The aim of this work was to develop an innovative experimental apparatus for the study of the motion field and of the performance of fume hoods, which are commonly used in chemical laboratories. The bibliographic research highlighted that a proper fluid-dynamic design of some hood features determines an improvement in performance and in energy consumption. The novelty of the present study consists in the realization of a test environment of reduced dimensions that employs water as a working fluid. This practice, widely used to simulate the diffusion of air in the environment, can reproduce the fluid-dynamic phenomena in an accurate way. Moreover, the motion field is characterized by speeds lower than the real ones and therefore it is easier to study. The experimental apparatus is equipped with a hydraulic circuit and a fluid diffusion system. Overall, it can reproduce the test conditions of real hoods as per European standard EN 14175-3 and it is suitable for performing investigations with the PIV (Particle Image Velocimetry) technique in order to visualize the motion. From the first qualitative surveys carried out with lasers and tracer particles, it was possible to compare the characteristics of the motion generated by a fume hood model with those highlighted in the scientific literature. In addition to the experimental activity, a simple CFD study (Computational Fluid Dynamics) was conducted employing a commercial software to confirm the validity of the observations made in the laboratory. The objectives achieved in this thesis work are the following: • study of the operation of fume hoods and of the reference standards for carrying out performance tests; • study of a portion of the extensive scientific literature concerning the fluid dynamics of fume hoods; • design and building of an experimental setup; • realization of the fluid-dynamic similitude to simulate the test conditions of fume hoods according to EN 14175-3, • visualization via PIV technique of vortex structures comparable with those of previous studies; • achievement of qualitative information useful for the correct design of fume hoods; • numerical comparison of the experimental investigations.
Lo scopo del lavoro è stato quello di mettere a punto un apparato sperimentale innovativo per lo studio del campo di moto e delle prestazioni delle cappe aspiranti comunemente utilizzate nei laboratori chimici. Dalla ricerca bibliografica si è potuto evidenziare come un attento design fluidodinamico di alcune feature della cappa determina un miglioramento delle prestazioni e dei consumi energetici. La novità del presente studio è costituita dalla realizzazione di un ambiente di test di dimensioni contenute che impiega l’acqua come fluido di lavoro. Questa pratica, ampiamente utilizzata per simulare la diffusione dell’aria in ambiente, ha il grande vantaggio di riprodurre fedelmente i fenomeni fluidodinamici con velocità inferiori a quelle reali e quindi di più facile studio. L’apparato sperimentale è dotato di un circuito idraulico e un sistema di diffusione del fluido nell’ambiente di test in grado di riprodurre le condizioni di prova di cappe reali come da normativa europea EN 14175-3 e ben si presta a tecniche PIV (Particle Image Velocimetry) per la visualizzazione del moto. Dalle prime indagini qualitative effettuate con laser e particelle traccianti si è potuto mettere a confronto le caratteristiche del moto generato da un modello di cappa con quelle evidenziate nella letteratura scientifica. A margine del lavoro sperimentale, si è condotto uno studio CFD (Computational Fluid Dynamics) con un software commerciale per avere conferma della bontà delle osservazioni effettuate in laboratorio. Gli obiettivi raggiunti in questo lavoro di tesi sono i seguenti: • lo studio del funzionamento delle cappe da laboratorio e delle normative di riferimento per l’esecuzione di test prestazionali; • lo studio di una parte della ampia letteratura scientifica inerente alla fluidodinamica delle cappe chimiche; • la progettazione e la costruzione di un setup sperimentale; • la realizzazione della similitudine fluidodinamica per simulare condizioni di test di cappe aspiranti secondo EN 14175-3, • la visualizzazione mediante particelle traccianti e laser di particolari strutture vorticose, confrontabili con i risultati presenti in letteratura; • l’ottenimento di informazioni qualitative utili per la corretta progettazione di cappe chimiche; • un confronto numerico delle indagini sperimentali effettuate.
Caratterizzazione del campo di moto di una cappa da laboratorio tramite analisi fluidodinamica e tecnica PIV
RUBBINI, FILIPPO
2017/2018
Abstract
The aim of this work was to develop an innovative experimental apparatus for the study of the motion field and of the performance of fume hoods, which are commonly used in chemical laboratories. The bibliographic research highlighted that a proper fluid-dynamic design of some hood features determines an improvement in performance and in energy consumption. The novelty of the present study consists in the realization of a test environment of reduced dimensions that employs water as a working fluid. This practice, widely used to simulate the diffusion of air in the environment, can reproduce the fluid-dynamic phenomena in an accurate way. Moreover, the motion field is characterized by speeds lower than the real ones and therefore it is easier to study. The experimental apparatus is equipped with a hydraulic circuit and a fluid diffusion system. Overall, it can reproduce the test conditions of real hoods as per European standard EN 14175-3 and it is suitable for performing investigations with the PIV (Particle Image Velocimetry) technique in order to visualize the motion. From the first qualitative surveys carried out with lasers and tracer particles, it was possible to compare the characteristics of the motion generated by a fume hood model with those highlighted in the scientific literature. In addition to the experimental activity, a simple CFD study (Computational Fluid Dynamics) was conducted employing a commercial software to confirm the validity of the observations made in the laboratory. The objectives achieved in this thesis work are the following: • study of the operation of fume hoods and of the reference standards for carrying out performance tests; • study of a portion of the extensive scientific literature concerning the fluid dynamics of fume hoods; • design and building of an experimental setup; • realization of the fluid-dynamic similitude to simulate the test conditions of fume hoods according to EN 14175-3, • visualization via PIV technique of vortex structures comparable with those of previous studies; • achievement of qualitative information useful for the correct design of fume hoods; • numerical comparison of the experimental investigations.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/142423