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The aim of this article was to examine the effect of hybrid nano - coating that could potentially impact the enhancement of heat transfer coefficient of distilled water, Reynolds number, and temperature through a swirl heat exchanger, as well as the indicator of the effect Zeta voltage in the coating process. In this experimental work, type of coating used was Aluminum (Al) + Aluminum oxide Al2O3. Outcomes of study showed that the coating of heat exchanger is much better than without coating in improving the thermal properties for liquids passing through heat exchanger as well as increasing the heat exchange through the surface of the exchanger. Results in the article indicated that the use of hybrid nano - structure coating is for inducing the feature of super - hydrophobicity for the surface that touches the fluid included within the heating transferring. Such feature can make an increase in the heating transferring factor and a decreasing in power losing produced via friction. This article indicated that the Zeta voltage analysis is to show the stability of the hybrid nanofluids used in the coating process. The enhanced technology depends upon the concept that exists in nature under the name "Lotus effect" to get super-hydrophobic surfaces. The rate of improvement in heat transfer using hybrid nanoparticles is 33% compared to that without coating condition. [ABSTRACT FROM AUTHOR]

This paper presents an experimental analysis on the heat transfer and pressure drop enhancement of oil nanofluid flow. In this analysis, the first method has used the helically coiled tube and shell, the oil nanofluids were employed instead of the base fluid (oil) in the second process. the two techniques were used to improve the heat transfer and pressure drop. Nanofluid oil concentrations utilized within range from 1 to 5 percent vol. This paper applied two forms of nanoparticles: copper (Cu (20 nm)) and zirconium oxide (ZrO2 (40 nm)) and base fluid (oil). The influence on the heat transfer coefficient for different factors such as the flow number of Reynolds, the temperature of the nanofluid oil, the concentration and shape of the nanoparticle, and the pressure gradient of the flow have examined. The results indicated that the value of a 40.35 percent in the heat transfer coefficient for Cu + oil and 28.42 percent for ZrO2 + oil increased compared with the base fluid (oil) at 5 percent vol concentration. Using oil nanofluids (Cu, ZrO2 - oil) instead of the base fluid (oil) led to increasing in the heat transfer coefficient and decreasing the pressure. In addition, the result showed that the heat transfer efficiency has enhanced using the helically coiled tube and shell, as well as increasing in the pressure drop was due to the curvature of the tube. Baes on the relationship between viscosity and shear intensity, the oil nanofluid behaviors were similar to the standard Newtonian fluids. Moreover, the related flow and heat transfer methods are used to present the output index. The exergy inflow, exergy destruction and exergy efficiency of oil nanofluid (Cu +oil) were greater than the oil nanofluid (ZrO2 +oil) and oil. The exergy inflow, exergy destruction, and exergy efficiency for the two type of oil nanofluid increased with increasing of nanoparticles concentration. [ABSTRACT FROM AUTHOR]

Low toxicity, high biodegradability, renewability and high viscosity index of the plant (vegetable) oils made it have immense potential to replace the mineral cooling fluids. This study aims to evaluate the wear and friction behaviour characteristics of the corn fluid as a renewable bio-fluid resource. Base on the ASTM G-99 standard, behaviour characteristics of fluid were examined in terms of kinematic viscosity, friction force, coefficient of friction, wear scar diameter, and flash temperature parameter. Each experiment was do during one hour and 800 rpm as a rotation speed of disk and under four different loads 5,10,15,20 kg using the ball on disk tester, the (Mobil hydraulic fluid 424) used as a mineral cooling hydraulic fluid sample for compared the results. Based on the results, it was found that under low loads (5 and 10kg) the performance of vegetable fluid (corn) is better than the mineral hydraulic fluid (463.38 & 469.84 µm under 5kg and 567.1&593.74 µm under 10 kg respectively), also the values of friction coefficient of vegetable fluids were lower under high load as in the case of normal load 20 kg., which was 0.0159 for the corn and 0.0230 for the mineral fluid. Finally, it is concluded that the corn fluid could be an alternative renewable working cooling fluid due to its adequate performance. [ABSTRACT FROM AUTHOR]

A numerical simulation is a method carried out to study the flow characteristics of compressible fluid through different channels. Two approaches using air as a working substance were used to study the flow characteristics. In the first approach, two inlets and one outlet horizontally in the x direction was depended on to generate different flow characteristics; the flow properties were calculated along the diagonal line inside the channel. In the second approach, one inlet and outlet horizontally with sudden change in the area of the channel was employed. In this research, the flow properties were calculated along the center line inside the channel and the flow fields have been investigated. A non-linear k - Є model is employed to solve the flow characteristics by using the finite difference method with a curvilinear coordinate system near the dead zone and the k - Є and Reynolds stress model area semi-empirical model based on modeling of the equations of transport that contain the dissipation rate (ε) as well as turbulent kinetic energy (k). The derivation of turbulent kinetic energy and its rate of dissipation derived from the Navier–Stokes equation. In this work, the simulation outcomes of the proposed k - ε turbulence model indicated a good compatibility with published correlations. In order to get an accurate solution, the value of 10–8 for the maximal normalized equation residual was considered to be the convergence between computation and steady solution. The model applied for flow velocity 30 m/s and the obtained results presented as curves, surface and contours for velocities turbulent kinetic energy, rate of dissipation of turbulent kinetic energy and vortices. The builder model can be utilized for academic purposes since it is widely used for many physical and engineering applications. [ABSTRACT FROM AUTHOR]

Latent heat of the fusion for the Phase changeable materials (PCM) can be utilized as heat energy store, and this energy can be employed in different applications. In present experimental work, effect of using the embedded longitudinal fins within the paraffin wax, on the energy and exergy performance for the solar air collector was investigated under the Baghdad governorate climate. Compared with the collector without paraffin wax, the results indicated that using of paraffin wax as a thermal storage material reduces the losses of energy and exergy of the collector, high levels of heat reduction by using PCM/Fins were about 33 and 40% respectively at the peak heat charging time (12:30 PM), while the decreasing in energy and exergy losses of the collector with PCM only was about 24 and 30% respectively at the same time of charging (12:30 PM). Due to the going of sum heat to store in the paraffin wax at the charging heat time, the energy along with exergy heat gains, while efficiencies were decreased with and without fins, this decreasing in the heat was the most by using PCM/Fins and it was around 30 and 44%, respectively for energy and exergy efficiencies, while it was about 20 and 31% by using PCM only at the same time of testing. The benefit of using embedded longitudinal fins in PCM is to enhance the thermal storage efficiency by about 6% compared with the solar collector that uses PCM only. [ABSTRACT FROM AUTHOR]

Plant (vegetable) oil has been evaluated as a substitute for mineral oil-based lubricants because of its natural and environmentally friendly characteristics. Availability of vegetable oil makes it a renewable source of bio-oils. Additionally, vegetable oil-based lubricants have shown potential for reducing hydrocarbon and carbon dioxide (CO2) emissions when utilized in internal combustion (IC) engines and industrial operations. In this study, sunflower oil was investigated to study its lubricant characteristics under different loads using the four-ball tribometer and the exhaust emissions were tested using a four-stroke, single-cylinder diesel engine. All experimental works conformed to American Society for Testing and Materials standard (ASTM D4172-B). Under low loads, sunflower oil showed adequate tribological characteristics (antifriction and antiwear) compared with petroleum oil samples. The results also demonstrated that the sunflower oil-based lubricant was more effective in reducing the emission levels of carbon monoxide (CO), CO2, and hydrocarbons under different test conditions. Therefore, sunflower oil has the potential to be used as lubricant of mating components. Implications: An experimental investigation of the characteristics of nonedible sunflower oil tribological behaviors and potential as a renewable source for biofluids alternative to the petroleum oils was carried out. The level of emissions of a four-stroke, single-cylinder diesel engine using sunflower oil as a biolubricant was evaluated. [ABSTRACT FROM AUTHOR]