Enthalpy value problem
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For enthalpy values, there is a reference state, and the enthalpy of other states is calculated with this as a basis. However, for the same temperature and the same substance, different references result in enthalpy values that can be positive or negative. For example, for water, the value in the tables related to chemical engineering principles is positive, but the value obtained through Hysys simulations is negative. This indicates that the reference points used are different. Yet, for the same substance under the same conditions, the enthalpy value can be either positive or negative, and its magnitude also varies. Could this affect calculations that involve enthalpy values? ? ? Confusion
No, because the same standard is used in the calculations, and enthalpy change is what is calculated at all times; thus, even if the standards differ, the results will remain the same
2# kzb7054: I’m not sure if anyone upstairs has used Hysys to calculate the enthalpy values. The enthalpy values of the standard points in Hysys are very large negative numbers; it seems they correspond to absolute zero. How were these values obtained?