The original idea for this thesis came during the stage that took place in AE s.r.l. - Appliances Engineering in Gavirate, province of Varese, where an instrument able to simulate the performance of refrigeration equipment getting an initial assessment on the thermodynamic system design in its main component was needed. The topic is very complex, that is justified by the fact that there are not many software around that treats it. The program will be used to simulate the performance of double door refrigerators with the maximum condition, which is 100%, with a compressor always working in order to give the client who will buy the machine one more justification of the project choices made. As a programming language for the composition of codes was used Visual Basic for Applications (VBA) associated with the program produced by Microsoft , Microsoft Excel, with which you can easily handle all the input and output parts of the system, rapidly modifying each parameter. The part of thermodynamics was handled entirely by REFPROP 9.1 , a program of the NIST that can evaluate both thermodynamic and transport properties of many refrigerants, and interacting with the computer codes was proved to be a very powerful tool and essential for the development of the project . The study of components was developed primarily by dividing them into smaller elements and doing mass and energy balances iteratively to evaluate the thermodynamic state. This method was applied for the condenser, the evaporator and the capillary tube, while was used a series of empirical formulas for the compressor, which were acquired directly from providers of the compressors itself. Three experimental tests were carried out on old projects obtaining findings acceptable despite the many uncertainties inherent in the problem, providing a general overview on system design associated with the structure of the refrigerator. Lastly, the products will be tested inside the laboratory of the department to verify the truthfulness and improve the convergence of the program in the future thanks to the experimental data, because there are no comparison in literature but a few isolated components.
L’idea originaria che ha prodotto la stesura di questo elaborato è stata maturata durante il tirocinio presso la AE s.r.l. - Appliances Engineering di Gavirate in provincia di Varese, nella quale serviva uno strumento in grado di simulare l’andamento e le prestazioni delle macchine frigorifere ottenendo una valutazione iniziale sul dimensionamento dell’impianto termodinamico nei suoi componenti principali. La complessità dell’argomento è giustificata anche dal fatto che sul mercato sono presenti ben pochi software che trattano questo tema. Il programma sviluppato sarà utilizzato per simulare il funzionamento di macchine frigorifere doppia porta in condizioni di funzionamento massimali, ovvero al 100% col compressore sempre in funzione, così da fornire al cliente che acquisterà la macchina un’ulteriore giustificazione delle scelte progettuali effettuate. Come linguaggio di programmazione per la composizione dei codici è stato utilizzato Visual Basic for Applications (VBA) associato al programma prodotto dalla Microsoft, Microsoft Excel, col quale si riesce a gestire facilmente tutta la parte di input e output del sistema, modificandone rapidamente ed intuitivamente i parametri. La parte termodinamica è stata gestita interamente da REFPROP 9.1, un programma della NIST in grado di valutare tutte le proprietà termodinamiche e di trasporto di molti refrigeranti ed interagendo coi codici di calcolo si è rivelato uno strumento molto potente ed essenziale per lo sviluppo del progetto. Lo studio dei componenti è stato sviluppato principalmente suddividendoli in elementi più piccoli e applicando i bilanci di materia ed energia iterativamente su di essi per valutarne lo stato termodinamico. Questo metodo è stato applicato per il condensatore, l’evaporatore ed il tubo capillare, mentre per il compressore sono state utilizzate formulazioni empiriche acquisite direttamente dai fornitori dei compressori. Sono state effettuate tre prove sperimentali su vecchi progetti ottenendo riscontri accettabili nonostante le numerose incertezze intrinseche nel problema, fornendo una panoramica generale sul dimensionamento dell’impianto associato alla struttura del frigorifero. Infine i prodotti verranno testati nel laboratorio presente all’interno del dipartimento per attestarne la veridicità e migliorare così la sensibilità del programma grazie ai dati sperimentali, in quanto la letteratura a riguardo è al momento sprovvista di riscontri numerici se non su alcuni componenti isolati.
Modellazione termodinamica di frigoriferi domestici con scambiatori statici
MORELLO, MARCO
2014/2015
Abstract
The original idea for this thesis came during the stage that took place in AE s.r.l. - Appliances Engineering in Gavirate, province of Varese, where an instrument able to simulate the performance of refrigeration equipment getting an initial assessment on the thermodynamic system design in its main component was needed. The topic is very complex, that is justified by the fact that there are not many software around that treats it. The program will be used to simulate the performance of double door refrigerators with the maximum condition, which is 100%, with a compressor always working in order to give the client who will buy the machine one more justification of the project choices made. As a programming language for the composition of codes was used Visual Basic for Applications (VBA) associated with the program produced by Microsoft , Microsoft Excel, with which you can easily handle all the input and output parts of the system, rapidly modifying each parameter. The part of thermodynamics was handled entirely by REFPROP 9.1 , a program of the NIST that can evaluate both thermodynamic and transport properties of many refrigerants, and interacting with the computer codes was proved to be a very powerful tool and essential for the development of the project . The study of components was developed primarily by dividing them into smaller elements and doing mass and energy balances iteratively to evaluate the thermodynamic state. This method was applied for the condenser, the evaporator and the capillary tube, while was used a series of empirical formulas for the compressor, which were acquired directly from providers of the compressors itself. Three experimental tests were carried out on old projects obtaining findings acceptable despite the many uncertainties inherent in the problem, providing a general overview on system design associated with the structure of the refrigerator. Lastly, the products will be tested inside the laboratory of the department to verify the truthfulness and improve the convergence of the program in the future thanks to the experimental data, because there are no comparison in literature but a few isolated components.| File | Dimensione | Formato | |
|---|---|---|---|
|
2015_07_Morello.pdf
accessibile in internet per tutti
Descrizione: Testo della tesi
Dimensione
2.09 MB
Formato
Adobe PDF
|
2.09 MB | Adobe PDF | Visualizza/Apri |
I documenti in POLITesi sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
https://hdl.handle.net/10589/109104