1,721,079 research outputs found
Evaluation and control of thermal losses and solar fraction in a hot water solar system
Full text linkWater heating for domestic needs contributes significantly to energy demands in the residential sector. The paper reports an energetic analysis of a solar hot water system performed on a dwelling located in different European cities. The study is focused on a group of apartments, where the domestic hot water is provided by a solar system coupled with a storage tank. A recirculation loop, composed by a pump and a system of pipes from the tank to the more distant apartment is also considered in the study. The loop overcomes the problem of long waiting times for hot water for the user by keeping it flowing inside the system. Since the recirculation loop is compulsory in this kind of plants, a dynamic energetic analysis is performed in order to analyze the pipe heat loss influence on the solar fraction. Dynamic simulations are performed using TRNSYS by interrupting the flow in the recirculation loop during the night and monitoring the temperature in the circulation loop. The study shows the sizing process of the whole system, the variation of the solar fraction and heat loss fraction for all the analyzed cases
convenzione di ricerca per lo studio teorico-sperimentale delle prestazioni energetiche, di comfort e di qualità dell’aria dei sistemi di climatizzazione Proter Imex a pannelli radianti e di sistemi tradizionali adottati nei reparti di Maternità (e similari) e ortopedia (e similari) dell’Ospedale Maggiore di Bologna - convenzione stipulata con Proter Imex srl - importo € 36.000,00
No full textLe attività si pongono l’obiettivo ultimo di definire sotto il profilo quantitativo e qualitativo le differenze di prestazioni, intese queste nel senso più ampio del termine, tra sistemi di climatizzazione per l’edilizia ospedaliera del tipo tradizionale (ad es. del tipo a fancoil o radiatori con o senza ricambio di aria primaria) e sistemi a pannelli radianti a soffitto con rinnovo di aria esterna, fermo restando che la validità dei risultati sarà estendibile anche ad ambienti a destinazione d’uso diversa, sia per applicazioni civili che industriali
CONVENZIONE DI RICERCA PER LO STUDIO DELLE CONDIZIONI TERMICHE INVERNALI DI TUBAZIONI ANTINCENDIO NON COIBENTATE ENTRO GALLERIE STRADALI UBICATE IN ALTA MONTAGNA IN REGIME DI RIPOSO E DI FUNZIONAMENTO IDRAULICO - convenzione tipualat con CIAB scrl - importo € 13.200,00
No full textLe condizioni di funzionamento invernale di tubazioni antincendio non coibentate poste in gallerie stradali, sia in caso di riposo (tubazione piena non funzionante) che in regime di lavoro (tubazione erogante la portata di progetto della rete), possono diventare particolarmente critiche in caso di temperature esterne rigide (– 20 °C costanti per intervalli temporali di 1 mese continuativo).
In tal caso, per la sicurezza di funzionamento idraulico è indispensabile conoscere l’andamento delle temperature interne della galleria in funzione
- del suo sviluppo
- della temperatura esterna,
- dei venti predominanti
- di eventuali fenomeni di ricambio di aria imputabili sia a mezzi meccanici che a eventi di convezione naturale innescati da differenze di quota tra imbocco e sbocco del tunnel
- della temperatura dell’acqua di reintegro nella tubazione.
L’obiettivo della ricerca consiste nella determinazione delle condizioni termiche invernali di tubazioni antincendio non coibentate entro gallerie stradali ubicate in alta montagna in regime di riposo e di funzionamento idraulico e nella individuazione delle possibili soluzioni per evitarne il collass
Energy performance of an existing office building in the northern part of Italy: Retrofitting actions and economic assessment
No full textIn recent years, the interest of the scientific community towards building energy performance has become more evident in order to meet the National and European Directives. In this context, retrofits that result in improved building energy performance are widely investigated. The paper presents a comparative analysis of two different and complementary strategies to enhance the energy performance of an existing tertiary building located in Bologna, Italy. The first retrofit action is to reduce the heat transfer by transmission (i.e. use of low-emissivity glass) and the second one is to decrease the ventilation losses (i.e. installation of a heat recovery system). Then a third case has been investigated: it contemplates simultaneously both the solutions of windows replacement and installing a ventilation recovery system. Potential energy savings were calculated by means of dynamic simulation assisted by Trnsys energy simulation tool. Finally, an evaluation of the simple payback time and the net present value was performed in order to investigate global cost assessment. The window replacement option in the analyzed building office proved to be absolutely unprofitable, even if it would appear as the first and simplest action to be performed. On the contrary, the installation of a total energy recovery system resulted in sensible reduction of energy consumption and at the same time generated good values of NPV with reference to all the three different analyzed variation of the cost of energy
The bin method to investigate the effect of climate conditions on the SCOP of air source heat pumps: the Italian case
Full text linkThe paper investigates the seasonal performances of electric air-to-water heat pumps specifically related to climatic conditions of the place where the heat pump is installed. The analysis is carried out using easily available weather data for some Italian towns differently located, and using the bin-method proposed by UNI/TS 11300-4. Two different types of heat pumps (on-off and inverter-driven variable speed compressor) are considered and comparisons between different types of heat pumps and different places of installation are performed. The analysis shows that the climate of the installation place is the most important factor that affects seasonal indexes of heat pumps; moreover, as expected, inverter heat pumps better perform than on-off ones
Energy savings in hospital patient rooms: The role of windows size and glazing properties
Full text linkLarge windows with increased exposure to daylight have strong positive effects on the well-being of building occupants and can provide energy savings when appropriate glazing specifications are employed. The work evaluates the impact of different window sizes and glazing on heating and cooling energy needs in a hospital patient room, in order to investigate the energy savings achievable by adopting wider openings and to identify the most effective glazing types. Simulations have been conducted for different commercially available glazing systems. The authors analyzed the energy performance of a base case window with 25% Window-to-Wall Ratio (WWR) and of a wall-to-ceiling window with 77% WWR, in rooms facing the four different orientations and located in Bologna, Italy. Results show that the adoption of wider windows with appropriate glazing can lower the heating and cooling energy demand
Effect of real temperature data on the seasonal coefficient of performance of air source heat pumps
Full text linkIn this paper, a transient analysis is performed in order to evaluate how effective climate data affect the determination of the seasonal coefficient of performance of ASHPs. Three Italian cities, characterized by different climates, are considered as reference case studies and the influence of real meteorological data, collected from different years, on the heat pump SCOP is performed. The analysis is carried out by employing the dynamic software TRNSYS. Numerical results show small variations in SCOP, while a significant influence on annual thermal energy demand can be observed. The analysis also underlines the absence of a general correlation between annual thermal energy supplied by the heat pump and SCOP and between HDD and SCOP
Retrofit Strategies Applied to a Tertiary Building Assisted by Trnsys Energy Simulation Tool
No full textAbstractThis paper describes an integrated passive design approach to reduce the heating demand for an existing tertiary building through an improved thermal envelope design and high efficiency windows. The numerical optimization has been performed dynamically by means of TRNSYS simulation tool. The model here treated is aimed at the determination of the thermal demand with reference to a tertiary building in Italy, which it is supposed to be located in two different climatic zones, i.e., Bologna and Rome. The final part of the paper deals with the investment costs analysis, applied to each retrofitting scenario: it has been demonstrated that the simple payback period results to be strongly affected by the climatic zone of the building location and by the national policies of fiscal incentives
Integrazione impiantistico architettonica in edifici storici a destinazione museale: il caso di Palazzo Pepoli a Bologna
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