Bekir Sami Yilbas

Bio: Bekir Sami Yilbas is an academic researcher from King Fahd University of Petroleum and Minerals. The author has contributed to research in topics: Laser & Heat transfer. The author has an hindex of 47, co-authored 860 publications receiving 12358 citations. Previous affiliations of Bekir Sami Yilbas include University of Birmingham & Hacettepe University.

A review on current status and challenges of inorganic phase change materials for thermal energy storage systems

Abstract: Latent heat energy storage system is one of the promising solutions for efficient way of storing excess thermal energy during low consumption periods. One of the challenges for latent heat storage systems is the proper selection of the phase change materials (PCMs) for the targeted applications. As compared to organic PCMs, inorganic PCMs have some drawbacks, such as corrosion potential and phase separation; however, there are available techniques to overcome or minimize these drawbacks. On the other hand, inorganic PCMs are found to have higher thermal conductivity and storage capacity over organic PCMs. As a result inorganic PCMs have a great potential in thermal energy storage field, especially in medium to high temperature applications where organic PCMs are not a viable option. In this study, a detailed review of research outcomes and recent technological advancements in the field of inorganic phase change materials is presented while focusing on providing solutions to the associated disadvantages of this class of PCMs. Long term stability, thermal cycling performance, and heat transfer enhancements are also discussed in the context of this review.

Heat transfer enhancement of phase change materials for thermal energy storage applications: A critical review

Abstract: This paper presents a state-of-the-art review on various techniques of heat transfer enhancement in latent heat thermal energy storage (LHTES) systems. Heat transfer enhancement in LHTES systems can be achieved through either geometric configuration and/or thermal conductivity enhancement. The use of extended surfaces such as fins or heat pipes is a common technique for heat transfer enhancement in LHTES systems and therefore, reviewed in details in this paper. Next, we studied the thermal conductivity enhancement techniques, which include the use of porous materials, nanoparticles with high thermal conductivity, and low-density materials. Finally, studies involving combined techniques for heat transfer enhancement are reviewed in the paper. The paper discusses research gaps in the methods of heat transfer enhancement for LHTES systems and proposed some recommendations.

Techno-economic analysis and optimization of solar and wind energy systems for power generation and hydrogen production in Saudi Arabia

Abstract: The objective of this study is to investigate the potentials of power generation and hydrogen production via solar and wind energy resources at different locations in the Kingdom of Saudi Arabia, namely; Dhahran, Riyadh, Jeddah, Abha and Yanbu. These locations represent the climatic conditions variety in the Kingdom with different solar radiation and wind speed potentials. At each location, different renewable off-grid power generation systems are considered to cover a load demand of a typical house incorporating; photovoltaic (PV) array, wind turbines, converter, batteries, electrolyzer, fuel cell (FC) and hydrogen tank. Six systems are considered in hourly base simulations; PV/battery bank, wind/battery bank, PV/wind/battery bank, PV/FC, wind/FC and PV/wind/FC. The simulations have been extended to cover two global locations, namely; Toronto (Canada) and Sydney (Australia). The simulations and the optimizations studies are carried out to identify the cost effective configurations. The results show that integration of 2 kW PV array, 3 wind turbines, 2 kW converter and 7 batteries storage bank is the best configuration that leads to the minimum levelized cost of energy (COE) of 0.609 $/kWh at Yanbu area. Replacing the battery bank by a combination of electrolyzer, fuel cell and hydrogen tank, storage system is possible; however, the cost increases due to the investment cost of the system components. Integrating PV/wind/FC in Abha area gives the minimum levelized cost of energy (COE) of 1.208 $/kWh and the cost of the hydrogen production (COH) is 43.1 $/kg.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Surface and Colloid Science

Abstract: 1: Magnetic Particles: Preparation, Properties and Applications: M. Ozaki. 2: Maghemite (gamma-Fe2O3): A Versatile Magnetic Colloidal Material C.J. Serna, M.P. Morales. 3: Dynamics of Adsorption and Oxidation of Organic Molecules on Illuminated Titanium Dioxide Particles Immersed in Water M.A. Blesa, R.J. Candal, S.A. Bilmes. 4: Colloidal Aggregation in Two-Dimensions A. Moncho-Jorda, F. Martinez-Lopez, M.A. Cabrerizo-Vilchez, R. Hidalgo Alvarez, M. Quesada-PMerez. 5: Kinetics of Particle and Protein Adsorption Z. Adamczyk.

Laser Material Processing

Abstract: In the laser treatment of a workpiece (9), e.g. for surface hardening, melting, alloying, cladding, welding or cutting, the adverse effect of reflectivity of the surface, when a pure, monochromatic laser (6) is used, is remedied by the simultaneous application of a relatively shorter wavelength beam (1). The two beams (1)(5) may be combined by a beam coupler (4) or may reach the workpiece (9) by separate optical paths (not shown). The shorter wavelength beam (1) improves the coupling efficiency of the higher- powered laser beam (5).

Nanoscale thermal transport. II. 2003–2012

Abstract: A diverse spectrum of technology drivers such as improved thermal barriers, higher efficiency thermoelectric energy conversion, phase-change memory, heat-assisted magnetic recording, thermal management of nanoscale electronics, and nanoparticles for thermal medical therapies are motivating studies of the applied physics of thermal transport at the nanoscale. This review emphasizes developments in experiment, theory, and computation in the past ten years and summarizes the present status of the field. Interfaces become increasingly important on small length scales. Research during the past decade has extended studies of interfaces between simple metals and inorganic crystals to interfaces with molecular materials and liquids with systematic control of interface chemistry and physics. At separations on the order of ∼1 nm, the science of radiative transport through nanoscale gaps overlaps with thermal conduction by the coupling of electronic and vibrational excitations across weakly bonded or rough interface...