Modular simulation of vapour compression systems with an object oriented tool

Abstract

The objective of this work is to simulate vapour compression refrigeration systems through a modular approach by means of an object - oriented numerical tool called NEST. For this purpose, the global system is modeled as a collection of different elements which are linked between them. Each element represents a specific part of the system (e.g. heat exchanger, compressor, expansion device, tube, cavity, wall, etc.) and can be independently solved for given boundary conditions. The global resolution procedure is carried out by solving all the elements iteratively, transferring information between them, until a converged solution is reached. The system is easily modified by adding, subtracting or substituting any of its elements. This feature gives great flexibility to the model, not only because the configuration of the system can be clearly altered, but also because the numerical model of any element can be easily replaced allowing different levels of simulation. In this work the object - oriented methodology together with the elements description and their resolution procedures are presented. The model is validated against experimental data obtained from a refrigeration cycle working with isobutane. In addition to this, an illustrative case is presented in order to show the system capabilities.