A beginner’s question: It’s still a problem related to enthalpy
Thread Content
I added a third substance to the simulation (a new substance for which there are no property parameters in the system); from its entry into the tower to its exit, only the temperature changes, while all other properties remain unchanged. The system requires the selection of equations for enthalpy and density; the enthalpy here is clearly not the reaction enthalpy or combustion enthalpy. Is the understanding of this enthalpy that it increases with temperature changes? In Aspen, can I use external programs to calculate density and enthalpy changes? Thank you
Let me give an example: in biomass gasification, the biomass is defined as a non-conventional component, as well as a non-reservoir component. It is necessary to define the analytical components of biomass and its general composition; after that, it is also required to specify the methods for calculating enthalpy and density (several methods are available for selection, such as HCOGEN, etc.). Without these thermodynamic data, it is impossible to carry out relevant simulations
Thank you to the person above; Aspen does recommend several models for calculating enthalpy and density, but there are better models available in many publications. Can’t it be calculated using a non-recommended model? Also, in which interface should new substances be defined? Please give your advice
Of course, it can be calculated using non-recommended models; Aspen is an open system. There are several methods: 1. Use the formulas found in the literature to write code in Aspen using the Fortran language (this is difficult for beginners); 2. Calculate the corresponding values at different temperatures in Excel using the formulas from the literature, and then use Aspen’s regression function. That is, data on the known enthalpy or density at different temperatures are entered, and then Aspen uses these values along with basic formulas to perform regression, thereby determining the various parameters of those basic formulas (which should preferably be in a form similar to those used in literature)