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Hydraulic Oil Leakage through a Pressure Reducing Valve Spool
H. A. Khan(하룬 아흐마드 칸),E. A. Jeong(정은아),J. W. Park(박정우),J. H. Hun(정황훈),S. N. Yun(윤소남) 유공압건설기계학회 2021 유공압건설기계학회 학술대회논문집 Vol.2021 No.11
Power losses in a hydraulic system are intrinsically linked to leakage, which is unwanted in any application. Depending on the use, pressure regulating valves feature two or three ports. Prior research on leakage in oil-hydraulic pressure reducing valves has not been extensively done which makes this study more significant. A data processing system and pressure sensors were installed as part of the experimental equipment used to test the valve. The test results were recorded and evaluated. The steady-state leakage of the valve was measured using a stop watch and a beaker with volume markings. Because of the unreliability of flow sensors at extremely low flow rates, a more fundamental method of volume per time was used. The valve was controlled by a solenoid with a variable output pressure. The leakage properties for various output pressures were investigated.
Investigation of Reliability of an Electro-Hydraulic Pressure Reducing Valve through Experiments
H. A. Khan(칸 하룬 아흐마드),S. N. Yun(윤소남),J. W. Park(박정우),Y. B. Ham(함영복),J. H. Park(박중호) 유공압건설기계학회 2020 유공압건설기계학회 학술대회논문집 Vol.2020 No.7
In this study, an electro-hydraulic proportional pressure reducing valve (EPPR valve) was tested to determine its reliability. The valve was subjected to a sinusoidal input voltage signal at a certain frequency. The output of the valve was sensed through a pressure transducer and recorded on a data acquisition system. The valve characteristics for different number of cycles are presented in this study. The results explain the durability or reliability of the valve for a certain number of operation cycles. The valve behavior was found to be consistent with time. Both static as well as dynamic characteristics of the valve were considered and documented. Pressure reducing valves are to control the pressure in a hydraulic circuit depending on application. In most applications, they are turned on and off frequently. This motivated us to determine the reliability or durability of such valves by turning them on and off continuously and monitoring the static and dynamic behavior.
M. Ijaz Khan,Sumaira Qayyum,S. Kadry,W. A. Khan,S. Z. Abbas 한국자기학회 2020 Journal of Magnetics Vol.25 No.1
Here nonlinear mixed convective entropy based nanofluid second order slip flow of magnetic and electric field is addressed. Both electric and magnetic field is considered for the problem formulation and the flow is generated by a stretched surface. Important slip factors, i.e., Brownian and thermophoresis diffusions are accounted. Total entropy rate subject to four types of irreversibilities (i) heat transfer (ii) chemical reaction (iii) fluid friction (iv) Joule or Ohmic heating is obtained through second law of thermodynamics. Thermal radiation, heat generation/absorption, dissipation, Brownian motion, Joule or Ohmic heating and thermophoresis effects are considered in the development of the energy equation. Activation energy to undergo the physical transportation or chemical transformation of atoms or molecules is further considered in the analysis of concentration. Firstly ordinary differential system is found, then numerically solved for flow field, entropy generation, concentration, temperature, skin friction, Nusselt number, Bejan number and Sherwood number through built-in- Shooting method.