排序方式: 共有109条查询结果,搜索用时 15 毫秒
71.
Anukorn Phuruangrat Thongtem Somchai Thongtem Titipun 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2018,92(10):2081-2085
Russian Journal of Physical Chemistry A - 0–3 wt % Sm-doped ZnO nanostructures were prepared by sonochemical process. The products were characterized by X-ray diffraction (XRD), scanning... 相似文献
72.
Chokchaichamnankit D Kongjinda V Khunnawutmanotham N Chimnoi N Pisutcharoenpong S Techasakul S 《Natural product communications》2011,6(8):1103-1106
A new prenylated isoflavone, pomiferin-4'-O-methyl ether, and a new prenylated chalcone, 2',4'-dihydroxy-4-methoxy-3'-(2-hydroxy-3-methylbut-3-enyl)chalcone, together with four known flavonoids, were isolated from the leaves of Derris malaccensis. All isolated compounds were evaluated for their cytotoxicity. 相似文献
73.
Two-phase flow of R-134a refrigerant during flow boiling through a horizontal circular mini-channel 总被引:1,自引:0,他引:1
Sira Saisorn Jatuporn Kaew-On Somchai Wongwises 《Experimental Thermal and Fluid Science》2011,35(6):887-895
This research focuses on heat transfer to R-134a during flow boiling in a 1.75 mm internal diameter tube. Flow visualisation and heat transfer experiments are conducted to obtain heat transfer coefficients for different flow patterns. The measured data in each flow regime are compared with predictions from a three-zone flow boiling model. The calculations are in fair agreement with the experimental results which correspond in particular to slug flow, throat-annular flow and churn flow regimes under conditions of low heat flux. 相似文献
74.
Kitti Nilpueng Chietta Supavarasuwat Somchai Wongwises 《Heat and Mass Transfer》2011,47(10):1219-1227
In the present article, the effect of heat source temperature, heat sink temperature, short-tube orifice diameter and short-tube
orifice length on the performance characteristics of HFC-140A and HFC-134a refrigeration system using a short-tube orifice
as expansion device, i.e., mass flow rate, cooling capacity, compressor pressure ratio, power consumption, and second law
efficiency are experimentally studied. The short-tube orifices diameters ranging from 0.849 to 1.085 mm with length ranging
from 10 to 20 mm are used in this examination. The test run are done at heat source temperature ranging between 16.5 and 18.5°C,
and heat sink temperature ranging between 30 and 35°C. The results show that the tendency of second law efficiency is increased
as the short-tube orifice diameter and heat source temperature are enhanced, but it is decreased by increasing the short-tube
orifice length and heat sink temperature. Under the similar conditions, the mass flow rate, cooling capacity, and compressor
power consumption obtained from HFC-410A are higher than those obtained from HFC-134a. 相似文献
75.
This paper is first of the two papers dealing with analytical investigation of resonant multi-modal dynamics due to 2:1 internal
resonances in the finite-amplitude free vibrations of horizontal/inclined cables. Part I deals with theoretical formulation
and validation of the general cable model. Approximate nonlinear partial differential equations of 3-D coupled motion of small
sagged cables – which account for both spatio-temporal variation of nonlinear dynamic tension and system asymmetry due to
inclined sagged configurations – are presented. A multi-dimensional Galerkin expansion of the solution of nonplanar/planar
motion is performed, yielding a complete set of system quadratic/cubic coefficients. With the aim of parametrically studying
the behavior of horizontal/inclined cables in Part II [25], a second-order asymptotic analysis under planar 2:1 resonance
is accomplished by the method of multiple scales. On accounting for higher-order effects of quadratic/cubic nonlinearities,
approximate closed-form solutions of nonlinear amplitudes, frequencies and dynamic configurations of resonant nonlinear normal
modes reveal the dependence of cable response on resonant/nonresonant modal contributions. Depending on simplifying kinematic
modeling and assigned system parameters, approximate horizontal/inclined cable models are thoroughly validated by numerically
evaluating statics and non-planar/planar linear/non-linear dynamics against those of the exact model. Moreover, the modal
coupling role and contribution of system longitudinal dynamics are discussed for horizontal cables, showing some meaningful
effects due to kinematic condensation. 相似文献
76.
77.
Somchai Lapanantnoppakhun Supharphorn Kasuwas Lucksagoon Ganranoo Jaroon Jakmunee Kate Grudpan 《Analytical sciences》2006,22(1):153-155
A simple spectrophotometric flow injection (FI) procedure for the determination of Cr(III) using ethylenediaminetetraacetic acid (EDTA) was developed. An FI system with a column packed with Amberlite IR-120(H) was employed for sample pretreatment. This leads to the possibility of a single standard calibration. A linear calibration in a range of 10-27 microg Cr(III) was obtained with a detection limit of 1 microg Cr(III) and RSD of 2% (18 microg Cr(III), n=12). The proposed procedure was applied for determination of Cr(III) in leachate and dietary supplement samples. The results agreed with those obtained by the standard methods. 相似文献
78.
This article reports a comparison of the differences between using measured and computed thermophysical properties to describe the heat transfer performance of TiO2–water nanofluids. In this study, TiO2 nanoparticles with average diameters of 21 nm and a particle volume fraction of 0.2–1 vol.% are used. The thermal conductivity and viscosity of nanofluids were measured by using transient hot-wire apparatus and a Bohlin rotational rheometer, respectively. The well-known correlations for calculating the thermal conductivity and viscosity of nanofluids were used for describing the Nusselt number of nanofluids and compared with the results from the measured data. The results show that use of the models of thermophysical properties for calculating the Nusselt number of nanofluids gave similar results to use of the measured data. Where there is a lack of measured data on thermophysical properties, the most appropriate models for computing the thermal conductivity and viscosity of the nanofluids are the models of Yu and Choi and Wang et al., respectively. 相似文献
79.
Darin Phukingngam Orathai Chavalparit Dararat Somchai Maneerat Ongwandee 《Chemical Papers》2011,65(5):644-651
Biodiesel-processing factories employing the alkali-catalyzed transesterification process generate a large amount of wastewater
containing high amount of methanol, glycerol, and oil. As such, wastewater has high potential to produce biogas using anaerobic
treatment. The aim of this research was to investigate the performance of an anaerobic baffled reactor for organic removal
and biogas production from biodiesel wastewater. The effect of different organic loading rates, varying from 0.5 kg m−3 d−1 to 3.0 kg m−3 d−1 of chemical oxygen demand, was determined using three 22 L reactors, each comprising five separate compartments. Wastewater
was pretreated with chemical coagulants to partially remove oil prior to experimentation. Results show that the anaerobic
baffled reactor operated at 1.5 kg m−3 d−1 of chemical oxygen demand and ten days of hydraulic retention time provided the best removal efficiencies of 99 % of chemical
oxygen demand, 100 % of methanol, and 100 % of glycerol. Increasing the organic loading rate over 1.5 kg m−3 d−1 of chemical oxygen demand led to excessive accumulation of volatile fatty acids thereby making the pH drop to a value unfavorable
for methanogenesis. The biogas production rate was 12 L d−1 and the methane composition accounted for 64–74 %. Phase-separated characteristics revealed that the highest chemical oxygen
demand removal percentage was achieved in the first compartment and the removal efficiency gradually decreased longitudinally.
A scanning electron microscopic study indicated that the most predominant group of microorganisms residing on the external
surface of the granular sludge was Methanosarcina. 相似文献
80.
Experimental studies are performed to evaluate the stability of zinc oxide (ZnO) nanoparticles suspended in a mixture of ethylene glycol and water with weight ratio of 40–60 as the base fluid. Different methods have been employed to disperse ZnO nanoparticles. It is found that using Gum Arabic leads to clustering and settle the nanoparticles. Also, the use of DI ammonium hydrogen citrate with weight ratio 1:1 (surfactant:nanoparticles) gives the acceptable stability. The density of nanofluids is measured and the results are compared with theoretical results. A helpful correlation for the measured densities of the stable nanofluids in a temperature range of 25–40 °C is presented which can used in practical applications. Finally based on the correlation a sensitivity analysis has been done. It is found that at higher temperatures the density is more sensitive to the increases in volume fraction. 相似文献