• Journal of the Korean Society of Industry Convergence
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• v.25 no.1
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• pp.131-139
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• 2022

The exchange of goods over the sea is a situation in which the amount of trade between countries is gradually increasing. In order to maintain the optimal operating condition, the ship maintains stability and optimal operating conditions by inserting or withdrawing ballast water from the ballast tank according to the loading condition of cargo capacity is also increasing. Control valves play an important role in controlling fluid flow in these pipes. When the flow rate is controlled using a control valve, problems such as cavitation, flashing, and suffocating flow may occur due to high differential pressure, and in particular, damage to valves and pipes due to cavitation is a major problem. Therefore, in this study, the cavitation phenomenon is reduced by installing orifices at the front and rear ends of the high differential pressure control butterfly valve to reduce the sudden pressure drop at the limiting part of the butterfly valve step by step. The flow coefficient according to the shape of the orifice, the degree of cavitation occurrence, and the correlation were analyzed using a CFD(Cumputational Fluid Dynamics), and an optimal orifice design for reducing cavitation is derived.

• International Journal of Automotive Technology
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• v.8 no.2
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• pp.219-224
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• 2007

Recently, atmospheric contaminations has become worse due to the increased number of automobile. The PCV (Positive Crankcase Ventilation) valve acts as a flow control to allow re-combustion of blow-by gas by having it flow from a crankcase to an inlet manifold suction tube. Also, during the fabrication of the PCV valve, micro cracks may occur in the valve body and be extended under operation. The excessive stress distribution and crack initiation on the PCV valve body would bring an unstable blow-by gas flow rate control and would cause valve failure. The purpose of this study is to examine the crack affects on the stress and strain variations on the PCV valve according to the inlet and outlet manifold under differential pressures. From the results, we can explain the behavior of the crack extension for a safe condition of PCV valve.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.8
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• pp.107-114
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• 2021

Butterfly valves are used in various industries to control the flow rate, flow direction, pressure, and temperature. These are gaining popularity in the field of plant industry to enable high-differential pressure because of their low maintenance costs and ease of installation. This study presents a numerical analysis method to analyze changes in the flow characteristics of a high-differential pressure control butterfly valve based on the location and shape of the orifice. The numerical analysis was conducted using a commercial CFD program. The analysis results show a correlation between the orifice shape and cavitation phenomenon.

• Journal of the Korean Society of Safety
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• v.20 no.1 s.69
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• pp.36-41
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• 2005

PCV(Positive Crankcase Ventilation) valve acts as a flow control valve to get a re-combustion of blow-by gas by having it flow from a crankcase to an inlet manifold suction tube. The blow-by gas of the crankcase should be eliminated or taken properly because it cause corrosion to critical parts, and contributes to increase crankcase pressure that can cause a drop in efficiency. The excessive stress and strain on the PCV valve that remove these harmful gas would be bring the difficult on the flow rate control and failure of the valve. Those condition inevitably induce the accident. Therefore, this study purpose is FEM evaluation of the stresses and deformation in the X3 PCV model according to the change of the differential pressure between inlet and outlet. From results, the maximum equivalent stresses increased linearly according to the increase of the differential pressure at the about 50mm from the inlet position and were under the yield strength of the valve. And the deformations were relatively small regardless of the in-outlet differential pressure variation.

• Journal of the Semiconductor & Display Technology
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• v.7 no.3
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• pp.29-34
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• 2008

This paper describes the fabrication and characterization of a differential pressure type integrated mass-flow controller made of stainless steel for reactive and corrosive gases. The fabricated mass-flow controller is composed of a normally closed valve and differential pressure sensor. A stacked solenoid actuator mounted on a base-block is utilized for precise and rapid control of gas flow. The differential pressure flow sensor consisting of four diaphragms can detect a flow rate by deflection of diaphragm. By a feedback control from the flow sensor to the valve actuator, it is possible to keep the flow rate constant. This device shows a fast response less than 0.3 sec. Also, this device shows accuracy less than 0.1% of full scale. It is confirmed that this device is not attacked by toxic gas, so the integrated mass-flow controller can be applied to advanced semiconductor processes which need fine mass-flow control corrosive gases with fast response.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.4_2
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• pp.541-547
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• 2022

Before making a prototype, we predicted the inlet/outlet differential pressure and flow coefficient, which are the most basic design data for the valve through the design and numerical analysis of the trim, which is the most important in the localization development of the 1500Ib high differential pressure control valve used for boiler feed water. As a result, the design value and the analysis value were found to be about 98% similar. The flow field within the fluid velocity of 23m/s to prevent cavitation was also found. The result of the numerical analysis on thermal stress due to the characteristics of valves exposed to high temperatures showed that it was found to be about 18% less than the allowable stress of the bolt fixing the trim. When all loads such as pressure, self-weight, and vibration are applied, however, it is judged to go beyond the currently calculated thermal stress, exceeding the allowable stress.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3074-3079
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• 2007

The conventional control valves have been used at the locations occurring high differential pressure and high temperature which causes cavitation, flashing, severe vibration due to abrupt flow change, and sudden pressure drop. Previous studies concerning control valves focused to prevent damage of valve trim due to the internal leak and low flow rate. The newly designed helical trim of control valve has been installed at the location of high pressure change and high temperature in a power plant, and operated for evaluation. It is confirmed that the new control valve developed in this study generates flow characteristics in comparison with previous helical trim of control valves.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.230-231
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• 2005

As environmental problems are important, automotive industries are developing various techniques to prevent air pollution. One of these is Positive Crankcase Ventilation (PCV) system. It removes blowby gas which includes about 30% hydrocarbon of total generated quantity. In this system, a PCV valve is attached in a manifold suction tube to control the flow rate of blowby gas which generates differently according to various operating conditions of an automotive engine. As this valve is very important, designers are feeling to design it because of both small size and high velocity. For this reason, we numerically investigated to understand both spool dynamic motion and internal fluid flow characteristics. As the results, spool dynamic characteristics, i.e. displacement, velocity, acting force, increase in direct proportion to the magnitude of differential pressure and indicate periodic oscillating motions. And, the velocity at the orifice region decreases according to the increase of differential pressure because of energy loss which is caused by the sudden decrease of flow area at the orifice region and the increase of flow volume in the front of spool head. Finally, the mass flow rate at the outlet decreases with the increase of spool displacement. We expect that PCV valve designers can easily understand fluid flow inside a PCV valve with our visual information for their help.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.13 no.3
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• pp.9-15
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• 2017

In this study, set values of PICV(Pressure Independent Control Valve) were simulated according to the pressure distribution and velocity. The higher the set value and the open rate, as the lower the pressure in the neck. On the contrary, the lower the set value and open rate, as the higher the pressure in the neck. When the set value was small, the pressure was distributed sufficiently and confirmed that the pressure was generated by the VOF, confirming that it could generate a vapor pressure. When the set value 100 %, the lower corn open rate of the differential pressure was 46 % to 29 %, set value 100 % was 29 % to 19 %, and set value 6 % was 12 % to 6 % for the lower corn open rate percentile, it was limited to within 50 %. Thus, the results of this study on the correlation between open rate and differential pressure of the set value of the PICV will be beneficial to improve performance of flow control valves and contribute to their efficient operation used for a hydronic system.

• Journal of Drive and Control
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• v.16 no.2
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• pp.30-35
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• 2019

EPPR (Electro-hydraulic Proportional Pressure Reducing) valves are pressure control valves. In this study, an independent metering valve (IMV), which is a combination of a spool valve opened and closed with the help of an EPPR valve, was discussed. The overall performance of the valve (IMV) was obtained by the respective modeling and simulation of the system. The valve investigated in this study is to be used for independent metering of hydraulic excavator actuator e.g. boom, arm, bucket etc. To design the model, continuity equations and force balance equations were used. The set of differential equations were then simulated in Simulink using ODE45 option in the configuration toolbox. The valve has to be able to control the flow rate going in and out of the cylinder separately, which is why the particular configuration was needed and selected.