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Test Fluids (test + fluid)
Selected AbstractsInitial exploration of tribological performance of novel triazine derivatives in waterLUBRICATION SCIENCE, Issue 4 2009Liping Sheng Abstract Two novel ashless and non-phosphorus triazine derivatives, 2,4,6-tri-[N-hydroxyethyl-amino-methylenesulfanyl]-s-triazine and 2,4,6-tri-[N,N-bishydroxyethyl-amino-methylenesulfanyl]-s-triazine, were synthesised and their structures were analysed through elemental analysis. Their tribological behaviours in water were evaluated with a four-ball machine, and the results indicate that their wear resistance and load-carrying properties were excellent. The chemical features of the worn steel surface were observed and examined by means of inverted metallurgical microscopy and energy dispersive X-ray spectroscopy. The analytical results of typical elements on the worn steel surface demonstrated, during the lubricating process, that the additives reacted with counter-face metal and generated a boundary lubricating and protecting film containing elements of S, N and others, which contributes to improve the tribological properties of the test fluid. Copyright © 2009 John Wiley & Sons, Ltd. [source] A Passive Magnetically and Hydrodynamically Suspended Rotary Blood PumpARTIFICIAL ORGANS, Issue 3 2009Martin Stoiber Abstract A combined hydrodynamic,magnetic bearing allows the design of rotary blood pumps that are not encumbered with mechanical bearings and magnets requiring sensors or electrical power. However, such pumps have so far needed very small and accurately manufactured gaps between rotor and housing to assure effective hydromagnetic bearing behavior. In order to use this concept in disposable pump heads, a design that allows larger rotor-housing gaps, and thus larger manufacturing tolerances, is needed. A pump with passive magnetic bearings and a gap between rotor and housing in the range of 0.5 mm was designed. Numerical simulations were performed to optimize the rotor geometry at low levels of shear stress. An experimental test stand was used to find a range of speeds and gap settings that resulted in low levels of vibration and useful pressure,flow relationships. Three different rotor geometries were tested using a viscosity-adjusted test fluid. Blood damage tests were conducted within the desirable range of speeds and gap settings. In this study stable pump performance was demonstrated at total gap widths between 0.3 and 0.7 mm at flows of 0,10 L/min, with afterloads up to 230 mm Hg. Best performance was achieved with rotors sliding on a fluid pillow between the rotor and the outer housing at a gap distance of 50 to 250 µm. The inner gap distance, between the rotor and the inner housing, could be as great as 500 µm. Hemolysis tests on the prototype within the chosen operating range showed lower values (NIH = 0.0029 ± 0.0012 g/100 L) than the Biomedicus BP-80 pump (NIH = 0.0033 ± 0.0011 g/100 L). In conclusion, it is possible to build rotary blood pumps with passive hydromagnetic bearings that have large gaps between their rotors and housings. Rotor behavior is sensitive to the position of the permanent magnetic drive unit. To minimize vibration and blood damage, the fluid gaps and the rotational speed have to be adjusted according to the desired operating point of the pump. Further study is needed to optimize the magnetic drive unit and to ascertain its ability to withstand inertial loads imposed by sudden movements and external shock. [source] Vapor Condensation Heat Transfer in a Thermoplate Heat ExchangerCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 7 2007J. Mitrovic Abstract The heat transfer and pressure drop in a thermoplate heat exchanger operating as a condenser have been investigated experimentally. In order to separate the heat transfer resistances in the condensation process, the single phase forced convection has been studied using distilled water and Marlotherm oil in the thermoplate and correlations developed for the Nusselt number and the friction factor. For the condensation experiments, an apparatus has been constructed comprising two identical condensers composed of the same thermoplate type as employed in the single phase experiments. Isopropanol is used as a test fluid at pressures below atmospheric pressure. The heat transfer resistances in the condensation experiments are separated and expressions for the condensation heat transfer and pressure drop are developed with the aid of the results obtained in the single phase studies. [source] JOURNAL of FOOD PROCESSING and PRESERVATION SEP 2000 Vol-24.4. DEVELOPMENT of A PROCESS FOR DETECTING NONTHERMAL EFFECTS of MICROWAVE ENERGY ON MICROORGANISMS AT LOW TEMPERATURE,JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 4 2000MICHAEL KOZEMPEL We developed an experimental process capable of isolating thermal and nonthermal effects of microwave energy relative to the destruction of microorganisms at low temperature. the concept combines instantaneous energy input to the food system by microwaves with rapid removal of thermal energy. the process used a double tube heat exchanger inside a continuous microwave dryer. the outer tube was transparent to microwaves, whereas the inner tube was stainless steel and was used for cooling the system. the microwave energy, 5,6 kW power, was absorbed by the process fluid in the annulus. the cooling water flowing in the inner tube removed the thermal energy from the process fluid to control temperature at or below 45C. the process was at turbulent flow to assure a uniform temperature and dwell time. There were no detected nonthermal effects from microwave energy for yeast, Pediococcus sp., Escherichia coli, Listeria innocua, or Enterobacter aerogenes in various test fluids, such as water, liquid egg, beer, apple juice, apple cider, and tomato juice. [source] The effects of polymer additives on the operating windows of slot coatingPOLYMER ENGINEERING & SCIENCE, Issue 10 2004C. K. Yang An experimental study was carried out to investigate the effects of polymer additives on the operating windows of slot coating. Two polymer additives,carboxylmethylcellolose (CMC) and polyacrylamide (PAA),were added to Newtonian glycerin solutions as test fluids. The flow experiment was performed on a lab coater. A flow visualization technique was employed to observe the shapes of coating beads. It was found that three types of defects appear at the lower bound of the operating window, i.e., ribbing, air entrainment, and break lines coupled with dripping. Adding a small amount of polymer additives has little effect on the operating window if the defect is ribbing, but it will expand the air entrainment region. The coating speed can be increased significantly if the defect is break lines coupled with dripping. Polym. Eng. Sci. 44:1970,1976, 2004. © 2004 Society of Plastics Engineers. [source] Spray Characteristics of Two-phase Feed NozzlesTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2003Siva Ariyapadi Abstract The present study focuses on understanding the spray characteristics of a turbulent gas-liquid jet (Reliq = 24,000). Air and water are used as the test fluids. The angles of injection of the two phases upstream of the nozzle are varied (, = 20°, 45° and 90°) and the effect of carrier gas on the droplet characteristics is are also investigated. The droplet size and velocity are non-intrusively measured using a Phase-Doppler Particle Analyzer (PDPA). In some respects, the characteristics of the present two-phase jet are similar to those noticed in previous studies, while revealing some important differences. The centreline mean droplet velocities (15 , 20 m/s) increase in the initial region of the jet, attain a maximum and then decrease at larger distances from the nozzle exit. Most of the entrainment occurs at the tip of the nozzle and the jet expansion rate decreases significantly at distances where the spray velocity profiles become self-similar. A Lorentz-type fit has been used to model the normalized radial velocity profiles. The results indicate that the test configuration with , = 45° may be beneficial for the scenario discussed. La présente étude vise à comprendre les caractéristiques d'une atomisation produite par un orifice d'alimentation biphasique. L'air et l'eau constituent les fluidesd'essai. Le mode d'injection des deux phases et l'effet du gaz porteur sur les caractéristiques de l'atomisation sont étudiés. La taille et la vitesse des gouttelettes sont mesurées de façon non intrusive à l'aide d'un analyseur de particules phases-doppler (PDPA). À certains égards, les caractéristiques du présent jet chargé en gouttelettes sont similaires à celles notées dans des études antérieures, tout en révélant quelques différences importantes. Les vitesses de gouttelettes moyennes le long de l'axe central augmentent dans la région initiale du jet, atteignent un maximum puis diminuent à des distances plus éloignées de la sortie de l'orifice. La majeure partie de l'entraînement survient à l'extrémité de l'orifice et la vitesse d'expansion du jet diminue de manière significative à des distances où les profils de vitesse de jet deviennent auto-semblables. On présente un modèle empirique simple pour représenter les profils de vitesse normalisés. [source] Slot die coating of dilute suspensionsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2009Yi-Tsun Lin Abstract An experimental study was carried out to investigate slot die coating of dilute suspensions. Polymethyl methacrylate (PMMA) particles of different sizes were added to glycerol solutions as test fluids. The coating flow experiment was performed on a lab coater. The operating window, which is a domain in which only a stable and uniform coating solution is possible, was determined experimentally. It was found that adding particles has little effect on the physical properties of glycerol solutions, as only the fluid viscosity increases slightly. Two coating defects are commonly observed; ribbing which is caused by flow instability refers to lateral waves on the coated surface, and air entrainment which implies that air bubbles are trapped in the coating solution. Adding particles has little effect on the operating window if the coating defect is ribbing. However, the operating window can be expanded substantially if the coating defect is air entrainment. Higher the particle concentration, or the smaller the particle size, more significant is the expansion of the operating window. The maximum coating speed may increase to 80% for high suspension particle density number. A previous study reported that there exists an optimal particle size which has the largest operating window for a given pure solution; this was not found in the present work. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | ||||||||||