The effects of using aqueous nanofluids containing covalently functionalized graphene nanoplatelets with triethanolamine (TEA-GNPs) as novel working fluids on the thermal performance of a flat-plate solar collector (FPSC) have been investigated. Water-based nanofluids with weight concentrations of 0.025%, 0.05%, 0.075%, and 0.1% of TEA-GNPs with specific surface areas of 300, 500, and 750 m2/g were prepared. An experimental setup was designed and built and a simulation program using MATLAB was developed. Experimental tests were performed using inlet fluid temperatures of 30, 40, and 50 °C; flow rates of 0.6, 1.0, and 1.4 kg/min; and heat flux intensities of 600, 800, and 1000 W/m2. The FPSC’s efficiency increased as the flow rate and heat flux intensity increased, and decreased as inlet fluid temperature increased. When using nanofluids in the FPSC, the measured temperatures of absorber plate and tube wall decreased down to 3.35% and 3.51%, respectively, with the increase in weight concentration and specific surface area, while the efficiency increased up to 10.53% for 0.1- wt% TEA-GNPs nanofluid with specific surface area of 750 m2/g, in comparison with water. When using water as heat transfer fluid, very good agreement was obtained between the experimental and predicted values of absorber plate temperature, tube wall temperature, and collector’s efficiency with maximum differences of 3.02%, 3.19%, and 3.26%, respectively. While, when using nanofluids, higher differences were found, up to 4.74%, 4.7%, and 13.47% for TEA-GNPs nanofluid with specific surface area of 750 m2/g, respectively. Accordingly, the MATLAB code was capable of simulating the thermal performance of FPSCs utilizing nanofluids as their heat transfer fluids with acceptable accuracy. Values of performance index were all greater than 1, and increased as weight concentration increased up to 1.104 for 0.1- wt% TEA-GNPs nanofluid with specific surface area of 750 m2/g, implying higher positive effects on efficiency than negative effects on pressure drop. Accordingly, the investigated nanofluids can efficiently be used in FPSCs for enhanced energy efficiency, and the 0.1- wt% water-based TEA-GNPs nanofluid with specific surface area of 750 m2/g was comparatively the superior one.
Exogenous levothyroxine dose modulation and euthyroidism achievement is a persistent challenge in clinical settings. This study strives to assess the adequacy of treatment and identify the patients’ factors that can be used to estimate the euthyroid levothyroxine dose. A secondary objective was to assess vitamin D supplementation impact on thyroid status.
A review of a prospectively collected information from 142 female patients from Baghdad Center of Nuclear Medicine from June 2019 until March 2020 who were receiving levothyroxine for different causes was done. After a follow-up period, the patients’ thyroid tests were assessed and the euthyroid doses for each cause category were statistically analyzed. Thyroid function was
... Show MoreABSTRACT Background: Color changes that are detectable to human eye can affect the esthetic appearance of ceramic veneers. The purpose of this study was to evaluate and compare the effect of artificial accelerated aging on the color of ceramic veneers cemented with different resin cements. Materials and Methods: Sixty discs were prepared with 0.5 mm thickness, 30 discs made from IPS e.max press (Ivoclar Vivadent) and 30 discs were made from VITA Enamic (VITA Zahnfabrik). The discs were cemented with three resin cements: Variolink Veneer MV 0 shade (Ivoclar Vivadent), Rely X veneer Translucent shade (3M ESPE) and NX3 Nexus Clear shade (Kerr Corporation) with 0.1 mm thickness. The spectrophotometer Easyshade Advance was used to measure the co
... Show MorePlant regeneration protocols were developed for medicinally important anise (Pimpinella anisum L.) that successfully achieved from seeds. Seeds were sterilized and inoculated on Murashige and Skoog (MS) medium with and without gibberellins (GA3) until full germination. The highest percentage of germination (100%) was recorded on MS medium treated with 2.0 mg/L GA3 after 7 days. For shoot proliferation, different concentrations of 6- benzyl adenine BA (1, 1.5, 2 mg/L) were used. To enhance shoot induction, 0.1 mg/L of naphthalene acetic acid (NAA) and 0.01 mg/L of thidiazuron (TDZ) were tested along with BA. Direct regenerated shoots were obtained on MS medium supplemented with BA alone (2mg/L) which gave (7shoot/explant), while the presence
... Show MoreEnhanced oil recovery is used in many mature oil reservoirs to increase the oil recovery factor. Surfactant flooding has recently gained interest again. To create micro emulsions at the interface between crude oil and water, surfactant flooding is the injection of surfactants (and co-surfactants) into the reservoir, thus achieving very low interfacial tension, which consequently assists mobilize the trapped oil.
In this study a flooding system, which has been manufactured and described at high pressure. The flooding processes included oil, water and surfactants. 15 core holders has been prepared at first stage of the experiment and filled with washed sand grains 80-500 mm and then packing the sand to obtain sand packs
... Show MoreTwelve samples of cigarettes have been collected from local markets of different types and origins by using (HPGe) detector, and measurement of the specific activity for series U238 and series Th232 in addition to K40 in order to estimate the health risk of cigarettes their by smokers, the results shown that highest specific activity value were be (12. 8±6. 3 Bq/kg, 8. 41±5. 8 Bq/kg, 125. 16±58. 3 Bq/kg), respectively, in the sample (MAC) MacBeth type cigarettes in Brazilian origin, this paper reports data such as (specific activity of K40, series U238, series Th232
For modeling a photovoltaic module, it is necessary to calculate the basic parameters which control the current-voltage characteristic curves, that is not provided by the manufacturer. Generally, for mono crystalline silicon module, the shunt resistance is generally high, and it is neglected in this model. In this study, three methods are presented for four parameters model. Explicit simplified method based on an analytical solution, slope method based on manufacturer data, and iterative method based on a numerical resolution. The results obtained for these methods were compared with experimental measured data. The iterative method was more accurate than the other two methods but more complexity. The average deviation of
... Show MoreThis study suggests using the recycled plastic waste to prepare the polymer matrix composite (PMCs) to use in different applications. Composite materials were prepared by mixing the polyester resin (UP) with plastic waste, two types of plastic waste were used in this work included polyethylene-terephthalate (PET) and Polyvinyl chloride (PVC) with varies weight fractions (0, 5, 10, 15, 20 and 25 %) added as a filler in flakes form. Charpy impact test was performed on the prepared samples to calculate the values of impact strength (I.S). Flexural and hardness tests were carried out to calculate the values of flexural strength and hardness. Acoustic insulation and optical microscope tests were carried out. In general, it is found that UP/PV
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