1,721,016 research outputs found
Heat pumps and solar energy: A review with some insights in the future
No full textA large fraction of the energy demand is due to space heating. Direct solar heating might reduce the need of fossil fuels. However the poor solar collector efficiency when outside temperature and solar radiation are low, as in the heating season, limit most of solar collectors application to domestic hot water heating. Similarly air source heat pumps are penalized just when the heating demand is higher. Then a possible solar contribution to the outside air as a heat pump cold source was first analyzed, evaluating different integration modes of the two sources. Subsequently the coupling of a ground source and a solar section appeared a more favourable application, also because solar heat could recharge the ground in periods of low or no heating demand. At the same time the solar section might reduce the length of the expensive boreholes. Solar assisted absorption heat pumps were successfully experimented. Recently studies were devoted to a solar assistance of heat pumps by PV/T collectors, that offer both a fraction of the electricity to drive the heat pump and a solar assistance to the heat pump cold source, be it the ground or the outside air
Energy analysis based on dynamic simulation of industrial heating by radiant modules with condensing unit
No full textIndustrial buildings are characterized by large dimension of the air-conditioned volume with respect to the occupied volume. This is mainly due to great heights and areas. Usually, industrial buildings are heated only. Radiant heating systems are particularly suitable for this kind of buildings, furthermore air systems are largely used as well. This paper reports on the dynamic simulation of a real industrial building coupled with an innovative condensing radiant heating system. A Trnsys type is modified in order to simulate the behavior of the high temperature condensing system. Energy performance is compared to that of two more traditional plants such as warm air heater and low temperature radiant floor coupled to condensing boiler. A comparison from the indoor thermal comfort point of view is reported as well
Heating and Cooling of a Building by Absorption Heat Pumps driven by Evacuated Tube Solar Collectors (ETCs)
Full text linkSolar assisted heat pumps till now have used the solar collectors as a cold source. Solar collectors provided when possible direct heating, otherwise they offered temperature levels higher than outside air for the heat pump evaporator. At the same time, solar thermal cooling exploits solar collectors and the absorption chiller only in hot months. The paper considers the possibility of employing ETCs to drive an absorption heat pump that is in summertime the absorption chiller. The cold source is the ground which is recharged by the solar collectors in mid seasons and by the cooling of absorber-condenser in summer. The study analyses the system behavior in yearly operation evaluating also the role of suitable storage capabilities in a temperate climate
Energy analysis of a heating and cooling plant equipped with a thermally driven heat pump and PV/T collectors
No full textSolar assisted heat pumps till now have used the solar collectors as a cold source. Solar collectors provided when possible direct heating, otherwise they offered temperature levels higher than outside air for the heat pump evaporator. At the same time, solar thermal cooling exploits solar collectors and the absorption chiller only in hot months. The paper considers the possibility of employing ETCs to drive an absorption heat pump that is in summertime the absorption chiller. The cold source is the ground which is recharged by the solar collectors in mid seasons and by the cooling of absorber-condenser in summer. The study analyses the system behaviour in yearly operation evaluating also the role of suitable storage capabilities in a temperate climate, considering the contribute to the energy balance of a PVT section
Pompa di calore a doppia sorgente per la climatizzazione di palestra e laboratori NZEB
No full textL’utilizzo di pannelli ibridi (PVT) accoppiati al terreno consente risparmi energetici importanti e la completa autosufficienza elettrica di un innovativo impianto con pompa di calore a doppia sorgente termica per la ristrutturazione di una palestra e laboratori a servizio di un istituto superiore
PVT and ETC coupling for annual heating and cooling by absorption heat pumps
Full text linkUntil recently, solar assisted heat pumps have used solar collectors as a cold source. Solar collectors provide, when possible, direct heat, otherwise they offer temperature levels to the heat pump evaporator higher than the outside air. At the same time, solar thermal cooling exploits the solar collectors and the absorption chiller only in hot months. Photovoltaic/Thermal (PVT) modules have been available on the market in recent years for solar cogeneration, but their utilization can be problematic due to PhotoVoltaic (PV) cell damage in cases where there is no heating request. This paper considers the possibility of coupling evacuated tube collectors and photovoltaic/thermal modules to drive an absorption heat pump-based plant operating as an absorption chiller in the summertime. The cold source is the solar energy and the ground, which is recharged by the solar thermal and photovoltaic/thermal collectors and by the cooling of the absorber-condenser in mid-seasons and summer. This study analyzes the system behavior in yearly operation and evaluates the role of suitable storage tanks in two different climates, varying the size of the two solar fields and the generator tank. In the best plant configuration, a primary energy ratio of 26.6 in colder climates with cloudy skies and 20 in hotter climates with clearer skies is obtained
Photovoltaic/Thermal (PV/T) to drive a dual source heat pump (ground and PV cooling): Performance analysis in a real application
No full textA large fraction (more than 80%) of the solar radiation impinging a PV panel is lost. A Photovoltaic/Thermal (PV/T or PVT) module allows not only to partially recover the otherwise lost heat, but also to cool the PV and increase its electrical efficiency. A retrofitted building located in Northern Italy will be equipped by a PVT dual source heat pump, operating with the ground as source/sink, whereas the PVT drives the heat pump compressor and acts as a dual source. When the heat pump does not need heat or operates for summer air conditioning the ground is the heat sink both for the heat pump and for the PVT cooling. A dynamic simulation allowed to size the plant, revealing high values of heat pump coefficient of performance for the favorable thermal levels of the heat source, and better thermal levels of the ground source that receives heat from the PVT panels when it is not required by the heat pump.Very high efficiency and low primary energy consumption are demonstrated for the whole plant, thanks the high energy independency from the grid
Photovoltaic/Thermal (PV/T)/ground dual source heat pump: Optimum energy and economic sizing based on performance analysis
Full text linkDual or multisource heat pumps were conceived to obviate to the defects of a single source, such as outside air, ground, water or solar radiation. Concerning the latter, the use of Photovoltaic/Thermal (PV/T or PVT) modules allows not only to partially recover the otherwise lost heat, but also to cool the PV and increase its electrical efficiency. Many studies simulated the possible behavior of combination of PVT with other sources, but generally unglazed PVT collectors were used. Only few results based on coupling glazed PVT to ground source heat pumps are available in literature. The use of glazed PVT increases thermal efficiency of the collector, and the coupling of ground allows to keep the electrical efficiency at high values without the risk of cells damage due to overheating. A refurbished building located in Northern Italy will be equipped by a PVT dual source heat pump, operating with the ground as source/sink, whereas the PVT drives the heat pump compressor and acts as a dual source. When the heat pump does not need heat or operates for summer air conditioning, the ground is the heat sink both for the heat pump and for the PVT cooling. A dynamic simulation allowed to size the plant and set up a suitable control logic of the main equipment. Very high efficiency and low primary energy consumption are demonstrated for the whole plant, thanks also to the high energy independency from the grid
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