1,720,980 research outputs found
Energy and economic analysis of small-scale distributed generation in the residential sector
No full textProgettazione e gestione degli impianti di cogenerazione nel libero mercato dell'energia
No full textDistributed generation and trigeneration: energy saving opportunities in Italian supermarket sector
No full textThis paper presents an analysis of the potential for introducing distributed generation systems in the
supermarket sector in the light of Italian legislation (inasmuch as concerns tax incentives and regulations)
with a view to arriving at some generally applicable criteria. The energy users in question are
characterized by a strong demand for energy for refrigeration for food preservation and for ambient
air-conditioning during the summer.
This makes supermarkets particularly suitable for trigeneration applications with the prime mover
coupled with absorption systems. This study analyses the feasibility of implementing trigeneration systems
for the combined production of electricity and ambient heating and air-conditioning energy or,
alternatively, for the combined generation of electrical energy and refrigeration for the preservation of
food. Finally, the hypothesis of combining trigeneration systems with photovoltaic systems aimed at
maximizing the energy saving achievable was also considered. This paper analyses the various technologies
from a technical, economic and environmental standpoint, enabling advantages and disadvantages
to be identified in relation to a real case
Comparison of refrigeration cycles with natural refrigerants for very rapid food freezing
No full textIn the industrial refrigeration natural refrigerants are gaining more and more importance, mainly because of increasing environmental concerns. In this work food processing applications are considered, with particular reference to very rapid freezing refrigeration, for which a temperature of -70°C is needed. Two alternative technologies are presented: (i) an open air cycle freezer; (ii) a cascade cycle using CO2 or blends of CO2 and natural refrigerants as low temperature working fluid. A comparison between the two technologies is performed. The purpose of the paper is to outline the main features of each system, comparing them on a technical point of view on the basis of theoretical models and experimental results on existing prototype units
Energy and economic analysis of an ICE-based variable speed-operated micro-cogenerator
No full textMicro-combined heat and power (CHP) systems are a key resource to meet the EUCO(2) reduction agreed in the Kyoto Protocol. In the near future they are likely to spread significantly through applications in the residential and service sectors, since they can provide considerably higher primary energy efficiencies than plants generating electricity and heat separately. A 28 kW(e) natural gas, automotive-derived internal combustion engine CHP system was modeled with a view to comparing constant and variable speed operation modes. Besides their energy performances, the paper addresses the major factors involved in their economic evaluation and describes a method to assess their economic feasibility. Typical residential and service sector applications were chosen as test cases and the results discussed in terms of energy performances and of profitability. They showed that interesting savings can be obtained with respect to separate generation, and that they are higher for the household application in variable speed operating conditions. In fact the plant's energy performance is greatly enhanced by the possibility, for any given power, to regulate the engine's rotational speed. From the economic viewpoint, despite the higher initial cost of the variable speed concept, the system involves a shorter pay-back period and ensures greater profit
Heat pumps and Demand Side Management for renewable energy integration in sustainable communities
No full textThe introduction of renewable energy is a key policy for sustainable communities. Some of them are variable energy resources (VERs) since their production varies over the time and are not easily and perfectly predictable. An increasing share of VERs can, indeed, badly impact on the electricity grid. The paper focuses on assessing the effect of introducing a high share of VERs production, taking as reference case a small-size sustainable community, located in Central Italy, which aims to reach, at least, a 30% CO2 emission reduction by 2025. Different energy scenarios have been considered on the basis of local energy policies defined by the Municipal Energy Plan, MEP. Demand Side Management (DSM) strategies related to the introduction of heat pumps (HP) systems powered by the excess derived from VERs, have been studied to reduce the impact into the power grid. In particular the performed analysis is aimed at finding the optimal configurations necessary to achieve thermal comfort in buildings where HP systems are introduced when Demand Side Management strategies are in action
Study of an innovative micro-CHP system fuelled by LPG
No full textThe work deals with an innovative micro-combined heat and power (micro-CHP) unit
based on Stirling engine technology. Although simplicity of design, low-noise operation
and multi-fuel feeding make Stirling engines a promising micro-CHP technology for
dwelling sector, power-to-heat ratio is lower than alternative technologies (i.e.
reciprocating engine, fuel cell, microturbine) resulting in poor global efficiency during
low heat demand periods. Switching the system off and buying energy from the grid is
demonstrated to be the best managing strategy in those periods, leading to fewer
operating hours and longer payback time, especially in the Mediterranean areas. The
present study investigates the application of a regenerative heat exchanger to recover
part of the thermal power discharged by the unit when the heat demand is low to
increase the electric efficiency of the micro-CHP device and its power-to-heat ratio. The
heat exchanger main design parameters are defined and the unit performances are
discussed on the basis of simulation data. Fuelling the system with liquefied petrol gas
(LPG), an electrical efficiency increase of 7% is achieved thus offering interesting
energy savings in dwelling sector. In addition LPG is characterized by lower emission
than other fuels and can be applied in many areas not connected to the natural gas grid,
improving the security of supply. A detached house is considered to assess the technoeconomic
unit performances with or without the regenerator. The solution studied
guarantees: i) higher Primary Energy Saving (PES) ii) six month reduction in the
payback time, iii) 800 increase in operating hours, iv) higher end-user self-efficiency,
aiding to reduce the electric input from the grid during peak periods and minimize the
risk of congestion of the network. Finally a sensitive analysis is developed,
demonstrating that a micro-CHP equipped with this innovative solution is less affected
by the variation of the LPG purchasing cost
Disturbo da movimenti stereotipati: caratteristiche cliniche e comorbidità in bambini di età prescolare
No full textEnergy and economic analysis of an ICE-based variable speed-operated micro-cogenerator
No full textMicro-combined heat and power (CHP) systems are a key resource to meet the EUCO(2) reduction agreed in the Kyoto Protocol. In the near future they are likely to spread significantly through applications in the residential and service sectors, since they can provide considerably higher primary energy efficiencies than plants generating electricity and heat separately. A 28 kW(e) natural gas, automotive-derived internal combustion engine CHP system was modeled with a view to comparing constant and variable speed operation modes. Besides their energy performances, the paper addresses the major factors involved in their economic evaluation and describes a method to assess their economic feasibility. Typical residential and service sector applications were chosen as test cases and the results discussed in terms of energy performances and of profitability. They showed that interesting savings can be obtained with respect to separate generation, and that they are higher for the household application in variable speed operating conditions. In fact the plant's energy performance is greatly enhanced by the possibility, for any given power, to regulate the engine's rotational speed. From the economic viewpoint, despite the higher initial cost of the variable speed concept, the system involves a shorter pay-back period and ensures greater profit
L’intervento riabilitativo integrato nel Disturbo della Coordinazione Motoria associato a difficoltà emotivo-comportamentali
No full text- …
