Experimental and numerical studies have been conducted for the effect of injected air bubbles on the heat transfer coefficient through the water flow in a vertical pipe under the influence of uniform heat flux. The investigated parameters were water flow rate of (10, 14 and 18) lit/min, air flow rate of (1.5, 3 and 4) lit/min for subjected heat fluxes of (27264, 36316 and 45398) W/m2. The energy, momentum and continuity equations were solved numerically to describe the motion of flow. Turbulence models k-ε was implemented. The mathematical model is using a CFD code Fluent (Ansys15). The water was used as continuous phase while the air was represented as dispersed. phase. The experimental work includes design, build and instrument a test rig for that purpose. A
circular vertical copper pipe test section of (length=0.7m, diameter= 0.05m, thickness= 1.5mm) is . designed and constructed, heated by an electrical heater fixed on its outer surface. Water . temperature at inlet is kept constant at (32°C). Water inlet and outlet temperatures, as well as radial temperature distribution within the pipe at seven sections along it between pipe surface and its center are measured. The results revealed that the secondary flow created by air bubbles have
significant effects on heat transfer enhancement and temperature profile. It is observed, that averaged Nusselt number enhancement for low heat flux of 27264 W/m2 and 4 lit/min air bubbles was 33.3 % and 23% in numerical and experimental, respectively.
the current study Included, evaluation the impact of Nitrofurantoin drug on liver in albino mice, 128 male albino mice have been used . Animals treared with (150,200 Mg/Kg) for 8 weeks . NFI caused histological changes in liver represented by , swelling of hepatocytes, disappearance of radial arrangement , vaculation of liver cells , increasing of kupffer cells and appearance of giant cells. NFT caused Congestion of blood vessels and infiltration of inflammatory cells in liver in all used concentrations.
This research is Interested in how the performance and implementation of factory production engine coolants of the General Company for Electrical Industries of its work, and to facilitate the flow of the decisions of senior management and access to all configurations, to ensure differentiation desired and reduce lost sales, resulting from poor scheduling of operations through the application of certain rules of scheduling operations in the production plant Engines Air-cooler, the objectives of research in identifying the best base and working to reduce the time and cost of Same Rules of Process which are considered the most influential of any organization and thr
... Show MoreIt is believed that culture plays an important role in the ELF classroom activities (Al- Mutawa, & Kilani, 1989:87). It is important for the teacher to recognize potential negative (culturally based) perceptions of their learners. In Iraq, for instance, it is not. Uncommon to meet silent expressionless students that arc supposedly English language learners. It is possible for the beginner to interpret this negatively as a lack of interest in the study of English. This interpretation may play a harmful role in the classroom methodology. An instructor has to be intercultural competent to be an effective teacher. It will be more effective if the instructor adopts a consistent style of instruction to allow learners to adapt within the bounds of
... Show MoreThis work was conducted to study the oxidation of phenol in aqueous solution using copper based catalyst with zinc as promoter and different carrier, i.e. γ-Alumina and silica. These catalysts were prepared by impregnation method.
The effect of catalyst composition, pH (5.6-9), phenol to catalyst concentration ratio (2-0.5), air feed rate (30-50) ml/s, stirring speed (400-800) rpm, and temperature (80-100) °C were examined in order to find the best conditions for phenol conversion.
The best operating conditions which lead to maximum phenol conversion (73.1%) are : 7.5 pH, 4/6 phenol to catalyst concentration, 40 ml/s air feed rate, 600 rpm stirring speed, and 100 °C reaction temperature. The reaction involved an induction period
The crude aqueous extract of menthespicata , the objective of this study was to investigate the effects of this extraction , on the histological changes of the ovares and levels of sex hormone , ( FSH , LH , Estradiol ) in albino female mice . the extract was given orally for( 45 ) days . fourty mature female mice were used in this study , the animals divided into four major groups . each group was include ten mice . the first three groups was given different concentration )) (21 , 14 , 7 %) . While the fourth group considered as control group which had been administrated tab water . For ( 45 ) days each group had been killed for hormonal assay in blood
... Show MoreThe aim of the present work is to develop a new class of natural fillers based polymer composites with sawdust (S.D) which used two particle sizes (1.2 μm & 2.3 μm) and different weight percentage from sawdust (10%, 15%, and 20%). The mechanical properties studied include hardness (shore D) for all samples at normal conditions (N.C). The unsaturated polyester (UPE) and its composites samples were immersed in water for 30 days to find the effect of particle size of sawdust (S.D) on the weight gain (Mt %) by water for all the samples, also to find the effect of water on their hardness. The results show that the composite materials of sawdust (S.D) fillers which has particle size (1.2 μm) better than (2.3 μm) particle size bef
... Show MoreThe ceramic composite with different proportions of clay and silica was prepared with a grain size of 70 μm and the weight percentage was selected for four groups (clayx silica100-x) were x q15, 25, 30 and 50. In this manuscript, for each pressured sample, a sintering procedure was carried out for 3 hours under static air and at various sintering temperatures (1000, 1100, 1200, 1400)°C. After sintering, the density, porosity, water absorption, compression strength and thermal conductivity were measured. The best results were obtained using a mixture of 15% clay and 85% silica which were sintering at 1400°C for three hours under air.
Titanium alloy surface properties have an essential role in the interaction of dental implants with bone, and alteration of the surface of the implant could improve osseointegration. This study was designed to investigate the effect of different heat treatment temperatures on titanium alloy surface properties for dental implants. The effect of different temperatures of heat treatment (750°C, 850°C, 950°C and 1050°C) were investigated on the surface topography, surface chemistry, titanium oxide layer thickness, blood contact angle, & blood drop diameter of titanium alloy. The disks were prepared from titanium alloy (Ti-6Al-4V) and the samples were divided into five groups depending on the different temperatures of heat treatment. The hea
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