How are the value and unit of the activation energy determined in Aspen dynamics inputs? -
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The lecture slides by Professor Wu Jia already provide the kinetic equations and the expressions for the reaction rate constants. When entering the activation energy into Aspen, it is necessary to consider that the unit of the pre-exponential factor should be the same as that of the rate constant; exp(-E/RT) should be a dimensionless value. R equals 8.314 J/mol K or kJ/kmol K, and the rate is based on molar concentration: kmol/m3. Why is the unit of E in Teacher Wu Jia’s question J/kmol? It should be J/mol or kJ/kmol, right? I seek advice from experts.
Follow the instructions in the help file to convert the dynamic equations to consistent units.
Thank you, it’s done. The help file doesn’t specify the unit for activation energy; the problem should indicate the unit for activation energy
I don’t know what version you have. Mine is V7.1; when you enter the activation energy value, there is an option to select the unit. In any case, as long as it can be ensured to become a dimensionless number.
The unit chosen must also be correct; the problem itself should specify the unit for the activation energy, otherwise it’s not possible to make a selection in Aspen, and it cannot be ensured that the exponent is dimensionless
But it’s strange that for many reactions, the activation energy is given without any units – what should be done? How do I tell?