Topology optimization for energy problems

The optimal design of energy systems is a challenge due to the large design space and the complexity of the tightly-coupled multi-physics phenomena involved. Standard design methods consider a reduced design space, which heavily constrains the final geometry, suppressing the emergence of design trends. On the other hand, advanced design methods are often applied to academic examples with reduced physics complexity that seldom provide guidelines for real-world applications. This dissertation offers a systematic framework for the optimal design of energy systems by coupling detailed physical analysis and topology optimization. Contributions entail both method-related and application-oriented innovations. The method-related advances stem from the modification of topology optimization approaches in order to make practical improvements to selected energy systems. We develop optimization models that respond to realistic design needs, analysis models that consider full physics complexity and design models that allow dramatic design changes, avoiding convergence to unsatisfactory local minima and retaining analysis stability. The application-oriented advances comprise the identification of novel optimized geometries that largely outperform industrial solutions. A thorough analysis of these configurations gives insights into the relationship between design and physics, revealing unexplored design trends and suggesting useful guidelines for practitioners. Three different problems along the energy chain are tackled. The first one concerns thermal storage with latent heat units. The topology of mono-scale and multi-scale conducting structures is optimized using both density-based and level-set descriptions. The system response is predicted through a transient conjugate heat transfer model that accounts for phase change and natural convection. The optimization results yield a large acceleration of charge and discharge dynamics through three-dimensional geometries, specific convective features and optimized assemblies of periodic cellular materials. The second problem regards energy distribution with district heating networks. A fully deterministic robust design model and an adjoint-based control model are proposed, both coupled to a thermal and fluid-dynamic analysis framework constructed using a graph representation of the network. The numerical results demonstrate an increased resilience of the infrastructure thanks to particular connectivity layouts and its rapidity in handling mechanical failures. Finally, energy conversion with proton exchange membrane fuel cells is considered. An analysis model is developed that considers fluid flow, chemical species transport and electrochemistry and accounts for geometry modifications through a density-based description. The optimization results consist of intricate flow field layouts that promote both the efficiency and durability of the cell

Artivismo antimilitarista: l’esperienza del Movimento No Dal Molin a Vicenza

L'esperienza del Movimento No Dal Molin nasce a Vicenza nel 2006 contro la costruzione di una nuova base militare Usa nell’ex aeroporto Dal Molin. Da allora il Presidio Permanente No Dal Molin diventa la casa comune di diverse realtà antimilitariste e lo spazio della creatività del movimento. L'arte ha un ruolo fondativo di tale attivismo politico, in diverse forme riconducibili alla sfera della public art. Mentre le basi militari vicentine imitano l'arte di Andrea Palladio, infatti, il Movimento No Dal Molin attraversa la città con performance e produzioni artistiche partecipative. L’articolo intende approfondire alcune delle forme artistiche proposte dal 2006 al 2014 e indagarne l’attuale eredità. Tra queste: le azioni di Teatro invisibile e teatro di strada che le donne del movimento hanno usato per stimolare inizialmente il dibattito pubblico sulla base militare; i contributi di artisti locali, come l’azione rivolta all’Unesco The Burning Cemetery, di Alberto Peruffo; infine Silent Play, un percorso audioguidato coordinato da Carlo Presotto e scritto collettivamente: nella fase di costruzione della base, ripercorreva luoghi ed eventi simbolo del movimento.The No Dal Molin Movement was born in Vicenza in 2006 against the construction of a new US military base in the former Dal Molin airport. Since then, the No Dal Molin Permanent Presidium has become the common home of various anti-militarist realities and the space for the movement's creativity.  Art has a founding role in this political activism, in various forms attributable to the sphere of public art. While the Vicenza military bases imitate the art of Andrea Palladio, in fact, the No Dal Molin Movement crosses the city with participatory artistic performances and productions. The article intends to deepen some of the artistic forms proposed from 2006 to 2014 and investigate their current legacy. Among these: the actions of invisible theater and street theater that the women of the movement used to initially stimulate the public debate on the basis; the contributions of local artists, such as the action addressed to Unesco The Burning Cemetery, by Alberto Peruffo; Silent Play, an audio-guided tour coordinated by Carlo Presotto and written collectively which, during the construction phase of the base, retraced the places and events that symbolize the movement

Design of effective fins for fast PCM melting and solidification in shell-and-tube latent heat thermal energy storage through topology optimization

This paper presents a unique solution to the problem of heat transfer intensification in shell-and-tube latent heat thermal energy storage units by means of high conducting fins. We developed a design approach using topology optimization and multi-phase computational fluid dynamics. No assumption is made about the fins layout, which freely evolves along the optimization process resulting in more efficient non-trivial geometries. At each optimization iteration, the fluid-dynamic response in the phase change material is computed by solving the transient Navier-Stokes equations augmented with a phase-change porosity term. Coupling large design freedom to detailed physics modeling allowed studying the effect of convective transport on both design and performance of latent heat thermal storage units. Results indicate that accounting for fluid flow in design optimization studies is crucial for performance. It is shown that melting and solidification can be enhanced remarkably through natural convection by using well engineered fins with specific design features, that could hardly be revealed with alternative design routes. These features make designs optimized for melting fundamentally different from those optimized for solidification

Topology optimization for heat transfer enhancement in Latent Heat Thermal Energy Storage

Performance of a Latent Heat Thermal Energy Storage depends strongly on the spatial layout of high conductive material and phase change material. Previous design studies have explored a limited design space and have rarely taken advantage of any formal optimization approach. This paper presents a topology optimization framework of a Thermal Energy Storage system involving phase change. We solve the Stefan problem for solidification with a fixed grid finite element method based on the apparent heat capacity technique, while the topology optimization problem is formulated using a density-based method. This approach allows to identify design trends that have been rarely investigated in the past. Firstly, we explore the inherent trade-off between discharged energy and required time for complete discharge. We obtain very different designs and highly varying performances at selected Pareto points. Secondly, by comparing results obtained in two and three dimensions we observe that 3D designs allow superior performances by presenting features that are not apparent in 2D. Thirdly, we propose a formulation of the design problem that yields a nearly constant thermal power output during the entire discharge process. If the maximum discharge time is sufficiently large, the optimized design presents fins that are disconnected from the internal tube

Inactivating SARS-CoV-2 Using 275 nm UV-C LEDs through a Spherical Irradiation Box: Design, Characterization and Validation

We report on the design, characterization and validation of a spherical irradiation system for inactivating SARS-CoV-2, based on UV-C 275 nm LEDs. The system is designed to maximize irradiation intensity and uniformity and can be used for irradiating a volume of 18 L. To this aim: (i) several commercially available LEDs have been acquired and analyzed; (ii) a complete optical study has been carried out in order to optimize the efficacy of the system; (iii) the resulting prototype has been characterized optically and tested for the inactivation of SARS-CoV-2 for different exposure times, doses and surface types; (iv) the result achieved and the efficacy of the prototype have been compared with similar devices based on different technologies. Results indicate that a 99.9% inactivation can be reached after 1 min of treatment with a dose of 83.1 J/m2

A forgotten life-threatening medical emergency: myxedema coma

Nowadays myxedema coma is a rare medical emergency but, sometimes, it still remains a fatal condition even if appropriate therapy is soon administered. Although physical presentation is very non-specific and diversified, physicians should pay attention when patients present with low body temperature and alteration of neurological status; the presence of precipitating events in past medical history can help in making a diagnosis. Here we discuss one such case: an 83-year-old female presented with abdominal pain since few days. Laboratory tests and abdomen computed tomography scan demonstrated alithiasic cholecystitis; she was properly treated but, during the Emergency Department stay she experienced a cardiac arrest. Physicians immediately started advance cardiovascular life support algorithm and she survived. Later on, she was admitted to the Intensive Care Unit where doctors discovered she was affected by severe hypothyroidism. Straightway they started the right therapy but, unfortunately, the patient died in a few hours

Agronomic performance of 21 new disease resistant winegrape varieties grown in northeast Italy

The goal of the field trial was to evaluate the agronomic performance of 21 (10 red and 11 white) winegrape varieties obtained from recent breeding programmes for disease resistance developed in Hungary, Germany, and Italy. The tested red varieties were as follows: ‘Cabernet Carbon’, ‘Cabernet Eidos’, ‘Cabernet Volos’, ‘Julius’, ‘Merlot Khorus’, ‘Merlot Kanthus’, ‘Monarch’, ‘Prior’, UD. 31.103, ‘Vinera’. The tested white varieties were as follows: ‘Aromera’, ‘Bronner’, ‘Fleurtai’, ‘Johanniter’, ‘Muscaris’, ‘Souvignier Gris’, ‘Sauvignon Kretos’, ‘Sauvignon Nepis’, ‘Sauvignon Rytos’, ‘Solaris’, ‘Soreli’. ‘Merlot’ (red) and ‘Glera’ (white) were included as control. The experimental vineyard was established in Castelfranco Veneto on the plain, in 2014. Spray treatments were applied against downy and powdery mildew, by using only copper and sulphur. Grape production, grape quality, and phenology were recorded over a six-year-period, while disease resistance (downy mildew, powdery mildew, black rot and anthracnose) was detected only during a few years. The most significant findings were: a) all varieties showed a good level of downy mildew resistance, especially ‘Cabernet Carbon’, ‘Monarch’, ‘Prior’, UD 31.103, ‘Muscaris’, ‘Solaris’, ‘Souvignier Gris’, ‘Bronner’, ‘Fleurtai’, ‘Aromera’; b) no powdery mildew attacks were detected in any variety; c) ‘Monarch’, ‘Muscaris’, ‘Solaris’ and ‘Souvignier Gris’ also showed a high level of resistance towards black rot and anthracnose; d) red grape varieties had an earlier bud burst as compared to ‘Merlot’, and, concerning ripening, some varieties were earlier than ‘Merlot’, other ones were later; e) white varieties had a later bud burst but an earlier ripening time as compared to ‘Glera’; f) grape production and quality changed significantly depending on the varieties, being titratable acidity higher than 6.4 g L-1 tartaric acid and pH lower than 3.5; also the year affected in a significant way those parameters as well as the interaction between the genotype and the year. In conclusion, the tested varieties behaved positively in terms of environmental sustainability