Adriana Del Borghi

Effects of Mass Transport on the Performance of Solid Oxide Fuel Cells Composite Electrodes

Composite electrodes are of great interest in the field of solid oxide fuel cells because their use can improve the performance of these cells. However, an important correlation exists between composition, microstructure, and thickness of an electrode and its performance. This correlation has been investigated in this work using a theoretical model. The model, in order to consider all the losses occurring in an electrode, includes Ohm’s law for ionic and electronic charge transport, and the Butler-Volmer equation to evaluate the activation polarizations, and mass transport equations, taking into account diffusion through porous media, to evaluate the concentration losses. The model shows that the best electrode performance is a trade-off between activation and concentration losses. This is because a decrease in the dimensions of the particles or an increase in its thickness result, on the one hand, in a reduction of the activation polarizations, because of a larger active area for the electrochemical reaction, and, on the other hand, in an increase in the concentration losses due to a more difficult gas diffusion. In particular, in order to understand the impact of concentration losses on the performance of composite electrodes, the simulations have been run with two models, one including and the other one neglecting the mass transport equations. The results show that concentration losses play a role only with thick electrodes composed of small particles, operating at high fuel utilization.

Catalytic ceramic membrane in a three-phase reactor for the competitive hydrogenation–isomerisation of methylenecyclohexane

Abstract Hydrogenation and oxidation reactions can be carried out in very mild conditions using a three-phase catalytic reactor. The challenge is to overcome the diffusion resistance that affects this type of reactor. The catalytic membrane reactor (CMR), where the membrane is used not only as physical selective barrier but also as a chemical reactor, can be an efficient alternative to more conventional systems in improving the contact among solid catalyst, gas and liquid. The performances of different catalytic membranes were explored in the hydrogenation–isomerisation of methylenecyclohexane, in a temperature range between 288 and 343 K. Comparisons between a classic batch stirred tank and CMR were also carried out. Various characteristics of the reacting system, such as the overall process rate, the effect of temperature, the reaction order with reference to the substrate and the hydrogen and reaction selectivity were studied.

Linearized kinetic models for the simulation of the mesophilic anaerobic digestion of pre-hydrolyzed woody wastes

The most common kinetic models available in the literature to describe the COD consumption during batch anaerobic digestion are checked and compared in their linearized forms in the case of prehydrolyzed mixtures simulating the composition of woody wastes. The introduction of the COD value at the end of batch digestion in both the First Order and the Monod models allows one to take into account the deviations due to the progressive increase in the fraction of difficultly-digestible substances present in the medium. The so-modified version of the First Order model as well as that proposed by Singh and co-workers not only show the best fits to the experimental data but also demonstrate that they are the simplest and easiest ones for immediate use.

Glass Packaging Design and Life Cycle Assessment: Deep Review and Guideline for Future Developments

The function of packaging is to keep a product unaltered from the producer to the consumer. Glass is one of the most extensively used materials for packaging, thanks to its skills and proprieties. The environmental burdens of this packaging material have been broadly studied, and several scientific papers on this topic are retrievable on literature. The aim of this work is to categorize and subdivide the existing scientific literature about glass packaging focusing to issues related to sustainability. Thus, the review and interpretation of Life Cycle Assessment literature was subdivided in different categories depending to the main goal. The main outcomes from the research studies are discussed. A recommendation list is presented as a bullet point with the aim of summarizing the general outcomes of the manuscripts under review and of giving advices for future development.

University campus waste prevention and reduction: A circular-economy approach

One of the most important challenges to improve sustainability is the management of climate change and the reduction of green house gas emissions. In 2014 the University of Genoa and the Ministry of the Environment signed an agreement to assess the Carbon foot-print of the university, in order to promote the mitigation of climate change and to study possible innovative solutions to reduce the environmental burdens. Following the agreement, the university want to implement a project for the sustainable management of waste within it. A circular economy methodology has been used to implement a project that will help in diminish the pollutants impacts deriving from the waste management recovering and recycling high quality materials. In cooperation with municipal local companies for the management of waste, the project foresees to implement studies and research in the field of guidelines, attitudes and behaviour of the population towards the recovery, recycling and reuse, pushing for a transition to a circular economic approach. Considered the lack of an accounting model and monitoring of waste products it has been decided to implement it. Waste produced by the university have been estimated and calculated through experiments and on field analyses and its GHG potential have been evaluated through a LCA methodology. The general outcome of this research shows that it is possible to create a circular economy model applicable to other universities and medium-sized communities, even if future development are presented in order to improve future investigation.