Operation Improvement, Reliability and Performance Optimization With Analysis and Simulation

Comparison of Kalina cycles for heat recovery application in cement industry

Establishment of a Model for a Combined Heat and Power Plant with ThermosysPro Library

Magnetic resonance velocimetry (MRV) measurements are performed in a 1:1 scale model of a single-cylinder optical engine to investigate the volumetric flow within the intake and cylinder geometry during flow induction. The model is a steady flow water analogue of the optical IC-engine with a fixed valve lift of \(9.21\) mm to simulate the induction flow at crank-angle \(270^{\circ }\)bTDC. This setup resembles a steady flow engine test bench configuration. MRV measurements are validated with phase-averaged particle image velocimetry (PIV) measurements performed within the symmetry plane of the optical engine. Differences in experimental operating parameters between MRV and PIV measurements are well addressed. Comparison of MRV and PIV measurements is demonstrated using normalized mean velocity component profiles and showed excellent agreement in the upper portion of the cylinder chamber (i.e., \(y \ge -20\) mm). MRV measurements are further used to analyze the ensemble average volumetric flow within the 3D engine domain. Measurements are used to describe the 3D overflow and underflow behavior as the annular flow enters the cylinder chamber. Flow features such as the annular jet-like flows extending into the cylinder, their influence on large-scale in-cylinder flow motion, as well as flow recirculation zones are identified in 3D space. Inlet flow velocities are analyzed around the entire valve curtain perimeter to quantify percent mass flow rate entering the cylinder. Recirculation zones associated with the underflow are shown to reduce local mass flow rates up to 50 %. Recirculation zones are further analyzed in 3D space within the intake manifold and cylinder chamber. It is suggested that such recirculation zones can have large implications on cylinder charge filling and variations of the in-cylinder flow pattern. MRV is revealed to be an important diagnostic tool used to understand the volumetric induction flow within engine geometries and is potentially suited to evaluate flow changes due to intake geometry modifications.

Economic analysis of CO2 capture from natural gas combined cycles using Molten Carbonate Fuel Cells

In 2017, the MHI Vestas released a 9.5-MW offshore wind turbine. It is also actively researching and developing a 10-MW offshore wind turbine. As the capacity of a wind turbine increases, the sizes of all its system components, including length and weight, correspondingly increase. Consequently, as a wind turbine becomes larger, it becomes necessary to analyze the fatigue load applied to its entire system. The first reason for such an analysis is to achieve a safe but not overly designed large wind turbine. Second, most wind turbine accidents involve aging turbines and are related to fatigue analysis. Accordingly, the purpose of fatigue analysis is to safely design a wind turbine that sustains repeated loads within its design life. In this study, the blades and loads for the fatigue analysis of a 12-MW floating offshore wind turbine are calculated based on the National Renewable Energy Laboratory (NREL) 5-MW wind turbine blades. The calculated loads are applied to the Markov matrix through a preprocessing, such as the cycle counting method. Finally, the equivalent fatigue load is estimated based on both mean and range. In this study, only the equivalent fatigue load on the turbine blade is calculated. However, if fatigue analysis is to be performed for all parts using equivalent loads, it is possible to design the wind turbine to fully withstand such loads throughout its design life, and prevent the overdesign of each part as well.

This study evaluates the thermal structural safety of the three-way catalyst(TWC) substrate for domestic passenger cars. Thermal-fluid boundary conditions on the TWC substrate were determined by D-optimal DOE. The thermal stresses on the TWC substrate were calculated by the temperature distribution obtained from the CFD results. The safety factors of the TWC substrate were determined by statistical strength and stress distributions and estimated to be 0.275. The thermal stresses for TWC substrate exceeded the strength of the material. Therefore, it is necessary to redesign the TWC substrate because it has much shorter service life than design life.

Vector Projectile Imaging: Time-Resolved Dynamic Visualization of Complex Flow Patterns

This paper presents a comparative aerodynamic analysis of two vehicle models—a hatchback and a sedan—using computational fluid dynamics (CFD) simulations conducted with SimScale software. The primary objective is to evaluate the behavior of the external flow around the body, focusing on determining the drag (Cd) and lift (Cl) coefficients, as well as analyzing the flow patterns and recirculation zones. The vehicle geometries were generated using the artificial intelligence tool Tripo3D.AI, to investigate the feasibility of automated models for aerodynamic analysis. The study was conducted with the k – ω SST turbulence model, suitable for simulations in regions with flow separation and boundary layers. The mesh was composed of polyhedral elements with local refinements in regions of interest, automatically generated by SimScale. The boundary conditions included velocity inputs of 25 m/s, walls with no-slip and slip conditions, and a lower wall with movement equal to the flow velocity. The results indicated a drag coefficient (Cd) of 0.308 for the sedan model and 0.601 for the hatchback, representing an increase of approximately 95% in Cd for the hatchback compared to the sedan. Regarding the lift force, a value of -0.00014 was observed for the sedan and -1.97 for the hatchback, indicating a greater vertical aerodynamic effect in the hatchback. The simulations showed good numerical convergence, validating the adopted approach.

Heat transfer and fluid flow characteristics of a turbulent wall jet with a wavy wall

During the hydraulic performance experiment, significant vibration and noise were observed in the mixed-flow pump operating in the hump region. Cavitation occurrence in the impeller flow channels was confirmed through the transparent chamber. To analyze cavitation flow structure evolution in the mixed-flow pump, this paper integrates numerical and experimental approaches, capturing cavitation flow structures under the valley condition through high-speed photography technology. During the various stages of cavitation development, the cavitation forms are mostly vortex cavitation, cloud cavitation, and perpendicular vortex cavitation. Impeller rotation induces downstream transport of shedding cloud cavitation shedding structures. Flow blockage occurs when cavitation vortexes obstruct specific passages, accelerating cavitation growth that culminates in head reduction through energy dissipation mechanisms. Vortex evolution analysis revealed enhanced density of small-scale vortex structures with stronger localized core intensity in the impeller and diffuser. Despite larger individual vortex scales, reduced core intensity persists throughout the full flow domain. Concurrently, velocity profile characteristics across flow rates and blade sections (spanwise from tip to root) indicate heightened predisposition to flow separation, recirculation zones, and low-velocity regions during off-design operation. This study provides scientific guidance for enhancing anti-cavitation performance in the hump region.

Within the flight mission envelope, the wing receives different aerodynamic loads in each mission stage, which results in bending and torsion alternating stress, which is prone to deformation or fatigue damage, threatening flight safety. Therefore, it is necessary to predict the fatigue life of the wing structure and maintain it in time to avoid accidents. Fluent software is used to analyze the aerodynamic load state of the wing when the lift-to-drag ratio is the largest under the three conditions of the climb, level flight, and landing, as the loading load of the wing, analyze the stress and strain of the dangerous points at each stage based on the finite element analysis platform, and determine Multiaxial fatigue state. The Brown-Miller multiaxial fatigue analysis method based on the critical surface was adopted, and the fatigue life analysis was carried out using the Fe-safe software and the Abaqus software. The results show that the minimum lifespan first appears at the root of the wing. In the Fe-safe analysis, the design life of the given wing structure is 40000 cycles, and the minimum life of the wing structure is calculated to be 58420 cycles, longer than the design life, and the life safety factor is 1.078, basically in line with the actual situation.

Heavy water production in India has achieved many milestones in the past. Two of the successfully running heavy water plants are on the verge of completion of their design life in the near future. One of these two plants, situated at Kota, is a hydrogen sulfide based plant and the other one at Tuticorin is an ammonia-based plant. Various exercises have been planned with an aim to assess the fatigue usage for the various components of these plants in order to extend their life. Considering the process parameters and the past history of the plant performance, critical piping systems and equipment are identified. Analyses have been carried out for these critical piping systems for mainly two kinds of loading, viz. sustained loads and the expansion loads. Static analysis has been carried out to find the induced stress levels due to sustained as well as thermal expansion loading as per the design code ANSI B31.3. Due consideration has been given to the design corrosion allowance while evaluating the stresses due to sustained loads. At the locations where the induced stresses (SL) due to the sustained loads are exceeding the allowable limits (Sh), exercises have been carried out considering the reduced corrosion allowance value. This strategy is adopted in view of the fact that the thickness measurements carried out at site at various critical locations show a very low rate of corrosion. It has been possible to qualify the system with reduced corrosion allowance values however, it is recommended to keep that location under periodic monitoring. The strategy adopted for carrying out analysis for thermal expansion loading is to qualify the system as per the code allowable value (Sa). If the stresses are more than the allowable value, credit of liberal allowable value as suggested in the code i.e., with the addition of the term (Sh-SL) to the term 0.25 Sh, has been taken. However, if at any location, it is found that thermal stress is high, fatigue analysis has been carried out. This is done using the provisions of ASME Code Section VIII, Div. 2 by evaluating the cumulative fatigue usage factor. Results of these exercises reveal that the piping systems of both of these plants are in a very healthy state. Based on these exercises, it has been concluded that the life of the plants can be safely extended further with enhanced in-service inspection provisions.

Stent deployment to treat coronary artery disease causes damage and loss of endothelial cells (EC). Repair of injured arteries by EC migration is co-ordinated by Rho family GTPases. It is also regulated by wall shear stress (WSS), a mechanical force exerted by flowing blood on the vessel wall, via mechanisms that are poorly understood. It was hypothesised that stent struts may impede repair of injured endothelium by inducing localised disturbances in WSS. To simulate a stented artery in vitro, chamber slides were fabricated with ridges (100 μm high) positioned perpendicularly to the flow direction. Confluent EC monolayers seeded on one side of either ridged or non-ridged (control) chambers were exposed to flowing culture medium (Ibidi® system). Flow patterns were determined by computational fluid dynamic (CFD) modelling and particle velocimetry. Live cell imaging and analysis using ImageJ® software enabled quantification of EC migration velocity and directional persistence (DP). EC on the non-ridged chamber slide were exposed to a uniform WSS of 13 dyn/cm2 and migrated relatively uniformly in parallel with the flow direction (average velocity 1.13 μm/min; DP 0.59). By contrast, CFD and particle velocimetry revealed spatial WSS differences over the ridged chamber, with significant spikes above physiological levels (>70 dyn/cm2) at the corners of the ridges and distinctive flow recirculation zone immediately downstream from ridges (-4 dyn/cm2). While EC were able to migrate over the ridges, cells that reached the recirculation zone displayed non-uniform directionality (DP 0.25) and reduced velocity (0.78 μm/min). Inhibition of the RhoA signalling pathway with ROCK inhibitors promoted EC forward migration within the recirculation zone by elevating DP (0.41) and velocity (1.16 μm/min). It was concluded that disturbed WSS downstream from stent strut-like ridges prevented the forward migration of EC. Inhibition of the RhoA/ROCK signaling pathway promoted EC migration and re-population of these sites. Our data suggest that treatment using a ROCK inhibitor may promote re-endothelialisation of stented arteries.

Methodologies for Supporting Sustainability in Energy and Buildings. The Contribution of Project Economic Evaluation

An investigation of the effectiveness of online combustion turbine axial compressor washing using various purity grade waters and commercial washing detergents was performed. For this project, blade surface fouling dirt was obtained from gas turbine axial compressor blades installed at various field sites. The dirt was analyzed to determine consistency of typical blade surface fouling materials. A representative dirt formula and blade coating procedure was developed so that comparative tests could be performed using various cleaning fluids. Dirt coated blades were installed in a wind tunnel capable of simulating compressor operating conditions. A spray nozzle upstream of the blade test section was used for washing blades with five different test liquids to determine the effectiveness or advantages of any liquid. Once this testing was completed, a similar test setup was then utilized to inject a mixture of formulated fouling dirt and the various online cleaning liquids upstream of the blade into the wind tunnel to assess redeposit characteristics. The effect of high-purity water versus regular water on fouling dirt was also studied in separate residue experiments. Results indicate that spraying cleaning fluid into a flowing air stream is a viable means of cleaning a compressor blade. Each of the fluids was able to clean the test blade at both low and high air velocities and at different blade incident angles. Within the parameters/fluids tested, the results indicate that: (1) The blade cleaning is primarily a mechanical function and does not depend on the type of fluid used for cleaning. The results showed that most of the cleaning occurs shortly after the cleaning fluid is introduced into the flow stream. (2) Dirt removed from the blades may redeposit in other areas as the cleaning fluid is evaporated. Redeposit occurred in flow recirculation zones during the cleaning tests, and heated flow tests demonstrated dirt deposit in the presence of a cleaning fluid. In addition, the type of fluid used for cleaning has no effect on the redeposit characteristics of the dirt. (3) Blade erosion was not found to be a significant issue for the short durations that online water-washing was performed. However, uncontrolled water-washing (or overspray) for extended periods of time did result in measureable leading and trailing edge blade erosions.