The building sector, as many others, is nowadays focusing its attention on renewable sources to follow the energy strategies of the EU countries to reduce greenhouse gases emissions and to increase energy efficiency. Space heating and cooling, mostly rely on fossil-fuel conventional systems. The present study aims at evaluating the performances of two Heat Pumps coupled with Photovoltaic/Thermal Panels (PV/Ts). A system like this is called Solar Assisted Heat Pump (SAHP) and in literature there are some cases analyzed but mostly coupled with thermal panels, the usage of PV/T panels is a promising prospective both for increasing of the electric performances of the panels and the energy independence of the entire system. One of the systems studied had a dual evaporator to work as air - water heat pump or air/water - water heat pump. This configuration has the potentiality of following the highest temperature between ambient and liquid from the panels to increase the performances (COP) during the year. Both heat pumps were first trials, one of them was a commercial air-water heat pump adopted to be a water-water type, the second one was a prototype heat pump. Finally, it was also proposed the comparison between conventional PV panels and the PV/T to emphasize the goodness of the hybrid technology. The results are not the expected ones but the problems can be linked to the fact that the pumps are not suited designed for the purpose; the technology is promising. In particular the air evaporator of the prototype heat pump is over dimensioned, so the benefits of having the temperature of the coolant of the PV/T higher than ambient one is limited; also the evaporator of the commercial heat pump adopted was not correctly dimensioned, thus evaporation is performed at low temperature. COP_commercial HP=3.40 , COP_(W/W)=6.36 , COP_(A/W)=4.09. The PV/T technology results better performing than standard PV looking at the electric power production that is enhanced by the cooling of the cell (η_el=15% and η_TOT>50 %), thus the power at high irradiation and ambient temperature is higher than the one obtained with conventional PV panels.
Il settore dell'edilizia, come molti altri, sta investendo risorse sulle fonti rinnovabili per seguire le strategie energetiche di riduzione delle emissioni di gas a effetto serra e di aumento dell'efficienza energetica, adottate dagli stati membri dell’Unione Europea. Oggigiorno il riscaldamento domestico è principalmente basato su sistemi tradizionali a combustibile fossile. Il presente studio mira a valutare le prestazioni di due pompe di calore accoppiate con i pannelli termici Fotovoltaici / Termici (PV / T) che prendono il nome di pompa di calore elioassistite (SAHP). In letteratura ci sono alcuni casi analizzati, soprattutto di sistemi accoppiati a pannelli termici; l'utilizzo di pannelli PV / T è una prospettiva promettente sia per l’aumento delle prestazioni elettriche dei pannelli sia per l'indipendenza energetica dell'intero sistema. Uno dei sistemi studiati era provvisto di un doppio evaporatore per funzionare come pompa di calore ad aria o pompa di calore aria / acqua avendo la possibilità di usare come sorgente di calore l’aria ambiente o il liquido uscente dai pannelli scegliendo la temperatura massima tra le due aumentando le prestazioni (COP) durante l'anno. Entrambe le pompe di calore rappresentavano le prime sperimentazioni della tecnologia adattando prodotti commerciali alla sperimentazione: una delle due pompe era una pompa commerciale ad aria alla quale è stato sostituito l’evaporatore con uno ad acqua per avere un sistema acqua-acqua, l’altra era un prototipo studiato in laboratorio ma l’evaporatore ad aria era un elemento commerciale. Infine, è stato proposto anche il confronto tra pannelli convenzionali e PV / T per sottolineare la bontà della tecnologia ibrida. I risultati non sono quelli sperati ma la colpa può essere imputata al fatto che le pompe non sono state progettate per lo scopo, la tecnologia risulta promettente. In particolare l'evaporatore ad aria della pompa di calore prototipo è sovra dimensionato, quindi i vantaggi di avere il calore disponibile dai PV/T a temperatura superiore a quello ambientale sono limitati. Anche l'evaporatore della pompa di calore commerciale adottata non è stato dimensionato correttamente, quindi l'evaporazione viene effettuata a bassa temperatura. COP_commercial HP=3.40 , COP_(W/W)=6.36 , COP_(A/W)=4.09. La tecnologia PV / T risulta più efficace del PV standard considerando la produzione di energia elettrica migliorato dal raffreddamento della cella (η_el=15% e η_TOT>50 %) ; quindi la potenza elettrica in caso di irraggiamento elevato e temperatura ambiente alta è maggiore di quella ottenuta con i pannelli convenzionali FV.
Experimental analysis of two heat pumps coupled with photovoltaic thermal panels : problems an potentiality of the technology
SAPELLI, MARTINA,MARIA
2016/2017
Abstract
The building sector, as many others, is nowadays focusing its attention on renewable sources to follow the energy strategies of the EU countries to reduce greenhouse gases emissions and to increase energy efficiency. Space heating and cooling, mostly rely on fossil-fuel conventional systems. The present study aims at evaluating the performances of two Heat Pumps coupled with Photovoltaic/Thermal Panels (PV/Ts). A system like this is called Solar Assisted Heat Pump (SAHP) and in literature there are some cases analyzed but mostly coupled with thermal panels, the usage of PV/T panels is a promising prospective both for increasing of the electric performances of the panels and the energy independence of the entire system. One of the systems studied had a dual evaporator to work as air - water heat pump or air/water - water heat pump. This configuration has the potentiality of following the highest temperature between ambient and liquid from the panels to increase the performances (COP) during the year. Both heat pumps were first trials, one of them was a commercial air-water heat pump adopted to be a water-water type, the second one was a prototype heat pump. Finally, it was also proposed the comparison between conventional PV panels and the PV/T to emphasize the goodness of the hybrid technology. The results are not the expected ones but the problems can be linked to the fact that the pumps are not suited designed for the purpose; the technology is promising. In particular the air evaporator of the prototype heat pump is over dimensioned, so the benefits of having the temperature of the coolant of the PV/T higher than ambient one is limited; also the evaporator of the commercial heat pump adopted was not correctly dimensioned, thus evaporation is performed at low temperature. COP_commercial HP=3.40 , COP_(W/W)=6.36 , COP_(A/W)=4.09. The PV/T technology results better performing than standard PV looking at the electric power production that is enhanced by the cooling of the cell (η_el=15% and η_TOT>50 %), thus the power at high irradiation and ambient temperature is higher than the one obtained with conventional PV panels.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/135353