The thermodynamic(energy and exergy)analysis of a condensate heating system,its segments,and components from a marine steam propulsion plant with steam reheating is performed in this paper.It is found that energy anal...The thermodynamic(energy and exergy)analysis of a condensate heating system,its segments,and components from a marine steam propulsion plant with steam reheating is performed in this paper.It is found that energy analysis of any condensate heating system should be avoided because it is highly influenced by the measuring equipment accuracy and precision.All the components from the observed marine condensate heating system have energy destructions lower than 3 kW,while the energy efficiencies of this system are higher than 99%.The exergy efficiency of closed condensate heaters continuously increases from the lowest to the highest steam pressures(from 70.10%to 92.29%).The ambient temperature variation between 5℃and 45℃notably influences the exergy efficiency change of both low pressure heaters and the low pressure segment equal to 31.61%,12.37%,and 18.35%,respectively.展开更多
The subject of this study is the oxidation of fuel rod cladding made of material Zr1Nb(0.1% O) in steam at temperatures in the range of 660℃ to 1200℃ with a surface in the initial state (after manufacturing - grindi...The subject of this study is the oxidation of fuel rod cladding made of material Zr1Nb(0.1% O) in steam at temperatures in the range of 660℃ to 1200℃ with a surface in the initial state (after manufacturing - grinding) and after additional chemical etching. The changes in the microstructure of tubes due to the interaction with steam were investigated. A comparison was made between the oxidation rate of this material (weight gain) and the data on the oxidation of other alloys for nuclear power plants. The oxidation rate of Zr1Nb(0.1% O) is close to the oxidation rate of other zirconium alloys. It is shown that after chemical treatment of the surface of the samples there is a more even growth of oxide films, and they have a smaller thickness for the same time of exposure than after mechanical grinding. Surface treatment before oxidation also affects the change of microstructure of samples when heated to high temperatures.展开更多
The ordered mesoporous aluminosilicate molecular sieve （MASMS-1） stable in the high-temperature steam has been successfully synthesized from the assembly of diluted ZSM-5-type precursor with mesoporous MCM-41. The m...The ordered mesoporous aluminosilicate molecular sieve （MASMS-1） stable in the high-temperature steam has been successfully synthesized from the assembly of diluted ZSM-5-type precursor with mesoporous MCM-41. The material was characterized by XRD, N2 adsorption-desorption, FE-SEM, TEM, FT-IR spectroscopy and 27A1 MAS NMR techniques. This mesoporous material shows high stability in the high-temperature steam [H2O （φ=20%） in N2 at 800 ℃ for 4 h], which might be ascribed to the synergistic effect of both thick walls containing zeolite-like five-membered ring subunits and highly condensed surface silanol groups.展开更多
基金This research is supported by the Croatian Science Foundation under the project IP-2018-01-3739,CEEPUS network CIII-HR-0108,European Regional Development Fund under the grant KK.01.1.1.01.0009(DATACROSS)project CEKOM under the grant KK.01.2.2.03.0004,CEI project“COVIDAi”(305.6019-20)University of Rijeka Scientific Grants uniri-tehnic-18-275-1447,uniritehnic-18-18-1146 and uniri-tehnic-18-14.
文摘The thermodynamic(energy and exergy)analysis of a condensate heating system,its segments,and components from a marine steam propulsion plant with steam reheating is performed in this paper.It is found that energy analysis of any condensate heating system should be avoided because it is highly influenced by the measuring equipment accuracy and precision.All the components from the observed marine condensate heating system have energy destructions lower than 3 kW,while the energy efficiencies of this system are higher than 99%.The exergy efficiency of closed condensate heaters continuously increases from the lowest to the highest steam pressures(from 70.10%to 92.29%).The ambient temperature variation between 5℃and 45℃notably influences the exergy efficiency change of both low pressure heaters and the low pressure segment equal to 31.61%,12.37%,and 18.35%,respectively.
文摘The subject of this study is the oxidation of fuel rod cladding made of material Zr1Nb(0.1% O) in steam at temperatures in the range of 660℃ to 1200℃ with a surface in the initial state (after manufacturing - grinding) and after additional chemical etching. The changes in the microstructure of tubes due to the interaction with steam were investigated. A comparison was made between the oxidation rate of this material (weight gain) and the data on the oxidation of other alloys for nuclear power plants. The oxidation rate of Zr1Nb(0.1% O) is close to the oxidation rate of other zirconium alloys. It is shown that after chemical treatment of the surface of the samples there is a more even growth of oxide films, and they have a smaller thickness for the same time of exposure than after mechanical grinding. Surface treatment before oxidation also affects the change of microstructure of samples when heated to high temperatures.
基金Project supported by Key Program of National Natural Science Foundation of China （Nos. 20433030, 90610002）, the National High-Tech Research and Development Program of China （No. 2006AA03Z328）, and the Natural Science Foundation of Zhejiang Province （No. Z406142）.
文摘The ordered mesoporous aluminosilicate molecular sieve （MASMS-1） stable in the high-temperature steam has been successfully synthesized from the assembly of diluted ZSM-5-type precursor with mesoporous MCM-41. The material was characterized by XRD, N2 adsorption-desorption, FE-SEM, TEM, FT-IR spectroscopy and 27A1 MAS NMR techniques. This mesoporous material shows high stability in the high-temperature steam [H2O （φ=20%） in N2 at 800 ℃ for 4 h], which might be ascribed to the synergistic effect of both thick walls containing zeolite-like five-membered ring subunits and highly condensed surface silanol groups.
