Wetchagarun S.,University of Washington |
Wetchagarun S.,Thailand Institute of Nuclear Technology |
Riley J.J.,University of Washington
Physics of Fluids | Year: 2010
The dispersion and temperature distribution of inertial particles are important in many turbulent, multiphase flow problems. In order to understand these better, direct numerical simulations (DNSs) are performed for inertial particles in a fluid with a constant temperature gradient and whose motion is either statistically stationary or decaying, isotropic turbulence. It is found that, for long times, the dispersion of inertial particles is the greatest when the Stokes number, Stη=τp/τη, is of order 1, where τp and τη are, respectively, the particle response time and the flow Kolmogorov time scale. A similar result is found for the long time behavior of the time rate of change of the mean-square particle temperature fluctuations, d
Chankow N.,Bangkok University |
Punnachaiya S.,Bangkok University |
Wonglee S.,Thailand Institute of Nuclear Technology
Applied Radiation and Isotopes | Year: 2010
The aims of this research are to study properties of a neutron imaging plate (NIP) and to test it for use in nondestructive testing (NDT) of materials. The experiments were carried out by using a BAS-ND 2040 Fuji NIP and a neutron beam from the Thai Research Reactor TRR-1/M1. The neutron intensity and Cd ratio at the specimen position were approximately 9×105 ns/cm2 s and 100 respectively. It was found that the photostimulated luminescence (PSL) readout of the imaging plate was directly proportional to the exposure time and approximately 40 times faster than the conventional NR using Gd converter screen/X-ray film technique. The sensitivities of the imaging plate to slow neutron and to Ir-192 gamma-rays were found to be approximately 4.2×10-3 PSL/mm2 per neutron and 6.7×10-5 PSL/mm2 per gamma-ray photon respectively. Finally, some specimens containing light elements were selected to be radiographed with neutrons using the NIP and the Gd converter screen/X-ray film technique. The image quality obtained from the two recording media was found to be comparable. Crown Copyright © 2009.
Rattanaphra D.,Thailand Institute of Nuclear Technology |
Rattanaphra D.,Kasetsart University |
Harvey A.P.,Northumbria University |
Thanapimmetha A.,Kasetsart University |
Srinophakun P.,Kasetsart University
Fuel | Year: 2012
Simultaneous catalysed transesterification of rapeseed oil and esterification of 10 wt% myristic acid with methanol was studied using sulphated zirconia and in the absence of catalyst. The maximum total FAME content of 86% was obtained at a catalyst loading of 3 wt%, temperature of 170°C, pressure of 22 bars, molar ratio of oil to methanol of 1:20 and stirring rate of 600 rpm for 60 min. At these conditions, FFA was observed to reach 2.95% (2.94 mg/ml sol.). Thermo/catalytic cracking and hydrolysis of triglyceride was presumed to form the FFA. Water was also formed: dehydration of methanol is likely to be the principal source. Three sets of main reactions occurred at distinctly different rates. Esterification of myristic acid was the most rapid reaction. Direct transesterification of triglyceride and side-reactions of thermo/catalytic cracking of triglyceride followed by esterification of fatty acid and hydrolysis of triglyceride followed by esterification of fatty acid occurred afterward. Dehydration of methanol was observed throughout the reaction, producing a constant supply of water, thereby facilitating hydrolysis reactions. © 2012 Elsevier Ltd. All rights reserved.
Silva K.,Thailand Institute of Nuclear Technology |
Okamoto K.,University of Tokyo
Nuclear Engineering and Design | Year: 2016
Nuclear accident consequence index (NACI) which can assess the overall consequences of a severe accident on people and the environment is developed based on findings from previous studies. It consists of three indices: radiation effect index, relocation index and decontamination index. Though the NACI can cover large range of consequences, its assessment requires extensive resources. The authors then attempt to simplify the assessment, by investigating the relations between the release parameters and the NACI, in order to use the release parameters for severe accident consequence assessment instead of the NACI. NACI and its components increase significantly when the release amount is increased, while the influences of the release period and the release starting time on the NACI are nearly negligible. Relations between the release amount and the NACI and its components follow simple power functions (y = axb). The exponent of the power functions seems to be the key to the relations. The exponent of the relation between the release amount and the NACI was around 0.8–1.0 when the release amount is smaller than 100 TBq, and it increased to around 1.3–1.4 when the release amount is equal to or larger than 100 TBq. © 2016 Elsevier B.V.
Jannoo K.,Kasetsart University |
Teerapatsakul C.,Kasetsart University |
Punyanut A.,Thailand Institute of Nuclear Technology |
Pasanphan W.,Kasetsart University
Radiation Physics and Chemistry | Year: 2015
Silver nanoparticles (AgNPs) in chitosan (CS) stabilizer were successfully synthesized using electron beam irradiation. The effects of irradiation dose, molecular weight (MW) of CS stabilizer, concentration of AgNO3 precursor and addition of tert-butanol on AgNPs production were studied. The stability of the AgNPs under different temperatures and storage times were also investigated. The AgNPs formation in CS was observed using UV-vis, FT-IR and XRD. The characteristic surface plasmon resonance (SPR) of the obtained AgNPs was around 418nm. The CS stabilizer and its MW, AgNO3 precursor and irradiation doses are important parameters for the synthesis of AgNPs. The optimum addition of 20% v/v tert-butanol could assist the formation of AgNPs. The AgNPs in CS stabilizer were stable over a period of one year when the samples were kept at 5°C. The AgNPs observed from TEM images were spherical with an average particle size in the range of 5-20nm depending on the irradiation doses. The AgNPs in CS solution effectively inhibited the growth of several fungi, i.e., Curvularia lunata, Trichoderma sp., Penicillium sp. and Aspergillus niger, which commonly found on the building surface. © 2015 Elsevier Ltd.