Explore the vast range of titles available.

A very important method of reducing carbon emissions is to make sure industrial plants are operated at optimal energy efficiency. The oil and petrochemical industries spend large amounts of energy in the transportation of petroleum and its various products that have high viscosities. A critical component in these plants is abrupt pipe contraction. Large amounts of energy are lost in pipe contractions. In this paper we investigate the energy losses in pipe contraction using the local entropy generation method after solving the detailed flow field around an abrupt pipe contraction. We have applied the method at various Reynolds numbers covering laminar and turbulent flow regimes. Furthermore, we have used an integral entropy analysis and found excellent agreement between the differential and integral entropy methods when the computational grid is well refined. The differential analysis was able to predict the local entropy generation and find where the large losses are located and therefore be able to minimize these losses effectively. Based on the detailed entropy generation field, it is recommended to use rounded contraction in order to reduce the losses. By introducing rounded contractions in laminar flow, the losses have been reduced by 22%. In the case of the turbulent flow regime, the losses were reduced by 96% by introducing a rounding radius to diameter ratio r/D2 of 10%. The turbulent flow results for the case of pipe entrance, which is a special case of abrupt contraction (D2/D1 goes to zero) agree very well with the present results. This work addresses a large range of D2/D1 for laminar and turbulent flows. It is recommended that companies involved in designing petrochemical plants and installations take these findings into consideration to reduce carbon emissions. These recommendations also extend to the design of equipment and piping systems for the food industry and micro-device flows.

The oil and gas industry is increasingly challenged by the global transition toward renewable energy systems aimed at reducing carbon emissions. Nevertheless, opportunities remain to mitigate the environmental impacts associated with ongoing oil and gas operations. One of the major environmental challenges in this sector is the extensive use and treatment of water. Membrane-based separation has emerged as an effective technology for oil–water separation due to its ability to overcome limitations associated with conventional treatment methods. This study aims to build a CFD model to investigates the influence of operational hydrodynamic conditions on membrane separation, including transmembrane pressure 202, 101, 50, 10 kPa, crossflow velocity 0.08 m/s, 0.116 m/s, 0.33 m/s, 0.66 m/s, and oil droplet diameter 1, 5, 10, 50, 100 µm, on membrane performance in addition to different oil concentrations 1%, 2%, 4%, 8% using Eulerian-Eulerian multiphase model. This is done by experimentally extracting the membrane water resistance, which is found to be 6.46 × 1010 (1/m) and using it as an input to the numerical model. The results indicate that permeate flux is primarily governed by transmembrane pressure, in agreement with Darcy’s law, while fouling development along the membrane length is mainly influenced by crossflow velocity and oil droplet size. Where it was found that for large droplets 100 µm and 50 µm the buoyancy forces were large enough to lift the oil droplets away from the membrane at velocities 0.08, 0.16 and 0.33 m/s while smaller droplets remained at the membrane surface In addition, backward diffusion, which has been emphasized in previous studies, was found to play a comparatively minor role in the present numerical analysis.

The Oberbeck-Boussinesq (OB) approximation is widely employed as a simplifying assumption for density-dependent flow problems. It reduces the governing differential equations to simpler forms, which can be handled analytically or numerically. In this study, a modified OB model is formulated to account for the variation of rock permeability and porosity with temperature during the hot fluid injection process in an oil-saturated porous medium under the assumption of local thermal equilibrium (LTE). The mathematical model is solved numerically using a fully implicit control volume finite difference discretization with the successive over relaxation (SOR) method to handle the non-linearity. Subsequently, the numerical model is validated with the analytical solution of the simplified problem successfully. Through detailed sensitivity analyses, the simulation results reveal the hot fluid injection rate as the most important operational parameter to be optimized for a successful thermal flood. The numerical runs show that that for single-phase core-flood simulation, the effect of temperature on the rock absolute permeability and porosity can be neglected without introducing any significant errors in the estimated recovery and temperature profile.

Fouling build-up is one of the most challenging problems for heat exchangers in industry. The presence of fouling leads to a degradation of system efficiency, an increase in operating cost, and possibly, a harmful environmental impact. For this reason, fouling analysis has become an extremely important research subject in order to have a safe and efficient operation. The analysis is more difficult where phase change of fluids is involved during the heat transfer process, as in the case of boilers and condensers, which are critical units in industrial facilities. Due to the lack of a comprehensive review of fouling analysis for the case of multiphase heat exchangers, this paper examines available approaches and techniques used for fouling characterization, modeling, monitoring, and prediction in heat exchangers for both single-phase and multiphase heat exchangers with a focus on fouling in thermal desalination systems. It also gives an overview of heat exchanger condition monitoring solutions available in the market.

This study explores a solar-driven hybrid desalination approach developed for Saudi Arabian climatic conditions, combining adsorption desalination (AD) based on a silica gel/CaCl2 composite with an ejector (EJ) and a HDH system. The proposed integration aims to enhance vapor utilization and reuse condenser heat to generate additional distillate. Two operating modes are examined, including a productivity-focused strategy that activates evaporator/condenser heat recovery (HR) when cooling is not required. Compared to raw silica gel (SG), the composite adsorbent improves adsorption cycle performance, raising the COP from about 0.38–0.43 to 0.55–0.63, and increasing SCP from roughly 130–240 W/kg to 320–675 W/kg. Without HR, the full AD–EJ–HDH system achieves SDWP of 52–100 m3/ton·day with GOR of 2.40–2.75 over the year. In HR-enabled operation, SDWP increases to 81–140 m3/ton·day and GOR rises to 2.7–2.95, reflecting stronger internal heat reuse and improved vapor management. Techno-economic results show that the solar-driven unit cost for AD–EJ–HDH decreases from winter values (2.7–2.9$/m3) to a minimum around June (1.53 $ /m3), while waste heat operation reduces the cost further to 0.49$/m3 in June (rising to ~0.76–0.80 $ /m3 in winter). With HR, the full AD–HR–EJ–HDH reaches around 1.44$/m3 (solar, June) and 0.38–0.40 $ /m3 (waste heat, summer), confirming the advantage of desalination-focused HR operation when cooling is not required. Finally, compared with SWRO, the AD–HR–EJ–HDH configuration delivers an approximately 90% lower carbon footprint on the same environmental assessment basis. The study highlights the environmental benefit of the intensified SG/CaCl2 hybrid configuration.

Thermoacoustic refrigerators have huge potential to replace conventional refrigeration systems as an alternative clean refrigeration technology. These devices utilize conversion of acoustic power and heat energy to generate the desired cooling. The stack plays a pivotal role in the performance of Standing Wave Thermoacoustic Refrigerators (SWTARs), as the heat transfer takes place across it. Performance of stacks can be significantly improved by making an arrangement of different materials inside the stack, resulting in anisotropic thermal properties along the length. In the present numerical study, the effect of multi-layered stack on the refrigeration performance of a SWTAR has been evaluated in terms of temperature drop across the stack, acoustic power consumed and device Coefficient of Performance (COP). Two different aspects of multi-layered stack, namely, different material combinations and different lengths of stacked layers, have been investigated. The combinations of four stack materials and length ratios have been investigated. The numerical results showed that multi-layered stacks produce lower refrigeration temperatures, consume less energy and have higher COP value than their homogeneous counterparts. Among all the material combinations of multi-layered stack investigated, stacks composed of a material layer with low thermal conductivity at the ends, i.e., RVC, produced the best performance with an increase of 26.14% in temperature drop value, reduction in the acoustic power consumption by 4.55% and COP enhancement of 5.12%. The results also showed that, for a constant overall length, an increase in length of side stacked material layer results in an increase in values of both temperature drop and COP.

Erosion causes substantial damage in many industrial equipment such as pump components, valves, elbows, and plugged tees. In most cases, erosion is coupled with corrosion, resulting in major financial loss (nearly 3.4% of the global gross domestic product) as evidenced in oil and gas industries. In most cases, the erosion occurs in a submerged water medium. In this paper, erosion characteristics of stainless steel 316 were investigated computationally in a water-submerged jet impingement setup. The erosion profiles and patterns were obtained for various parameters over ranges of inlet velocities (3 to 16 m/s), nozzle diameters (5 to 10 mm), nozzle–target distances (5 to 20 mm), nozzle shapes (circular, elliptical, square, and rectangular), impingement angles (60° to 90°), and particle sizes (50 to 300 µm). The range of Reynolds number studied based on nozzle diameters is 21,000–120,000. The Eulerian–Lagrangian approach was used for flow field prediction and particle tracking considering one-way coupling for the particle–fluid interaction. The Finnie erosion model was implemented in ANSYS-Fluent 19.2 and used for erosion prediction. The computational model was validated against experimental data and the distributions of the erosion depth as well as the locations of the of maximum and minimum erosion points are well matched. As expected, the results indicate an increase in loss of material thickness with increasing jet velocity. Increasing the nozzle diameter caused a reduction in the maximum depth of eroded material due to decreasing the particle impact density. At a fixed fluid inlet velocity, the maximum thickness loss increases as the separation distance between the nozzle outlet and target increases, aspect ratio of nozzle shape decreases, and impingement angle increases. The erosion patterns showed that the region of substantial thickness loss increases as nozzle size/stand-off height increases and as particle size decreases. In addition, increasing the aspect ratio and impingement angle creates skewed erosion patterns.

Achieving sustainable cooling and freshwater requires high-performance, eco-friendly technology that produces both cooling and desalinated water. This study presents a novel utilization of promising composite adsorbent materials for a solar-powered adsorption cooling and desalination system. The proposed study utilizes silica gel-calcium chloride (SG/CaCl 2 ), as well as sodium polyacrylate-calcium chloride (SP/CaCl 2 ) and Maxsorb-calcium chloride (Max/CaCl 2 ) composites as potential adsorption materials. These adsorbents are employed in the adsorption cycle with and without evaporator-condenser heat recovery, in a four-bed-two-evaporator mode. The system is simulated and validated with previous experimental data. The findings indicate that the SP/CaCl 2 (with four beds and two evaporators mode) has the highest freshwater production, at 40.5 m 3 /ton.day, followed by Max/CaCl 2 at 38.6 m 3 /ton.day, and then SG/CaCl 2 at 36.4 m 3 /ton.day. The system also produces a cooling effect of about 773 W/kg per Max/CaCl 2 , followed by SG/CaCl 2 with 728 W/kg. The study expresses the freshwater cost, indicating the potential of utilizing the proposed configuration (4-beds-two evaporators mode) using these selected adsorbent materials for producing a sustainable cooling effect and freshwater. With waste heat, the levelized freshwater cost falls as low as $0.63 m −3 for SP/CaCl 2 and reaches $0.82 m −3 for SG/CaCl 2.

With recent advancements in the petroleum industry, the need for multiphase pumps to transport multiphase products, such as the product of oil, water, and natural gas, arises along with their challenges. A helico-axial multiphase pump should be capable of converting fluid kinetic energy into pressure by avoiding gas–liquid separation and the gas-locking phenomenon, enabling smooth pump operation at higher gas volume fractions. In this paper, erosion on a helico-axial pump is evaluated at different flow conditions using sand particles mixed with water. A very important practical finding of this investigation is that the erosion rate increased when the flow conditions deviated from the design point of 3600 RPM. Operating the pump in off-design conditions not only reduced its hydraulic efficiency but also increased the erosion rates and hence reduces its life. It was observed that at 4800 RPM, the pump efficiency decreased by 11% and the erosion rate increased by 80%. This increase in erosion rate was attributed to the formation of local vortices upstream of the blade leading edge affecting the particle flow path and increasing its impact on the blade surface.

Carbon capture is one of the recently raised technologies to mitigate greenhouse gas emissions. Adsorption was introduced as an energy-efficient carbon capture process, and the literature primarily shows the utilization of circular cross-sectional adsorption beds for this purpose. In this regard, this paper investigates different shapes of adsorbent beds to determine the thermal and adsorption uptake enhancements. Three geometries are considered: circular, square, and triangular cross-sectional beds. Mg-MOF-74 is used as an adsorbent, and numerical simulation is developed using a user-defined function coupled with ANSYS-Fluent. The results show that the triangular cross-sectional bed exhibits better adsorption capacity and thermal management compared to other beds. For example, the triangular cross-sectional bed shows 6 K less than the circular one during the adsorption process. It is recommended that the triangular cross-sectional bed be used for temperature swing adsorption when pumping power is not important. The square bed comes second after the triangular one with a lower pressure drop, suggesting such beds as good candidates for pressure swing adsorption. The square bed could be an excellent choice for compact beds when CO2 uptake and pumping power are both important.