Nonsteady combustion of fuel surface in diffusional conditions

1986 ◽  
Vol 22 (1) ◽  
pp. 30-36
Author(s):  
N. N. Smirnov
Keyword(s):  
Fuel Surface ◽  
Nonsteady Combustion

Leaching of Used Candu Fuel: Results from a 19-Year Leach Test Under Oxidizing Conditions

1996 ◽  
Vol 465 ◽  
Author(s):  
S. Stroes-Gascoyne ◽  
L. H. Johnson ◽  
J. C. Tait ◽  
J. L. McConnell ◽  
R. J. Porth
Keyword(s):  
Grain Boundary ◽  
Cross Sections ◽  
Peak Power ◽  
Physical State ◽  
Fuel Pellet ◽  
Fuel Surface ◽  
Pellet Surface ◽  
Fuel Bundle ◽  
Dissolution Behaviour ◽  
Congruent Dissolution

ABSTRACTA fuel leaching experiment has been in progress since 1977 to study the dissolution behaviour of used CANDU fuel in aerated aqueous solution. The experiment involves exposure of 50-mm clad segments of an outer element of a Pickering fuel bundle (burnup 610 GJ/kg U; linear and peak power ratings 53 and 58 kW/m, respectively), to deionized distilled water (DDH2O, ∼2 mg/L carbonate) and tapwater (∼50 mg/L carbonate). In 1992, it was observed that the fuel in at least one of the leaching solutions showed some signs of deterioration and, therefore, in 1993, parts of the fuel samples were sacrificed for a detailed analysis of the physical state of the fuel, using SEM and optical microscopy. Leaching results to date show that even after >6900 days only 5 to 7.7% of the total calculated inventory of 137Cs has leached out preferentially and that leach rates suggest a development towards congruent dissolution. Total amounts of 137Cs and 90Sr leached are slightly larger in tapwater than in DDH2O. SEM examinations of leached fuel surface fragments indicate that the fuel surface exposed to DDH2O is covered in a needle-like precipitate. The fuel surface exposed to tapwater shows evidence of leaching but no precipitate, likely because uranium is kept in solution by carbonate. Detailed optical and SEM microscopy examinations on fuel cross sections suggest that grain-boundary dissolution in DDH2O is not prevalent, and in tapwater appears to be limited to the outer %0.5 mm (pellet/cladding) region of the fuel. Grain boundary attack seems to be limited to microcracks at or near the surface of the fuel. It thus appears that grain-boundary attack occurs only near the fuel pellet surface and is prevalent only in the presence of carbonate in solution.

Effects of Flow Passage Expansion or Contraction on Jet-Fuel Surface Deposition

2012 ◽  
Vol 28 (4) ◽  
pp. 694-706 ◽  
Author(s):  
Hua Jiang ◽  
Jamie Ervin ◽  
Steven Zabarnick ◽  
Zachary West
Keyword(s):  
Jet Fuel ◽  
Surface Deposition ◽  
Flow Passage ◽  
Fuel Surface

Experimental Study on Water Mist Suppression of Poly(Methyl Methacrylate) PMMA Fires

Volume 4 ◽  
2004 ◽  
Author(s):  
B. Yao ◽  
J. Qin ◽  
W. K. Chow
Keyword(s):  
Methyl Methacrylate ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Water Mist ◽  
Doppler Velocimetry ◽  
Confined Space ◽  
Surface Cooling ◽  
Fuel Surface ◽  
Poly Methyl Methacrylate

Suppression of Poly(methyl methacrylate) PMMA fires by water mist will be studied in this paper. A simple test is developed to study the critical water flow rate under different radiant heat flux. The test is found to be suitable for studying the extinguishment effects of fine water droplets involving oxygen displacement, gas phase and fuel surface cooling. Water mist is generated by a single pressure nozzle, with the water mist characteristics measured by the Laser Doppler Velocimetry or the Adaptive Phase Doppler Velocimetry System (LDV/APV system). The interaction between water mist and the PMMA flame will be studied in a confined space with ventilation control in a cone calorimeter. The heat release rate, oxygen, carbon dioxide and carbon monoxide concentrations, and other important parameters of the interaction under various conditions are measured. It is found that discharging adequate amount of water mist would suppress the diffusion flame in the confined space. Reignition might occur once water mist stopped discharging to the fuel surface. Higher heat release rate and more smoke and toxic gases were produced than from those in first ignition.

Flame spread over an inclined thin fuel surface

1976 ◽  
Vol 26 ◽  
pp. 163-177 ◽  
Author(s):  
Takashi Kashiwagi ◽  
David L. Newman
Keyword(s):  
Flame Spread ◽  
Fuel Surface

scholarly journals Modified Regression Rate Formula of PMMA Combustion by a Single Plane Impinging Jet

2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
Tsuneyoshi Matsuoka ◽  
Kyohei Kamei ◽  
Yuji Nakamura ◽  
Harunori Nagata
Keyword(s):  
Control Volume ◽  
Rocket Motor ◽  
Displacement Sensor ◽  
Pure Oxygen ◽  
Hybrid Rocket ◽  
Single Plane ◽  
Regression Rate ◽  
Fuel Surface ◽  
Hybrid Rocket Motor ◽  
Quenching Distance

A modified regression rate formula for the uppermost stage of CAMUI-type hybrid rocket motor is proposed in this study. Assuming a quasi-steady, one-dimensional, an energy balance against a control volume near the fuel surface is considered. Accordingly, the regression rate formula which can calculate the local regression rate by the quenching distance between the flame and the regression surface is derived. An experimental setup which simulates the combustion phenomenon involved in the uppermost stage of a CAMUI-type hybrid rocket motor was constructed and the burning tests with various flow velocities and impinging distances were performed. A PMMA slab of 20 mm height, 60 mm width, and 20 mm thickness was chosen as a sample specimen and pure oxygen and O2/N2mixture (50/50 vol.%) were employed as the oxidizers. The time-averaged regression rate along the fuel surface was measured by a laser displacement sensor. The quenching distance during the combustion event was also identified from the observation. The comparison between the purely experimental and calculated values showed good agreement, although a large systematic error was expected due to the difficulty in accurately identifying the quenching distance.

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