Seal Section Research Articles

Study on structure optimization and performance improvement of Y-shaped water seal of rock drill

Purpose The rock drill’s drill tail experiences high-frequency fretting simultaneously in the rotational and axial directions. Due to the complex working characteristics and the low viscosity of the water medium, the pure water seal is susceptible to damage and failure. The purpose of this paper is to enhance the water seal’s performance. Design/methodology/approach The Y-shaped seal ring is modeled and simulated using orthogonal testing. Through analysis of the impact of various seal section parameters on sealing performance, the maximum contact stress and maximum Von Mises stress are selected as indicators of sealing effectiveness. Findings The maximum contact stress is proportional to lip thickness and chamfer length but inversely proportional to lip length. Meanwhile, the maximum Von Mises stress is directly influenced by lip depth and the included angle of the lip and drill tail but is inversely proportional to the lip thickness. The enhanced Y-shaped water seal sees reductions of 15% and 45% in maximum contact stress and maximum Von Mises stress, respectively. Originality/value This paper used analytical method and model that is helpful for design of the water seal’s structure in complex working characteristics and the low viscosity of the water medium. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2023-0366/

Structural optimization and performance improvement of rock drill seals based on orthogonal test

The drill tail of a rock drill meets high-frequency fretting in both the rotational and axial axes. The pure water seal is prone to damage and failure owing to its difficult working features and the low viscosity of the water medium. Orthogonal testing is used to simulate and model the Y-shaped seal ring to enhance the performance of the water seal. The maximum contact stress and maximum Von Mises stress are selected as indicators of sealing effectiveness based on an assessment of the effects of different seal section parameters on sealing performance. These insights serve to improve the building of the water seal. Maximum contact stress is demonstrated to be linked to lip thickness and chamfer length, but inversely proportional to lip length. Meanwhile, the maximum Von Mises stress is directly influenced by lip depth, including the angle of the lip and drill tail, and is inversely linked to lip thickness. Maximum contact stress and maximum Von Mises stress are lowered by 15% and 45%, respectively, in the revised Y-shaped water seal, resulting in greatly better sealing performance.

Study Explores Design, Potential of Electric Submersible Generators

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 214361, “Electric Submersible Generators: Using ESPs in an Unfamiliar Way,” by Charles E. Collins, Kenneth J. Frazier, and Bryan Coates, SPE, Baker Hughes. The paper has not been peer reviewed. _ The electrical submersible generator (ESG) is a modern interpretation of an old idea. The ESG can generate electricity to meet surface power needs or feed directly into the grid to create a revenue stream under the proper injection conditions. In typical configurations, a standard centrifugal pump is used in combination with an induction motor operated in such a way for the mechanical work of the pump to be converted into electrical energy. The complete paper explores ESG design considerations, theoretical underpinnings, and potential applications. What Is an ESG? A generic geothermal power plant typically consists of production wells that can be either artesian or artificially lifted. The heated well fluid will transfer the heat to a working fluid that rotates turbines to generate electricity. The reservoir fluid eventually will be reinjected into the formation to be warmed again and reproduced. It is common to use conventional electrical submersible pump (ESP) equipment to produce the fluids from the formation. The ESG concept focuses on injection wells from these power plants. Instead of drawing power from a source and moving fluid to the surface, the ESG takes injected fluid from the surface and creates power that can be used to offset surface power requirements onsite or sold directly back to the grid to generate revenue. The components of the ESG are very similar to those of an ESP, with an intake, discharge, seal, and cable attached to the motor. However, many of the components act essentially in reverse. The motor becomes a generator as it is driven by the pump acting as a turbine. The conventional ESP discharge becomes the intake, and the intake becomes the discharge. The cable still transmits the energy from the motor to the surface and vice versa. The seal section isolates the generator from the well fluid, handles thrust from the turbine, and equalizes the external pressure of the well with the internal pressure of the system. The generator effectively acts as a brake for the turbine. While most ESP stages are not typically designed to operate as a turbine, many will still maintain a system efficiency expected of ESPs. Application Guidelines As with conventional ESP systems, proper application of this equipment ensures desired run life and optimal electrical generation. General steps of equipment selection include the following: - Collect basic wellbore information - Verify flow rate, temperature, and pressure of injected fluid - Size the turbine accordingly based on the expected flow rate and pressure - Determine the size of the generator based on the load from the turbine and the expected heat rise

Investigation on the flow-induced tangential force characteristic of labyrinth seals under different operation parameters

The flow-induced tangential force Ft is crucial for the annular gas seal stability. In this paper, a three-dimensional CFD model is established to study the Ft characteristics of the labyrinth seal. The overall Ft of the seal section is decomposed into each seal cavity. The Ft characteristic of each seal cavity versus rotation speed ω and inlet pressure pin is analyzed. The result shows that the sign of Ft in each seal cavity changes from the negative to the positive along the leakage direction, resulting in a specific crossing tooth number Nc at which Ft≈ 0 N. When the tooth number is smaller than Nc, the seal stability increases with the increase of ω and pin. When the tooth number is larger than Nc, the trend is reversed. When the tooth number equals Nc, the seal stability is in a critical state, showing no dependency to the ω and pin. The Nc is a novel index for the labyrinth seal stability.

APPLICATION OF MUD GAS DATA AND LEAKAGE PHENOMENA TO EVALUATE SEAL INTEGRITY OF POTENTIAL CO2STORAGE SITES: A STUDY OF CHALK STRUCTURES IN THE DANISH CENTRAL GRABEN, NORTH SEA

Depleted chalk oilfields and chalk structures in the Danish Central Graben, North Sea, are potential CO2storage sites. In most of these fields, the main reservoir is the Upper Cretaceous – Danian Chalk Group and the Eocene – Miocene mudstones of the Horda and Lark Formations constitute the primary seal. In a few fields, the reservoir is composed of the Lower Cretaceous Tuxen and Sola Formations. Here the main seal is assumed to be the Chalk Group which however has poor gas sealing characteristics; the Horda and Lark Formations constitute an efficient secondary seal although they are quite high in the section. This study documents a workflow that may help to evaluate the seal integrity of the structures from an integration of mud gas data from wells with seismic data. Mud gas data provide detailed information about the distribution and types of gas (biogenic or thermogenic) throughout the seal section and overburden. The presence of higher carbon number gases (C3–C5, propane to pentane) in the seal indicates migration of thermogenic gas into the thermally immature sealing mudstones; whereas the dominance of C1(methane) and partly C2(ethane) likely reflects the presence of in situ generated biogenic gas in the mudstones, thus indicating that there are no seal integrity issues. The vertical thermogenic gas migration front has been determined, and a “traffic light” indicator system has been used for seal integrity evaluation. Where no or minor migration of thermogenic gas into the primary seal has occurred and a primary seal >30 m thick is present, the seal is considered to have good matrix seal integrity (green). If some significant thermogenic gas migration has occurred into the primary seal but more than 30 m of primary seal is present above the thermogenic gas migration front, the seal integrity is reduced (yellow). In structures where thermogenic gas migration is recorded through the primary seal and into the overburden, seal integrity is considered to be poor (red). In areas where significant leakage of thermogenic gas has occurred into the seal, high density, low porosity carbonate beds frequently occur encapsulated within the sealing mudstones and are interpreted to be composed of methane‐derived authigenic carbonates (MDACs). Seismic data show that there is a convincing correlation between leakage as indicated from mud gas data and the presence of vertical wipe‐out zones (gas chimneys), bright zones (gas‐charged sediments or MDACs), and depressions (pockmarks). In general, potential CO2storage sites in the study area in tectonically inverted structures show good seal integrity, but this may locally be reduced and require additional analyses. Storage sites associated with salt diapirs generally show poor seal integrity and are likely to be poor candidates for CO2storage. In combination, mud gas and seismic data are therefore powerful tools to investigate (palaeo‐) leakage phenomena and provide support for seal integrity evaluation at local to regional scales.

Short-Term Field Performance and Cost-Effectiveness of Crumb-Rubber Modified Asphalt Emulsion in Chip Seal Applications

Chip sealing is a commonly used pavement maintenance technique that aims to delay pavement deterioration by reducing water infiltration and restoring skid resistance. The objective of this study was to evaluate the short-term field performance and cost-effectiveness of chip seals prepared with different types of asphalt emulsion and application rates. A newly introduced crumb-rubber modified asphalt emulsion was evaluated, one that allows chip seal installation at the same temperature as a standard emulsion. Types of emulsion included a crumb-rubber modified asphalt emulsion (CRS-2TR), a polymer-modified emulsion (CRS-2P), and a conventional unmodified emulsion (CRS-2). Application rates were obtained from the Louisiana Department of Transportation and Development (DOTD), the Texas Department of Transportation (DOT) specifications, and from the chip seal design method recommended in NCHRP Report 680. Seven chip seal sections were constructed and monitored regularly over a 12-month period. In the northbound lane, the chip seal section constructed with CRS-2TR (0.37 gal per square yard [gsy]) was the best performer statistically. In the southbound lane, the chip seal sections constructed with CRS-2TR and CRS-2P (0.31 gsy) performed similarly. Furthermore, the maximum Service Life Extension (SLE) was observed for the CRS-2TR (0.31 gsy) chip seal sections, whereas the chip seal sections constructed with CRS-2 had the lowest SLE. In addition, the most cost-effective chip seal section was achieved by the application of CRS-2TR emulsion at the Louisiana DOTD recommended emulsion application rate.

Oil submersible pumps reliability during cyclic operation

The ESP reliability analysis was conducted to determine the correlation between ESP operation mode and ESP component reliability. The analysis was based on operation data of more than 700 ESP. The reliability of operating mode-dependent ESP components was analyzed. ESP and seal section test results under cyclic and constant operation conditions were shown. As a result, it was determined that periodic operation negatively affect ESP components lifetime. Recommendations for ESP cyclic operation were proposed.

Construction quality acceptance performance-related specifications for chip seals

The research described herein details the establishment of a framework for construction quality acceptance performance-related specifications (PRS) for chip seal surface treatments. This paper establishes acceptance quality characteristics (AQCs) and relationships between the AQCs and related chip seal performance measures. This work is a critical step in developing PRS for constructed chip seal treatments and establishing suitable guidelines for the PRS. The main objective of this paper is to determine appropriate test methods to evaluate each defined AQC. The relationships that are established between the AQCs and chip seal performance are used to define performance ranges and threshold values for a particular performance measure. These performance ranges and threshold values then can be used to define pay factors for the constructed chip seal section. The threshold values and pay factors for each AQC described herein are preliminary recommendations and require further validation prior to implementation. However, this research demonstrates how these PRS would be utilized to ensure acceptable chip seal construction quality in the field. The developed construction quality acceptance PRS framework uses the percent within limits (PWL) concept to determine whether a chip seal lot passes the PRS threshold values and whether the contractor receives full pay, is subject to a pay penalty, or fails the construction PRS and must correct the chip seal within the first year in service, which constitutes the typical warranty period for contracted chip seal work. Finally, recommendations are made as to the next steps in the development and validation of these construction quality acceptance PRS that are needed for implementation by contractors and state roadway maintenance agencies. • A framework is developed for the performance-related specification of chip seal surface treatments. • Relationships are identified between acceptance quality characteristics (AQCs) and critical chip seal performance measures. • Practical test methods are identified to measure the AQCs. • Recommendations are made for the establishment and future implementation of pay factors for chip seal construction.

Service-Induced Damages of the Ceramic Thrust Bearing Pivot in the Seal Section of Electrical Centrifugal Pump System

The paper provides the results of studying the condition of the working pivot of thrust bearings made of reaction- sintered silicon carbide-based ceramics (SiSiC-ceramics) removed from the seal section of the electrical centrifugal pump system. The working surface of the pivot demonstrates numerous service-induced damages of different origin resulting from friction. Based on categorization of these damages, recommendations were made concerning the improvement of the ceramic thrust bearing design.

A Numerical Investigation of the Effect of Inlet Preswirl Ratio on Rotordynamic Characteristics of Labyrinth Seal

Full three-dimensional (3D) computational fluid dynamics (CFD) simulations are carried out using ANSYS cfx to obtain the detailed flow field and to estimate the rotordynamic coefficients of a labyrinth seal for various inlet swirl ratios. Flow fields in the labyrinth seal with the eccentricity of the rotor are observed in detail and the detailed mechanisms that increase the destabilizing forces at high inlet swirl ratios are discussed based on the fluid governing equations associated with the flow fields. By evaluating the contributions from each term of the governing equation to cross-coupled force, it is found that circumferential velocity and circumferential distribution of axial mass flow rate play key roles in generating cross-coupled forces. In the case that circumferential velocity is high and decreases along the axial direction, all contributions from each term are positive cross-coupled force. On the other hand, in the case that circumferential velocity is low and increases along the axial direction, one contribution is positive but the other is negative. Therefore, cross-coupled force can be negative in the local chamber depending on the balance even if circumferential velocity is positive. CFD predictions of cross-coupled stiffness coefficients and direct damping coefficients show better agreement with experimental results than a bulk flow model does by considering the force on the rotor in the inlet region. Cross-coupled stiffness coefficients derived from the force on the rotor in the seal section agree well with those of the bulk flow model.

Self-sealing experiments and gas injection tests in a backfilled microtunnel of the Mont Terri URL

Abstract This paper describes a large-scale experiment on gas transport and hydromechanical processes around underground structures as part of a long-term geoscientific research programme at the Mont Terri Underground Rock Laboratory in the Jura Mountains of Switzerland. A horizontal microtunnel with a diameter of 1 m and a length of 13 m was drilled in an overconsolidated claystone formation. After installing monitoring instruments in the open tunnel, the end of the tunnel was backfilled with sand (test section) and a large hydraulic packer was emplaced in the seal section. The packer was inflated and subsequently the test interval was saturated with a synthetic pore-water. Following saturation an extended programme of hydraulic testing was performed over a two year period. A series of gas injection tests was then performed over a period of approximately 1.5 years. Following this first series of gas injections, a long post-gas hydraulic test has been initiated. The paper presents data and interpretation of the gas injections and subsequent hydraulic testing. The ability of the excavation damage zone to transport gas at pressures below fracturing is demonstrated. The post-gas hydraulic performance is considered and related to the self-sealing of the damage zone observed during saturation and hydraulic testing.

Nonlinear Analysis of Rotary Sealing Performance of Rubber O-Ring

The two-dimensional O-ring seal nonlinear axisymmetric finite element model are established which is used for swinging hydraulic cylinder. Some factors influencing rubber O-ring sealing performance were taken into account, such as rotating shaft diameter, O-ring seal section diameter. The results indicate that when medium pressure is zero, the two factors influence Von Mises and maximum contact stress of sealing face greatly. Under medium pressure (P=10Mpa), the two factors have a little influence to Von Mises and maximum contact stress.

Analysis of Premium Connection of Connecting and Sealing Ability Loaded by Axial Tensile Loads

It is necessary to know the connecting and sealing ability of premium connection for appropriate choices of different working conditions. By finite element method, the finite element model of premium connection is established and the stresses of seal section, shoulder zone and thread surface of tubing by axial tensile loads are analyzed. The results show that shoulder zone is subject to most axial stresses at made-up state, which will make distribution of stresses on thread reasonable. With the increase of axial tensile loads, stresses of thread on both ends increase and on seal section and shoulder zone slightly change. The maximum stress on some thread exceed the yield limit of material when axial tensile loads exceed 400KN. Limited axial tensile loads sharply influence the contact pressures on shoulder zone while slightly on seal section. Although the maximum contact pressure on shoulder zone drop to 0 when the axial tensile load is 600KN, the maximum contact pressure on seal section will keep on a high level.

Improved elastomeric seal design based on nonhomogeneous material properties

The goal of this research was improving elastomeric seal performance based on seal material design. The specific seal failure mode considered was permanent deformation or compression set of O-rings, and sealing performance degradation due to this process is common to all types of elastomeric seals. The basis for seal design was identified as reducing the elastic strain energy in the seal since it drives the growth of permanent material deformation. The design concept developed was using variation of material behavior over the seal section to manipulate the level and distribution of elastic strain energy. Design studies used finite element analyses with experimentally measured material behavior to quantify effects of varying seal material characteristic on seal performance. Sealing performance was described in terms of compression set and seal-counterface contact pressure. Experimental O-rings were produced based on designs that included regions of less stiff material in the larger surrounding seal section. Performance of new design seals was compared to conventional one-material seals and improved sealing performance was demonstrated. With the modified design seals, both compression set and the rate of sealing contact pressure loss over time were decreased. There was a loss of initial maximum contact pressure with the inclusion of less stiff material regions, but it was shown that this effect can be mitigated by properly locating the softer material in the overall seal section. In summary, properly implemented material variations over the seal will result in lower strain energy content, lower rate of permanent deformation development and decreasing rate of loss of seal-counterface contact pressure.

Identification of Force Coefficients in a Squeeze Film Damper With a Mechanical Seal: Large Contact Force

Squeeze film dampers (SFDs) aid to reduce excessive vibration levels due to rotor imbalance and to raise stability thresholds in rotor-bearing systems. SFDs commonly include end seals to increase their damping capability with a lesser lubricant flow. Seals also aid to reduce the occurrence of air ingestion/entrapment that severely reduces the damper forced performance. However, most conventional end seals do not completely eliminate lubricant side leakage, which limits their effectiveness to prevent air ingestion. A novel end seal arrangement incorporates a spring loaded, contacting mechanical seal that effectively prevents lubricant side leakage and air ingestion. The mechanically sealed damper is intended for use in power engines for unmanned aircraft vehicles. The test damper journal is 2.54 cm in length and 12.7 cm in diameter, with a radial clearance of 0.127 mm. Prior literature reports dynamic load tests on the seal-SFD and measurements of orbital motions to characterize the mechanical parameters of both the mechanical seal and squeeze film damper section. The test data to date include damper operation for a single contact load (90 N) closing the mechanical seal. Presently, measurements of damper dynamic load performance are conducted with a larger contact force (260 N). A nonlinear parameter identification method in the frequency domain determines simultaneously the squeeze film damping and inertia coefficients and the seal dry-friction force. The test results show that the system equivalent viscous damping coefficients are twice as large as those obtained earlier with the smaller contact force. On the other hand, as expected, the squeeze film damper coefficients are nearly identical for both test configurations. Predicted squeeze film damping coefficients, from an improved model that includes the flow in the damper feed and discharge grooves, correlate well with the test data for small and moderate orbit radii. The experimental fluid added mass coefficients are in par with the actual mass of the bearing housing and accurately predicted.

Improving the Long-Term Performance of Elastomeric Seals by Material Behavior Design

Previously it was shown that including smaller inset regions of less stiff material in the larger O-ring section at locations of high stress results in lower strain energy density in the section. This lower energy content is expected to lead to improved long-term seal performance due to less permanent material deformation and so less loss of seal-housing contact pressure. The shape of the inset region, the time-dependent change in material properties, and hence change in seal behavior over time in use were not considered. In this research experimental and numerical simulation studies were conducted to characterize the time-dependent performance of O-ring section designs with small inset regions of different mechanical behaviors than the larger surrounding section. Seal performance in terms of the rate of loss of contact pressure of modified designs and a baseline elastic, one-material design was calculated in finite element models using experimentally measured time-dependent material behavior. The elastic strain energy fields in O-ring sections were calculated under applied pressure and applied displacement loadings. The highest stress, strain, and strain energy regions in O-rings are near seal-gland surface contacts with significantly lower stress in regions of applied pressure. If the size of the modified region of the seal is comparable to the size of the highest energy density region, the shape of the inset is not a major factor in determining overall seal section behavior. The rate of loss of seal-housing contact pressure over time was less for the modified design O-ring sections compared with the baseline seal design. The time-dependent performance of elastomeric seals can be improved by designing seals based on variation of mechanical behavior of the seal over the seal section. Improvement in retention of sealing contact pressure is expected for seal designs with less stiff material in regions of high strain energy density.

Through-Tubing-Conveyed ESP Replacement - Live Well Intervention

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 116822, "Thru- Tubing Conveyed ESP Pump Replacement - Live-Well Intervention," by Walter Dinkins, SPE, and Steve Tetzlaff, Baker Hughes; John C. Patterson, SPE, Hai Hunt, SPE, Peter Nezaticky, SPE, and James Rogers, SPE, ConocoPhillips; and Bret Chambers, BP plc, originally prepared for the 2008 SPE Annual Technical Conference and Exhibition, Denver, 21-24 September. The paper has not been peer reviewed. Through-tubing-conveyed (TTC) electrical-submersible-pump (ESP) technology was developed to address the high cost and long lead times associated with North Slope rig workovers to pull and replace worn or plugged pumps. TTC technology allows ESPs to be changed in live wells without the need to kill the well and work it over. When a TTC pump replacement is performed, the pump is pulled and replaced with slickline or coiled tubing while the tubing, seal section, motor, power cable, and downhole gauges remain in place. Introduction The first TTC systems were installed in West Sak development wells on the North Slope of Alaska in 1998. The first systems were TTC electrical submersible progressing-cavity pumps (TTCESPCPs). In 2001, TTC technology was expanded to include centrifugal pumps to achieve higher production rates. The centrifugal TTC pumps were given the designation TTCESP. TTCESP lift systems continue to be the preferred equipment for the West Sak field. TTC technology is particularly applicable in wells with high solids production in which the pump is the primary failure mode. TTC technology also provides a means to upsize, downsize, or add pump components such as rotary gas separators without rig intervention on live wells. TTCESPCP and TTCESP Components From bottom to top, the rig-deployed (tubing-conveyed) components of a TTCESPCP consists of motor centralizer, motor, gear-reduction unit, tandem seal sections, and TTC crossover. A power cable is clamped to the outside of the tubing and is run from the motor to surface, and a separate instrument wire is run for a downhole gauge located in a side-pocket mandrel above the ESP assembly. The TTC crossover (Fig. 1) is what allows pumps to be pulled while the motor, gear-reduction unit, seal section, tubing, instrument wire, and power cable are left downhole. The slickline-deployed TTC components consist of a pump assembly, a packoff assembly, and a slipstop. The pump assembly consists of a pump "eye" (Fig. 2), which couples the pump to the TTC crossover, and pump and discharge assembly, which includes a centralizer and fishing neck.

Examining of the segmented electrode use from the viewpoint of the electrolyte volatilizing in molten carbonate fuel cell

Molten carbonate fuel cells (MCFCs) have entered the pre-commercialization phase, and have been experimentally demonstrated in real world applications, including beer brewery, etc. However, though MCFCs have a high potential and an enough operating experience as an energy supply system, they are not explosively widespread. One of these reasons is cost of cell components. Because the thickness of both electrodes is 0.8 mm and both electrodes are made of porous plates of 1 m 2 of the electrode area, they are often broken by a thermal stress in the sintering process of an electrode and by a worker's carelessness at the cell assembly process. Generally, because these cracking electrodes can potentially cause electrolyte leakage and gas crossover, they are not used to a MCFC stack and are disposed of. Therefore, it made the cost of MCFC be raised. The performance of a cell that uses a mosaic electrode has been evaluated. However, the causal relation between the cracking of an electrode and an electrolyte-leakage has not been yet confirmed. If this causal relationship is elucidated, a cracking electrode or a mosaic electrode can be used to MCFC, such that the cost of MCFC systems would consequently decrease. Therefore, we studied the causal relation between the cracking of an electrode and electrolyte leakage and gas crossover using a visualization technique. In the case of an anode electrode where the centre section of a cell has crack of about 1 mm, the electrolyte leakage from this crack could not be observed by the visualization technique. Moreover, the gas crossover could not be also observed by the visualization technique, and nitrogen in the anode exhaust gas was not detected by a gas chromatography. However, the electrolyte leakage observed from the wet-seal section though the gap between the separator and the electrode was always 1 mm or less. Therefore, electrolyte leakage hardly occurs, even if a cracked anode electrode is installed into the centre section of the cell. On the other hand, although the volatile substance gushes from the wet seal section, the electrolyte leakage/volatilization phenomenon does not occur at the centre of the cell or at the gap between each segmented cathode. The volatile substance in the cathode gas-distributor-channel is composed of the electrolyte mist and the electrolyte volatile substance, and the rate of release is about 2.5 times that of anode side. Although the segmented electrode can be applied to the anode in a MCFC, it cannot be applied to a cathode from the viewpoint of the electrolyte leakage/volatilization.

Volatilization Behavior of Li/Na Carbonate as an Electrolyte in MCFC

We have been elucidating the volatile Li/K electrolyte behavior in MCFC since 2003 using a visualization technique. Regarding the 62Li2CO3/ 38K2CO3 electrolyte, the molten salt is produced as KOH with the water generated with the cell reaction, and K2CO3, which is the volatile matter, is generated as the KOH reacts with CO2 in the anode gas. Conversely, the volatile matter in the cath-ode channel is due to the dispersion of molten salt. In this paper, we aim to elucidate the fundamental electrolyte volatilizing mechanism of 52Li2CO3/ 48Na2CO3 and the influence of the elec-trolyte leakage from the wet seal section on the electrolyte's vola-tile behavior. As a result, the volatile matter Li/Na electrolyte is not observed under the generation mode even as the current density in-creases. However, a large amount of electrolytes that originated in the leakage from the wet seal section are discharged beginning immediately after operation and lasting until about one week later on the Li/Na electrolyte.

Leakage Characteristics of Scroll Compressor by Two Phase Flow Model in Consideration of Wall Oil Film Thickness.

Two-phase leakage model in consideration of the film thickness on the wall surface has been proposed to improve the estimation accuracy of the leakage in a scroll compressor. The oil adhesion rate was introduced as a parameter which gives the probability that the oil in a compression chamber adheres to the scroll wall surface. In order to obtain the oil adhesion rate computationally, the flow in a scroll compression chamber was simulated by the MAC method which is a kind of non-compressing viscosity flow analysis, and the adhesion position to the wall surface was computed by tracking oil particles in a flow field. The average oil adhesion rate in the seal section was 0.21 by numerical computation. This means that 21% of the oil in a compression chamber adheres to the wall surface. The scroll leakage loss was measured for verification of the two-phase leakage model in two kinds of different suction volumes compressors. The rate of oil adhesion identified from the experiment result was 0.2 to 0.45. Leakage losses by experiments agree with the numerical results within 2% to 4%, so that the effectiveness of the two-phase leakage model were confirmed.