Secondary Outlet Research Articles

Interacting Influences of Diurnal Tides, Winds, and River Discharge on a Large Coastal Plume

AbstractThe dispersal of large river plumes in the coastal ocean depends on multiple factors, and in some cases, can be categorized into distinct dynamical regimes: a tidally dominated near‐field, a rotational mid‐field, and a coastal current far‐field. In this study, observations and modeling are used to evaluate the factors controlling the variability in the buoyant plume from Mobile Bay. Rather than distinct dynamical regimes, the Mobile Bay plume depends on forcings that act at overlapping temporal and spatial scales: diurnal tides, river discharge events, and winds. Satellite synthetic aperture radar images along with shipboard in‐situ sampling and marine radar are used to observe plume fronts in spring 2021. Hydrodynamic model simulations are compared with observations and used to characterize a large coastal plume at consistent tidal phase across a range of forcing conditions. The along‐shore position of the plume depends primarily on advection by wind‐driven surface currents. The cross‐shore extent and plume area depend primarily on the tidal amplitude and river discharge, and secondarily on northerly (seaward) winds. Along‐shore winds influence the buoyancy anomaly by altering salinity in the estuary and offshore. Upwelling winds increase the buoyancy anomaly and advect previous plumes away from the mouth. Downwelling winds reduce the buoyancy anomaly by trapping previous plumes near the coast and directing freshwater discharge toward a secondary outlet. Thus, the combined, overlapping influences of the tide, wind, and discharge dominate the variability in freshwater delivery to the shelf at time scales of days and distances of tens of km.

Optimization study of a Z-type airflow cooling system of a lithium-ion battery pack

The present study aims to optimize the structural design of a Z-type flow lithium-ion battery pack with a forced air-cooling system known as BTMS (battery thermal management system). The main goal is to minimize Tmax (maximum temperature) and ΔTmax (maximum temperature difference) while ensuring an even airflow distribution within the battery module. The present study thoroughly investigates critical factors, such as the inlet air velocity, tapered inlet manifold, and the number of secondary outlets, to evaluate their impact on thermal performance and airflow uniformity within the battery module. Increasing the inlet air velocity from 3 to 4.5 m/s significantly improves the thermal cooling performance of the BTMS, resulting in a decrease of 4.57 °C (10.05%) in Tmax and 0.29 °C (9.79%) in ΔTmax compared to the original 3 m/s velocity. Further, the study assesses the significance of a tapered inlet manifold as a critical factor, revealing its substantial impact on cooling performance and temperature reductions in battery cells 3–9. It also facilitates a more uniform airflow distribution, decreasing the velocity difference between channel 9 and channel 1 from 3.32 to 2.50 m/s. Incorporating seven secondary outlets significantly improves the heat dissipation ability of the BTMS, resulting in a decrease of 0.894 °C (2.18%) in Tmax and 2.23 °C (72.84%) in ΔTmax compared to the configuration with 0 secondary outlets. By optimizing these parameters, the aim is to enhance BTMS's capabilities, improving LIB (lithium-ion battery) packs' performance and reliability. The optimized structural design parameters proposed in this study yield practical applications that extend beyond theoretical insights, impacting diverse fields reliant on lithium-ion battery technology. Through enhanced thermal management systems, applications in electric vehicles and portable electronics are poised to experience improved performance and longevity. Furthermore, these advancements inform the development of next-generation battery packs, promising reduced overheating risks and extended battery life. Such innovations are critical in energy storage systems for renewable energy applications and electric vehicle technology, facilitating faster charging times and increased driving range. Moreover, the implications extend to aerospace applications, ensuring the reliability of batteries in extreme environmental conditions.

Efficient Design of Battery Thermal Management Systems for Improving Cooling Performance and Reducing Pressure Drop

The air-cooled system is one of the most widely used battery thermal management systems (BTMSs) for the safety of electric vehicles. In this study, an efficient design of air-cooled BTMSs is proposed for improving cooling performance and reducing pressure drop. Combining with a numerical calculation method, a strategy with a varied step length of adjustments (∆d) is developed to optimize the spacing distribution among battery cells for temperature uniformity improvement. The optimization results indicate that the developed strategy reduces the optimization time by about 50% compared with a strategy using identical ∆d values while maintaining good performance of the optimized system. Furthermore, the system’s pressure drop does not increase after the spacing optimization. Based on this characteristic, a structural design strategy is proposed to improve the cooling performance and reduce the pressure drop simultaneously. First, the appropriate flow pattern is arranged and the secondary outlet is added to reduce the pressure drop of the system. The results show that the BTMS with U-type flow combined with a secondary outlet against the original outlet can effectively reduce the pressure drop of the system. Subsequently, this BTMS is further improved using the developed cell spacing optimization strategy with varied ∆d values while the pressure drop is fixed. It is found that the final optimized BTMS achieves a battery temperature difference below 1 K for different inlet airflow rates, with the pressure drop being reduced by at least 45% compared with the BTMS before the optimization.

How Effective Is Reverse Cross-Docking and Carbon Policies in Controlling Carbon Emission from the Fashion Industry?

The present consumer behavior is manipulated by “fast fashion”, where purchasing new, trendy, affordable clothes is preferred over recycling old ones. This changing mannerism has escalated the GHG emissions from the fashion industry. Energy-intensive raw material production, preparation, and processing contribute to considerable emissions. The management of the returned goods from the primary market and further processing through the secondary outlets indulge in reverse logistics. In this paper, efforts are made to minimize the total cost and the carbon emission amount during the process of managing the return articles from the primary market to the reverse distribution center, further processing of the articles at the secondary outlet, and the return of the unsold or excess articles from the secondary outlet. Reverse cross-docking has been implemented in managing the return articles, while environmental concerns over GHG emissions have been addressed by investing in green technology under a strict carbon cap policy. In this research, return articles from the primary and secondary markets, rework of the returned articles, and disposal of the impaired returned articles have been considered. The carbon emission cost at all stages of transportation, rework, or disposal has also been incorporated into this model. A constrained mixed integer linear programming model is proposed and solved considering green investment. A numerical example has been formulated to investigate the effect of green technology on the total cost. The results portray that, though the total cost increases by nearly 2% due to investment in green technology, it ensures a considerable drop of 23% in the carbon emission amount. Also, the result is successful in establishing that reverse cross-docking is a better option than traditional warehousing in terms of minimizing the cost.

Cooling performance optimization of air cooling lithium-ion battery thermal management system based on multiple secondary outlets and baffle

Air cooling has attracted extensive attention in the field of battery thermal management (BTMS). A comprehensive optimization scheme adding secondary outlets and baffle was proposed in this paper to improve the cooling performance of the BTMS. Computational fluid dynamics (CFD) was conducted to investigate the influences of the number and width of secondary outlets and baffles on the cooling performance of the BTMS. The effectiveness of CFD method was verified by the air cooling heat dissipation experiment of battery pack. Firstly, the effects of the number and width of the secondary outlets were discussed and optimized. The results showed that, comparing with the initial Z-type BTMS, the maximum temperature (Tmax) and the maximum temperature difference (ΔTmax) were reduced by 1.84 °C (4.20%) and 3.66 °C (75%) after optimization, respectively. Then, based on the above optimization model, a baffle had been added in the cooling channel to further better the air volume distribution and enhance the cooling performance. Compared with the initial Z-type BTMS, Tmax of the optimum model was reduced by 2.17 °C (4.95%) and ΔTmax was reduced by 4.49 °C (91.89%). It can be seen that the optimization method proposed in this paper could be used to design the BTMS for electric vehicle.

MP29-12 TRANSURETHRAL BIPOLAR ENUCLEATION (TUBE): IMPROVED OUTCOMES VERSUS STANDARD BIPOLAR TRANSURETHRAL PROSTATE RESECTION (TURIS) WITHOUT A SIGNIFICANT LEARNING CURVE MAY EASE ADOPTION OF ENUCLEATION TECHNIQUES INTO CLINICAL PRACTICE

You have accessJournal of UrologyCME1 May 2022MP29-12 TRANSURETHRAL BIPOLAR ENUCLEATION (TUBE): IMPROVED OUTCOMES VERSUS STANDARD BIPOLAR TRANSURETHRAL PROSTATE RESECTION (TURIS) WITHOUT A SIGNIFICANT LEARNING CURVE MAY EASE ADOPTION OF ENUCLEATION TECHNIQUES INTO CLINICAL PRACTICE Zachary Tully, Brian Barnes, Ryan Steinberg, and Bradley Erickson Zachary TullyZachary Tully More articles by this author , Brian BarnesBrian Barnes More articles by this author , Ryan SteinbergRyan Steinberg More articles by this author , and Bradley EricksonBradley Erickson More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002572.12AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Despite ample evidence of safety and superiority, transurethral enucleation procedures, most commonly with the holmium laser (HOLEP), have not been widely adopted (<5% in US), likely due to a combination of a steep learning curve and technological barriers. Herein we present our experience with transurethral enucleation using the Olympus® bipolar electrode, a technology with wide availability, use, and surgeon familiarity. METHODS: We reviewed consecutive transurethral outlet procedures using bipolar energy for benign prostatic hyperplasia (BPH) from a single institution from 2010-20 and divided them into two cohorts: standard transurethral resection in saline (TURis; n = 383) and transurethral bipolar enucleation (TUBE; n = 208). All TUBE procedures were performed by a single surgeon. Perioperative characteristics between the two cohorts were compared with unpaired two-tailed t-tests and Chi-squared tests. A separate learning curve analysis was performed for the TUBE procedures that determined the impact that case number had on operative time and tissue resection. RESULTS: Comparisons are shown in the Table. The TUBE cohort was more likely to be catheter dependent pre-operatively and have a higher pre-op PSA. TURis operative time was 10 minutes less on average, but TUBE tissue resection weights were significantly greater. Hospital and catheter times were statistically similar. Post-operatively, TUBE led to a greater reduction in PSA, catheter dependence and BPH medication use. De novo incontinence and need for secondary outlet procedures were higher in TURis. De novo PDE-5 use was greater in TUBE. Cancer detection was greater after TURis. The variability in TUBE operative time (r2 = 0.0024) and resection weight (r2 = 0.007) was not related to surgery number/surgeon experience. CONCLUSIONS: Utilizing the same instrumentation and electrodes, the TUBE technique offers significant advantages to a standard TURis loop resection without an appreciable learning curve. Widespread instrument familiarity, as well as the ability to perform both resection and enucleation maneuvers in the same case, may increase the likelihood of adoption into clinical practice for those hesitant to learn HOLEP. Source of Funding: none © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e473 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Zachary Tully More articles by this author Brian Barnes More articles by this author Ryan Steinberg More articles by this author Bradley Erickson More articles by this author Expand All Advertisement PDF DownloadLoading ...

Design and Numerical Simulation of Biomimetic Structures to Capture Particles in a Microchannel

The study of separating different sizes of particles through a microchannel has been an interest in recent years and the primary attention of this study is to isolate the particles to the specific outlets. The present work highly focuses on the design and numerical analysis of a microchip and the microparticles capture using special structures like corrugated dragonfly wing structure and cilia walls. The special biomimetic structured corrugated wing is taken from the cross-sectional area of the dragonfly wing and cilia structure is obtained from the epithelium terminal bronchioles to the larynx from the human body. Parametric studies were conducted on different sizes of microchip scaled and tested up in the range between 2–6 mm and the thickness was assigned as 80 µm in both dragonfly wing structure and cilia walls. The microflow channel is a low Reynolds number regime and with the help of the special structures, the flow inside the microchannel is pinched and a sinusoidal waveform pattern is observed. The pinched flow with sinusoidal waveform carries the particles downstream and induces the particles trapped in desired outlets. Fluid particle interaction (FPI) with a time-dependent solver in COMSOL Multiphysics was used to carry out the numerical study. Two particle sizes of 5 µm and 20 µm were applied, the inlet velocity of 0.52 m/s with an inflow angle of 50° was used throughout the study and it suggested that: the microchannel length of 3 mm with corrugated dragonfly wing structure had the maximum particle capture rate of 20 µm at the mainstream outlet. 80% capture rate for the microchannel length of 3 mm with corrugated dragonfly wing structure and 98% capture rate for the microchannel length of 2 mm with cilia wall structure were observed. Numerical simulation results showed that the cilia walled microchip is superior to the corrugated wing structure as the mainstream outlet can conduct most of the 20 µm particles. At the same time, the secondary outlet can laterally capture most of the 5 µm particles. This biomimetic microchip design is expected to be implemented using the PDMS MEMS process in the future.

Numerical CFD investigation of liquid-liquid two-phase flow separation in a microseparator

ABSTRACT Two-phase flow liquid-liquid separation in a microseparator has promising use in microfluidic field such as downstream biodiesel purification. The present study aims to investigate the effect of daughter channel (DC) geometry on liquid-liquid separation in a new design of microseparator. Olive oil and water were selected as continuous and dispersed phase, respectively. Different DC intervals (500–1000 µm) and angles (60°-120°) were designed to generate nine single-sided DC microseparator configurations. Further, these were arranged in mirrored configurations to generate nine double-sided DC microseparator configurations. At continuous phase flow rate (QCP) of 0.5 ml/h, interval of 500 µm and angle of 90° achieved best performance with highest oil purity of 100% in secondary channel outlet (SC_Outlet) and lowest oil purity of 26% in main channel outlet (MC_Outlet). The results revealed that the design of DC with lower pressure drop led to better separation performance. Furthermore, the occurrence of Jamin effect in the DC could cause hindrance in the two-phase flow liquid-liquid separation. The use of double-sided DC microseparator configuration further improves the separation performance. Overall, an excellent separation of oil was successfully achieved.

Modeling and Experiment on Combustion Characteristics for Biomass Rotary Burner

Background: A biomass pellet rotary burner was chosen as the research object in order to study the influence of excess air coefficient on the combustion efficiency. The finite element simulation model of biomass rotary burner was established. Methods: The computational fluid dynamics software was applied to simulate the combustion characteristics of biomass rotary burner in steady condition and the effects of excess air ratio on pressure field, velocity field and temperature field was analyzed. Results: The results show that the flow velocity inside the burner gradually increases with the increase of inlet velocity and the maximum combustion temperature is also appeared in the middle part of the combustion chamber. Conclusion: When the excess air coefficient is 1.0 with the secondary air outlet velocity of 4.16 m/s, the maximum temperature of the rotary combustion chamber is 2730K with the secondary air outlet velocity of 6.66 m/s. When the excess air ratio is 1.6, the maximum temperature of the rotary combustion chamber is 2410K. When the air ratio is 2.4, the maximum temperature of the rotary combustion chamber is 2340K with the secondary air outlet velocity of 9.99 m/s. The best excess air coefficient is 1.0. The experimental value of combustion temperature of biomass rotary burner is in good agreement with the simulation results.

Distinct Frontal Ablation Processes Drive Heterogeneous Submarine Terminus Morphology

AbstractCalving and submarine melt drive frontal ablation and sculpt the ice face of marine‐terminating glaciers. However, there are sparse observations of submarine termini, which limit estimates of spatially varying submarine melt. Here we present a detailed survey of a west Greenland glacier to reveal heterogeneity in submarine terminus morphology. We find that the majority of the terminus (~77%) is undercut, driven by calving in the upper water column and submarine melting at depth. The remaining ~23% of the terminus is overcut, driven by calving alone. We use observations of six subglacial discharge outlets, combined with a plume model, to estimate spatially varying discharge fluxes. While small discharge fluxes (&lt;43 m3/s) feed numerous, deeply undercut outlets with subsurface plumes, ~70% of the net subglacial flux emerges at the terminus center, producing a vigorous, surface‐reaching plume. This primary outlet drives large, localized seasonal retreat that exceeds calving rates at secondary outlets.

Design and optimization of microfluidic device for generating robust uniform concentration gradients

Increasing interest in chemotaxis or cell migration in the presence of concentration gradient of certain chemical species has motivated the need for generating stable uniform concentration gradients in fluid systems. To this end, microfluidic devices have been used for studying chemotaxis over the last two decades. However, challenges in generating stable concentration gradients persist since small fluctuations in pressure or flow rates can destabilize the concentration gradient which may take considerable time to re-establish. In the present work, we propose a novel microfluidic device and optimize several design parameters using computational fluid dynamics simulations to obtain robust uniform chemical gradients. We modified a microfluidic device with a standard Y-shaped ladder design, which originally comprised of one outlet and two inlet streams, by introducing an optimized contact zone for inlet streams and a secondary outlet from this contact zone. Our simulations show that such a device can withstand flow differences as high as 50% between the inlet streams without adversely affecting the concentration gradient generated under ideal conditions (equal flow rate at the inlets).

Sensitivity Analysis on Neural Network Algorithm for Primary Superheater Spray Modeling

ABSTRACTNonlinear, large inertia with long dead time is always associated with the main steam temperature parameter in coal fired power plant. Successful control of the main steam temperature within ±2°C of its setpoint is the ultimate target for coal-fired power plant operators. Two of the most common main steam temperature circuit are primary superheater spray and secondary superheater spray. Various methods were used to model the primary superheater spray control valve opening, and the neural network remains one of the most popular choices among researchers. It remains inconclusive which neural network algorithm types, setup, number of layers, and training algorithm will give the best result. As such, the paper shows the best setup for the neural network algorithm based on sensitivity analysis methodology for one hidden layer. The inputs selected for the neural network are generator output, main steam flow, total spray flow, and secondary superheater outlet steam temperature, while the output selected is primary spray flow control valve opening.

Rural people who inject drugs: A cross-sectional survey addressing the dimensions of access to secondary needle and syringe program outlets

To better understand issues related to access to injecting equipment for people who inject drugs (PWID) in a rural area of New South Wales (NSW), Australia. Cross-sectional face-to-face survey using convenience and snowball sampling. Six regional and rural population centres in Northern NSW, within the Hunter New England Local Health District. The sample included 190 PWID who had accessed a needle and syringe program outlet within 4weeks of the survey. Data include demographic information, preferred location for accessing injecting equipment, reasons for that preference, whether they obtained enough equipment, travelling distance to an NSP and self-reported hepatitis C virus status. Sixty percent self-identified as Aboriginal people. The median age of respondents was 32years and 60% were men. A significantly larger proportion (P<0.05) of the Aboriginal respondents were women (27% versus 11.6%) and younger (37.6 versus 12.7%) compared to non-Aboriginal respondents. Most preferred to access injecting equipment at a community health facility (62.6%), as opposed to other secondary outlets, where they gained enough equipment (67.4%). Just over 80% said they were tested for HCV in the past year, with about 37% told they had tested positive. There are complex dimensions affecting how rural PWID access secondary NSP outlets. Although access is similarly limited as other rural health services because of the nature of injecting drug use and sensitivities existing in rural communities, there is potential for application of unique access models, such as, promoting secondary distribution networks.

Hydrodynamic modelling and characterisation of a shallow fluvial lake: a study on the Superior Lake of Mantua

This paper presents a numerical modelling framework developed to simulate circulations and to generally characterise the hydrodynamics of the Superior Lake of Mantua, a shallow fluvial lake in Northern Italy. Such eutrophied basin is characterised by low winds, reduced discharges during the summer and by the presence of large lotus flower (&lt;em&gt;Nelumbo&lt;/em&gt; &lt;em&gt;nucifera&lt;/em&gt;) meadows, all contributing to water stagnation. A hydrodynamic numerical model was built to understand how physical drivers shape basic circulation dynamics, selecting appropriate methodologies for the lake. These include a 3D code to reproduce the interaction between wind and through-flowing current, a fetch-dependent wind stress model, a porous media approach for canopy flow resistance and the consideration of wave-current interaction. The model allowed to estimate the circulation modes and water residence time distributions under identified typical ordinary, storm and drought conditions, the hydrodynamic influence of the newly-opened secondary outlet of the lake, the surface wave parameters, their influence on circulations and the bottom stress they originate, and the adaptation time scales of circulations to storm events. Some probable effects of the obtained hydrodynamic characteristics of the Superior Lake of Mantua on its biochemical processes are also introduced.

Study on the Structure Optimization and the Operation Scheme Design of a Double-Tube Once-Through Steam Generator

A double-tube once-through steam generator (DOTSG) consisting of an outer straight tube and an inner helical tube is studied in this work. First, the structure of the DOTSG is optimized by considering two different objective functions. The tube length and the total pressure drop are considered as the first and second objective functions, respectively. Because the DOTSG is divided into the subcooled, boiling, and superheated sections according to the different secondary fluid states, the pitches in the three sections are defined as the optimization variables. A multi-objective optimization model is established and solved by particle swarm optimization. The optimization pitch is small in the subcooled region and superheated region, and large in the boiling region. Considering the availability of the optimum structure at power levels below 100% full power, we propose a new operating scheme that can fix the boundaries between the three heat-transfer sections. The operation scheme is proposed on the basis of data for full power, and the operation parameters are calculated at low power level. The primary inlet and outlet temperatures, as well as flow rate and secondary outlet temperature are changed according to the operation procedure.

Consumers’ evolving definition and expectations for local foods

Purpose – Although locally sourced and produced foods are a growing trend in food marketing, they are not yet clearly understood nor consistently defined. There is no lack of definitions currently offered, however, based on expanding, evolving, and sometimes conflicting, dimensions. The purpose of this paper is to investigate various emerging definitional elements of local foods to determine which elements may be as important to food shoppers today as the prevailing food miles definition. Design/methodology/approach – A shopper survey is fielded and repeated measures ANOVA conducted to measure the relative importance of various definitional elements, assess where shoppers expect to acquire local foods, the price premium they are willing to pay, and differences that may exist across customer groups. Findings – The study finds that consumers do consider other definitional elements as important as distance in their definition of local foods and they expect to find them in secondary outlets beyond farmers markets and the produce department. Consumers are willing to pay a price premium and there are differences across light, medium, and heavy users. Practical implications – This study provides researchers with an expanded and clearer definition of local foods for future research and practitioners with guidance on what shoppers expect and value today and how to better source, merchandise, and promote local foods. Originality/value – By combining definitional elements from across industry, government, and academia and analyzing them together, this study offers a more comprehensive definition of local foods and consumer expectations.

Pelvic Ultrasound Evaluation for Benign Prostatic Hyperplasia: Prediction of Obstruction

Global improvements in water quality, management of infectious diseases, and other medical therapeutics have resulted in a growing population of healthy aging men. One obligate anatomic consequence of aging for these men is the development of benign prostatic hyperplasia (BPH) with secondary bladder outlet obstruction. Although the voiding symptoms associated with the change in bladder health over time predominantly impact the quality of a man's daily experience, there are also significant medical consequences of BPH that require intervention. It is a challenge to distinguish men who are at risk for these medical consequences from the much larger population of older men with voiding symptoms (lower urinary tract symptoms, LUTS). A variety of national guidelines have been developed to establish a diagnostic paradigm for meeting this challenge, but all suffer from inadequate sensitivity for the early identification of men at risk for permanent bladder injury. It is likely that the application of a thorough pelvic ultrasound designed to identify the pertinent anatomic aspects of both the bladder and prostate will improve the sensitivity of these diagnostic paradigms, with subsequent improvement in the outcomes for men with BPH/LUTS.

A novel electrospun polyurethane nanofibre membrane – production parameters and suitability for wastewater (WW) treatment

The aim of this study was to investigate the suitability of a novel electrospun polyurethane nanofibre material for water-treatment purposes. Bacterial removal efficiency was tested in the laboratory by filtering artificial water spiked with Escherichia coli through a 0.25 µm nanofibre membrane. The results were compared with those obtained using a commercial microfiltration material (MV020T) with a similar pore size (0.20 µm). Alongside the laboratory experiments, we also determined filtration efficiency with semi-pilot scale experiments using actual wastewater from the secondary sedimentation tank of a wastewater treatment plant. The laboratory experiments indicated very high log10 removal efficiency, ranging from 5.8 to 6.8 CFU (colony-forming units)/ml. These results were better than those of the commercial membrane (3.8-4.6 CFU/ml). The semi-pilot scale experiment confirmed the membrane's suitability for microbial filtration, with both E. coli and total culturable microorganisms (cultured at both 22 and 36 °C) showing a significant decline compared to the non-filtered control (wastewater from the secondary outlet).

Modeling Performance of a Tangential Flow Cyclone: Effects of Secondary Outlet Geometry and Boundary Conditions

Numerical calculation of the performance of cyclones for gas-particle separation is becoming a popular tool for cyclone analysis and design. A traditionally accepted way to treat these problems is by solving the flow field and particle transport equations in the spatial domain (C1) limited by the inlet and overflow outlet cross-sections, where the flow is usually assumed fully developed, and the dust outlet cross-section. Formulation of the boundary conditions for the flow and particles’ transport at the dust outlet cross-section remains an open question. We address this problem numerically by comparing results of calculations performed by the above traditional approach, i.e., treating the problem in configuration C1, as well as in extended domains, namely those including a dust collecting bin (configuration C2) and a downcomer tubular outlet (configuration C3). Two boundary conditions at the downflow outlet were checked for each configuration, namely, a blocked outlet (zero velocity) and an open outlet (zero gas flow rate). Toward this goal, an efficient computational fluid dynamic (CFD) model of turbulent flow based on the Reynolds Stress turbulent closure scheme was developed, validated, and used to calculate velocity field and the pressure drop as well as particle cut size and separation efficiency in several Stairmand-type tangential flow cyclones. The results were tested and corroborated against the experimental data reported in the literature, including careful measurements performed by Gottschalk and Bohnet (1995, 1998) for a 225 mm tangential flow cyclone, with downflow outlet connected to a tubular extension. Particle separation in the traditional C1 cyclone configuration was shown to be most sensitive with respect to the choice of the boundary conditions at the downflow outlet, whereas with the dust outlet connected to a bin (C3 configuration) this condition has a much weaker effect on the fractional efficiency. Solutions for the C1 and C2 configurations, both combined with the blocked downflow outlet boundary condition yielded the cyclone's pressure drop in agreement with the Gottschalk and Bohnet's data. However, C2 configuration which contained a downcomer tubular extension was found preferable for correlating the measured fractional efficiency.

Metallurgical Assessment of Heads Containing ID Cracks on a Secondary Superheater Outlet Header

During a routine plant outage, ID surface cracks were found on the two heads of a secondary superheater outlet header (SSHOH). The continued service of the SSHOH was dependent on a postmortem metallurgical assessment performed on the defective heads. The assessment techniques included visual and optical examination, oxide-scale crack dating, hardness measurement, materials identification, and multiple-heat parametric remaining creep life estimation. The assessment indicated that the ID surface cracks were formed at the very early stage of the header service, and the continued service of the header would not be compromised.