1,721,037 research outputs found
A methodology for impact assessment and acoustic monitoring of quarry activities
No full textThe work presents a methodology to assess the acoustic impact around extractive areas, the validation of which was made through the study of a quarry situated in Perugia (Italy). A preliminary analysis was conducted to locate sensitive areas, to characterize all the various noise sources in the quarry and to determine their contribution to the global acoustic climate. Afterwards, a simulation model for the noise sources in the quarry was implemented: through noise measurements, its reliability was verified. A detailed study on the quarry was therefore carried out, simulating different exercise conditions, corresponding to different noise sources at work in the quarry or to different morphologies during all the quarry life. The model allowed the individualisation of the specific contribution of each source to the global noise, to create different noise maps, to assess the effectiveness of the acoustic mitigation. The reliability of the model was also assessed by a one-year noise monitoring of the area of the quarry
The role of town energy planning in reducing urban transport emissions
No full textThe paper presents the main results obtained in the Energy Plan of the town of Perugia (Italy), which prominently features traffic aspects. For each possible action in this field, a very detailed technical analysis has been carried out. The actions have been divided into five groups:
- traffic planning (infrastructures, traffic restrictions, mobility management);
- alternative mobility (lifts, escalators, surface undergrounds and other kinds of public transport);
- alternative fuels (biodiesel, bioethanol, “white” gas oil);
- alternative vehicles (electric, hybrid, fuel cells);
- shared mobility (car pooling, car sharing and others).
For each group, technical, environmental, social and economic aspects have been taken into account; particular emphasis has been put on energy saving aspects and on the evaluation of greenhouse gases emissions reduction.
The paper gives useful indications to municipalities to choose the best solutions to reduce traffic consumptions and impact on a local scale, according to current technologies
Small size absorption refrigerators: a comparison among different solutions in solar feeding applications
No full textAbsorption refrigerating machines represent an interesting alternative to compression machines, especially when waste heat or heat produced by solar energy is available; the market is beginning to propose small-size absorption machines especially designed for air conditioning in residential buildings. A recognition of small size absorption refrigerators is reported, with particular emphasis on their performances in the case that the thermal source is constituted by solar energy. The examined machines cover different chilling powers (from 4 to 15 kW) and have different working principles. The study is conducted through the data supplied by manufacturers and collected in the experimental set-up available at the Labs of the University of Perugia; different refrigerators are compared taking into account the most significant parameters such as hot source and chilled water temperature, cooling circuit characteristics, coefficient of performance, weight and dimensions. Energy and environmental advantages deriving from the solar supply are also evaluated
Studio territoriale della risorsa eolica nel Comune di Perugia: aspetti metodologici, energetici ed ambientali
No full textNell’ambito del Piano Energetico e Ambientale del Comune di Perugia si è effettuato uno studio sulla disponibilità della risorsa eolica all’interno del territorio comunale. L’indagine si è sviluppata a partire dai dati anemometrici relativi a due stazioni di presenti nella zona, integrate con un codice di calcolo che, attraverso una serie di modelli numerici, ha reso possibile l’elaborazione della mappa del vento. Sono stati così individuati due siti potenzialmente idonei, per i quali si è condotta un’analisi di fattibilità tecnico-economica. Soltanto una delle due località è risultata valida per l’installazione di un campo eolico e per essa si è quindi proceduto alla valutazione delle prestazioni in termini di riduzione delle emissioni di gas serra; si è infine messa a punto una metodologia per la definizione dettagliata dell’impatto visivo della centrale eolica
Caratterizzazione delle prestazioni acustiche di infissi antirumore con misure di laboratorio
No full textIl rumore prodotto dalle sorgenti sonore esterne si trasmette all’interno degli edifici attraverso le superfici dell’involucro edilizio meno resistenti al passaggio delle onde sonore; sono questi componenti ad influenzare pertanto la prestazione acustica globale della facciata. Nella maggioranza dei casi i componenti più deboli sono rappresentati dalle finestre, dagli infissi e dai cassonetti per gli avvolgibili; risulta pertanto estremamente importante la caratterizzazione in laboratorio delle proprietà acustiche di questi elementi, al fine di consentire ai progettisti la scelta del componente più idoneo a garantire le prestazioni acustiche di facciata richieste.
Il Laboratorio di Acustica della Facoltà di Ingegneria di Perugia dispone di due camere riverberanti accoppiate nelle quali sono stati testati negli ultimi anni numerosi prototipi di infissi antirumore, con particolare riguardo alla tipologia innovativa di infissi ventilati antirumore, nonché diversi cassonetti per avvolgibili dotati di elevate proprietà di isolamento acustico.
Il lavoro presenta la metodologia per la misura del potere fonoisolante R secondo la norma UNI EN ISO 140-3 e dell’indice del potere fonoisolante RW secondo la norma UNI EN ISO 717-1, al fine di definire le proprietà di isolamento acustico globali dei campioni sottoposti a prova. Inoltre, sono illustrate le metodiche per la misurazione dei livelli di intensità sonora con sonda intensimetrica, grazie alle quali è possibile costruire le mappe acustiche in prossimità dei campioni testati ed avere una visione più dettagliata del comportamento dei singoli componenti degli infissi testati, localizzando le fughe sonore. Tali tecniche sono fondamentali in vista del perfezionamento e dell’ottimizzazione delle proprietà acustiche di prototipi di componenti finestrati.
Il lavoro è completato dai risultati delle campagne di misura più significative realizzate in questi ultimi anni dal Laboratorio di Acustica dell’Università di Perugia
Messa a punto di una strumentazione spettrofotometrica per misure di trasmittanza e riflessione di materiali trasparenti
No full textInfluence of air thermohygrometric properties on mechanical draft evaporative towers: a calculation method to predict effects in power plants and refrigerating absorption machines
No full textThe paper describes a simulation model for the evaluation of heat exchanges occurring to a flow of water falling down in
counterflow with humid air, during its path through a mechanical draft cooling tower. The contemporary heat transfer by
evaporation and forced convection are separately taken into account, assuming simplified hypotheses such as water flow
divided into spherical drops, constant relative speed between air and water and constant thermodynamic conditions of water
and air through the tower. The model has been calibrated and validated through two existing evaporative towers: a small-size
one serving a refrigerating absorption machine and a medium-size one connected with the condenser of a coal-fired power
plant; the comparison with the well-known Merkel and Poppe models showed only slight differences on thermodynamic
parameters involved in the process.
The simulation predicts water outlet conditions starting from the air inlet temperature and relative humidity, once the power to
be drained is fixed. The knowledge of outlet air thermohygrometric conditions allows the definition of water outlet
temperature minimum value and the evaluation of the mass flow to be reintegrated for the evaporated water replacement.
Since the outlet water temperature level affects the performances of plants connected with the evaporative towers, it is
interesting to vary the air external conditions, investigating the repercussions on plants’characteristics. While the influence on
power plants remains circumscribed to a light variation on the produced electric power, refrigerating absorption machines
result more sensitive, showing considerable fluctuations of chilling power and Coefficient Of Performance (COP)
Thermal transmittance measurements with the hot box method: Calibration, experimental procedures, and uncertainty analyses of three different approaches
No full textA large amount of heat loss through building envelopes takes place via inhomogeneous components such
as windows, doors, and thermal bridges. This loss can be approximated by measuring in lab the actual
thermal transmittance of these components with the use of a hot box. The calibration and experimental
procedures can be performed, taking into account three standards for calibrating hot boxes: the European
EN ISO 8990; the American ASTM C1363-05; and the Russian GOST 26602.1-99. An experimental setup
for testing the accuracy of these standards has recently been created at the University of Perugia; after a
measurement campaign for the validation of the test rig, the differences of the approaches were evaluated.
Results showed that although the EN ISO 8990 and ASTM C1363-05 are similar in terms of procedures
definition, methodology of thermal transmittance calculation, and level of uncertainty, theGOST26602.1-
99 differs from the others since it adds individual measurements of the thermal characteristics of each
sample component. The analysis highlighted that the ideal procedure should include the Russian method
to define the thermal behavior of each component under analysis, with a contemporary validation of the
global results to be performed with one of the other two approaches
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