Electric-controlled pressure relief valve for enhanced safety in liquid-cooled lithium-ion battery packs

The liquid-cooled battery energy sto rage system(LCBESS) has gained significant attention due to its superior thermal management capacity.However,liquid-cooled battery pack(LCBP) usually has a high sealing level above IP65,which can trap flammable and explosive gases from battery thermal runaway and cause explosions.This poses serious safety risks and challenges for LCBESS.In this study,we tested overcharged battery inside a commercial LCBP and found that the conventionally mechanical pressure relief valve(PRV) on the LCBP had a delayed response and low-pressure relief efficiency.A realistic 20-foot model of an energy storage cabin was constructed using the Flacs finite element simulation software.Comparative studies were conducted to evaluate the pressure relief efficiency and the influence on neighboring battery packs in case of internal explosions,considering different sizes and installation positions of the PRV.Here,a newly developed electric-controlled PRV integrated with battery fault detection is introduced,capable of starting within 50 ms of the battery safety valve opening.Furthermore,the PRV was integrated with the battery management system and changed the battery charging and discharging strategy after the PRV was opened.Experimental tests confirmed the efficacy of this method in preventing explosions.This paper addresses the safety concerns associated with LCBPs and proposes an effective solution for explosion relief.

Structural Style and Hydrocarbon Prospectivity of the Growth Faults Related Structures in the Bengal Basin

The structural and tectonic evolution of the Bengal Basin is characterized by a complex interplay of factors, including sedimentation, the rise of the Himalayan Mountains, and the movements of Jurassic syn-rift faults. This study aims to comprehend the progression of growth faults inside the basin by examining fault geometry, basin development, and structural relief patterns. We used high-quality 2D seismic lines from the PK-MY-8403, classical seismic interpretation techniques and modeling were carried out to reveal the plate tectonic conditions, stratigraphy, and sedimentation history of the basin. The break-up unconformity, Paleocene and Eocene submerged conditions, and crucial geological formations including the Sylhet Limestone, Barail Group, and Surma Group were among the notable features recognized in seismic section. With an emphasis on growth strata and pre-growth strata, significant variations in layer thickness and relief were remarked in different stratigraphic levels. Basin development events like the evolution of the Miocene remnant ocean basin, sedimentation in Oligocene, Eocene Himalayan collision, and the Pliocene reverse fault development are analyzed. In the early the Pliocene compressional forces outpaced sedimentation rates and syn-depositional normal faults of Oligocene time began to move in opposite direction. Syn-depositional growth faults may have formed in the Bengal Basin as a result of this reversal. This research provides a detailed comprehensive knowledge of growth fault development in the Bengal Basin following the seismic interpretation, modelling, and thickness/relief analysis. The outcomes point to a substantial hydrocarbon potential, especially in regions like the Eocene Hinge Zone, where the prospectivity of the area is enhanced by carbonate reefs and Jalangi shale. However, the existence of petroleum four-way closure in the investigated region requires further investigation.

Exploitation technology of pressure relief coalbed methane in vertical surface wells in the Huainan coal mining area

Exploitation technology of pressure relief coalbed methane in vertical surface wells is a new method for exploration of gas and coalbed methane exploitation in mining areas with high concentrations of gas, where tectonic coal developed. Studies on vertical surface well technology in the Huainan Coal Mining area play a role in demonstration in the use of clean, new energy resources, preventing and reducing coal mine gas accidents and protecting the environment. Based on the practice of gas drainage engineering of pressure relief coalbed methane in vertical surface wells and combined with relative geological and exploration en- gineering theories, the design principles of design and structure of wells of pressure relief coalbed methane in vertical surface wells are studied. The effects of extraction and their causes are discussed and the impact of geological conditions on gas production of the vertical surface wells are analyzed. The results indicate that in mining areas with high concentrations of gas, where tectonic coal developed, a success rate of pressure relief coalbed methane in surface vertical well is high and single well production usually great. But deformation due to coal exploitation could damage boreholes and cause breaks in the connection between aquifers and bore-holes, which could induce a decrease, even a complete halt in gas production of a single well. The design of well site location and wellbore configuration are the key for technology. The development of the geological conditions for coalbed methane have a significant effect on gas production of coalbed methane wells.

An analysis on the effect of mining height and floor lithology on pressure relief of upper protective layers

In order to understand the effect of mining height and floor lithology at the upper protective layer face on the pressure relief of protected coal seams, this paper uses a numerical simulation method to model the pressure changes at protected coal seam during mining upper protective layer. The results show that the taller the mining height at the upper protective layer face, the greater the protection on protected coal seam due to the higher level of pressure release; the upper protective layer face with hard rock floor impedes the pressure release at the protected coal seam, which affects the overall effect of the pressure release at protected coal seam using the protective layer mining method.

Geostress measurements near fault areas using borehole stress-relief method

To minimize negative effects of geostress distribution on mining safety near the fault areas, the UPM40 triaxial geostress testing system was introduced to conduct in-situ geostress measurements at three sites and nine points by the borehole stress-relief method. The results of strain?confining pressure curves show that rock masses at the three measuring sites exhibit comprehensive linear elasticity in spite of various fissures or cracks within rocks. Horizontal and vertical stress components distribute discrepantly near the fault areas, and the maximum lateral pressure coefficient is as high as 6.15. The maximum principle stress ranges from 8.01 to 14.93 MPa, and stress directions are in the range of N78.07°W?N17.55°W. Geostresses near fault areas are dominated by the horizontal tectonic stresses, while the lower values, compared to those under similar geological conditions are due to stress release by the fault. Additionally, the fault and shear stress nearby are partially responsible for asymmetric elongation and southwesterly migration of orebodies.

A Study on the Dynamic Adjustment of Pressure Relief Gas Drainage Drilling in Mined-Out Areas

With the development of coal mine equipment mechanization, the wide application of “hole instead of roadway” technology greatly reduces the cost of gas control engineering, but puts forward higher requirements for the effect of gas drainage. At present, the drainage effect of coal mine inspection boreholes is mainly evaluated by the drilling field, but the flow rate and gas concentration of each borehole in the drilling field are not the same, which causes the gas drainage effect not to be correctly mastered. In the present study, the pressure relief drilling in the goaf of the working face of a typical multi-coal seam group high gas outburst mining area was taken as the research object. Through the newly developed portable drilling inspection device, the pure amount of drilling drainage was investigated, and the drilling design was dynamically adjusted. The enhancement of the goaf pressure relief gas control effect ensures the gas safety of the mining face. At the same time, this improves the gas extraction rate and reduces the emission of greenhouse gases. If the data from the borehole investigation can be transmitted in real time and analyzed in big data, the optimal extraction negative pressure can be predicted through a regression algorithm. Under the control of the negative pressure of each borehole by the actuator, the extraction system can have the function of intelligent judgment.

Mechanical analysis of effective pressure relief protection range of upper protective seam mining

This paper analyzes the control mechanism of coal and gas outbursts and proposes the concept of an effective pressure relief protection range, based on the stress relief of the underlying coal-rock mass and the development of a plastic zone. Also this study developed a stress change and fracture development model of the underlying coal-rock mass. In addition, the stress and depth of fracture of any point in the floor were deduced with the application of Maple Calculation Software. The specific engineering parameters of the Pingdingshan No. 12 colliery were applied to determine the relationship between the depth of fracture in the floor and the mining height. The pressure-relief principle of the underlying coal-rock mass was analyzed while varying the mining height of the upper protective seam. The findings indicate that as the depth of fracture in the floor increases, the underlying coal-rock mass experiences a limited amount of pressure relief, and the pressure relief protection range becomes narrower.Additionally, the stress distribution evolves from a ‘‘U" shape into a ‘‘V" shape. A 2.0 m mining height of protective seam situates the outburst-prone seam, Ji_(15), within the effective pressure relief protection range. The fracture development and stress-relief ratio rises to 88%, ensuring the pressure-relief effect as well as economic benefits. The measurement data show that: after mining the upper protective seam, the gas pressure of Ji_(15) dropped from 1.78 to 0.35 MPa, demonstrating agreement between the engineering application and the theoretical calculation.

Pressure relief and structure stability mechanism of hard roof for gob-side entry retaining

In order to explore the pressure relief and structure stability mechanism of lateral cantilever structure in the stope under the direct coverage of thick hard roof and its impact on the gob-side entry retaining, a lateral cantilever fractured structural mechanical model was established on the basis of clarification for the stress environment of gob-side entry retaining, and the equation of roof given deformation and the balance judgment for fracture block were obtained. The optimal cantilever length was proposed based on the comparison of roof structural characteristics and the stress, deformation law of surrounding rocks under six different cantilever lengths by numerical simulation method. Double stress peaks exist on the sides of gob-side entry retaining and the entry located in the low stress area. The pressure of gob-side entry retaining can be relieved by reducing the cantilever length. However, due to the impact of arch structure of rock beam, unduly short cantilever would result in insufficient pressure relief and unduly long cantilever would bring larger roof stress which results in intense deformation. Therefore, there is optimal cantilever length, which was 7-8 m in this project that enables to achieve the minimum deformation and the most stabilized rock structure of entry retaining. An engineering case of gob-side entry retaining with the direct coverage of 10 m thick hard limestone roof was put forward, and the measured data verified the reasonability of conclusion.

Optimum location of surface wells for remote pressure relief coalbed methane drainage in mining areas

Based on engineering tests in the Huainan coal mining area,we studied alternative well location to improve the performance of surface wells for remote pressure relief of coalbed methane in mining areas.The key factors,affecting location and well gas production were analyzed by simulation tests for similar material.The exploitation results indicate that wells located in various positions on panels could achieve relatively better gas production in regions with thin Cenozoic layers,low mining heights and slow rate of longwall advancement,but their periods of gas production lasted less than 230 days,as opposed to wells in regions with thick Cenozoic layers,greater mining heights and fast rates of longwall advancement.Wells near panel margins achieved relatively better gas production and lasted longer than centerline wells.The rules of development of mining fractures in strata over panels control gas production of surface wells.Mining fractures located in areas determined by lines of compaction and the effect of mining are well developed and can be maintained for long periods of time.Placing the well at the end of panels and on the updip return airway side of panels,determined by lines of compaction and the effect of mining,would result in surface wells for remote pressure relief CBM obtaining their longest gas production periods and highest cumulative gas production.

Pressure relief, gas drainage and deformation effects on an overlying coal seam induced by drilling an extra-thin protective coal seam

Numerical simulations and field tests were used to investigate the changes in ground stress and deformation of, and gas flow from, a protected coal seam under which an extra-thin coal seam was drilled. The geological conditions were: 0.5 meter mining height, 18.5 meter coal seam spacing and a hard limestone/fine sandstone inter-stratum. For these conditions we conclude: 1) the overlying coal-rock mass bends and sinks without the appearance of a caving zone, and 2) the protected coal seam is in the bending zone and undergoes expansion deformation in the stress-relaxed area. The deformation was 12 mm and the relative defor- mation was 0.15%. As mining proceeds, deformation in the protected layer begins as compression, then becomes a rapid expansion and, finally, reaches a stable value. A large number of bed separation crannies are created in the stress-relaxed area and the permeability coefficient of the coal seam was increased 403 fold. Grid penetration boreholes were evenly drilled toward the protected coal seam to affect pressure relief and gas drainage. This made the gas pressure decrease from 0.75 to 0.15 MPa, the gas content decrease from 13 to 4.66 m3/t and the gas drainage reach 64%.

Principle and engineering application of pressure relief gas drainage in low permeability outburst coal seam

With the increase in mining depth, the danger of coal and gas outbursts increases.In order to drain coal gas effectively and to eliminate the risk of coal and gas outbursts, we used a specific number of penetration boreholes for draining of pressure relief gas.Based on the principle of overlying strata movement, deformation and pressure relief, a good effect of gas drainage was obtained.The practice in the Panyi coal mine has shown that, after mining the C11coal seam as the protective layer, the relative expansion deformation value of the protected layer C13 reached 2.63%, The permeability coefficient increased 2880 times, the gas drainage rate of the C13 coal seam increased to more than 60%, the amount of gas was reduced from 13.0 to 5.2 m3/t and the gas pressure declined from 4.4 to 0.4 MPa, which caused the danger the outbursts in the coal seams to be eliminated.The result was that we achieved a safe and highly efficient mining operation of the C13 coal seam.

Influence of fault slip on mining-induced pressure and optimization ofroadway support design in fault-influenced zone

This paper presents an investigation on the characteristics of overlying strata collapse and mining-induced pressure in fault-influenced zone by employing the physical modeling in consideration of fault structure. The precursory information of fault slip during the underground mining activities is studied as well. Based on the physical modeling, the optimization of roadway support design and the field verification in fault-influenced zone are conducted. Physical modeling results show that, due to the combined effect of mining activities and fault slip, the mining-induced pressure and the extent of damaged rock masses in the fault-influenced zone are greater than those in the uninfluenced zone. The sharp increase and the succeeding stabilization of stress or steady increase in displacement can be identified as the precursory information of fault slip. Considering the larger mining-induced pressure in the fault-influenced zone, the new support design utilizing cables is proposed. The optimization of roadway support design suggests that the cables can be anchored in the stable surrounding rocks and can effectively mobilize the load bearing capacity of the stable surrounding rocks. The field observation indicates that the roadway is in good condition with the optimized roadway support design.

Characterization of carbon dioxide leakage process along faults in the laboratory

It is important to understand the process of multiphase carbon dioxide(CO_(2))leakage in faults for the risk assessment of carbon capture and storage(CCS).To quantitatively characterize the CO_(2)leakage process in the fault,pressure sensors,fiber Bragg grating(FBG)temperature and strain sensors were simultaneously used to monitor CO_(2)leakage in the fault.Ten experiments were carried out,including five groups of gaseous CO_(2)leakage tests with initial pressures of 1-5 MPa and five groups of liquid CO_(2)leakage tests with initial pressures of 6-10 MPa.The results indicate that when liquid CO_(2)leaked with an initial pressure of 7-10 MPa,the pressure and temperature of CO_(2)dropped rapidly in the first few seconds and then remained unchanged.The behavior that CO_(2)continues to leak while maintaining temperature and pressure unchanged is defined as“temporary pseudo-sealing(TPS)”behavior,which continues for the first 1/3 of the leakage period.However,this TPS behavior did not occur in gaseous CO_(2)leakage.If only the pressure and temperature data were used to evaluate whether CO_(2)leakage occurred,we would misjudge the risk of leakage in CCS projects during the TPS period.The causes and conditions of TPS behavior were further studied experimentally.The results show that:(1)TPS behavior is caused by the phase transition energy generated when liquid CO_(2)leaks.(2)The condition for TPS behavior is a small leak aperture(0.2 mm).Only a small leakage rate can make the phase transition energy and pressure change from a dynamic equilibrium,and(3)The compression zone caused by the Bernoulli effect and fault“barrier”could reduce the CO_(2)leakage rate and further promote the occurrence of TPS behavior.This study provides technical and theoretical support for the quantitative characterization of the CO_(2)leakage process in faults of CCS projects.

On the Reactivation of the Pre-Existing Normal Fault

The reactivation of pre-existing faults is a common phenomenon in a basin. This paper discusses the relationship between the pre-existing faults and the newly formed Coulomb shear fractures regarding pore fluid pressures. Based on the Coulomb fracture criterion and Byerlee frictional sliding criterion, an equation relating pore pressure coefficient (λe), minimum dip angle (αe) of the reactive pre-existing fault and the intersection point depth (z) between the pre-existing fault and a newly formed Coulomb shear fault in an extensional basin, is established in this paper. This equation enhanced the understanding on the reactivation of pre-existing faults and can be used to calculate paleo-pore fluid pressures. The bigger the pore fluid pressure in a pre-existing fault is, the less the minimum dip angle for a reactive pre-existing fault will be. The minimum dip angle is less in shallow area than that in deep area. This will be of significance in petroleum exploration and development.

Experimental investigation of thermal transfer coefficient by a simplified energy balance of fault arc in a closed air vessel

The themial transfer coefficient that represents the portion of energy heating the surrounding gas of fault arc is a key parameter in evaluating the pressure effects due to fault arcing in a closed electrical installation.This paper presents experimental research on the thermal transfer coefficient in a closed air vessel for Cu,Fe and A1 electrode materials over a currcni range from 1-20 kA with an electrode gap from 10-50 mm and gas pressure from 0.05-0.4 MPa.With a simplified energy balance including Joule heating,arc radiation,ihc energies related to electrode melting,vaporization and oxidation constructed,and the influences of different factors on thermal transfer coefficient are studied and evaluated.This quantitative estimation of the energy components confirmed that the pressure rise is closely related to the change in heat transport process of fault arc.particularly in consideration of the evaluation of Joule healing and radiation.Factors such as the electrode material,arc current,filling pressure and gap length between electrodes have a considerable effect on the thermal transfer coefficient and thus,the pressure rise due to the differences in the energy balance of fault arc.

Quantitative evaluation of lateral sealing of extensional fault by an integral mathematical-geological model

To evaluate the lateral sealing mechanism of extensional fault based on the pressure difference between fault and reservoir, an integral mathematical-geological model of diagenetic time on diagenetic pressure considering the influence of diagenetic time on the diagenetic pressure and diagenetic degree of fault rock has been established to quantitatively calculate the lateral sealing ability of extensional fault. By calculating the time integral of the vertical stress and horizontal in-situ stress on the fault rock and surrounding rock, the burial depth of the surrounding rock with the same clay content and diagenesis degree as the target fault rock was worked out. In combination with the statistical correlation of clay content, burial depth and displacement pressure of rock in the study area, the displacement pressure of target fault rock was calculated quantitatively. The calculated displacement pressure was compared with that of the target reservoir to quantitatively evaluate lateral sealing state and ability of the extensional fault. The method presented in this work was used to evaluate the sealing of F_(1), F_(2) and F_(3) faults in No.1 structure of Nanpu Sag, and the results were compared with those from fault-reservoir displacement pressure differential methods without considering the diagenetic time and simple considering the diagenetic time. It is found that the results calculated by the integral mathematical-geological model are the closest to the actual underground situation, the errors between the hydrocarbon column height predicted by this method and the actual column height were 0–8 m only, proving that this model is more feasible and credible.

Pressure Transient Analysis of an Intersecting Rollover Faulted Crest Boundary in Niger Delta Oil Field

Pressure transient analysis has been extensively applied to detect anomalies in a reservoir system.These anomalies may be presented in the form of an intersection of the crestal and the antithetic fault associated with a growth fault.Interpretation of this fault can only be achieved through the use of pressure transient analysis.The objective of the research work is to analyze and test the faulted crest,depth of the anticline structure and examine the near well bore conditions in order to evaluate whether the well productivity is governed by wellbore effects(skin effects+well bore effect)or the reservoir at large.A case study of a well in the Niger delta is considered with a series of build up test carried out in two intervals of both upper and lower gauge readings.In this study,a computer aided design which uses a pressure derivative approach is used in this work to match the pressure derivative of an intersecting fault(angle)model to the field data,and the model assumes the characteristics of the reservoir.Based on the result of the interpreted data,simulation is done by using a non linear regression method(least square).The simulated data interpreted are achieved through the regression coefficient which provides a quantitative measure of the agreement between field data and the model.In conclusion,the best cases are taken from all the results and a nodal analysis is performed to diagnose the inflow performance of the well through the transient analysis in order to optimize the recovery of the oilfield.

Relief Degree of Land Surface and Population Distribution of Mountainous Areas in China

Evaluation on the population pressure in the mountainous areas is a necessary condition for the protection and good governance. The evaluation depends on accurate population density assessment. Traditional methods used to calculate population density often adopt the administrative region as a scale for statistical analysis. These methods did not consider the effects of the relief degree of land surface(RDLS) on the population distribution. Therefore they cannot accurately reflect the degree of population aggregation, especially in mountainous areas. To explore this issue further, we took the mountainous areas of China as the research area. China has A total area of 666 km2 can be classified as mountainous area,accounting for 69.4% of the country's total landmass. The data used in this research included the digital elevation model(DEM) of China at a scale of 1:1,000,000, National population density raster data, the DEM and the national population density raster data. First, we determined the relief degree of land surface(RDLS). Next, we conducted a correlation analysis between the population distribution and the RDLS using the Statistical Package for Social Science(SPSS). Based on the correlation analysis results and population distribution, this new method was used to revise the provincial population density of themountainous areas. The revised results were used to determine the population pressure of different mountainous areas. Overall, the following results were obtained:(1) The RDLS was low in most mountainous areas(with a value between 0 and 3.5) and exhibited a spatial pattern that followed the physiognomy of China;(2) The relationship between the RDLS and population density were logarithmic, with an R2 value up to 0.798(p<0.05), and the correlation decreased from east to west;(3) The difference between the revised population density(RPD) and the traditional population density(PD) was larger in the southeastern region of China than in the northwestern region;(4) In addition, compared with traditional results, the revised result indicated that the population pressure was larger. Based on these results, the following conclusions were made:(1) the revised method for estimating population density that incorporates the RDLS is reasonable and practical,(2) the potential population pressure in the southeastern mountainous areas is substantial,(3) the characteristics of the terrain in the high mountainous areas are important for the scattered distribution of the population, and(4) the population distribution of mountainous areas in China should be guided by local conditions, such as social, economic, and topographic conditions.

Pressure Control of a Large-scale Hydraulic Power Unit Using π Bridge Network

The steady state and dynamic characteristics of pressure output of a hydraulic power unit are important to the hydraulic system behavior.Because of the compact structure,the B-half bridge resistance network is widely used in the pilot controlled pressure relief valves.However the steady-state pressure error might be unacceptably big in those pressure control systems.A constant pressure power unit is typically assumed in analysis of steady state and dynamic behavior of hydraulic systems.The flow-pressure relationship seems to be much complex,in particular when big flow variation takes place.In this paper,the π bridge hydraulic resistance network pilot stage is designed in order to get better flow-pressure characteristics.Based on the similarity of electrical circuits,the main factors influencing flow-pressure characteristics are analyzed.Moreover,the optimum diameters of both constant hydraulic resistor and dynamic resistor are proposed.Flow-pressure characteristics are compared with different constant hydraulic resistors,dynamic resistor and spring stiffness by simulations and experiments.Results of simulations and experiments show that flow-pressure characteristics depend very little on the spring stiffness in whole flow range.Good controlled pressure characteristics can be achieved with suitable constant resistors.Overshoot can be reduced with the small diameter of the dynamic resistor.Flow-pressure characteristics of pressure relief valve can be improved with a π bridge pilot stage.The proposed pressure control method will provide some positive guidelines and be helpful to design a high performance hydraulic system with large flow.