The characteristics of an organic Rankin cycle designed to operate with a low temperature geothermal source and constant temperature cooling water supplied from freshwater ponds typical to those found near Waddan City...The characteristics of an organic Rankin cycle designed to operate with a low temperature geothermal source and constant temperature cooling water supplied from freshwater ponds typical to those found near Waddan City in the Al Jufrah region of Libya were examined. Two working fluids were examined and it was concluded that the most suitable for this application was R-245fa. The off design performance of the organic Rankine cycle was examined and it was shown that the cycle is controlled by the performance of the condenser which is cooling water side temperature limited.展开更多
Unlike other types of renewable energy resources, geothermal energy provides a stable source of energy as it can be exploited regardless of meteorological conditions. Using organic cycle, geothermal energy can be util...Unlike other types of renewable energy resources, geothermal energy provides a stable source of energy as it can be exploited regardless of meteorological conditions. Using organic cycle, geothermal energy can be utilized for power generation. In such systems, the heat is exchanged between the surrounding rock mass and transport fluid. Consequently, the temperature of extracted geofluid from the well decreases with the time in accordance with the working parameters. Those parameters includeenergy extraction rate, temperature difference between inlet and outlet of the well, and the thermal conductivity of the ground. Current work, aims to develop a reliable computer model to specify the optimal working parameters so that the geofluid temperature will not reach a low value that is not acceptable for electricity generation, and the energy availability of geothermal resource is maximized. In the current study the ground thermal properties, the geothermal gradient and well dimensions are based on realistic data in Qatar and neighboring countries. The proposed model was developed for different heat extraction rate, different ground thermal properties, and for varied temperature difference between inlet and outlet of the well. Simulation shows that selecting the optimal working parameters can increase the availability of geothermal resource significantly.展开更多
The criteria of sustainable design have been already received for reducing heating energy consumption （i.e. Passivhaus standard and first fulfillment of the EPDB Directive）. Nowadays, many research are being involve...The criteria of sustainable design have been already received for reducing heating energy consumption （i.e. Passivhaus standard and first fulfillment of the EPDB Directive）. Nowadays, many research are being involved to extend the passive standard to buildings in mild climate areas. Compared to building efficiency in the middle European area, the requirements for sustainable development of construction in the Mediterranean area imply an higher and more articulated passive control of outside/inside energy flows in order to extend energy efficiency measures to the whole year. This is based on an intense interaction between external climatic conditions and the building whole performance, with a dynamic behavior according to climate seasonal changes and inside comfort. Consequently, the integrated design of building fabrics, conceived not as separated components but as complex organism and system of interaction, increases its potential and strategic aim for reducing building consumptions of whole year in the mild climate. This paper demonstrates, both in new constructions and in the renovation of existing buildings, that the whole performance approach is the most suitable for sustainable design in a typical Mediterranean climate in order to increase the efficiency with controlled investments. The aim of this research is to show, through some case studies in Sardinia, that this sensitive and performance approach could optimize the ratio between economic costs and energy and environmental benefits. Only through an integrated and intelligent design of the architectural organism it is possible to achieve the new targets for sustainable building development, even for mild climate areas, required by European Directive 2002/91/EC.展开更多
文摘The characteristics of an organic Rankin cycle designed to operate with a low temperature geothermal source and constant temperature cooling water supplied from freshwater ponds typical to those found near Waddan City in the Al Jufrah region of Libya were examined. Two working fluids were examined and it was concluded that the most suitable for this application was R-245fa. The off design performance of the organic Rankine cycle was examined and it was shown that the cycle is controlled by the performance of the condenser which is cooling water side temperature limited.
文摘Unlike other types of renewable energy resources, geothermal energy provides a stable source of energy as it can be exploited regardless of meteorological conditions. Using organic cycle, geothermal energy can be utilized for power generation. In such systems, the heat is exchanged between the surrounding rock mass and transport fluid. Consequently, the temperature of extracted geofluid from the well decreases with the time in accordance with the working parameters. Those parameters includeenergy extraction rate, temperature difference between inlet and outlet of the well, and the thermal conductivity of the ground. Current work, aims to develop a reliable computer model to specify the optimal working parameters so that the geofluid temperature will not reach a low value that is not acceptable for electricity generation, and the energy availability of geothermal resource is maximized. In the current study the ground thermal properties, the geothermal gradient and well dimensions are based on realistic data in Qatar and neighboring countries. The proposed model was developed for different heat extraction rate, different ground thermal properties, and for varied temperature difference between inlet and outlet of the well. Simulation shows that selecting the optimal working parameters can increase the availability of geothermal resource significantly.
文摘The criteria of sustainable design have been already received for reducing heating energy consumption （i.e. Passivhaus standard and first fulfillment of the EPDB Directive）. Nowadays, many research are being involved to extend the passive standard to buildings in mild climate areas. Compared to building efficiency in the middle European area, the requirements for sustainable development of construction in the Mediterranean area imply an higher and more articulated passive control of outside/inside energy flows in order to extend energy efficiency measures to the whole year. This is based on an intense interaction between external climatic conditions and the building whole performance, with a dynamic behavior according to climate seasonal changes and inside comfort. Consequently, the integrated design of building fabrics, conceived not as separated components but as complex organism and system of interaction, increases its potential and strategic aim for reducing building consumptions of whole year in the mild climate. This paper demonstrates, both in new constructions and in the renovation of existing buildings, that the whole performance approach is the most suitable for sustainable design in a typical Mediterranean climate in order to increase the efficiency with controlled investments. The aim of this research is to show, through some case studies in Sardinia, that this sensitive and performance approach could optimize the ratio between economic costs and energy and environmental benefits. Only through an integrated and intelligent design of the architectural organism it is possible to achieve the new targets for sustainable building development, even for mild climate areas, required by European Directive 2002/91/EC.
