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This paper presents a review of the design parameters, mathematical techniques and simulations used in the design of parabolic trough solar systems, along with a review on their applications. Recent studies that analyze the deployment of solar parabolic trough collectors (SPTC) in different countries and the operational SPTC plants are also presented and discussed. The paper also discusses the different kinds of software and test methods of solar collectors developed since 1981 which can be distinguished by their particular mathematical models or tracking techniques. In particular, since the mathematical models are especially required for the design, analysis, testing and validation of the systems results as they provide an approximation of the dynamic behavior of the physical properties of the system, they are discussed in depth. The mathematical models allow the calculation of different parameters of the solar parabolic trough system, the angle of inclination of the collecting surface and the forces acting on the system. The validity and experimental validation of the major mathematical models on practical solar parabolic trough concentrators, receivers and other components of different dimension are also reviewed. The paper showed the optical efficiency values are close to 63% and the theoretical peak optical efficiency reached 75%. [ABSTRACT FROM AUTHOR]

Polymer flooding in HPHT reservoirs using modified biopolymers and their composites acquire incremental attention nowadays. Some literature reported about limitations of native starch through enhanced oil recovery applications regarding bacterial degradation, thermal and ionic stability under severe reservoir environment. In the present study, functionalization of the starch biopolymer with thiol derivative then oxidation of thiol to sulfonic acid by environmentally friendly oxidants has been prepared and confirmed, after that starch derivative copolymerized with vinyl-containing monomers by free radical/redox emulsion polymerization in presence of silica seeds. Spectroscopic characterization and structure determination carried out by different spectroscopic techniques comprising FTIR, 1 H NMR, while particles size measured through DLS and TEM, and thermal analysis determined by TGA analysis. Evaluation of the prepared composite as a novel enhanced oil recovery (EOR) candidate as well as the precursors conducted at simulated reservoir condition, where the oil recovery factor and water cut percentage calculated relevant to injected pore volume. The flooding data indicate that the prepared starch functionalized sulfonic acid co-imidazolium/silica composite is favorable for enhanced oil recovery applications as it can withstand high temperature and salinity conditions and the recovery factor reaches 39% of residual oil saturation. [ABSTRACT FROM AUTHOR]

New promising samples of silver nanoparticles: (SNPs)-chitosan (CT) nanocomposite (NC) abbreviated as (SNPs-CTNC) have been synthesized and characterized using the novel green chemistry approach. All the synthesized formulations showed innovative corrosion inhibition for the mild steel samples in the cooling water system. The experimental conditions for the green synthesis of eco-friendly silver nanoparticles (SNPs) using chitosan (CT) biopolymer as both reducing and protecting coating agent for SNPs have been optimized. The synthesis route presented herein was performed by the reduction of silver nitrate (AgNO 3) by CT in an autoclave reactor vessel under 1 bar applied pressure at the reaction temperature of 120 °C and various contact time (2, 4, 8, and 16 h) between (AgNO 3) and chitosan (CT). The four prepared samples of SNPs-CT NC have been abbreviated in terms of the reaction or the contact time as (2 h, 4 h, 8 h, and 16 h). The four SNPs-CT NC samples were characterized using: UV–Visible spectroscopy; Fourier transform infrared (FTIR); X-ray diffraction (XRD) and transmission electron microscopy (TEM). The SNPs coated by chitosan biopolymer showed good antimicrobial activity, and have extremely fine particle size approaching that of the quantum dots nanoparticles. The particle size distribution of all the prepared nanocomposite samples lies around the nanometer scale range of 3–6 nm. The corrosion rate of the standard corrosion coupons of mild steel in the industrial chilled water in the absence and the presence of different concentrations of SNPs-CTNC samples were measured by the gravimetric method as well as the electrochemical impedance spectroscopy (EIS) and DC-potentiodynamic polarization techniques. The inhibition efficiency (%IE) of SNPs-CTNC achieved up to 97–98% at the concentration of 150 ppm SNPs-CTNC of all the prepared samples (from chemical gravimetric weight loss results). The inhibition efficiency (%IE) of the best performance SNPs-CTNC sample (8 h) showed inhibition efficiency above 80% at 100 ppm (as evident by the further electrochemical techniques: impedance and potentiodynamic polarization results). Both the inhibition efficiency and the antimicrobial activity of SNPs-CT NC samples remained unchanged on aging for twelve months storage where: The percent inhibition efficiency of all SNPs-CTNC samples remain above the percentage of 93% on aging for this relatively long storage time period, the sample 2 h showed the most constant inhibition efficiency (97.6% for the fresh prepared sample and 97.5% for the twelve months aged sample). In addition, the scanning electron (SEM) micrographs have been showed that: A clean and bright metal surface was maintained after the exposure to the chilled water in the presence of SNPs-CTNC along the immersion time of one year. The nanocomposite samples acted by spontaneous physisorption on the metal surface as indicated by the negative value of ΔG° adsorption (equals −18.002 kJ·mol−1). The adsorption data represented in the surface coverage (θ) were found to be linearly fitted well to Langmuir adsorption isotherm with positive and relatively large value of the binding equilibrium constant (K) (43.6) that represented the strong attraction forces between the adsorbed nanocomposite particles and the metal surface. The mode of the adsorption of these nanocomposite particles on the metal surface has been interpreted in terms of the electrostatic interaction between the negatively charged colloidal SNPs and the positively the charged metal surface. • Silver nanoparticles - Chitosan nanocomposite (AgNPs-CT-NC) • Cooling water system • Chilled water • Novelty • Inhibition efficiency [ABSTRACT FROM AUTHOR]

Abstract Nowadays, chemical and petroleum engineers give incremental attention to different techniques of chemical enhanced oil recovery (CEOR) owing to continual and scared energy consumption, and enormous trapped oil reserves after primary and secondary flooding. Hydrogels are three-dimensional crosslinked macromolecules which retain excessive water amounts. In this research, we investigate the synthesis and spectroscopic characterization of Lutensol AT 25 E -Methacrylate surfmer, then its copolymerization with acrylates monomers through free radical polymerization, which considered an effective tool to generate block copolymers with hydrophilic and hydrophobic moieties. Characterization and structure determination occurs by traditional spectroscopic techniques. Since mathematical formulation and prediction of hydrogel swelling ability has incremental consideration recently, so mathematical modeling of different rheological properties including swelling performance, post-degraded gel viscosity, gel strength, viscoelastic properties as well as shear thinning effects, salinity resistance, and long-term thermal aging was investigated at simulated harsh reservoir conditions. Modeling analysis showed that the Herschel-Bulkley model fits effectively the stress performance of the hydrogel suspensions, while the power law model fits the viscosity-shearing behavior. Dynamic properties examined by oscillatory tests indicating that hydrogel suspension exhibits viscoelastic performance since elastic modulus (G′) predominate viscous modulus (G″). On lab scale, sandpack flooding tests performed on a linear assembly at imitated reservoir environment, where the results indicate that the hydrogel able to reduce water permeability, adjust profile conformance, so increase incremental oil recovery up to 85.35% and alter rock wettability which assessed through relative permeability curves at different water saturation. On a field scale, a simulated run on actual reservoir data written by Fortran 90 visual studio carried out through UTCHEM software to evaluate hydrogel compatibility as an enhanced oil recovery candidate. Highlights • Preparation of surfmer-co-poly acrylates for profile conformance • Investigation and mathematical modeling of gel properties • Evaluation of rheological criteria at simulated reservoir conditions • Assessment of water shut-off and permeability reduction • Simulation through actual field data by applying UTCHEM simulator [ABSTRACT FROM AUTHOR]