Calorific value calculation
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The composition of the elements in a mixture is known. How to calculate its calorific value
To calculate the heat released, it is not sufficient to know only the elemental composition; at the very least, it is necessary to know the state of the elements – whether they are in free form or combined – as well as their oxidation state. It is best to provide information on the composition and state of the compound as well!
1. First, it is necessary to determine whether the heat value refers to reaction heat or combustion heat. 2. Write the reaction equations and combustion equations for each component in the mixture, indicating in these equations whether the reaction is endothermic or exothermic, as well as the amount of reaction heat. The values for reaction heat or combustion heat can be found in relevant books. 3. Determine how much of each component in the mixture participates in the reactions, and calculate the heat of reaction for each reaction. 4. Add up the heat of reaction for all reactions to find the heat release of the mixture. You can find information on this in a book titled “Calculations of Material Balance and Heat Balance”*
What is a mixture? If theoretical calculations are too complicated, you can look for empirical formulas. For example, there are similar empirical formulas for the calorific value of coal.
1. Determine the P, V, T conditions for calculating heat generation； 2. Determine the reaction type (combustion products). 3. Determine the basic thermodynamic constants of various components (enthalpy of formation, specific heat). 4. Perform cumulative summation. Is it the calorific value of liquid hydrocarbons or gas?
It’s impossible to calculate just with these conditions. For example, the heat released when 12 kg of C + 32 kg of O2 \"burn\" is different from that when 44 kg of CO2 is produced.
Treat specific issues differently; please, the original poster, state the question.
There are empirical formulas; for coal, such formulas are available. Ignoring the heat of reaction, the calculation is usually done based on the calorific value and specific gravity of each component, or simply by using empirical formulas.
Find the specific heat capacity of tar based on its average temperature, and then calculate Q = ΔT·m·cp
This post was last edited by a602516723 on 2017-7-5 14:08. The calorific value can be estimated based on elemental analysis using Mendeleev’s empirical formula or the formulas developed by the Coal Research Institute. https://wenku.baidu.com/view/9a3bdc94770bf78a6529548b.html