This thesis work presents the experimental analysis conducted on sliding-vane expanders, employing steam and an organic fluid (R1233zd), in collaboration with Ing. Enea Mattei S.p.A. Moreover, the operating principles of sliding-vane machines have been analyzed via the pre-existing pV tool, a code for the reconstruction of the indicated diagram, developed by Ing. Enea Mattei on Matlab. For the steam expander M200X, two experimental campaigns have been performed: the first allows to assess the reliability of the system with steam as working fluid, the second campaign leads to assess the stability during long-run and the performances of the system. Two main modifications have been implemented with respect to the pre-existing configuration: clearances on the bushings were increased and composite material vane were applied instead of cast iron, proving a 24.5% increase in mechanical power. Nevertheless, the discharge pressure proved to require a modification to the oil-separator, consequently the discharge section has been enlarged and the filter inside it removed to reduce the pressure drops. This last modification has been assessed in the second campaign together with stability and performances in long-run. The expansion ratio is diminished but with a lower intensity respect to the previous campaign, reducing the problem related to the discharge pressure. No mechanical failures were encountered and the produced mechanical power is the highest measured till now, reaching values of 28 kW, with peaks above 30 kW. Regarding the ORC plant, a new control logic has been developed according to the basic operating principles of a Rankine cycle and tested, both in Mattei and on-field in a customer plant. The main issue encountered was the stability of the system during the start-up phase which has been overcome defining a ramp for the rotational speed of pump and expander, reaching respectively the design value of 1800 rpm and 1600 rpm. In the end, during on-field tests, the system reached the expected stability, providing a power output of 2.17 kW, a first law efficiency of 7.28% and a second law efficiency of 39.90 %. Lastly, a deep reorganization and optimization of pV code has been carried out, providing a fast, reliable and highly automated tool able to reconstruct the pressure trend inside sliding-vane machines from data measured by piezoelectric pressure transducers, allowing to study the effect of lubricant oil, suction and delivery port on the machine performances.
Il presente elaborato propone uno studio sperimentale condotto su espansori a palette, utilizzando vapore e un fluido organico (R1233zd), in collaborazione con Ing. Enea Mattei S.p.A. Inoltre, è stato analizzato il principio di funzionamento delle macchine a palette tramite il preesistente software pV, un codice per la ricostruzione del diagramma indicato, sviluppato da Ing. Enea Mattei in Matlab. Per l'espansore a vapore M200X, sono state eseguite due campagne sperimentali: la prima permette di valutare l'affidabilità del sistema usando il vapore come fluido di lavoro, la seconda campagna permette di valutare la stabilità durante prove di lunga durata e le prestazioni del sistema. Due modifiche principali sono state introdotte rispetto alla configurazione preesistente: l'aumento dei giochi delle bronzine e l'utilizzo di materiale composito per le palette invece della ghisa, dimostrando un aumento del 24.5% della potenza meccanica. Tuttavia, la pressione allo scarico ha mostrato la necessità di una modifica al separatore dell'olio, aumentando la sezione d'uscita e rimuovendo il filtro all'interno per ridurre le perdite di pressione. Quest'ultima modifica è stata valutata nella seconda campagna insieme alla stabilità e alle prestazioni. Il rapporto di espansione è diminuito ma con una minore intensità rispetto alla precedente campagna, riducendo il problema legato alla pressione allo scarico. Nessun problema meccanico è stato riscontrato e la potenza meccanica prodotta è stata la più alta sino ad ora, raggiungendo valori di 28 kW, con picchi sopra i 30 kW. Per quanto riguarda l'impianto ORC, la nuova logica di controllo è stata sviluppata secondo il principio di funzionamento di un ciclo Rankine e testata sia in Mattei che sul campo presso l'impianto di un cliente. Il principale problema incontrato fu la stabilità del sistema durante la fase di avviamento, la quale è stata superata utilizzando una rampa per le velocità di rotazione di pompa ed espansore, le quali, in condizioni di progetto raggiungono rispettivamente 1800 rpm e 1600 rpm. Alla fine, durante il test sul campo, il sistema ha raggiunto la stabilità prevista, fornendo una potenza in uscita di 2.17 kW, un'efficienza di primo principio del 7.28% e una di secondo del 39.90%. Da ultimo, è stata effettuata una profonda riorganizzazione e ottimizzazione del codice pV, fornendo uno strumento veloce, affidabile e altamente automatizzato in grado di ricostruire il trend di pressione all'interno delle macchine a palette partendo dai dati misurati dai sensori di pressione piezoelettrici, permettendo uno studio sugli effetti dell'olio lubrificante, delle luci di aspirazione e mandata sulle prestazioni della macchina.
Experimental investigation and control logic development of sliding-vane expanders for steam and organic fluid applications
FUMAGALLI, CRISTIAN
2018/2019
Abstract
This thesis work presents the experimental analysis conducted on sliding-vane expanders, employing steam and an organic fluid (R1233zd), in collaboration with Ing. Enea Mattei S.p.A. Moreover, the operating principles of sliding-vane machines have been analyzed via the pre-existing pV tool, a code for the reconstruction of the indicated diagram, developed by Ing. Enea Mattei on Matlab. For the steam expander M200X, two experimental campaigns have been performed: the first allows to assess the reliability of the system with steam as working fluid, the second campaign leads to assess the stability during long-run and the performances of the system. Two main modifications have been implemented with respect to the pre-existing configuration: clearances on the bushings were increased and composite material vane were applied instead of cast iron, proving a 24.5% increase in mechanical power. Nevertheless, the discharge pressure proved to require a modification to the oil-separator, consequently the discharge section has been enlarged and the filter inside it removed to reduce the pressure drops. This last modification has been assessed in the second campaign together with stability and performances in long-run. The expansion ratio is diminished but with a lower intensity respect to the previous campaign, reducing the problem related to the discharge pressure. No mechanical failures were encountered and the produced mechanical power is the highest measured till now, reaching values of 28 kW, with peaks above 30 kW. Regarding the ORC plant, a new control logic has been developed according to the basic operating principles of a Rankine cycle and tested, both in Mattei and on-field in a customer plant. The main issue encountered was the stability of the system during the start-up phase which has been overcome defining a ramp for the rotational speed of pump and expander, reaching respectively the design value of 1800 rpm and 1600 rpm. In the end, during on-field tests, the system reached the expected stability, providing a power output of 2.17 kW, a first law efficiency of 7.28% and a second law efficiency of 39.90 %. Lastly, a deep reorganization and optimization of pV code has been carried out, providing a fast, reliable and highly automated tool able to reconstruct the pressure trend inside sliding-vane machines from data measured by piezoelectric pressure transducers, allowing to study the effect of lubricant oil, suction and delivery port on the machine performances.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/151376