Numerical modelling of HySun, an innovative hybrid air treatment technology within RE-COGNITION project

The building sector has a remarkable importance on the overall EU final energy consumption and CO2 emissions (with a share of 40% and 36% respectively), with about a third of the buildings constructed more than 50 years ago, meaning low energy efficiency and little or no renewable energy sources exploited. Simultaneously, EU has set challenging goals to achieve by 2030: curtailment of greenhouse gas emissions by, at least, 40% (with respect to 1990 levels), growth of the renewable energy share to 32%, improvement in energy efficiency by 32.5%. In order to improve the actual situation moving towards the targets set by EU, RE-COGNITION, a Horizon 2020 project, presents a solution which aims at employing on a large-scale Renewable Energy Sources (RES) in buildings, reaching zero-energy, or even energy positive buildings. One of the main objectives of RE-COGNITION project is to propose cutting-edge technology innovations using RES. This thesis will focus on one of the technologies presented in the project: HySun, a solar hybrid air cooling technology based on adsorption process. The core of the system is a finned heat exchanger coated with silica-gel, which exploits the desiccant material adsorption capacity to capture water vapor from air, dehumidifying it. When the adsorption process is terminated, silica-gel needs to be regenerated by supplying heat, which can be provided by a wide range of technologies (such as solar thermal collectors, heat pump, waste heat, district heating system). In this thesis, a numerical model of the adsorption heat exchanger is built by defining the energy and mass balances between the species involved in the process. Afterwards, the model is implemented on MATLAB in order to be able to simulate different working conditions. Firstly, a parametric study is carried out with the aim of understanding how the system performance varies with different operative conditions and configurations. Subsequently, dynamic simulations are accomplished with the purpose of analyzing the system performance in a real operating environment.