Check Valve Research Articles

Transient performance of a dual disc check valve during the opening period

Check valves are essential components to prevent reverse flow within the nuclear industry. Check valves enable the parallel pump systems operating at part load that only some of their branches are put into operation, consequently energy is saved. Many researchers have focused on check valve closure transient and the water hammer phenomena induced, yet few papers have been published on its opening transient characteristics. This paper elaborates on the transient study of a dual disc check valve during the opening period. An unsteady CFD method is applied to simulate the transient characteristics and the internal flow field of the check valve. The experiment of transient characteristics is conducted on a typical pump-valve test bench, which verifies the validity of the CFD results. An approximation of disc rotation characteristics is given, based on the comparison between the experimental results and the CFD approaches. The approximation method is verified on another check valve simulation with different boundary conditions and external moments. The visualization of the internal flow field evolutions is analyzed for a better understanding of the flow fields inside the check valve and its transient characteristics. This paper gives a detailed description of dual disc check valve opening during the pump starting period.

Моментные характеристики обратных клапанов в наклонных трубопроводах

Моментные характеристики обратных клапанов в наклонных трубопроводах

Development of a pulsating heat pipe with a directional circulation of a working fluid

The paper presents the results of development and experimental investigation of a pulsating heat pipe (PHP) with check valves (CV). The PHP was made of a copper capillary tube with an inside diameter of 1.25mm and curved in the form of a flat spiral with a total of 40 turns. The PHP was joined to an aluminum plate, which served as a thermal interface for contact with the heat-load source and sink. The working fluid was freon R-152a. Tests were conducted to compare the efficiency of two types of CV: one was patterned after a capillary barrier, the other, after a floating ball valve. The tests were carried out in the horizontal mode and the top heat mode. The results of the experiments have shown the high efficiency of ball check valves and the inefficiency of capillary barriers for organizing a directional circulation of a working fluid. It was shown that ball check valves made it possible to organize a directional circulation of a working fluid. At the cost of this the isothermality of the PHP heating zone increases, and its thermal resistance and orientation sensitivity decrease. Besides, the value of the limiting heat load increases by 10–14%.

Modeling of a Fast Plate Type Hydraulic Check Valve

Check valve dynamics plays an important role in many fluid systems, such as in compressors, hydraulic pumps, and hydraulic switching converters. Plate type check valves are a frequently employed valve type in dynamically challenging cases. Despite the relevancy of plate valve dynamics, only few exhaustive works can be found in the literature, focusing on the behavior of hydraulic check valves for high-frequency applications. This paper presents an in-depth characterization of a plate valve designed as rectifier of a high-frequency oscillation pump working at 300 Hz. The aim is to identify a sufficiently simple mathematical model, which permits to optimize the design of the valve for the considered application. The paper analyses the different phenomena contributing to the dynamics of such a valve and presents the results of simulation and experimental activity. The results show how small details in the design and manufacturing of those valves (namely, the contact surfaces) have important consequences on the dynamics of the pump system. In general, a good agreement between model and reality is achieved.

냉열발전을 위한 극저온 체크밸브의 유동해석

Abstract: Swing check valve is opened when the flow direction is forward, when the flow is reversed, the valve is automatically closed by back pressure. In this study, the internal flow field analysis of the valve was conducted by Fluent. The working fluid used in the study, using liquefied methane -165 ℃ (CH4) and velocity field, pressure field, pressure drop coefficient were simulated by varying separately the opening divergence into four intervals from 0 to 100%. The approximate research result are as follow : When the opening divergence is smaller, it appears high pressure on the upstream side, this value is relaxed when the opening divergence is large. Flow rate coefficient of the valve shows a larger value as the degree of opening becomes larger, confirming that the check valve used in the study is in the effective flow rate counting range. Key Words ：Cryogenic, LNG, Swing Check Valve, Flow Analysis, Flow Coefficient, Pressure Drop Coefficient *†문정현(교신저자) : 선박해양플랜트연구소 해수플랜트연구센터E-mail : moonjh@kriso.re.kr, Tel : 033-630-5028 *†Jung-Hyun Moon(corresponding author) : Korea Research Institute of Ships & Ocean Engineering, Seawater Utilization Plant Research CenterE-mail : moonjh@kriso.re.kr, Tel : 033-630-5028

발전소용 Y형 체크밸브에 관한 수치해석 연구

발전소용 Y형 체크밸브에 관한 수치해석 연구

Check valve slam analysis in pumping station

Pumping station supplies water for technological process. The check valve in the station was replaced with a new one. The regular test of black out discovered the high pressure pulsations accompanied with noticeable pipeline movement of discharge pipe. It was caused by late check valve closing, probably, when the back flow reached the highest possible velocity. This statement was supported with analysis of results of pressure measurement near the check valve and with a numerical simulation of the flow in the pipeline system.

宇宙用逆止弁付振動流型ヒートパイプの軌道上実証結果

宇宙用逆止弁付振動流型ヒートパイプの軌道上実証結果

A Simulation Study of Spring Quotient's Impact upon the Opening Process of Passive Shuttle Check Valve

A Simulation Study of Spring Quotient's Impact upon the Opening Process of Passive Shuttle Check Valve

A Novel Approach Using a System Dynamic Model for Logistics Adjustments of Check Valve Flow

A Novel Approach Using a System Dynamic Model for Logistics Adjustments of Check Valve Flow

Numerical Simulation of Closing Process of Shuttle Check Valve

For studying the kinetic characteristics of passive shuttle check valve at the moment that it closes its valve core on the condition of high pressure differences, this paper first constructs the equation of motion of the valve core and twodimensional geometrical model by using computation fluid dynamics method, then with the help of the calculation method and physical model provided by Fluent software, employing the dynamic mesh and user-defined functions, simulates the unsteady flow in the valve core’s closing process under the different pressure fluctuations, and obtains the stress nephogram, the velocity vector diagram, the speed curve, and pressure curve of the interior flow field of the valve. The results show that the bigger the value of valve fluctuation is, the larger the fluid pressure that the valve core is subjected to, the openness of the core and the speed fluctuation of the core are, and that in the case of sudden decompression at the entrance, the core can be shut down quickly with the steady speed field and pressure field. The simulation results are conducive to the design and optimization of structure parameter of shuttle check valve.

Parametric Consideration of a Thermal Water Pump and Application for Agriculture

This research studied the effects of suction heads on the efficiency of a thermal water pump with steam. In order to save energy, the authors also studied the appropriate amount of air added to a steam working fluid. Cooling time was attempted to be shorten, direct contact cooling was employed. The system comprised feed water tank (FT), liquid piston tank (LT), heat tank (HT), storage tank (ST), well tank (WT), and check valve (CV). It was directly cooled by cooling water. Thermal energy input was supplied by an electric heater as a substitute of heat sources such as firewood. An operation of the pump consisted of five stages: heating, pumping, vapor-flow, cooling, and suction. In conclusion, increasing the suction head raised the pumping efficiency until the maximum was achieved. Using air in conjunction with the steam working fluid could lower the working temperature suitable for solar application. In addition, the simulation of a thermal pump with steam was merely presented. A good agreement between the test and the model was found. The larger pump size was selected to be constructed and tested in order to increase the pump efficiency. Agricultural application of the larger pump could obtain energy source from waste of firewood at no cost.

ICONE23-1896 DEVELOPMENT OF CHECK VALVE INSPECTION SYSTEM

We have developed Check Valve Inspection System using acoustic emission sensor and ultrasonic sensor, for the purpose of detecting degradation and detailed operating state (Full open, Tapping, Oscillation, etc.) of the swing check valve. The operating state of the swing check valve is identified as follow. First, the rough location of swing arm or disk is examined by obtaining the reflected echo from valve disk. Second, the detail motion of swing arm or disk, whether the valve disk is oscillating or is stable, is determined by analyzing the observation time of the reflected echo. Finally, it is investigated using acoustic emission sensor to see if the disk or the arm is tapping against the backstop repeatedly. Degradation in the valve is evaluated by detecting acoustic pulses collected by acoustic emission sensor. If such deterioration progresses in the driving parts, the number of acoustic pulses by collision increases. The rate of deterioration of the swing check valve is determined from the change in the number of acoustic pulses. As an example of the application of the system, the case of check valves in the seawater system line installed in a nuclear power plant were shown. The examination was carried out before and after replacing the check valve. By comparing the results of the inspection system and the results of overhaul, the detectability of the inspection system was evaluated.

ТЕПЛОВЫЕ ХАРАКТЕРИСТИКИ СИСТЕМЫ, СОСТОЯЩЕЙ ИЗ ЗАМКНУТОЙ ТЕПЛОВОЙ ТРУБКИ И ЗАПОРНЫХ КЛАПАНОВ, ПРИ РЕЖИМЕ НАГРЕВА СВЕРХУ ОСЦИЛЛИРУЮЩЕГО ПОТОКА РАБОЧЕЙ ЖИДКОСТИ

ТЕПЛОВЫЕ ХАРАКТЕРИСТИКИ СИСТЕМЫ, СОСТОЯЩЕЙ ИЗ ЗАМКНУТОЙ ТЕПЛОВОЙ ТРУБКИ И ЗАПОРНЫХ КЛАПАНОВ, ПРИ РЕЖИМЕ НАГРЕВА СВЕРХУ ОСЦИЛЛИРУЮЩЕГО ПОТОКА РАБОЧЕЙ ЖИДКОСТИ

Development of novel passive check valves for the microfluidic CD platform

Microfluidic CD platforms are utilized to perform different biological processes and chemical analyses. In general, a microfluidic CD implements the centrifugal force that is created by the spinning of the platform to pump liquid through the microfluidic network of chambers and channels. Over the last few decades, a wide range of active and passive valving methods were proposed and tested on various microfluidic platforms. Most of the presented valves are too complex to design and involve lengthy fabrication processes. In this paper, easy to fabricate air and liquid check valves for centrifugal microfluidic platforms are presented: a Terminal Check Valve (TCV) and a Bridge Check Valve (BCV). To understand the characteristic of the proposed valves, theoretical and experimental studies are conducted. Moreover, to test the effectiveness of these valves, liquid swapping is demonstrated by integrating TCV and BCV chips with thermo-pneumatic (TP) pumping on a CD. The valves are shown to accurately control flow direction which makes them an excellent choice for a variety of complex microfluidic processes. The experimental and theoretical results also indicate that these valves require low pressure for actuation. Furthermore, the theoretical results confirm the ability to adjust the required actuation pressure by changing the valve chip size. Finally, as a proof of concept for implementing the check valves on a biological application, an enzyme linked immunosorbent assays (ELISA) is performed. The result shows that the TCV and BCV valving chips enhance the operating range of the processes that can be performed on the microfluidic CD.

Pressure Transients Caused by Tilting-Disk Check-Valve Closure

Check valves are normally installed at pumping stations to prevent reverse flow through pumps after pump shutdown. Check-valve slam appears to be among the most common causes of water hammer in water supply systems. A methodology for the selection of a suitable check valve for a new pumping station to prevent water hammer after pump shutdown appears to be inadequate at present. A method for analyzing pressure surges caused by check-valve closure after pump shutdown, taking into account valve characteristics as well as characteristics of the pumping system, is proposed in this paper. This method can be used to select the most economical check valve at the design stage that will prevent slamming by limiting the pressure surge to a desired value.

Damping of Self-Excited Pressure Pulsations in Petrodiesel Pipeline

A pumping station in a fuel storage suffered from pressure pulsations in a petrodiesel pipeline. Check valves protecting the station against back flow made a big noise when disc hit a seat. Due to employees complaints we were asked to solve the problem, which could lead to serious mechanical problems. Pressure measurement in the pipeline showed great pulsations, which were caused by self-excited oscillation of control valves at the downstream end of pipeline. The operating measurement did not catch it because of too low sampling frequency. One dimensional numerical model of the whole hydraulic system was carried out. The model consisted of check valve, pipeline and control valve, which could oscillate, so it was possible to simulate the unsteady flow. When the model was validated, a vessel with nitrogen was added to attenuate pressure pulsations. According to the results of numerical simulation, the vessel was installed on the location. Subsequent measurement proved noticeably lower pulsations and almost no noise.

A Fuzzy Logic Based Model to Predict Weld Width – A Case Study of Hard Facing Process Using MIG Welding on Dual Plate Check Valve

Welding input parameters play a very significant role in determining the quality of a weld joint. The joint quality can be defined in terms of weld-bead geometry. The 23 replication with 4 center points experiments are performed on non-return valve material WCB by varying various MIG Welding process parameters. Here welding current, welding speed and gas flow rate are considered as input parameters with two levels. A fuzzy model is developed to predict the weld width in context of these input parameters. Fuzzy model uses fuzzy expert rules, triangular membership function and centroid area method for defuzzyfication process using MATLAB fuzzy logic tool box. The developed model is validated by performing experiments at center points. The result shows prediction may lie in the range of 95.18-100%.

Coupled Physics Modelling for Bi-Directional Check Valve System

This paper describes the development of a high speed on/off bi-directional check valve. The design was characterized using coupled-physics modelling tools, and a prototype was constructed and tested in the laboratory. The simulated and experimental results were compared. The high speed on/off bi-directional check valve (BDCV) utilizes positive feedback of flow forces and differential port pressure to quickly open and close the primary poppet. The coupled-physics model incorporates mechanical and fluid domains, which was solved through conducting finite element analysis (FEA) on a 2D planar model. After characterizing the BDCV, the system model was expanded for a single piston pumping system using two BDCVs and the simulation on system full displacement pumping was conducted. The modelling results showed a moderate agreement with measurements, which demonstrated the capability of the coupled physics model to effectively investigate the dynamic performances of a BDCV operating in a digital pump system.

The Study on Small Generator using a Hydraulic for Sensor Nodes

This paper is to realize an electric power generator utilizing wave force through hydraulic mechanism. The wave power generator using hydraulic mechanism is very useful since it produces energy in the ocean. This experiment used a check valve, oil pressure tube, and generator to embody the wave power generator through hydraulic mechanism. Check valve was used to make the fluid flow in one direction, and oil pressure tube for the movement of the fluid. The volume and pressure of the fluid in the structure were calculated. The factors which affected the volume and pressure of the fluid in the structure were analyzed. And the results from this study shall be applied to the actual marine construction, and utilized in the research for the reinforcement of the structure.