.75 joules (J); 1 kcal/h = 1.163 watts = 1.163 J/s. There are three ways to express the output of hot water boilers: kilocalories per hour (Kcal/h), tons per hour (t/h), and megawatts (MW). (1) Kilocalories per hour is a unit of measurement in the metric system; it indicates the amount of heat released by a hot water boiler per hour. (2) “Ton” or “steam ton” is a colloquial term borrowed from steam boilers. It refers to the amount of heat that a hot water boiler can supply per hour; this amount is equivalent to the heat required to heat a certain mass of water (usually expressed in tons) from 20°C and completely convert it into steam. (3) The megawatt (MW) is the unit of power in the International System of Units; its base unit is the watt (W). (1 MW = [image] W). This manner of expression should be used in official documents. The conversion relationships among the three units of measurement are as follows: 600,000 kilocalories/hour (60 × the value in kcal/h shown in the image) ≈ 1 steam ton/hour [1 t/h] ≈ 0.7 MW of coal heat. When performing calculations, it is necessary to determine both the quality of the coal and the requirements for the steam to be generated; thereafter, the following data can be used. Standard coal is an equivalent concept defined based on a certain calorific value. It is specified that the lower heating value of 1 kilogram of standard coal is 7,000 kcal or 29,274 kJ.