Ensuring both food quality and safety to the global population through the cold chain is the major challenge for the refrigeration sector. At the same time guaranteeing, a constant temperature throughout the entire cold chain determines a high-energy consumption and related CO2 emissions into the atmosphere. Therefore, in this dissertation, different approaches aimed at improving refrigerated storage and transport systems performance by Phase Change Materials (PCMs) application have been investigated. The first study have focused on the application of PCM layer to the external side of a refrigerated container envelope, in order to reduce and shift the cooling load in comparison with a conventional enclosure. To that end, the proposed technology was evaluated using a numerical and experimental design study. The calculation results were compared with the experimental values in order to validate the mathematical model. In the field of refrigerated storage, the application of a PCM air heat exchanger near the evaporator of a cold room was experimentally investigated. The study purposes were to reduce the cooling energy consumption during normal operating conditions and the rate of temperature increase throughout the course of a power failure event. Moreover, in order to help refrigerated transport companies to define and implement the right efficiency measures for cold production by using PCM, a calculation tool has been developed. The final study have focused on the application of PCM layer to the internal compartment walls of a storage cold room, in order to reduce the peak air temperature and energy consumption during different door openings. To that end, the proposed technology was evaluated using an experimental design study. The overall dissertation results highlighted that the PCM addition in the proposed refrigerated technologies can lead to interesting reduction in both energy consumption and related CO2 emissions into the atmosphere.
Mantenere la qualità e la sicurezza degli alimenti lungo tutta la catena del freddo, rappresenta una delle principali sfide per il settore della refrigerazione. Allo stesso tempo, garantire una temperatura costante lungo la filiera del freddo determina un elevato consumo energetico, comportando elevate emissioni di CO2 in atmosfera. A tale proposito l’attività di ricerca è stata finalizzata alla sperimentazione di diverse possibilità di utilizzo dei materiali in passaggio di fase (PCMs), per ottimizzare le prestazioni energetiche dei sistemi di trasporto e stoccaggio refrigerati. Inizialmente l’attività di ricerca si è focalizzata sull’applicazione del PCM nell’involucro di un container refrigerato, al fine di ridurre e sfasare temporalmente il carico di raffreddamento. Tale tecnologia è stata valutata mediante approccio numerico e sperimentale, consentendo pertanto di validare il modello numerico. In un secondo momento, sono stati valutati i benefici energetici legati ad uno scambiatore di calore contenete PCM posizionato in prossimità dell’evaporatore di una cella frigorifera. Gli obiettivi di tale attività sono stati quelli di ridurre il consumo di energia elettrica in condizioni di regime stazionario ed il tasso di incremento della temperatura all’interno del vano in caso di black-out. Inoltre, al fine di aiutare le compagnie di trasporto refrigerato ad implementare le giuste misure di efficienza per la produzione del freddo è stato prodotto un tool di calcolo. Infine, l’attività di ricerca è stata focalizzata sull’applicazione del PCM nelle pareti interne del vano refrigerato di una cella frigorifera, allo scopo di ridurre il picco di temperatura dell’aria ed il consumo di energia elettrica durante differenti aperture della porta. Complessivamente i risultati ottenuti hanno evidenziato come l’applicazione dei PCM nelle diverse tecnologie refrigerate, determina una interessante riduzione dei consumi di energia elettrica e delle emissioni di CO2 in atmosfera.
Phase Change Materials (PCMs): an Opportunity for Energy Saving in the Cold Chain
COPERTARO, BENEDETTA
2017
Abstract
Ensuring both food quality and safety to the global population through the cold chain is the major challenge for the refrigeration sector. At the same time guaranteeing, a constant temperature throughout the entire cold chain determines a high-energy consumption and related CO2 emissions into the atmosphere. Therefore, in this dissertation, different approaches aimed at improving refrigerated storage and transport systems performance by Phase Change Materials (PCMs) application have been investigated. The first study have focused on the application of PCM layer to the external side of a refrigerated container envelope, in order to reduce and shift the cooling load in comparison with a conventional enclosure. To that end, the proposed technology was evaluated using a numerical and experimental design study. The calculation results were compared with the experimental values in order to validate the mathematical model. In the field of refrigerated storage, the application of a PCM air heat exchanger near the evaporator of a cold room was experimentally investigated. The study purposes were to reduce the cooling energy consumption during normal operating conditions and the rate of temperature increase throughout the course of a power failure event. Moreover, in order to help refrigerated transport companies to define and implement the right efficiency measures for cold production by using PCM, a calculation tool has been developed. The final study have focused on the application of PCM layer to the internal compartment walls of a storage cold room, in order to reduce the peak air temperature and energy consumption during different door openings. To that end, the proposed technology was evaluated using an experimental design study. The overall dissertation results highlighted that the PCM addition in the proposed refrigerated technologies can lead to interesting reduction in both energy consumption and related CO2 emissions into the atmosphere.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.14242/95464
URN:NBN:IT:UNIVPM-95464