modelling

It is demonstrated how Modelica™ is used in an application to develop models that are useful when solving real problems. Modelica is a new unified modeling language being developed in an international effort to promote object-oriented and non-causal modelling, and exchange of model libraries. The application is a heat exchanger where1 the media are liquids, typically water. This type of heat exchangers can be used for district heating of houses and for production of hot tap water. The model developed illustrates very nicely the power of Modelica.

The paper deals with simulation of the heat exchanger and model evaluation. There are presented partial differential equations of heat exchanger model, which assume liquid mediums. Presented, in the paper, model is used as an approximation for three different type heat exchangers. The purpose of these investigations was to explain weather the same model could match well to different of shape and type exchangers by adjusting some model parameters. There is shown a method of determining model parameters. Results of simulation are compared with measured data.

A new language called Modelica TM for physical modeling is developed in an international effort. The main objective is to make it easy to exchange models and model libraries. The design approach builds on noncausal modeling with true ordinary differential and algebraic equations and the use of object-oriented constructs to facilitate reuse of modeling knowledge. There are already several modeling language based on these ideas available from universities and small companies. There is also significant experience of using them in various applications.

Europe. Numerous studies have been devoted to the analysis of the physical phenomena related to natural ventilation. These phenomena are very complex and our degree of understanding them often leaves a lot to be desired. Research on this topic within the framework of PASCOOL included experimental and modeling work aiming to fill existing gaps in our knowledge of indoor air conditions in naturally ventilated buildings.