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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]

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]