The large-scale penetration of renewable sources in the European energy system is leading to management and control issues on the electricity distribution network, due to the randomness of the energy coming from these sources and to the lack of adequate storage capacities. In this regard, an interesting solution currently being considered is represented by Power-to-Gas technology and chemical energy storage. In fact, renewable electricity surplus can be used to power water electrolysers producing green hydrogen to be injected in natural gas pipelines, with the dual effect of solving production-consumption mismatches in the electricity network and decarbonizing the natural gas system. In the present work, a mathematical model has been developed to study the hourly operation of an integrated multi-gas system for green hydrogen production via photovoltaic-powered electrolysers and its injection upstream of a Regulating and Measuring Station (RMS). Different operating conditions are investigated and a scenario of increasing photovoltaic production is considered. Obtained results show that higher fractions of hydrogen in the blend can be achieved during summer operations when the lowest natural gas consumption and the highest solar production occur.

The ventilation flow in a car cabin has been experimentally investigated. The study has been carried out in a car commercially available, by testing one ventilation mode (panel-vent mode) at one fan strength (level 3 of the 4 available) with fresh air intake (without any re-circulation). The flow velocity at the exit of the vents has been measured using a 5-hole pressure probe. The flow velocity fields inside the car cabin have been measured by particle image velocimetry (PIV) in three longitudinal sections: (i) the car centre plane, including both the front and rear area; (ii) the driver’s seat centre plane, only in the front area; (iii) the passenger’s seat centre plane, only in the front area. At these longitudinal planes, the time-average flow velocity is presented and discussed. The experimental results provide new insights in the ventilation flow in a car cabin.