Supercritical CO2 drying of food matrices

[EN] This work explore the use of supercritical CO2 drying as alternative technique for the obtainment of pasteurized and high quality dried product. Several tests were conducted on animal, vegetable and fruit matrixes in order to investigate the effectiveness of SC-CO2 drying process at different process conditions. Design of experiment was performed to find the optimal process conditions for vegetable and fruit matrices, using the final water activity of the products as key indicator for the drying efficiency. The inactivation of naturally present microorganisms and inoculated pathogens demonstrated the capability of SC-CO2 drying process to assure a safe product. Moreover, retention of nutrients was compared with conventional drying methods. Results suggest that supercritical drying is a promising alternative technology for food drying.The research leading to these results received funding from the European Community’s Horizon 2020, Call H2020-SFS-2014-2 “Future Food” project and from the Progetto Strategico di Dipartimento SID of the Department of Industrial Engineering (University of Padua). M.T. and G.P. thank Regione Veneto that supported their fellowship through the grant FSE.Zambon, A.; Vizzotto, TM.; Morbiato, G.; Toffoletto, M.; Poloniato, G.; Dall’acqua, S.; De Bernard, M.... (2018). Supercritical CO2 drying of food matrices. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 17-23. https://doi.org/10.4995/IDS2018.2018.7753OCS172

Wind energy harvesting from transport systems: A resource estimation assessment

Many recent patents worldwide address the concept of harvesting wind energy from aerodynamic losses in motorways, however the mechanics of a specific device dedicated to the task has never been described. The lack of a characterization of the energy resource likely explains why the international market is still to acknowledge any technology related to the concept. Here, an experimental activity is presented to investigate the flow field generated by traffic in motorways and eventually develop an innovative technology that complies with emerging energy policies. In the case of traffic source, the energetic rationale seems to have a double motivation: there will always be an optimal energy supply associated with an increment in transport demand and, contrary to other renewables, the transport aerodynamic losses belong to a source of costs, making them a remarkably sustainable energy source. After a thorough analysis of the correlation between truck flow and wind speed classes, the characterization of a resource indicator for time of wind above a cut-in speed is given, with an account for the effects of traffic clusters and traffic related wind-drops. We demonstrate how during weekdays daytime hours the traffic-generated resource can allow an energy conversion beyond a threshold possibly permitting a positive energetic balance of the system. A study on the effect of traffic related wind-drops is also carried out to investigate how the issue could be relevant in the transient behavior and ultimately in the performance of a mini wind turbine in the kW-range. While many findings relate to the motorway site where the campaign was sited, fitting of the experimental data to the generic motorway case permits to explore a complete range of traffic flows

Numerical analysis of a synchronization phenomenon: Pedestrian-structure interaction

The pedestrian-structure interaction is considered by developing a non-linear double pendulum model, representing the lateral walking of the pedestrian and the horizontal vibration mode of the structure. To understand the synchronization phenomenon, the two oscillators were considered in their phase spaces, and a ring-dynamics approach was applied. As synchronization occurs, pedestrian motion becomes in phase quadrature with a quarter-of-period in advance of the bridge motion: this ensures stability of walking conditions on a moving deck, but causes random cancellation of forces typical of an incoherent crowd. Correspondingly, the lateral force transmitted to the structure increases its value, approaching resonance conditions