The Radio-Frequency Corona Ignition System is characterised by a wide initial combustion volume and precursors production, via radical insemination by the streamers, in addition to high released thermal energy. These features lead to faster combustion, a higher tolerance for lean mixtures and EGR dilutions and, in general, more adaptability. The thermal energy released by the igniter to the surrounding medium can help to understand the performance, the behaviour and the application range. This paper proposes a systematic experimental analysis of the thermal energy released by the igniter at room temperature, via pressure-based calorimetry. This analysis, carried out at different pressures (up to 10 bar) and medium type (air or nitrogen), is extended to the whole range of the corona igniter control parameters, namely streamer duration and driving voltage. The latter is proportional to the maximum electrode voltage, as shown in the model here presented, and as confirmed by experiments. The results show, for all the vessel pressures, the high energetic efficiency of the ignition system and the high amount of the released energy. The latter is found to increase linearly with the corona streamers duration and quickly with the driving voltage up to the streamer-to-arc transition threshold. The efficiency tends to reach a defined upper limit. For each tested point, the energy released to pure nitrogen is higher than to air, which evidences the impact of the oxygen presence under streamer exposure.

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Late frosts are one of the major impact factors on agriculture worldwide with large economic losses for agricultural crops, with a significant impact also in wine production. Given the importance of the wine sector in the world, more and more efforts are being made to identify innovative techniques capable of creating a low-cost and effective protection for vine shoots, as well as reducing energy consumption. In a previous work, cotton candy was identified as an insulating material to solve the problems related to late frosts on vineyards and limit its damages as much as possible. From the results of the previous research, it has proved that cotton candy is an excellent thermal insulator, but it degrades quickly in windy conditions. Thus, climatic tests carried out in windy condition showed that straw can greatly slow down the degradation of cotton candy over time, giving an indirect contribution to the protective effectiveness of cotton candy. In addition, several tests were conducted with different amounts of sugar and straw without wind to evaluate whether the straw can itself make a contribution in terms of thermal insulation, as well as contribute to the protective effectiveness of cotton candy, minimizing energy use as well.

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Retro-reflectivity is a promising surface capability, which has attracted the interest of researchers for building applications in order to counteract Urban Heat Island (UHI) effects. This work aims at studying the impact of the substrate material on the optic performance of retro-reflective (RR) coatings. Three types of substrate materials were investigated: smooth pine wood panels, rough plywood panels, and smooth acetate sheets. The RR coating samples were made by firstly adding a high reflective white paint onto the substrate material and a homogeneous RR glass beads layer on the top. As a reference case, also diffusive samples, without RR beads, were developed. Samples have been tested through a spectrophotometric and an angular reflectivity analysis. Results show that, despite a lower global reflectance of the RR samples with respect to the diffusive ones, the glass beads coating provides a good retro-reflective capability to all the diffusive samples. Additionally, the roughest RR sample exhibited the highest RR capability of up to 16%, with respect to the other smoother samples. Future developments may involve the optimum design of RR coatings, in terms of their optic performance by varying the substrate materials and roughness, the glass beads density and dimension.