Small-hydro power station is often used in remote areas beside a river,but it doesn't match electricity demand so well,especially in dry seasons. A photovoltaic (PV) system with battery is a suitable option to com...Small-hydro power station is often used in remote areas beside a river,but it doesn't match electricity demand so well,especially in dry seasons. A photovoltaic (PV) system with battery is a suitable option to complement the electricity gap. In this paper,a new structure of megawatt-class PV system integrating battery at DC-bus (DC: direct current) is proposed to be used in hydro/PV hybrid power system,and 4 main designing considerations and several key equipments are discussed. In 2011,a 2 MWp PV station with the proposed structure was built up in Yushu,China. From stability analysis,the station shows a strong stability under load cut-in/off and solar irradiance's fluctuation.展开更多
Strategy of the shaft eccentricity is introduced to enhance the mixing characteristics in a flat bottomed cylindrical vessel without baffles. The mixing is ensured by a six-curved blade impeller. Three solutions which...Strategy of the shaft eccentricity is introduced to enhance the mixing characteristics in a flat bottomed cylindrical vessel without baffles. The mixing is ensured by a six-curved blade impeller. Three solutions which are models of food emulsions are used as working fluids. These solutions have a shear thinning behavior modeled by the power-law. The effects of fluid properties, stirring rates, impeller rotational direction and impeller eccentricity on the 3D flow fields and power consumption are investigated. Three values of impeller eccentricity are considered, namely 0%, 24% and 48% of the vessel diameter. It is found that the opposite clockwise rotational direction reduces the power consumption, compared with the clockwise rotational direction. Also, the obtained results show that an impeller placed at an eccentric position between 24% and 48% of the vessel diameter and at the third of the vessel height may ensure the best mixing characteristics.展开更多
Compressive and flexural strength,fracture energy,as well as fatigue property of pervious cement concrete with either supplementary cementitious materials (SCMs) or polymer intensified,were analyzed.Test results show ...Compressive and flexural strength,fracture energy,as well as fatigue property of pervious cement concrete with either supplementary cementitious materials (SCMs) or polymer intensified,were analyzed.Test results show that the strength development of SCM-modified pervious concrete (SPC) differs from that of polymer-intensified pervious concrete (PPC),and porosity has little effect on their strength growth.PPC has higher flexural strength and remarkably higher flexural-to-compressive strength ratio than SPC at the same porosity level.Results from fracture test of pervious concrete mixes with porosity around 19.5% show that the fracture energy increases with increasing the dosage of polymer,reflecting the ductile damage features rather than brittleness.PPC displays far longer fatigue life than SPC for any given failure probability and at any stress level.It is proved that two-parameter Weibull probability function describes the flexural fatigue of pervious concrete.展开更多
Phase equilibrium in binary gas + water mixtures over wide ranges of temperatures and pressures are modeled and tested for thermodynamic consistency. For modeling, the Peng-Robinson equation of state was used and the ...Phase equilibrium in binary gas + water mixtures over wide ranges of temperatures and pressures are modeled and tested for thermodynamic consistency. For modeling, the Peng-Robinson equation of state was used and the Wong-Sandler mixing rules were incorporated into the equation of state parameters. In the Wong-Sandler mixing rules the van Laar model for the excess Gibbs energy was applied. In addition, a reasonable and flexible method is applied to test the thermodynamic consistency of pressure-temperature-concentration(P-T-x) data of these binary mixtures.Modeling is found acceptable in all cases, meaning that deviations in correlating the pressure and the gas phase concentration are low. For all cases the thermodynamic consistency method gives a clear conclusion about consistency or inconsistency of a set of experimental P-T-x data.展开更多
A SOFC （solid oxide fuel cell） cycle running on natural gas was integrated with a ST （steam turbine） cycle. The fuel is desulfurized and pre-reformed before entering the SOFC. A burner was used to combust the rema...A SOFC （solid oxide fuel cell） cycle running on natural gas was integrated with a ST （steam turbine） cycle. The fuel is desulfurized and pre-reformed before entering the SOFC. A burner was used to combust the remaining fuel after the SOFC stacks. The off-gases from the burner were used to produce steam in a HRSG （heat recovery steam generator）. The bottoming steam cycle was modeled with two configurations： （1） a simple single pressure level and （2） a dual pressure level with both a reheat and a pre-heater. The SOFC stacks in the present SOFC-ST hybrid cycles were not pressurized. The dual pressure configuration steam cycle combined with SOFC cycle （SOFC-ST） was new and has not been studied previously. In each of the configuration, a hybrid recuperator was used to recovery the remaining energy of the off-gases after the HRSG. Thus, four different plants system setups were compared to each other to reveal the most superior concept with respect to plant efficiency and power. It was found that in order to increase the plant efficiency considerably, it was enough to use a single pressure with a hybrid recuperator instead of a dual pressure Rankine cycle.展开更多
Biological aerated filter （BAF） is an advanced oxidation process that can sustain high volumetric loads with high quality effluent. However, backwashing process needed for the system limits its applicability. This s...Biological aerated filter （BAF） is an advanced oxidation process that can sustain high volumetric loads with high quality effluent. However, backwashing process needed for the system limits its applicability. This study is to investigate the possibility of removing carbon and nitrogen simultaneously in a biological aerated filter （BAF） with partially packed media without any backwashing process. The upper part of BAF up to 0.5 m depth is packed with plastic media （Kaldnes K1） with diameter and length of 10 mm and 7 mm respectively. This partially packed BAF creates a hybrid system of attached growth and suspended growth combined in a single reactor. Three C：N ratios, i.e. 15, 10 and 4, were compared during this study by varying the nitrogen loading while the carbon loading was kept constant at 1.0±0.54 kg COD/（m^3·d）. The organic loading rate （OLR） ratios were calculated based on carbon and TKN loading. The carbon removal percentage of 86.7±7.3%, 85.1±10.3%, and 91.0±5.6% and TKN removal percentage of 24.7±11.6%, 48.0±25.9% and 62.8±7.9% were achieved after steady-state for the C：N ratio of 15, 10, and 4 respectively. Suspended solid concentration in the effluent was found to be high throughout the treatment, but no clogging occurred during the 4 months of operation period even though backwashing was eliminated.展开更多
基金Chinese Academy of Science (No.KGCX2- YW- 366)Ministry of Science and Technology(No. 2011AA05A106)
文摘Small-hydro power station is often used in remote areas beside a river,but it doesn't match electricity demand so well,especially in dry seasons. A photovoltaic (PV) system with battery is a suitable option to complement the electricity gap. In this paper,a new structure of megawatt-class PV system integrating battery at DC-bus (DC: direct current) is proposed to be used in hydro/PV hybrid power system,and 4 main designing considerations and several key equipments are discussed. In 2011,a 2 MWp PV station with the proposed structure was built up in Yushu,China. From stability analysis,the station shows a strong stability under load cut-in/off and solar irradiance's fluctuation.
文摘Strategy of the shaft eccentricity is introduced to enhance the mixing characteristics in a flat bottomed cylindrical vessel without baffles. The mixing is ensured by a six-curved blade impeller. Three solutions which are models of food emulsions are used as working fluids. These solutions have a shear thinning behavior modeled by the power-law. The effects of fluid properties, stirring rates, impeller rotational direction and impeller eccentricity on the 3D flow fields and power consumption are investigated. Three values of impeller eccentricity are considered, namely 0%, 24% and 48% of the vessel diameter. It is found that the opposite clockwise rotational direction reduces the power consumption, compared with the clockwise rotational direction. Also, the obtained results show that an impeller placed at an eccentric position between 24% and 48% of the vessel diameter and at the third of the vessel height may ensure the best mixing characteristics.
基金Project(kfj080205)supported by Key Laboratory of Road Structure and Material of Ministry of Transport(Changsha),China
文摘Compressive and flexural strength,fracture energy,as well as fatigue property of pervious cement concrete with either supplementary cementitious materials (SCMs) or polymer intensified,were analyzed.Test results show that the strength development of SCM-modified pervious concrete (SPC) differs from that of polymer-intensified pervious concrete (PPC),and porosity has little effect on their strength growth.PPC has higher flexural strength and remarkably higher flexural-to-compressive strength ratio than SPC at the same porosity level.Results from fracture test of pervious concrete mixes with porosity around 19.5% show that the fracture energy increases with increasing the dosage of polymer,reflecting the ductile damage features rather than brittleness.PPC displays far longer fatigue life than SPC for any given failure probability and at any stress level.It is proved that two-parameter Weibull probability function describes the flexural fatigue of pervious concrete.
基金the National Council for Scientific and Technological Research,CONICYT,for its grant FONDECYT 3020020the Center for Technological Information (La Serena-Chile) for computer and library support+1 种基金CAF thanks the Direction of Research of the University of Concepción for the support through the research grant DIUC 211.011.054-1.0JOV thanks the University of La Serena for especialsupport
文摘Phase equilibrium in binary gas + water mixtures over wide ranges of temperatures and pressures are modeled and tested for thermodynamic consistency. For modeling, the Peng-Robinson equation of state was used and the Wong-Sandler mixing rules were incorporated into the equation of state parameters. In the Wong-Sandler mixing rules the van Laar model for the excess Gibbs energy was applied. In addition, a reasonable and flexible method is applied to test the thermodynamic consistency of pressure-temperature-concentration(P-T-x) data of these binary mixtures.Modeling is found acceptable in all cases, meaning that deviations in correlating the pressure and the gas phase concentration are low. For all cases the thermodynamic consistency method gives a clear conclusion about consistency or inconsistency of a set of experimental P-T-x data.
文摘A SOFC （solid oxide fuel cell） cycle running on natural gas was integrated with a ST （steam turbine） cycle. The fuel is desulfurized and pre-reformed before entering the SOFC. A burner was used to combust the remaining fuel after the SOFC stacks. The off-gases from the burner were used to produce steam in a HRSG （heat recovery steam generator）. The bottoming steam cycle was modeled with two configurations： （1） a simple single pressure level and （2） a dual pressure level with both a reheat and a pre-heater. The SOFC stacks in the present SOFC-ST hybrid cycles were not pressurized. The dual pressure configuration steam cycle combined with SOFC cycle （SOFC-ST） was new and has not been studied previously. In each of the configuration, a hybrid recuperator was used to recovery the remaining energy of the off-gases after the HRSG. Thus, four different plants system setups were compared to each other to reveal the most superior concept with respect to plant efficiency and power. It was found that in order to increase the plant efficiency considerably, it was enough to use a single pressure with a hybrid recuperator instead of a dual pressure Rankine cycle.
文摘Biological aerated filter （BAF） is an advanced oxidation process that can sustain high volumetric loads with high quality effluent. However, backwashing process needed for the system limits its applicability. This study is to investigate the possibility of removing carbon and nitrogen simultaneously in a biological aerated filter （BAF） with partially packed media without any backwashing process. The upper part of BAF up to 0.5 m depth is packed with plastic media （Kaldnes K1） with diameter and length of 10 mm and 7 mm respectively. This partially packed BAF creates a hybrid system of attached growth and suspended growth combined in a single reactor. Three C：N ratios, i.e. 15, 10 and 4, were compared during this study by varying the nitrogen loading while the carbon loading was kept constant at 1.0±0.54 kg COD/（m^3·d）. The organic loading rate （OLR） ratios were calculated based on carbon and TKN loading. The carbon removal percentage of 86.7±7.3%, 85.1±10.3%, and 91.0±5.6% and TKN removal percentage of 24.7±11.6%, 48.0±25.9% and 62.8±7.9% were achieved after steady-state for the C：N ratio of 15, 10, and 4 respectively. Suspended solid concentration in the effluent was found to be high throughout the treatment, but no clogging occurred during the 4 months of operation period even though backwashing was eliminated.
