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.

Comparison Study of Different Drainage Tube Diameters with Negative Pressure Suction after Valve Replacement Surgery

Objective: This study aims to compare the effects of different drainage tube diameters (22F vs. 26F) combined with negative pressure suction on patients after valve replacement surgery, including postoperative indicators and complications. Methods: A total of 104 patients undergoing valve replacement surgery were included and divided into a 22F group (45 patients) and a 26F group (59 patients). The basic characteristics, postoperative ICU stay duration, drainage duration, postoperative complications, and pain scores were compared between the two groups. All data were analyzed using SPSS statistical software, with p Results: There were no significant differences between the two groups in terms of age, sex, and underlying diseases. The ICU stay duration and drainage duration showed no significant differences (p > 0.05). The total drainage volume in the 22F group was significantly lower than that in the 26F group (225 vs. 380 ml, p = 0.035), and the pain scores on the third postoperative day were also significantly lower in the 22F group (p Conclusion: Compared to the 26F group, patients in the 22F group exhibited less postoperative drainage volume and lower pain scores, suggesting that the 22F drainage tube may have better clinical outcomes after valve replacement surgery.

Effect of Radial Resistance Gap on the Pressure Drop of a Compact Annular-Radial-Orifice Flow Magnetorheological Valve

A compact annular-radial-orifice flow magnetorheological(MR)valve was developed to investigate the effects of radial resistance gap on pressure drop.The fluid flow paths of this proposed MR valve consist of a single annular flow channel,a single radial flow channel and an orifice flow channel through structure design.The finite element modelling and simulation analysis of the MR valve was carried out using ANSYS/Emag software to investigate the changes of the magnetic flux density and yield stress along the fluid flow paths under the four different radial resistance gaps.Moreover,the experimental tests were also conducted to evaluate the pressure drop,showing that the proposed MR valve has significantly improved its pressure drop at 0.5 mm width of the radial resistance gap when the annular resistance gap is fixed at 1 mm.

Pneumatic resistance network analysis and dimension optimization of high pressure electronic pneumatic pressure reducing valve

The structure and working principle of a self-deigned high pressure electronic pneumatic pressure reducing valve (EPPRV) with slide pilot are introduced.The resistance value formulas and the relationship between the resistance and pressure of three typical pneumatic resistances are obtained.Then,the method of static characteristics analysis only considering pneumatic resistances is proposed,the resistance network from gas supply to load is built up,and the mathematical model is derived from the flow rate formulas and flow conservation equations,with the compressibility of high pressure gas and temperature drop during the expansion considered in the model.Finally,the pilot spool displacement of 1.5 mm at an output pressure of 15MPa and the enlarging operating stroke of the pilot spool are taken as optimization targets,and the optimization is carried out based on genetic algorithm and the model mentioned above.The results show that the static characteristics of the EPPRV are significantly improved.The idea of static characteristics analysis and optimization based on pneumatic resistance network is valuable for the design of pneumatic components or system.

STUDY ON VARIATION OF SETTING AND STOPPING PRESSURES OF SAFETY VALVE WITH STRUCTURAL MODIFICATION

The possibility of pressure control with the structural change of a safety valve is investigated Safety valve is commonly used as safety devices for numerous applications which include boilers,ships,industrial plants,and piping Setting and stopping pressures of a safety valve, p set and p sto ,are traditionally adjusted with a fine tuning of seat ring and valve ring heights, h sr and h vr However, it is not easy to achieve the proper setting and stopping pressures of a safety valve in practice The depth of inside and outside grooves in a valve, d i and d o are modified and their effects on setting and stopping pressures of a safety vlave are tested The most appropriate values appear 1 0 mm in d i and 0 5～1 0 mm in d o,respectively The valve ring height, h vr ,shows that the best results can be achieved at 2 3 mm for setting pressures of 0 1～0 4 MPa and 1 0 mm for setting pressures of 0 5～1 0 MPa The stopping pressures increases with the increase of seat ring height, h sr , upto certain h sr value and then becomes independent to the seat ring height This implies that there exists the optimum h sr ,which provides the largest flow rate and the proper stopping pressure Stopping pressures of a safety valve are adjusted with the seat ring and valve ring heights This study,however,demonstrated that the modification of value grooves also changes setting and stopping pressures of a safety valve Therefore,the proper selection in dimensions of the inside and outside grooves should be considered for the safety valve design

PRESSURE COMPENSATION METHOD OF UNDERWATER HYDRAULIC SYSTEM WITH HYDRAULIC POWER UNIT BEING UNDER ATMOSPHERIC CIRCUMSTANCE AND PRESSURE COMPENSATED VALVE

Based on the analysis of the-state-of-the-art of pressure compensation of underwater hydraulic systems （UHSs）, a new method of pressure compensation of UHSs, whose hydraulic power unit is in the atmospheric circumstance, is proposed. And a pilot-operated relief valve with pressure compensation is realized. The pressure compensation precision is guaranteed by direct detection. Its dynamic performance and stability are improved by a dynamic feedback. Theoretical study, simulation and experiment show that the pilot-operated relief valve with pressure compensation has a fine property of tracking underwater ambient pressure and meet the requirement of underwater ambient pressure compensation.

Pressure Regulating Pressure of A New Pressure Regulating Valve with Spring

A new type of pressure regulating valve for agriculture irrigation, which used spring to regulate pressure was studied. Through the spring regulating pres-sure test, it concluded that for the pressure regulating valve with same spring mod-el, the outer pressure became smal er than the inlet pressure of the system and with the changes of inlet pressure, the outlet pressure remained almost the same, and that when inlet pressure was constant, the valve with smal er spring diameter had lower outlet pressure, indicating that the pressure regulating effect of the spring was more obvious with smal er diameter.

Study on a Novel Digital Electro－Hydraulic Pressure Valve with a Capillary Damping Tube Regulating Pressure

A digital electro-hydraulic 4-port differential pressure control valve with a novel principle and structure is presented. The valve is designed by applying the regulating pressure technique of a capillary damping tube and also making full use of double freedom of the spool motion. Thevalve can implement digitizing interface easily. The theoretical analysis and experimental resultsshow that the valve is not only very simple in structure and convenient in use, but also has manygood properties, such as fast response, no-null-shift, etc.

DESIGN OF NOVEL HIGH PRESSURE-RESISTANT HYDROTHERMAL FLUID SAMPLE VALVE

Sampling study is an effective exploration method, but the most extreme environments of hydrothermal vents pose considerable engineering challenges for sampling hydrothermal fluids. Moreover, traditional sampler systems with sample valves have difficulty in maintaining samples in situ pressure. However, decompression changes have effect on microorganisms sensitive to such stresses. To address the technical difficulty of collecting samples from hydrothermal vents, a new bidirectional high pressure-resistant sample valve with balanced poppet was designed. The sample valve utilizes a soft high performance plastic ＂PEEK＂ as poppet. The poppet with inapposite dimension is prone to occur to plastic deformation or rupture for high working pressure in experiments. To address this issue, based on the fmite element model, simulated results on stress distribution of the poppet with different structure parameters and preload spring force were obtained. The static axial deformations on top of the poppet were experimented. The simulated results agree with the experimental results. The new sample valve seals well and it can withstand high working pressure.

Effect of Dynamic Pressure Feedback Orifice on Stability of Cartridge-Type Hydraulic Pilot-Operated Relief Valve

Current research on pilot-operated relief valve stability is primarily conducted from the perspective of system dynamics or stability criteria,and most of the existing conclusions focus on the spool shape,damping hole size,and pulsation frequency of the pump.However,the essential factors pertaining to the unstable vibration of relief valves remain ambiguous.In this study,the dynamic behavior of a pilot-operated relief valve is investigated using the frequency-domain method.The result suggests that the dynamic pressure feedback orifice is vital to the dynamic characteristics of the valve.A large orifice has a low flow resistance.In this case,the fluid in the main spring chamber flows freely,which is not conducive to the stability of the relief valve.However,a small orifice may create significant flow resistance,thus restricting fluid flow.In this case,the oil inside the main valve spring chamber is equivalent to a high-stiffness liquid spring.The main mass-spring vibration system has a natural frequency that differs significantly from the operating frequency of the relief valve,which is conducive to the stability of the relief valve.Good agreement is obtained between the theoretical analysis and experiments.The results indicate that designing a dynamic pressure feedback orifice of an appropriate size is beneficial to improving the stability of hydraulic pilot-operated relief valves.In addition,the dynamic pressure feedback orifice reduces the response speed of the relief valve.This study comprehensively considers the stability,rapidity,and immunity of relief valves and expands current investigations into the dynamic characteristics of relief valves from the perspective of classical control theory,thus revealing the importance of different parameters.

Lumped Parameter Mass Flow Rate and Pressure Control Characteristics Model for High-Speed Pneumatic PWM on/off Valve

Aiming at solving the problem of strong coupling characteristic of the key parameters of high-speed pneumatic pulse width modulation( PWM) on / off valve, a general lumped parameter mathematical model based on the valves time periods was well developed. With this model,the mass flow rate and dynamic pressure characteristics of constant volumes controlled by high-speed pneumatic PWM on /off valves was well described. A variable flow rate coefficient model was proposed to substitute for the constant one used in most of the prior works to investigate PWM on /off valves' dynamical pressure response, and a formula for disclosing the inherent relationship among the PWM command signal,static mass flow rate,and sonic conductance of the valve was newly derived.Finally,an extensive set of analytical experimental comparisons were implemented to verify the validity of the proposed mathematica model. With the proposed model, PWM on /off valves' characteristics,such as mass flow rate,step pressure response of the valve control system,mean pressure and ripple amplitude,not only in the linear range,but also in the nonlinear range can be wel predicted; Good agreement between measured and calculated results was obtained,which proved that the model is helpful for designing a control strategy in a closed loop control system.

Equilibrating Pressure with Auto-Control Valve in Water Distribution Networks

This paper probes into the feasibility of equilibrating pressure of water distribution network through (using auto-control valves) in theory and in the economy. An optimal valve control model is designed to minimize the sum of squares of residual pressure in the network. Such an analog simulation has been performed on the year 2003 programming network of a certain littoral district in North China, through which this paper confirms that it is feasible to equilibrate pressure with auto-control valves in theory. The research work has brought about a discovery of applicable conditions of valves in economic feasibility, which avoids a great economic loss due to the wild use of auto-control valve. In addition, simulated annealing algorithm is applied to optimize valve settings and shown to identify global optimum or near-optimum.

Development of a Novel Parallel-spool Pilot Operated High-pressure Solenoid Valve with High Flow Rate and High Speed

High-pressure solenoid valve with high flow rate and high speed is a key component in an underwater driving system.However,traditional single spool pilot operated valve cannot meet the demands of both high flow rate and high speed simultaneously.A new structure for a high pressure solenoid valve is needed to meet the demand of the underwater driving system.A novel parallel-spool pilot operated high-pressure solenoid valve is proposed to overcome the drawback of the current single spool design.Mathematical models of the opening process and flow rate of the valve are established.Opening response time of the valve is subdivided into 4 parts to analyze the properties of the opening response.Corresponding formulas to solve 4 parts of the response time are derived.Key factors that influence the opening response time are analyzed.According to the mathematical model of the valve,a simulation of the opening process is carried out by MATLAB.Parameters are chosen based on theoretical analysis to design the test prototype of the new type of valve.Opening response time of the designed valve is tested by verifying response of the current in the coil and displacement of the main valve spool.The experimental results are in agreement with the simulated results,therefore the validity of the theoretical analysis is verified.Experimental opening response time of the valve is 48.3 ms at working pressure of 10 MPa.The flow capacity test shows that the largest effective area is 126 mm2 and the largest air flow rate is 2320 L/s.According to the result of the load driving test,the valve can meet the demands of the driving system.The proposed valve with parallel spools provides a new method for the design of a high-pressure valve with fast response and large flow rate.

Pressure Surge Dependence on Valve Operations in a Pipeline Loading System

This paper discusses the influence of valve operations on pressure surge in a pipeline. The valve is a protective type which remains open in a pipeline loading system during normal operation but shut down the system when there is an emergency such as storm. The data for the study were obtained from measurements at Agbada 1 flow station as well as log sheets. Also, calculations were made using existing and derived formulas to obtain the values of Crude Oil and Pipe parameters that could not be measured directly or derived from data or log sheets. Surge analysis was carried out on the pipeline system to ascertain changes in pressure and flow rates along the pipeline following valve shut down at any time using developed pressure and flow equations. The results of the simulation analysis showed remarkable changes in the fluid pressure and flow rates along the pipe on shut down at any time. The pipeline recorded the highest pressure of 37.4 bar against initial pressure of 25 bar at length 6000 m in 1.5 second valve closure. There is also remarkable pressure drop along the pipe capable of reducing the crude oil pressure below its vapour pressure. The flow is turbulent even before valve operation with Reynolds number as high as 57024.53. The model equations compute changes in pressure and flow rates at different points in a pipeline installed with emergency-relief coupling valve. This enables point of extreme and low pressure to be detected accurately in a pipeline which guides the engineer while positioning surge suppression devices which cushion the effects of pressure surge in any pipeline.

DYNAMIC CHARACTERISTICS OF ELECTRO-HYDRAULIC PROPORTIONAL PRESSURE-FLOW HYBRID VALVE

The structure principles under the flow and pressure working conditions are studied, in order to investigate the dynamic characteristics of the electro-hydraulic proportional pressure-flow hybrid valve. According to the structure principles under the two different working conditions, the transfer functions under such conditions are derived. With the transfer functions, some structure elements that may affect its performance, are investigated, afterwards some principles of optimality and effective methods for improving the dynamic performance of the valve are proposed. The conclusions can be used to instruct engineering applications and products designing. The test results conform to the results of the theoretical analysis and simulation, which proves the correctness of the study and simulation works.

Pressure pulsation in stages of electric submersible pump at shut-off under various speeds

Electric submersible pumps were widely used in agricultural fields,petroleum and various other industries. The pressure pulsation caused fatigue failure due to vibration in electric submersible pump and affects the life and performance of its system. The objective of this study was to experimentally investigate the characteristics of pressure pulsation which were generated at various stages of a multistage electric submersible pump during closed valve operation at different speeds. An electric submersible pump with five stages was selected for conducting experiments. A variable frequency drive( VFD)was used to operate the electric submersible pump at five different speed settings from 40 to 60 Hz. Piezoresistive pressure transducers were mounted at each stage of the electric submersible pump to capture the unsteady pressure signals. At each speed setting,the electric submersible pump was operated at the shut-off condition and the signals of unsteady pressure from all the five stages were captured. A fast fourier transformation( FFT) was carried out on the pressure signals to convert into frequency domain.From the spectra of pressure pulsation signals,the characteristics of pressure pulsation are obtained for each stage and for various speed settings which were then used to understand its variation with speed and stages.

Long-term success of ahmed glaucoma valve in refractory glaucoma

AIM:To evaluate the long-term results and complications of ahmed glaucoma valve (AGV) implantation in refractory glaucoma.· METHODS:A retrospective review of 13 patients (13 eyes) with refractory glaucoma who underwent AGV implantation and had a minimum follow-up of 18 months was performed.All patients underwent a complete ophthalmologic examination and intraocular pressure (IOP) measurement before surgery and at 1 month,3 months,6 months,1 year after surgery and yearly afterwards.Complications and the number of antiglaucoma medications needed were recorded.· RESULTS:Mean age was 27.3±16.0 years.All eyes (100%) had at least one prior incisional surgery.Mean follow-up was 61.3±30.8 months.IOP was reduced from a mean of 35.0±7.0mmHg to 18.2±7.9mmHg at 12 months and to 17.0±4.1mmHg at 96 months (P <0.05) with a lower number of medications from baseline,76.9% patients required additional procedures to achieve the success criteria set by previously published series.The most common complications were encapculated cyst formation in eight eyes (61.5%) and tube exposure in four eyes (30.8%).· CONCLUSION:Encapsulated cyst formation was the most common complication which hindered succesful IOP control after AGV implant insertion for refractory glaucoma.Despite cyst excision with anti-fibrotic agents,successful IOP reduction was not achieved in 76.9% of the patients without antiglaucoma medication.

RESEARCH ON THE PERFORMANCE OF NEW TYPE OF PROPORTIONAL PESSURE AND FLOW CONTROL VALVE

A new closed loop flow controlling principle through correcting the valve'sopening area while load pressure is changing is carried out. Further more a principle using only oneproportional valve to compound control pressure and flow is suggested. By using very simpleproportional throttle valve in structure, the functions that five kinds of proportional valves orany two of them combined possess can be complimented. After analyzing, comparing, and testing thedynamic and static characteristics of valve with different controlling principles and main valvestructure styles, the optimized structure styles and control methods are achieved.

Numerical Simulation and Analysis of Gas Flow Field in Serrated Valve Column

A three-dimensional computational fluid dynamics （CFD） model for gas flow through a serrated valve tray was presented. The flow field, as well as the dry-pressure drop of the valve under the full-opening condition was simulated based on the proposed model by using FLUENT 6.0 software. Compared with the values of dry-pressure dro.p in different turbulent models, the.simulated.results using RNG κ-ε model are in reasonable agreement with experimental data, indicating that RNG κ-ε model is suitable in simulating gas flow through the serrated valve tray. Then the CFD model combining RNG κ-ε model was used to study the three-dimensional gas flow through the considered serrated valve tray. The simulated results showed that various eddies existed on the serrated valve tray, and both the eddy and the non-eddy areas were nearly equal. The existence of addendum can decrease the eddy area caused by gas passing through the lateral outlet slots. The size of eddies can be reduced by optimizing the distance between valves.

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.