An innovative approach towards solar desiccant cooling systems yearly simulations

The solar desiccant cooling system performance depends on the interaction of various components under the influence of changing ambient air conditions and cooling load. Design point calculations provide preliminary estimates of performance but can be scarcely applied for the potential viability assessment of a particular system concept. The competitiveness of a solar desiccant cooling system depends on its seasonal operation, which is not assessable from the design point data alone. Computer simulations of seasonal performance provide a more accurate estimate of system viability and the potential impact on the consumer in terms of energy and costs. Furthermore, system simulations are a tool for investigating control strategies that maximise the thermal performance and minimise the parasitic power requirements. Solar desiccant systems have been extensively studied in the past decades, but few works were in regards to their simplified mathematical modelling for seasonal system performance assessment through computer simulations. In this paper an original set of models of solar desiccant cooling system components and control are presented. The algorithms, implementing the latter models, are meant to be used for yearly solar desiccant cooling system simulations based on one hour time-steps. Moreover, the tools, the procedure and the results of a set of yearly simulations are described. The models implemented for the TRNSYS platform include a desiccant air-handling unit (called type 275) and a control unit (type 276). A service library where all the mathematical models describing the physical processes through each component has been implemented. Beside a description of the models the paper presents results of a design study for an application in the Germany