King Abdullah City for Atomic and Renewable Energy

Polymer nanocomposites have recently been introduced as lead-free shielding materials for use in medical and industrial applications. In this work, novel shielding materials were developed using low-density polyethylene (LDPE) mixed with four different filler materials. These four materials are cement, cement with iron oxide, cement with aluminum oxide, and cement with bismuth oxide. Different weight percentages were used including 5%, 15%, and 50% of the cement filler with LDPE. Furthermore, different weight percentages of different combinations of the filler materials were used including 2.5%, 7.5%, and 25% (i.e., cement and iron oxide, cement and aluminum oxide, cement and bismuth oxide) with LDPE. Bismuth oxide was a nanocomposite, and the remaining oxides were micro-composites. Characterization included structural properties, physical features, mechanical and thermal properties, and radiation shielding efficiency for the prepared composites. The results show that a clear improvement in the shielding efficiency was observed when the filler materials were added to the LDPE. The best result out of all these composites was obtained for the composites of bismuth oxide (25 wt.%) cement (25 wt.%) and LDPE (50 wt.%) which have the lowest measured mean free path (MFP) compared with pure LDPE. The comparison shows that the average MFP obtained from the experiments for all the eight energies used in this work was six times lower than the one for pure LDPE, reaching up to twelve times lower for 60 keV energy. The best result among all developed composites was observed for the ones with bismuth oxide at the highest weight percent 25%, which can block up to 78% of an X-ray.

The viscoelastic fluid flow over a non linear stretching porous sheet is considered in this analysis. The case of suction and injection is also discuused. The effects of thermophoresis and brownain motion with viscous dissipation is taken into account. Under the flow assumptions, boundary layer approximation applied on the mathematical model and developed the partial differential equations. The similarity variable is applied on the partial differential equations which converted into ordinary differential equations. The dimensionless system further solved through numerical technique bvp4c method. The results of the current problem achieved after solving the problem which presented through graphs and table. Influence of numerous physical parameters on velocity function, concentration function and temperature function are manipulated through graphs. The tabular results are schemed to display skin friction and local Nusselt number. The higher values of Nb which enhanced the velocity profile but declines velocity profile due to higher values of Ec. The thermal thickness enhances due larger values of γ and Pr but thermal thickness declines due to higher values of Ec and Nt. The concentration profile enhances due to enhancing the values of Ec and Pr but concentration profile declines due to increasing the values of Nt. Nusselt number enhaced due to higher values of Ec,Sc and Nt but declines of higher values of Pr.

The present study reveals the behavior of shear-thickening and shear-thinning fluids in magnetohydrodynamic flow comprising the significant impact of a hybrid nanofluid over a porous radially shrinking/stretching disc. The features of physical properties of water-based Ag/TiO2 hybrid nanofluid are examined. The leading flow problem is formulated initially in the requisite form of PDEs (partial differential equations) and then altered into a system of dimensionless ODEs (ordinary differential equations) by employing suitable variables. The renovated dimensionless ODEs are numerically resolved using the package of boundary value problem of fourth-order (bvp4c) available in the MATLAB software. The non-uniqueness of the results for the various pertaining parameters is discussed. There is a significant enhancement in the rate of heat transfer, approximately 13.2%, when the impact of suction governs about 10% in the boundary layer. Therefore, the heat transport rate and the thermal conductivity are greater for the new type of hybrid nanofluid compared with ordinary fluid. The bifurcation of the solutions takes place in the problem only for the shrinking case. Moreover, the sketches show that the nanoparticle volume fractions and the magnetic field delay the separation of the boundarylayer.

Graphene, a two-dimensional (2D) layered material has attracted much attention from the scientific community due to its exceptional electrical, thermal, mechanical, biological and optical properties. Hence, numerous applications utilizing graphene-based materials could be conceived in next-generation electronics, chemical and biological sensing, energy conversion and storage, and beyond. The interaction between graphene surfaces with other materials plays a vital role in influencing its properties than other bulk materials. In this review, we outline the recent progress in the production of graphene and related 2D materials, and their uses in energy conversion (solar cells, fuel cells), energy storage (batteries, supercapacitors) and biomedical applications.

In this paper, an artificial bee colony optimized self-tuning proportional integrator (PI) regulator is proposed for the finite control set model predictive current control (FCS-MPCC) of the permanent magnet synchronous machine (PMSM). In view of the MIT rule hypothesis, the self-tuning laws were defined. The optimized coefficients for the PI regulator were calculated using a custom defined objective function for artificial bee colony algorithm to manage external (load) and internal disturbances. The proposed self-tuning PI controller with optimized coefficients result in smaller steady state torque bias error with improved dynamic speed response especially during the speed reversal. Furthermore, the self-tuning laws are extremely basic and can be easily implemented. Numerical simulations were carried out to show the effectiveness of the proposed speed controller and comparison was drawn with the classical PI under the same test in the MATLAB/Simulink environment.

Abstract Thermal energy transfer in combined thin films consisting of silicon and diamond is considered. The combined films are thermally disturbed by a temperature oscillation at the silicon left edge and the influence of pulse length of temperature oscillation on energy transport characteristics is investigated. A nano-size gap with varying length is adopted at the films interface. The Boltzmann equation is adopted for the predictions of phonon intensity in the combined structure. The cut-off mismatch model is accommodated formulating interface conditions. The contribution of the near field radiation, due to evanescent waves, is also included at the interface. Equivalent equilibrium temperature is used quantifying phonon intensity distribution in the combined structure. It is found that the influence of the temperature oscillation on the phonon transport is significant at the silicon interface, i. e., increasing pulse length reduces phonon intensity at the silicon interface. Temporal behavior of equivalent equilibrium temperature is similar to the temperature oscillation introduced at the left edge of the silicon. The rise in temperature in the combined film is faster in the beginning of the heating cycle.

Abstract Currently, water desalination is an essential solution for the high demand for water worldwide. A sea water reverse osmosis (SWRO) facility fulfills the need for pure water. Conventionally, these plants use open-ocean water that is rich with natural organic matter (NOM) and transparent exo-polymers (TEP). Marine flora increases the demand for fouling the membrane in the SWRO facility that raises the pressure and results in the halting of the station. Therefore, water samples were collected from SWRO stages during high-pressure problems to probe the factors that play a key role in membrane biofouling. NOM and TEP particles physically disappeared after the dual-media filter (DMF). However, turbidity significantly increased after the DMF stage, which is indicative of the fragmentation of NOM and TEP particles. Chlorophyll and phycoerythrin disappeared after the DMF stage but were observed in the reject stage (brine). Therefore, NOM and TEP are playing a role indirectly in membrane biofouling. Fifteen potential species of heterotrophic prokaryotes are identified and recorded in all stages of the SWRO. The characteristics of these species imply that they form a cooperative consortium that potentially creates the biofilm in the RO membrane. Therefore, SWRO facilities that use open-ocean water must develop highly sophisticated pretreatment technology to eliminate the seeds of the biofilm that fouls RO membranes.

The collaboration between the Research Center for Renewable Energy Mapping and Assessment (ReCREMA) at Masdar Institute of Science and Technology and the King Abdullah City for Atomic & Renewable Energy (KACARE) aims to create an interactive web tool integrated in the Renewable Resource Atlas where different solar thermal electricity (STE) utility-scale technologies will be simulated. In this paper, a methodology is presented for sizing and performance simulation of the solar field of parabolic trough collector (PTC) plants. The model is used for a case study analysis of the potential of STE in three sites located in the central, western, and eastern parts of Saudi Arabia. The plant located in the north (Tayma) has the lowest number of collectors with the best production along the year.