Showing papers by "Hussein A. Mohammed published in 2021"

Heat transfer augmentation of parabolic trough solar collector receiver's tube using hybrid nanofluids and conical turbulators

Abstract: Background Parabolic Trough Solar Collector (PTSC) is one of the most popular and an effective device that converts solar radiation into a heat or useful energy. However, it suffers from high temperature gradient and low thermal efficiency. The solution for this problem is to use new advanced coolants (hybrid nanofluids) in order to enhance PTSC's thermal efficiency. Methods A numerical analysis on the thermo-hydraulic performance of a PTSC receiver's tube equipped with conical turbulators is presented. The Navier-Stokes equations are solved using Finite Volume Method (FVM) coupled with Monte Carlo Ray Tracing (MCRT) method. The flow and thermal characteristics as well as entropy generation of the PTSC's receiver tube are investigated for three hybrid nanofluids (Ag-SWCNT, Ag-MWCNT, and Ag-MgO) having a mixing ratio of (50:50) dispersed in Syltherm oil 800, Reynolds number (5000 to 100,000) and fluid inlet temperatures (400 to 650 K). Significant findings The conical turbulators effectively augmented the thermal performance by 233.4% utilising Ag-SWCNT/Syltherm oil instead of pure Syltherm oil. The performance evaluation criterion is found to be in the range of 0.9–1.82. The thermal and exergetic efficiencies increased by 11.5% and 18.2%, respectively. The maximum decrement in the entropy generation rate and entropy generation ratio are 42.7% and 33.7%.

Experimental and Theoretical Analysis of Energy Efficiency in a Flat Plate Solar Collector Using Monolayer Graphene Nanofluids

Abstract: Flat-plate solar collectors are one of the cleanest and most efficient heating systems available. Studies on the presence of covalently functionalized graphene (Gr) suspended in distilled water as operating fluids inside an indoor flat-plate solar collector (FPSC) were experimentally and theoretically performed. These examinations were conducted under different testing conditions namely 0.025 wt.%, 0.05 wt.%, 0.075 wt.%, and 0.1 wt.%, 0.5, 1, and 1.5 kg/min, 30, 40, and 50 °C, and 500, 750, and 1000 W/m2. Various techniques were used to characterize the functionalized nanofluids’ stability and morphological properties namely UV/Vis spectrophotometry, EDX analysis with a Scanning Electron Microscope (SEM), zeta potential, and nanoparticle size. The results showed that the collected heat improved as the percentage of GrNPs and the fluid mass flow rates increased, although it decreased as the reduced temperature coefficient increased, whereas the maximum increase in collector efficiency at higher concentration was 13% and 12.5% compared with distilled water at 0.025 kg/s. Finally, a new correlation was developed for the base fluid and nanofluids’ thermal efficiency as a function of dropped temperature parameter and weight concentration with 2.758% and 4.232% maximum deviations.

MXene Based Palm Oil Methyl Ester as an Effective Heat Transfer Fluid

Abstract: In this research, MXene (Ti3C2) nanoflakes are implanted for the first time with Palm oil methyl ester (POME) to improve the nanofluids (POME/MXene) thermo-physical properties. The preparation, characterization, thermal and rheological properties was evaluated. POME/MXene nanofluid was induced with five different concentrations (0.01, 0.03, 0.05, 0.08, and 0.1 wt.%) of MXene to achieve the optimal properties that would be superior for a new heat transfer fluid. It is found that introducing more MXene nanoflakes into POME would expand the thermo-physical properties which will induce the rapid cooling of MXene based-nanofluids. Maximum enhancement of thermal conductivity for a MXene concentration and temperature of 0.1 wt.% and 65 oC respectively was measured to be ~ 176 % compared to the base fluid. Increasing amount of MXene did not effect the viscosity of the nanofluid. These results enable it to be utilized as a promising heat transfer fluid.

Graphene Nanoplatelets Suspended in Different Basefluids Based Solar Collector: An Experimental and Analytical Study

Abstract: A flat plate solar collector (FPSC) was analytically studied, with functionalized graphene nanoplatelets (f-GNPs) as its working fluid Four samples (wt % nanofluids) were prepared in different base fluids such as ethylene glycol (EG), distilled water (DW):EG (70:30), and DW:EG (50:50) Experimental results (via DW) were used to verify the effectiveness of the analytical model Some of the operating conditions were taken into account in this research, including temperatures, power, and mass flow rates Experimental techniques were used to elucidate the modified nanofluids’ physicochemical properties, such as its particle sizes, stability, and morphology, involving electron microscopes (EMs), UV–VIS, and X-ray techniques Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were applied to test the thermal analysis The findings confirmed that the use of f-GNPs nanofluids enhanced the performance of the FPSC relative to the use of base fluids for all testing conditions The maximum enhancement of the collector’s effectiveness at a mass flow rate of 15 kg min−1 and a weight concentration of 01 wt %, increased to 1269%, 1260%, and 1262% in the case of EG, DW:EG (70:30), and DW:EG (50:50), respectively The results also confirmed an improvement in both the heat gain (FR(τα)) and heat loss (FRUL) coefficients for the f-GNPs nanofluid