排序方式: 共有109条查询结果,搜索用时 453 毫秒
61.
Amani Mohammad Amani Pouria Bahiraei Mehdi Wongwises Somchai 《Journal of Thermal Analysis and Calorimetry》2019,135(2):901-910
Journal of Thermal Analysis and Calorimetry - This paper assesses the contribution of TiO2 nanoparticles on thermal performance of a 0.5 mass% aqueous solution of carboxymethyl cellulose... 相似文献
62.
Surface of Ti-52 at% Al alloy was modified via current heating technique. The Ti-52 at% Al alloy with 20 mm diameter × 1.5 mm thick disks was placed in graphitic powder in a glass tube and pressed against it. During the coating process, the direct current was applied across the samples at electrical power of 100-200 W for 10 min. By using X-ray diffraction (XRD), TiC was detected on the alloy treated at 180 W and above. Scanning electron microscopy (SEM) micrographs show the different morphologies, after treatment under different conditions. Energy dispersive X-ray spectroscopy (EDS), SEM and hardness tester show that the carbon concentration, particle size, void size and the hardness of the alloy were increased with the increasing of the applying electrical power, due to the formation of the carbide on the alloy surface. 相似文献
63.
PbS was produced from different lead (Pb(CH3COO)2·H2O, PbCl2·2.5H2O, Pb(NO3)2) and sulfur (CH3CSNH2, CH5N3S, NH2CSNH2) sources in propylene glycol using a cyclic microwave radiation at different powers and prolonged times. PbS (cubic) was detected using X-ray diffraction (XRD) and selected area electron diffraction (SAED) techniques. The interpreted and simulated patterns are in good accord. Raman spectrometer revealed the presence of vibrations at 138, 273 and 439 cm−1. Different morphologies (nano-sized particles, hexapods, cubes, ferns and magic squares) were characterized using a scanning electron microscope (SEM) and a transmission electron microscope (TEM). The product morphologies were influenced by the starting agents, microwave powers and prolonged times. 相似文献
64.
Heat transfer and two-phase flow characteristics of refrigerants flowing under varied heat flux in a double-pipe evaporator 总被引:1,自引:0,他引:1
Wisis?Sripattrapan Tawatchai?Wongchang Somchai?WongwisesEmail author 《Heat and Mass Transfer》2004,40(8):653-664
A mathematical model based on the annular flow pattern is developed to simulate the evaporation of refrigerants flowing under varied heat flux in a double tube evaporator. The finite difference form of governing equations of this present model is derived from the conservation of mass, energy and momentum. The experimental set-up is designed and constructed to provide the experimental data for verifying the simulation results. The test section is a 2.5 m long counterflow double tube heat exchanger with a refrigerant flowing in the inner tube and heating water flowing in the annulus. The inner tube is made from smooth horizontal copper tubing of 9.53 mm outer diameter and 7.1 mm inner diameter. The agreement of the model with the experimental data is satisfactory. The present model can be used to investigate the axial distributions of the temperature, heat transfer coefficient and pressure drop of various refrigerants. Moreover, the evaporation rate or the other relevant parameters that is difficult to measure in the experiment are predicted and presented here. The results from the present mathematical model show that the saturation pressure and temperature of refrigerant decrease along the tube due to the tube wall friction and the flow acceleration of refrigerant. The liquid heat transfer coefficient increases with the axial length due to reducing the thickness of the liquid refrigerant film. Due to increase of the liquid heat transfer coefficient, increasing wall heat flux is obtained.Finally, the evaporation rate of refrigerant increases with increasing wall heat flux. 相似文献
65.
In this study, effect of electrohydrodynamic (EHD) on the condensation heat transfer enhancement and pressure drop of pure
R-134a are experimentally investigated. The test section is a 2.5 m long counterflow double tube heat exchanger with refrigerant
flowing in the inner tube and cooling water flowing in the annulus. The inner tube is made from smooth horizontal copper tubing
of 9.52 mm outer diameter. The electrode is made from stainless steel wire of 1.47 mm diameter. The test runs are performed
at average saturated temperatures ranging between 40 and 60°C, mass flux ranging between 200 and 600 kg/m2 s, heat flux ranging between 10 and 20 kW/m2 and applied voltage at 2.5 kV. For the presence of the electrode, the experimental results indicate that the maximum heat
transfer enhancement ratio is around 30% while the maximum increase in pressure drop is about 25%. 相似文献
66.
Hartwell SK Somprayoon D Kongtawelert P Ongchai S Arppornchayanon O Ganranoo L Lapanantnoppakhun S Grudpan K 《Analytica chimica acta》2007,600(1-2):188-193
Alkaline phosphatase (ALP) has been used as one of the biomarkers for bone resorption and liver diseases. Normally, total alkaline phosphatase is quantified along with other symptoms to determine the releasing source of the alkaline phosphatase. A semi-automated flow injection-bead injection system was proposed to conveniently and selectively assay bone alkaline phosphatase (BALP) based on its specific binding to wheat germ coated beads. Amount of BALP in serum was determined from the intensity of the yellow product produced from bound BALP on the retained beads and its substrate pNPP. The used beads were discarded and the fresh ones were introduced for the next analysis. The reaction cell was designed to be opened and closed using a computer controlled solenoid valve for a precise incubation time. The performance of the proposed system was evaluated by using it to assay BALP in human serum. The results were compared to those obtained by using a commercial ELISA kit. The system is proposed to be an easy and cost effective system for quantification of BALP as an alternative to batch wise wheat germ specific binding technique. 相似文献
67.
In the present study, the heat transfer characteristics in dry surface conditions of a new type of heat exchanger, namely
a helically coiled finned tube heat exchanger, is experimentally investigated. The test section, which is a helically coiled
fined tube heat exchanger, consists of a shell and a helical coil unit. The helical coil unit consists of four concentric
helically coiled tubes of different diameters. Each tube is constructed by bending straight copper tube into a helical coil.
Aluminium crimped spiral fins with thickness of 0.5 mm and outer diameter of 28.25 mm are placed around the tube. The edge
of fin at the inner diameter is corrugated. Ambient air is used as a working fluid in the shell side while hot water is used
for the tube-side. The test runs are done at air mass flow rates ranging between 0.04 and 0.13 kg/s. The water mass flow rates
are between 0.2 and 0.4 kg/s. The water temperatures are between 40 and 50°C. The effects of the inlet conditions of both
working fluids flowing through the heat exchanger on the heat transfer coefficients are discussed. The air-side heat transfer
coefficient presented in term of the Colburn J factor is proportional to inlet-water temperature and water mass flow rate.
The heat exchanger effectiveness tends to increase with increasing water mass flow rate and also slightly increases with increasing
inlet water temperature. 相似文献
68.
Giwa S. O. Sharifpur Mohsen Meyer Josua P. Wongwises Somchai Mahian Omid 《Journal of Thermal Analysis and Calorimetry》2021,143(2):1037-1050
Journal of Thermal Analysis and Calorimetry - The hybridization of nanoparticles is a concept employed for the improvement of the thermal properties of nanofluids. Presently, there is a scarcity of... 相似文献
69.
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
70.
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