Effect of Oil on the Dynamics of Compressor Suction Valve

1997 ◽  
Author(s):  
H. Ezzat Khalifa ◽  
Xin Liu
Keyword(s):  
Relative Effect ◽  
Viscous Force ◽  
Reciprocating Compressor ◽  
Cylinder Pressure ◽  
Oil Viscosity ◽  
Valve Seat ◽  
Rapid Release ◽  
Valve Stiction ◽  
Valve Opening ◽  
Reed Valve

Abstract The presence of oil on the suction valve of a reciprocating compressor has long been known to be responsible for the so-called valve stiction phenomenon. With stiction, the opening of the valve is delayed until later in the suction stroke, which results in a reduction in volumetric efficiency and increases the probability of valve failure. In this paper, a model is presented for analyzing the dynamic behavior of a round reed valve in the presence of oil. It is shown that the primary reason for stiction is the viscous force arising from dilating the oil film between the valve and its seat. This dilation takes place as the cylinder pressure on one side of the valve reed falls below the suction pressure in the intake plenum upstream of the valve. The viscous force delays the valve opening until later in the suction stroke. Because the film dilation resistance is directly proportional to the oil viscosity and decreases rapidly as the film thickens, the film eventually breaks and the valve begins to accelerate rapidly until it impacts the valve stop. The delayed rapid release of the valve and the associated impact are shown to subject the valve to much higher forces than would be experienced without the effect of stiction. The relative effect of oil viscosity and valve/seat contact area on valve force is presented for a representative reciprocating compressor equipped with suction valves.

An Experimental Study on Opening Delay of a Reed Valve for Reciprocating Compressors

2011 ◽  
Author(s):  
Fumitaka Yoshizumi ◽  
Yasuhiro Kondoh ◽  
Kazunori Yoshida ◽  
Takahiro Moroi ◽  
Masakazu Obayashi ◽  
...  
Keyword(s):  
High Speed ◽  
Gas Flow ◽  
Valve Seat ◽  
Film Rupture ◽  
Air Conditioners ◽  
Oil Film ◽  
Gas Compression ◽  
Valve Opening ◽  
Reed Valve ◽  
Opening Process

Automatic reed valves are widely used to control refrigerant gas flow in reciprocating compressors for automotive air conditioners. The oil film in the clearance between the reed and the valve seat causes a delay in opening of the valve. This opening delay of the discharge valve leads to over compression, which increases losses such as friction in sliding components and gas overheating. Therefore it is important to understand the behavior both of the oil film and the elastic reed deformation in order to reduce losses due to the delay. This study aims to develop an experimental setup that enables simultaneous visualization of the oil film rupture and measurement of the reed deformation, and to observe this behavior during the valve opening process. The gas-compression stroke is simulated by controlling compressed air with an electromagnetic valve. The oil film rupture is visually observed using a high speed camera through a special valve seat made of glass. The total deformation of the cantilever reed is identified by multipoint strain measurement with 12 strain gauges. The experiment finds that the opening process is divided into four stages. In the first stage, the reed remains stuck to the seat and deforms while the bore pressure increases. In the second stage, cavitation occurs in the oil film and the film starts to rupture. In the third stage, the oil film ruptures and the bore pressure starts to decrease. Finally, in the fourth stage, the reed is separated from the seat and the gas flows through the valve. Reducing the reed/seat contact area changes the reed deformation in the first stage, thereby increasing the reed/seat distance and realizing an earlier oil film rupture and a shorter delay.

Reciprocating compressor valve damage estimation under varying speeds through the acoustic emission technique

2019 ◽  
Vol 10 (5) ◽  
pp. 621-633
Author(s):  
Hoi-Yin Sim ◽  
Rahizar Ramli ◽  
Ahmad Saifizul
Keyword(s):  
Acoustic Emission ◽  
Regression Analysis ◽  
Flow Rate ◽  
Reciprocating Compressor ◽  
Damage Estimation ◽  
Content Type ◽  
Air Compressor ◽  
Ae Signal ◽  
Valve Opening ◽  
Ae Signals

Purpose The purpose of this paper is to examine the effect of reciprocating compressor speeds and valve conditions on the roor-mean-square (RMS) value of burst acoustic emission (AE) signals associated with the physical motion of valves. The study attempts to explore the potential of AE signal in the estimation of valve damage under varying compressor speeds. Design/methodology/approach This study involves the acquisition of AE signal, valve flow rate, pressure and temperature at the suction valve of an air compressor with speed varrying from 450 to 800 rpm. The AE signals correspond to one compressor cycle obtained from two simulated valve damage conditions, namely, the single leak and double leak conditions are compared to those of the normal valve plate. To examine the effects of valve conditions and speeds on AE RMS values, two-way analysis of variance (ANOVA) is conducted. Finally, regression analysis is performed to investigate the relationship of AE RMS with the speed and valve flow rate for different valve conditions. Findings The results showed that AE RMS values computed from suction valve opening (SVO), suction valve closing (SVC) and discharge valve opening (DVO) events are significantly affected by both valve conditions and speeds. The AE RMS value computed from SVO event showed high linear correlation with speed compared to SVC and DVO events for all valve damage conditions. As this study is conducted at a compressor running at freeload, increasing speed of compressor also results in the increment of flow rate. Thus, the valve flow rate can also be empirically derived from the AE RMS value through the regression method, enabling a better estimation of valve damages. Research limitations/implications The experimental test rig of this study is confined to a small pressure ratio range of 1.38–2.03 (free-loading condition). Besides, the air compressor is assumed to be operated at a constant speed. Originality/value This study employed the statistical methods namely the ANOVA and regression analysis for valve damage estimation at varying compressor speeds. It can enable a plant personnel to make a better prediction on the loss of compressor efficiency and help them to justify the time for valve replacement in future.

Mechanism Design of Equivalent Simulation of Cylinder Pressure Load in Reciprocating Compressor Fault System

2019 ◽  
Vol 893 ◽  
pp. 84-88
Author(s):  
Shun Gen Xiao ◽  
Meng Meng Song ◽  
Xiao Hu Sang ◽  
Li Xia Huang ◽  
Hong Long Chen ◽  
...  
Keyword(s):  
Test Bench ◽  
Fault System ◽  
Time Varying ◽  
Reciprocating Compressor ◽  
Cylinder Pressure ◽  
Motion Simulation ◽  
Compression Process ◽  
Pressure Load ◽  
New Ideas ◽  
New Type

In this paper, by designing a new type of mechanism, the time-varying cylinder load ofthe reciprocating compressor is simulated. The time-varying cylinder pressure load includes fourprocesses of expansion, suction, compression and exhaust, where the pressure of the expansionprocess is gradually reduced until it is equal to the suction pressure, and the pressures of the suctionand exhaust processes are almost constant. The pressure of the compression process is graduallyincreased until it is equal to the exhaust pressure value. Through the motion simulation of themechanism, four processes of time-varying cylinder pressure load can be realized. This newmechanism will provide new ideas for the time-varying load involved in the simulation of thereciprocating compressor fault test bench.

A Novel Friction Model Basing on Journal Bearing Theory for Reciprocating Compressor

2013 ◽  
Vol 456 ◽  
pp. 320-323 ◽  
Author(s):  
Le Wang ◽  
Bin Tang ◽  
Yuan Yang Zhao
Keyword(s):  
Friction Coefficient ◽  
Piston Ring ◽  
Sliding Friction ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Dynamic Change ◽  
Friction Model ◽  
Reciprocating Compressor ◽  
Oil Viscosity ◽  
Compressor Performance

The paper presents a comprehensive friction model of reciprocating compressor which is able to evaluate friction losses in moving parts. The model consists of crankshaft, connecting rod and piston all supported by bearings as well as the piston ring/cylinder interface viewed as sliding friction. Hydrodynamic lubrication theory reveals relationship between load and friction coefficient and was demonstrated to be helpful to give insight to the lubrication characteristics of journal bearing. The model gave the composition of friction losses, friction coefficient dynamic change with orbiting angle and effect of oil viscosity on compressor performance. The results showed that the friction losses of piston ring/cylinder interface and the rod big end bearing was most part of the friction losses and it was necessary to choose suitable oil viscosity to reach the optimum compressor performance.

scholarly journals application based comparison of statistical versus deep learning approaches to reciprocating compressor valve condition monitoring

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Jason Kolodziej ◽  
Jacob Chesnes
Keyword(s):  
Deep Learning ◽  
Condition Monitoring ◽  
Frequency Analysis ◽  
Reciprocating Compressor ◽  
Learning Approaches ◽  
Early Assessment ◽  
Valve Seat ◽  
Repeated Impact ◽  
Time Frequency Analysis ◽  
Time Frequency

This paper presents a vibration-based condition monitoring approach for early assessment of valve wear in an industrial reciprocating compressor. Valve seat  wear is a common fault mode that is caused by repeated impact and accelerated by chatter. Seeded faults consistent with valve seat wear are installed on the head-side discharge valves of a Dresser-Rand ESH-1 industrial reciprocating compressor. Due to the cyclostationary nature of these units a time-frequency analysis is employed where targeted crank angle positions can isolate externally mounted, non-invasive, vibration measurements. A region-of-interest (ROI) is then extracted from the time-frequency analysis and used to train a suitably sized convolutional neural network (CNN). The proposed deep learning method is then compared against a similarly trained discriminant classifier using the same ROIs where features are extracted using texture and shape image statistics. Both methods achieve > 90% success with the CNN classification strategy nearing a perfect result.

An Analysis of the Engine Blowdown Process Using Multidimensional Computations

1987 ◽  
Vol 109 (4) ◽  
pp. 459-464 ◽  
Author(s):  
T. Uzkan
Keyword(s):  
Parametric Analysis ◽  
Initial Period ◽  
Cylinder Pressure ◽  
Global Features ◽  
Separation Line ◽  
Piston Speed ◽  
Crank Angle ◽  
Computational Code ◽  
Valve Opening ◽  
Speed Of Propagation

The details of the blowdown period were studied for the EMD-710 diesel engine by using a multidimensional computational code for in-cylinder flows. Computed results are presented describing both global and detailed features of the flow field during the blowdown period. Global features include variations of cylinder pressure, mass, angular momentum, turbulence kinetic energy, and the exhaust mass. A parametric analysis has shown that the percent pressure drop and the percent mass exhausted are almost invariable with the initial cylinder pressure or mass. Details of the mass convection process within the cylinder are investigated through development of the line separating the downward and upward flowing gas regions. The location and speed of propagation of this separation line are also found to be independent of initial cylinder pressure and mass. The results show that the speed of the separation line is about twice the piston speed for an initial period of 15 deg crank angle. Then it starts to decrease and becomes equal to the piston speed at about 26 deg after the exhaust valve opening. Beyond this time the separation line is slower than the piston speed.

Model Study on the Oil Stiction of a Discharge Reed Valve in Compressors

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Fumitaka Yoshizumi ◽  
Yasuhiro Kondoh ◽  
Takahiro Moroi ◽  
Shinji Tamano ◽  
Yohei Morinishi
Keyword(s):  
Film Thickness ◽  
Simulation Model ◽  
Contact Area ◽  
Delay Time ◽  
Bubble Radius ◽  
Oil Viscosity ◽  
Cavitation Model ◽  
Oil Film ◽  
Initial Film ◽  
Reed Valve

In a discharge reed valve for compressors, the oil stiction by the oil film between the reed and the valve seat is investigated experimentally, and a simulation model is developed. Through a model experiment, the initial oil film thickness is measured by an interferometry method, and the valve displacement and the bore pressure are measured from the stiction to the valve opening. The opening delay time together with the initial oil film thickness is measured while changing the contact area and the oil species. In the simulation model, the deformation of the reed and the pressure of the oil film as a result of cavitation are coupled. In order to take into account the tensile stress in the oil film, a cavitation model directly simulating the expansion of cavitation bubbles is developed (herein, dynamic cavitation model). In the experiment, a smaller contact area, a larger initial film thickness, and a smaller oil viscosity yield a shorter delay. In the simulation, the dynamic cavitation model is advantageous in representing the experimental delay time. In particular, with respect to the relationship between the initial film thickness and the delay time, the dynamic cavitation model with an initial bubble radius that depends on the oil film thickness yields results similar to the experimental results.

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