Sealed System Research Articles

COMPUTATIONAL SIMULATION OF CYCLICAL STEAM INJECTION AND PNEUMATIC ARTIFICIAL LIFT SYSTEM WITH WATER SEAL FOR OIL RECOVERY

Cyclic steam injection is an enhanced oil recovery (EOR) process which is characterized by oil viscosity reduction after the injection of steam into the well. However, like any thermal method, there is great concern regarding the excess of heat coming into the oil well casing, which is susceptible to thermal stress and may damage the reservoir. In order to solve this problem, the company ENGEPET developed the Cyclical Steam Injection and Pneumatic Artificial Lift with water seal (CSI/PAL/WS) system for temperature control in oil well casings. This work proposes a model for predicting the thermal exchange between the water and steam inside the CSI/PAL/WS system using Computational Fluid Dynamics (CFD). A simplified model was proposed and results show that it has great potential to contribute to the study of the CSI/PAL/WS system, as well as to predict operating conditions that may prevent the temperature of well casings to exceed safety limits.

A Magnetohydrodynamic System for Pumping Liquid Metal Media in a Plasma Source of Extreme Ultraviolet Radiation

A sealed compact system based on two series-connected magnetohydrodynamic pumps for pumping liquid metal media with an operating temperature as high as 450°C is described. The system is designed to produce a renewable target in the form of a liquid lithium jet in a pulsed-repetition rate source of extreme ultraviolet (EUV) radiation based on laser plasma. The system provides a head pressure of 2 bar and a flow rate of up to 80 cm3/s and is characterized by reliability, simplicity of design, the absence of moving parts, convenient handling, and the ability to pump aggressive conductive liquids. The system is easily scalable in both the head pressure and the flow rate. The long-term operation of the system has been demonstrated in a laser-produced plasma EUV source, where it provided a jet velocity of up to 22 m/s.

CLOSURE OF THE CYSTIC DUCT DURING LAPAROSCOPIC CHOLECYSTECTOMY BY THE LIGASURE VESSEL SEALING SYSTEM

Laparoscopic cholecystectomy is the “gold standard” in the treatment of symptomatic gallbladder lithiasis. Nevertheless, some pitfalls are associated with the use of the monopolar hook, such as the risk of thermal injuries and biliary complications. The present study assessed the efficacy of the Liga-Sure Vessel Sealing System (LVSS) when used for cystic duct closure during laparoscopic cholecystectomy. The laparoscopic cholecystectomy was done beginning with visualization of Calot’s triangle, and dissection of Calot’s triangle was achieved using a monopolar cautery device. Once the cystic duct was exposed, sealing was performed and divided using the LVSS. The records were compared withthose of patients undergoing laparoscopic cholecystectomy with closure of the cystic duct with clips during the same period. The results showed that during the study period, 218 laparoscopic cholecystectomies were performed; 82 of these were performed with the Liga-Sure. The work was experienced a single case of bile leakage from the cystic duct due to missed stone in the common bile duct that was managed using ERCP.

Investigating material removal mechanism of Al-Si base abradable coating in labyrinth seal system

Labyrinth seal systems are used in aero-engines to seal the clearance between turbine blades and the surrounding engine casing, and an understanding of the wear mechanism by which this occurs is necessary to achieve better sealing performance. In this work a series of tests are conducted on a high-speed test rig capable of fin tip speeds of 100 m/s. The mechanism by which the fin removes material is investigated over a range of incursion rates, with force and temperature measurements along with high-speed imaging recorded in each case. Surface examination and sectioning is also performed using microscopy post-test. The wear mechanism was found to be incursion rate dependent. At low incursion rates (0.02 µm/pass), abradable material is removed via a cyclic process, where it is first compacted in the worn groove, until ductility is lost and material fractures away from the surface of the groove. At high incursion rates (2 µm/pass), material is extruded out of the sides of the groove forming lips, before fracturing off. This process is more efficient, with lower relative forces and temperatures. As the incursion rate increases from low to high, the mechanism shows a gradual transition, with compaction being replaced with extrusion.

Development of an Automated Sealing System for Polythene Bag

Development of an Automated Sealing System for Polythene Bag

RbB11O16(OH)2: First Hydroxyl Rubidium Borate with the B‐O 2D Layer Featuring Large Birefringence in the Rb‐B‐O‐H System

AbstractA new hydroxyl rubidium borate, RbB11O16(OH)2, has been obtained in the sealed system. Its structure consists of a two‐dimensional layered anionic framework, which is composed of the fundamental building block, [B11O18(OH)2]5−. Detailed structural comparison with other hydroxyl rubidium borates indicates that RbB11O16(OH)2 is the first hydroxyl rubidium borate with a B−O layered structure. First‐principle theoretical studies have been conducted to help understand the electronic structure and its optical properties, and the results suggest that RbB11O16(OH)2 can be regarded as the potential birefringent crystal.

Water Condensation in Traction Battery Systems

Lithium-ion traction battery systems of hybrid and electric vehicles must have a high level of durability and reliability like all other components and systems of a vehicle. Battery systems get heated while in the application. To ensure the desired life span and performance, most systems are equipped with a cooling system. The changing environmental condition in daily use may cause water condensation in the housing of the battery system. In this study, three system designs were investigated, to compare different solutions to deal with pressure differences and condensation: (1) a sealed battery system, (2) an open system and (3) a battery system equipped with a pressure compensation element (PCE). These three designs were tested under two conditions: (a) in normal operation and (b) in a maximum humidity scenario. The amount of the condensation in the housing was determined through a change in relative humidity of air inside the housing. Through PCE and available spacing of the housing, moisture entered into the housing during the cooling process. While applying the test scenarios, the gradient-based drift of the moisture into the housing contributed maximum towards the condensation. Condensation occurred on the internal surface for all the three design variants.

Interactions of HCl and H2O with the surface of PuO2

In order to explore the potential of heat treatment to decontaminate chloride-contaminated legacy plutonium dioxide (PuO2) powders from the UK stockpile, samples retrieved from storage have been heated in air from 400 to 950 °C. These samples also contain high levels of other adsorbed gases from the atmosphere, including water. The amounts of chloride remaining on the PuO2 particles after heat treatment (measured by a caustic leaching process) decrease whilst the amounts of volatilised chloride increase with increasing heat treatment temperature. Clear evidence for a non-leachable (strongly bound) chloride species on the PuO2 surface is found from the thermal treatments. The lattice parameter decreases with increasing heat treatment temperature, reflecting annealing of structural defects caused by over 35 years of radiation damage, with no change in the fcc Fm3¯m crystal structure. Heating chloride-contaminated PuO2 powder to ∼230 °C and cooling back to ambient temperature in a sealed vessel reveals the production of H2, He, NO and CO gases. Water adsorption/desorption behaviour with the untreated PuO2 powder is remarkably different than PuO2 which had previously been heat treated at 700 °C. From thermal treatments in open and sealed systems it is concluded that water and chloride co-adsorb and interact on the PuO2 surface and each affects the adsorption/desorption behaviour of the other. These data also support practical considerations for repackaging of chloride-contaminated PuO2 for long term safe and secure storage at Sellafield.

Investigation on Rotor-Labyrinth Seal System with Variable Rotating speed

Abstract The following paper presents dynamic leakage rate and coupled interaction for variable speed rotor-labyrinth (LABY) seal, with rotating speed from 18 to 30 krpm. Variable speed rotor vibration characteristics are incorporated into transient computational fluid dynamic (CFD) calculations as boundary conditions of seal flow field to show the real-time effect of rotordynamic in seal flow field. Leakage rate across a variable speed rotor-seal increases with rotor vibration, but this effect is prominent at lower speed than at higher speed. Leakage characteristic is determined by differences in rotor vibration amplitude rather than rotating speed. The results also reveal that aerodynamic forces of labyrinth seal flow field can improve rotor stability, and this interaction between rotor and seal decreases with the increase of rotating speed.

Comparative bioavailability study of phenytoin in healthy Nepalese volunteers

Our study aimed to assess and compare the bioavailability of Eptoin 100 mg and Epileptin 100mg tablets in Nepalese healthy volunteers. A randomized, two-treatment cross-over study with two weeks’ wash-out period was conducted in 12 healthy non-smoker and non-alcoholic Nepalese male volunteers over a period of 6 months in the department of Clinical Pharmacology and Therapeutic at B. P. Koirala Institute of Health Sciences, Dharan, Nepal after approval from the Institutional Review Committee. The participants were randomized using sealed envelope system and received a single 100 mg oral tablet of either of the formulations with a two week washout period. Blood samples were collected predose and at regular intervals postdose upto 72 hours. Plasma phenytoin levels were estimated by reverse phase high performance liquid chromatography. The analytical method was validated prior to the start of study. Cmax (Peak Plasma Concentration), Tmax (Time to achieve maximum Plasma Concentration), AUC0-72 (Area under plasma concentration time curve 0 to 72 hours), AUC0-∞ (Area under plasma concentration time curve 0 to ∞) and T½ (Elimination half-life) and Kel (Elimination rate constant) were calculated and 80-120% margin (90% confidence interval) was used to assess bioequivalence. ANOVA test was used to analyze the data at P-value of 0.05. All volunteers completed the study. The log-transformed values of Cmax, Tmax, AUC0-t, and AUC0-∞ of the both formulations were within the specified limits and were bioequivalent according to the regulatory definition of bioequivalence based on the rate and extent of absorption. Both products can be considered equally effective in medical practice.
 Keywords: Bioavailability, Bioequivalence, healthy volunteer, Nepal, phenytoin sodium.

Analysis of whirling motion for the dynamic system of floating ring seal and rotor

In turbopumps, the dynamic characteristics of the floating ring seal and rotor system are important, especially when the floating ring seal fails to lock up. To investigate the motion of the system with the unlocked floating ring seal, a dynamic model for the whirling system is established in this study. On the basis of the perturbation method, the nonlinear model is simplified into a steady whirling model superimposed with perturbation motion. The transient bulk flow model is improved to calculate the hydrodynamic force in the seal clearance. The results show that the floating ring seal is able to steadily follow the rotor whirling motion and reduce the rotor whirling amplitude when the friction is not enough to lock the seal. The perturbation motion is calculated and proved stable, as the direct rotordynamic coefficients of the floating ring seal are much larger than the cross-coupled coefficients. Further, the effects of the mass and the friction of the floating ring seal, the rotor whirling amplitude and the interaction between the seal and the rotor on the dynamic characteristics of the whirling system are investigated.

Rearing and breeding of germ-free mice for over 1 year in a sealed positive pressure cage system

Rearing and breeding of germ-free mice for over 1 year in a sealed positive pressure cage system

Ionic liquid as a green solvent for ionothermal synthesis of 2D keto-enamine-linked covalent organic frameworks

Abstract Covalent organic frameworks (COFs) are usually synthesized under solvothermal conditions in a mixture of high-boiling organic solvents in a sealed system. By using a room temperature ionic liquid (IL) as a solvent, we presented the preparation of two-dimensional (2D) keto-enamine-linked COFs in an open container at ambient pressure. The as-synthesized 2D keto-enamine-linked COFs have ordered open channels and so the IL can be completely removed from the pores to provide the sole formation of crystalline 2D COFs. Not only the imidazolium-based IL acted as both solvent and catalyst, it was also recycled for further use without activity loss.

Analysis of a tunnel failure caused by leakage of the shield tail seal system

This paper presents an analysis of a tunnel failure accident during shield tunnel construction on Foshan Metro Line 2 in China. The failure is caused by the leakage of the multilayer seal system, which consists of several brush seals at the tail of the shield. Four different failure modes for the multilayer seal system are discussed. A simple structural analysis of the brush seals is then conducted, and failure mode 4 (failure due to brush seal deformation) is identified as a major reason for the Foshan tunnel accident. A finite element method (FEM) analysis is employed to validate the conclusions drawn from the simple structural analysis of the brush seals.

Vent Valve Thrust Force for Surface Effect Ships

The Surface Effect Ship (SES) holds promise as a viable and appealing alternative for transferring crew to offshore wind farms and oil platforms due to its superior seakeeping capability, high comfort and speed. A SES is a marine craft with catamaran hull, with flexible stern- and bow rubber -seal system. The air cushion is defined as the enclosed volume between the hull, seals and water plane. Centrifugal lift fans blow air into the air cushion, pressurizing the air cushion that lifts up to 90 % of the vessel weight. Modern SES are also equipped with adjustable vent valves allowing outflow air from the pressurized cushion. By mounting the vent valves on the hull sides, the thrust force coming from the air exiting the vent valves can be seen as an extra actuator on the ship. Using Vent valve to control the ship’s position requires an accurate thrust force model. This paper develops two thrust force models and investigates their performance. Both models are compared to computational Fluid Dynamic (CFD) analysis and experimental tests. Results show that both models may be used to estimate the maximum thrust, However, one holds higher promise to be used for control design.

Frequency‐Domain‐Based Nonlinear Response Analysis of Stationary Ring Displacement of Noncontact Mechanical Seal

Dynamic characteristics affect the operational reliability of noncontacting mechanical seals, which involves the complex relationship between the system of noncontact mechanical seals, excitation, and response. Hence, it is one of the hot topics of current research. However, domestic and foreign scholars mainly calculate the response in the time domain by establishing a linear dynamic model so that the response results can be used for system stability and tracking analysis. In this study, according to the harmonic excitation, the stationary ring’s output response was expressed via the famous Volterra series and solved with a new method, which can be used to analyze the frequency response and to calculate the displacement response of the stationary ring with single and double harmonic excitation. Based on the analysis of the response results, the parameter (stationary ring mass, axial damping, stiffness, etc.) selection scheme of noncontact mechanical seals at high and low frequencies was obtained.

Carbon-reduction as an easy route for the synthesis of VO2 (M1) and further Al, Ti doping.

A low-cost and facile method to synthesize highly crystallized VO2 (M1) particles is proposed, using carbon black as the reducing agent mixed with V2O5 nanopowders comparing two types of vacuum systems for the thermal activation. In a sealed vacuum system, CO gas is generated in the first reductive step, and continues to reduce the new born VO2, until all the V (+4) is reduced to V (+3), resulting in V2O3 formation at 1000 °C. In contrast, in a dynamic vacuum system, CO gas is ejected through pumping as soon as it is generated, leading to the formation of pure VO2 (M1) at high temperatures (i.e. in the range 700 °C ≤ T ≤ 1000 °C). The evolution of the carbon content, determined by CHNS, of each sample versus the synthesis conditions, namely temperature and type of vacuum system, confirms that the transformation of V (+5) into V (+4) or V (+3) can be controlled. The characterization of the morphologies and crystal structures of two synthesized VO2 (M1) at 700 °C and 1000 °C shows the possibility to tune the crystallite size from 1.8 to more than 5 μm, with a uniform size distribution and highly crystallized powders. High purity VO2 (M1) leads to strong physical properties illustrated by a high latent energy (∼55 J g-1) during the phase transition obtained from DSC as well as high resistivity changes. In addition, with this method, dopants such as Ti4+ or Al3+ can be successfully introduced into VO2 (M1) thanks to the preparation of Al or Ti-doped nano-V2O5 by co-precipitation in polyol medium before carbon-reduction.

Experimental data revealing explosion characteristics of methane, air, and coal mixtures.

Whenever air and gases mix with pulverised coal, explosions are possible. Such explosions constitute a primary category of safety concerns during coal bed methane mining. This study investigated the explosion parameters and characteristics of methane–air–coal dust mixtures by using an XKWB-1 sealed explosion system. Maximum explosion pressure (Pmax), maximum explosion pressure rise rate (dP/dt)max, and explosion index (K) were recorded and calculated. Findings showed that relative to the maximum explosion pressure of an air–methane gas mix Pmax-G, that of a gas–dust mixture Pmax-GD was elevated when a 7.0 vol% methane–air mixture coexisted with 500.0 g m−3 of coal dust in the explosion. Pmax-GD decreased as CG increased and increased as Vad increased for a methane–air–coal dust mixture. Both Pmax-GD and (dP/dt)max-GD increased first, but were diminished with an increase in CD. The Copt values of five coal samples of HC, KZD, DFS, TC, and YMZ were 400.0, 500.0, 500.0, 500.0, and 600.0 g m−3, respectively. Based on the coal dust explosion pathways, the effects of coal dust volatility on the explosion characteristics were analysed. Finally, with respect to 7.0 vol% methane, the data showed that the explosion index of a gas Kg was consistently lower than the explosion index of a gas–dust mixture Km; that is, Kg < Km.

All-Iron Hybrid Flow Batteries with In-Tank Rebalancing

Principles of sealed iron flow batteries are introduced and a semi-empirical model that incorporates the hydrogen evolution reaction and electrolyte rebalancing is developed. Hydrogen generation rates are measured using pressure measurements in sealed vessels. Electrolyte dynamics with and without electrolyte rebalancing are simulated and discussed, and a good agreement is found between measured and simulated pressure responses. The sealed battery system with in-tank rebalancing demonstrates stable operation at low hydrogen partial pressure during 10 days and 100 cycles at ± 100 mA cm−2 at room temperature.

Contact Force Analysis of a Rotor-Brush Seal System With Eccentricity and Airflow

The mechanics properties of brush seals are usually very complicated. Here, the contact force of a rotor-brush seal system was analyzed based on the bending deformation theory considering the interaction of eccentricity and flow induced force. The seal force expression was established by using the Bernoulli-Euler beam equation and superposition method, and the effects of eccentricity, friction coefficient, bristle lay angle, and uniform force of flow on the acting force of rotor system was analyzed. An experimental test rig of a Stodola-Green rotor-brush seal system was set up, and the effect of seal force on vibration characteristics of the rotor system was evaluated by the experiment. The results showed that with a flow induced force, the contact force of the rotor decreases with the increase of eccentricity. The contact force increased with the increase of flow induced force as well. The theoretical results were in accordance with the experimental results and, thus, validate the seal force of the brush seal.