URBAN AIR CLEANER DESIGN AND FEASIBILITY STUDY

In the past decades, the rising levels of air pollution in urban areas are threatening the natural environment and the human health. This Thesis focuses on the development (CAD design) and feasibility investigation (evaluation of introduced losses) of a prototype device for passive air cleaning, after an initial review of the existing technologies in the field. The guideline of the project has been to use the device mounted on cars, taking advantage of their motion for the passive suction of the external air. To give the work a more practical resonance, the study has been based on the Barcelona urban area framework. Prior to the mentioned steps, an evaluation on the air pollution levels in Barcelona city, through institutional data processing via MATLAB, has been carried. The analysis, besides proving a seasonality of the pollution problem, showed that the regulatory limits are often exceeded, along the seven monitored months. The best technology, for the removal of a wide range of compounds from the air, is the impregnated activated carbon, in pellets or granulated, that uses the principle of chemical adsorption. After designing the first shape of the prototype, it has been firstly simulated through a 2D COMSOL model to estimate and compare the aerodynamic losses introduced by the presence of the device while mounted in different positions, like roof or hood of the car. The study lead to the conclusion that the hood position has to be preferred, for its smaller drag induced and enhanced air flow rate. Analysing the flow field other optimisation are brought that implied the shape change of the device, the position of the activated carbon and the addition of some deflectors. Once determined the best position, the same configuration has been simulated in 3D. An estimation of the average cars emissions in province of Barcelona, together with the simulations results, in terms of drag losses introduced and air flow rate generated, have been used to evaluate the feasibility of the device. It emerged that, with the actual configuration, the ratio airflow generated vs drag losses is not high enough to justify the use of the device. Further experimental tests on the filtering media real parameters, together with an improvement of the device shape, must be done in the future to re-evaluate the feasibility of the project.