1,721,078 research outputs found
High Temperature Heat Pump with Combined Cooling, Heat and Power Plant in Industrial Buildings: An Energy Analysis
Full text linkIn this paper, the coupling of a high temperature heat pump with a combined cooling, heat, and power system is investigated. The plant converts the input energy source (natural gas) into electricity and useful thermal energy by means of a cogenerator. Part of the thermal energy feeds an absorption chiller that produces the cooling energy to satisfy the cooling load of an existing industrial building located in northern Italy. The heat pump enhances the low temperature heat from the condenser and absorber of the absorption chiller to high temperature heat to integrate the hot water produced by the cogenerator. The energy performance of the entire plant is analyzed by means of steady-state simulations at both fixed conditions and on an annual operation to meet the heating, cooling, and electric needs of the building varying different parameters and compared to traditional systems for energy production. As the main results, the integrated system provides flexibility and achieves valuable energy performances, in the range of a few tens of percent with respect to benchmark energy production systems
Heating Industrial Buildings with Heat Pump Air Systems: Is It Always the Most Advantageous Option?
Full text linkAccording to extant Italian legislation implementing the Renewable Energy Directive, the mandatory renewable quota for a new building is 60% referring to a single service (e.g., heating during winter) or to multiple services (e.g., heating during winter and air conditioning during summer), depending on which services are actually present. The obligation to satisfy this minimum value often leads heating and ventilation plant designers to provide heat pump systems in industrial buildings, typically air/water or direct expansion type coupled with air terminals (air heaters or ventilation units) or radiant floors. The question is: Is this always the most advantageous option for industrial buildings? A typical industrial building was modeled by Trnsys® in two different climates. Based on the calculated thermal heating loads, the condensing radiant tubes and heat pump coupled with the air heaters systems were analyzed through dynamic simulation, evaluating their performance from an energy, environmental impact, and economic point of view. The analysis carried out revealed that a heat pump system is not always the most advantageous solution depending on the climate, the characteristics of the building (less or more thermal insulation, which corresponds to existing buildings rather than new ones), and the size of the photovoltaics system eventually installed on the roof
Heating and Cooling Feasibility of Absorption Heat Pumps Driven by Evacuated Tube Solar Collectors: An Energy and Economic Analysis
Full text linkThermal compression-driven heat pump plants usually use solar collectors only providing direct heating when possible and low-temperature (but higher than outside air) cold sources for the heat pump evaporator otherwise. At the same time, solar collectors drive absorption chillers only during summer. In this paper, the possibility of employing evacuated tube collectors to drive an absorption heat pump that operates in summer as a chiller was evaluated from both energy and economic points of view. The ground and solar energy at low temperature were used as cold sources. The ground can be recharged by the cooling of the absorber/condenser in the summer and by solar energy during the mid-seasons. The yearly operation analysis in two different climates here proposed also considered also the utilization of suitable storage capabilities varying the size of the ground probes, solar field, and Generator Tank. A primary energy ratio of 4.75 in a cold and cloudy climate and of 5.9 in a warmer and clearer sky climate was obtained in the best plant configuration. An economic analysis on the actual investment costs was presented. The final evaluation considered a cost reduction on the basis of recent price lists available on the Asian market
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
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
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
Risparmio energetico, efficienza energetica o energie rinnovabili: quale scelta privilegiare per la decarbonizzazione del settore residenziale in Italia?
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