Regarding the research on alternatives for monopropellant hydrazine, several so called green propellants are currently under investigation or qualification. Aside others, the DLR Institute of Space Propulsion investig...Regarding the research on alternatives for monopropellant hydrazine, several so called green propellants are currently under investigation or qualification. Aside others, the DLR Institute of Space Propulsion investigates a N20/C2I-I4 premixed green propellant. During the research activities, flashback from the rocket combustion chamber into the feeding system has been identified as a major challenge when using the propellant mixture. This paper shows the results of ignition experiments conducted in a cylindrical, optical accessible ignition chamber. During the ignition and flame propagation process, pressure, temperature and high-speed video data were collected. The high speed video data were used to analyze the flame propagation speed. The obtained propagation speed was about 20 rn/s at ignition, while during further propagation of the flame speeds of up to 120 m/s were measured. Additionally, two different porous materials as flame arresting elements were tested： Porous stainless steel and porous bronze material. For both materials Peclet numbers for flashback were derived. The critical Peclet number for the sintered bronze material was around 20, while for the sintered stainless steel the critical Peclet number seems to be larger than 40. Due to the test results, sintered porous materials seem to be suitable as flashback arresters.展开更多
Compound [Co 3(BTC)(HBTC)(H 2BTC)(C 2H 4O 2) 3]·3(DMF)·6(H 3O) was synthesized under mild conditions and its crystal structure was determined by using single crystal X-ray diffraction. The crystal structure ...Compound [Co 3(BTC)(HBTC)(H 2BTC)(C 2H 4O 2) 3]·3(DMF)·6(H 3O) was synthesized under mild conditions and its crystal structure was determined by using single crystal X-ray diffraction. The crystal structure was solved by direct method and refined by full-matrix least-square method. The crystal is monoclinic and belongs to space group Cc with a=2.645 3(5) nm, b= 1.670 4(3) nm, c=1\^821 6(4) nm, β=128.16(3) °, V=6.329(2) nm 3, Z=2 , D c=20.200 Mg/m 3, M r= 1 314.744, μ=10.274 mm -1, F(000) =38 226, GOF=0.99, R=0.094 1, ωR=0.257 3.展开更多
A new zinc hydrogen phosphite C4H8N2H4·Zn（HPO3）2 was prepared by hydrothermal method in the presence of piperazine as a structure-directing agent and the crystal structure was determined by single-crystal X-ray...A new zinc hydrogen phosphite C4H8N2H4·Zn（HPO3）2 was prepared by hydrothermal method in the presence of piperazine as a structure-directing agent and the crystal structure was determined by single-crystal X-ray diffraction analysis and further characterized by X-ray powder diffraction, IR, ICP, elemental analysis and TG analysis. This compound has one-dimensional anionic chains containing four-membered rings built from corner-sharing linked alternating ZnO4 tetrahedra and HPO3 pseudo pyramids. The zinc hydrogen phosphite chains are interacted with the templates of diprotonated piperazine by N—H…O hydrogen bond. Crystal data for C4H8N2H4·Zn（HPO3）2∶monoclinic, space group C2/c. a=1.774 8（2） nm, b=0.724 28（9） nm, c=0.880 87（11） nm, β= 105.345（3）°, V=1.091 9（2） nm 3, Z=4, Dc=1^907 Mg/m 3, R1=0.022 9, wR2=0.058 8.展开更多
A novel coordination polymer, [Fe(C 5H 4NCOO) 2] n, was synthesized by hydrothermal reaction and characterized by elemental analysis as well as IR spectroscopy. The crystal structure (with a novel 3-D network) of this...A novel coordination polymer, [Fe(C 5H 4NCOO) 2] n, was synthesized by hydrothermal reaction and characterized by elemental analysis as well as IR spectroscopy. The crystal structure (with a novel 3-D network) of this compound belongs to monoclinic, space group P2 1/n, a=0.49544(1) nm, b=1.32443(2) nm, c=1.04983(1) nm, β=101.586(1)°. The diffuse reflectance spectra (200～2500 nm) showed that the polymer had strong absorbance in 375～563 nm (E g≈2.5 eV) region and weak absorbance from 720 to 2500 nm (near infrared spectra).展开更多
文摘Regarding the research on alternatives for monopropellant hydrazine, several so called green propellants are currently under investigation or qualification. Aside others, the DLR Institute of Space Propulsion investigates a N20/C2I-I4 premixed green propellant. During the research activities, flashback from the rocket combustion chamber into the feeding system has been identified as a major challenge when using the propellant mixture. This paper shows the results of ignition experiments conducted in a cylindrical, optical accessible ignition chamber. During the ignition and flame propagation process, pressure, temperature and high-speed video data were collected. The high speed video data were used to analyze the flame propagation speed. The obtained propagation speed was about 20 rn/s at ignition, while during further propagation of the flame speeds of up to 120 m/s were measured. Additionally, two different porous materials as flame arresting elements were tested： Porous stainless steel and porous bronze material. For both materials Peclet numbers for flashback were derived. The critical Peclet number for the sintered bronze material was around 20, while for the sintered stainless steel the critical Peclet number seems to be larger than 40. Due to the test results, sintered porous materials seem to be suitable as flashback arresters.
文摘Compound [Co 3(BTC)(HBTC)(H 2BTC)(C 2H 4O 2) 3]·3(DMF)·6(H 3O) was synthesized under mild conditions and its crystal structure was determined by using single crystal X-ray diffraction. The crystal structure was solved by direct method and refined by full-matrix least-square method. The crystal is monoclinic and belongs to space group Cc with a=2.645 3(5) nm, b= 1.670 4(3) nm, c=1\^821 6(4) nm, β=128.16(3) °, V=6.329(2) nm 3, Z=2 , D c=20.200 Mg/m 3, M r= 1 314.744, μ=10.274 mm -1, F(000) =38 226, GOF=0.99, R=0.094 1, ωR=0.257 3.
文摘A new zinc hydrogen phosphite C4H8N2H4·Zn（HPO3）2 was prepared by hydrothermal method in the presence of piperazine as a structure-directing agent and the crystal structure was determined by single-crystal X-ray diffraction analysis and further characterized by X-ray powder diffraction, IR, ICP, elemental analysis and TG analysis. This compound has one-dimensional anionic chains containing four-membered rings built from corner-sharing linked alternating ZnO4 tetrahedra and HPO3 pseudo pyramids. The zinc hydrogen phosphite chains are interacted with the templates of diprotonated piperazine by N—H…O hydrogen bond. Crystal data for C4H8N2H4·Zn（HPO3）2∶monoclinic, space group C2/c. a=1.774 8（2） nm, b=0.724 28（9） nm, c=0.880 87（11） nm, β= 105.345（3）°, V=1.091 9（2） nm 3, Z=4, Dc=1^907 Mg/m 3, R1=0.022 9, wR2=0.058 8.
文摘A novel coordination polymer, [Fe(C 5H 4NCOO) 2] n, was synthesized by hydrothermal reaction and characterized by elemental analysis as well as IR spectroscopy. The crystal structure (with a novel 3-D network) of this compound belongs to monoclinic, space group P2 1/n, a=0.49544(1) nm, b=1.32443(2) nm, c=1.04983(1) nm, β=101.586(1)°. The diffuse reflectance spectra (200～2500 nm) showed that the polymer had strong absorbance in 375～563 nm (E g≈2.5 eV) region and weak absorbance from 720 to 2500 nm (near infrared spectra).
