Dynamic simulation of Chemical Engineering systems using OpenModelica and CAPE OPEN
Abstract Modelica has emerged as a strong contender in the arena of dynamic simulation languages. It was developed to be a standard, with an open specification and a large and usable standard library. OpenModelica is an Open Source implementation of a Modelica compiler and environment which is being developed actively. Modelica's object oriented design makes it easy to develop chemical engineering unit operations and connect them to one another. Unfortunately, most proprietary databases of thermodynamic and physical properties and reaction data are not supplied in equation form, but rather as part of closed software. This means that such data must be exchanged with the programs that contain them if they are to be used in custom simulation codes. The CAPE OPEN specification provides a standard architecture for these exchanges, in addition to support for incorporating new unit operations or algorithms into existing proprietary simulations. In this study, a Modelica library allowing interface between Modelica and CAPE OPEN is developed. Its functionality is demonstrated using a model of a ten plate distillation column simulated in OpenModelica on a Linux machine, with thermodynamic and property data from Honeywell Unisim on aWindows machine. The data interfacing was done over a TCP/IP network using CORBA. It is found that real time operation is possible, but that network overhead makes up a significant fraction of the running time, posing problems for faster than realtime off line simulation and optimization.