1,720,980 research outputs found
Esercizi di Termodinamica Applicata
No full textNella mia ormai trentennale esperienza di insegnamento di Termodinamica Applicata nei corsi di Ingegneria,
più volte mi sono interrogato sull’opportunità di scrivere un testo che proponesse alle studentesse
e agli studenti una raccolta di esercizi, con l’obiettivo di essere di aiuto alla preparazione per le prove di
esame.
Sono molto grato, quindi, ai colleghi, coautori di questo volume, che mi hanno proposto di collaborare
a un progetto che ritengo non sia solo una raccolta di esercizi, ma anche un tentativo di aiutare lo studente a
costruirsi un metodo di approccio alla soluzione degli esercizi stessi.
A questo fine sono stati introdotti forti richiami alla teoria per evidenziare che lo studio di quest’ultima
e la soluzione degli esercizi non sono due momenti separati, ma fortemente connessi; inoltre, si è
cercato di evidenziare come il primo passo, per una corretta impostazione della soluzione, sia cercare una
rappresentazione schematica, se possibile, della situazione descritta nel testo dell’esercizio.
Per molti anni il Prof. Michele Calì ed io abbiamo avuto la responsabilit`a dell’insegnamento della Termodinamica
Applicata in corsi paralleli; con lui ho condiviso l’impostazione e la struttura del corso e il materiale
utilizzato in aula che ovviamente rispecchia i contenuti del testo M. Calì e P. Gregorio Termodinamica
(Esculapio, Bologna, 1996).
Nel testo la notazione utilizzata ed i richiami di teoria sono quindi coerenti con quanto proposto nel
corso e con l’ordine di presentazione degli argomenti nello stesso. Si inizia con alcuni esercizi per aiutare
lo studente a familiarizzare con le equazioni di stato ed i concetti di calore e lavoro; si prosegue con esercizi
dedicati all’applicazione dei principi fondamentali della Termodinamica per passare poi all’esame di
situazione pi`u vicine alle applicazioni reali come le macchine motrici e operatrici ed il condizionamento
dell’aria
"Carbon Exergy Tax (CET): Impact on Conventional Energy Systems Design and Its Contribution to Advanced Systems Utilisation",
No full textAvanced modeling for the control of tunnel ventilation during excavation and operation
No full textInnovative tools are necessar y to obtain the optimal operating conditions of the ventilation systems in a reasonable lapse of time and accurately. This can be achieved both with appropriate numerical approaches to the full domain as the model order reduction techniques and with the domain decompositions methods as the multi-scale physical decomposition technique. The reduced order mode techniques such as the Proper Orthogonal Decomposition - POD are based on the snapshots method, which provides an optimal linear basis for the reconstruction of multidimensional data. The physical decomposition achieved through mul-ti-level approaches uses the accuracy of the Computational Fluid Dynamics - CFD code in the near field, e.g. the region close to the fire source, and takes advantage of the low computational cost of the 1-D model in the region where gradients in the transversal direction are negligible. In this paper, the features of these two approaches when applied to the control of tunnel ventilation systems are presented. In particular, the use during construction the phase and during operation are discussed
"Carbon tax vs CO2 sequestration e.ects on environomic analysis of existing power plants",
No full textDigital Platforms for Renewable Energy Communities Projects: An Overview
Full text linkThe European Union energy policy agenda of achieving the transition to carbon neutrality has been established by an important legislative package called "Clean Energy for all Europeans". A novel approach introduced was to put the citizen at the center of the energy transition. On one side, by powering his freedom of action and, on the other side, by asking him an exceptional engagement in energy consumption reduction activities and in participating in the investments for new distributed Renewable Energy Sources (RES) power plants. The Renewable Energy Communities (REC) is the policy framework used to implement this strategy introduced by the Renewable Energy Directive Recast (RED II). In particular, RECs promote citizen’s active role by encouraging energy consumption reduction and energy demand flexibility while reducing the Not In My Bachyard (NIMBY) effect towards RES. Each member state is transposing the RED II directive, adapting it to national legislation and energy transition strategy. Pioneers countries like Italy have already started the experimentation of this framework and developing the first pilot projects. The citizens’ interest and their will to participate in REC projects indicate the need for supporting tools guiding them along all the project development stages: “design”, “creation”, and “operation”. This work presents three categories of supporting digital tools and platforms required to develop REC projects: Commercial, EU Founded and Freeware. We analyzed 30 tools, evaluating the services provided in each of the different stages of REC project implementation
Development of a methodology for studying tunnel climate in long railway tunnels and for optimizing the design process of cross-passage cooling systems
Full text linkWhen it comes into operation in 2026, the Koralmtunnel in Austria will be the world́s seventh longest railway
tunnel. The installation of the power supply, telecommunications and electro-mechanical services is currently
ongoing. Parts of these systems have to be protected from temperature and humidity variations and from the high
dust loads which are characteristic of the tunnel atmosphere. In particular, cooling systems are required to
counteract the significant amounts of heat released by some installations. Information on a large number of
parameters (e.g. tunnel air temperatures) is required in the design process. However, such information is only
partly available in the design stage. Hence, a prediction of tunnel air temperatures has to be made. Additionally,
since hardly any information about the tunnel climate in long railway tunnels is available and in-situ mea-
surements are not possible, as thermal conditions differ significantly between the construction/equipping phase
and the operation phase, a novel methodology for the prediction of the tunnel climate had to be developed. This
article presents a description of a new method comprising four main investigative steps and of its application to
the Koralmtunnel as a selected case study. While steps 1 and 2 provide information about the actual cooling
requirement and tunnel air temperatures for a period of 50 years, steps three and four of the investigation aim at
the technical and economic optimization of cooling systems
Data informed physical models for district heating grids with distributed heat sources to understand thermal and hydraulic aspects
Full text linkThe aim of the study was to develop data informed physical models for simulation of district heating (DH) grids for better presentation of hydraulic and thermal aspects in the DH grids integrating heat prosumers. A DH grid organized as a ring and integrating a heat prosumer from a data center was analyzed. In this study, an extensive analysis for thermal and hydraulic aspects of theDH grid considering different configurations of distributed sources was performed. Different configurations for the prosumer connection, the return to return and the return to supply, together with the pressure and temperature control, were investigated. The results showed that increasing the share of renewable heat from the prosumer to the DH grid caused a pressure imbalance in substations close to it. Variable speed pump control was the solution for these issues and it gave up to 34% electricity savings. Lowering temperature levels in the DH network led to a decrease in DH heat losses of up to 14%. The return to supply configuration showed advantages in integrating the prosumer, as regards lower return temperatures and better waste heat utilization. The results indicated the main hydraulic and thermal features of integrating the prosumer in the DH grid
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
- …
