Experiences With Simulation of Reciprocating Compressor Valve Dynamics

1996 ◽  
Author(s):  
Brian Howes ◽  
Leonard Lin ◽  
Val Zacharias
Keyword(s):  
Gas Flow ◽  
Economic Effect ◽  
Operating Conditions ◽  
Valve Lift ◽  
Reciprocating Compressor ◽  
Compression Process ◽  
Flow Area ◽  
Valve Dynamics ◽  
Compressor Performance ◽  
Cylinder Flow

Experience with compressor valve modelling has shown that reciprocating compressor performance can sometimes be improved by subtle changes in valve design. Modelling has led to a better understanding of the physical behaviour of valves and of the compression process. Three compressor valve studies presented here demonstrate the benefits of valve modelling. Case 1 challenges the commonly held assumption that reducing the lift of a compressor valve will reduce the efficiency of the compressor. The capacity of this compressor is increased by reducing the valve lift. A plot of BHP/MMSCFD versus valve lift shows an inflection point that assists the analyst in optimizing the design. Case 1 also presents a method of calculating the economic effect of improvements in valve performance. Case 2 demonstrates the effect of inadequate flow area through the valve. Pressure in the clearance volume cannot decrease fast enough if flow areas are inadequate; the result is late valve closure, and therefore decreased valve life. Case 3 shows the importance of considering the design of the cylinder casting in addition to that of the valves. Here, insufficient cylinder flow area constricted gas flow. Since these cases were simulated, the analyst had the opportunity to evaluate the proposed solution over the entire range of operating conditions. He was able to select a valve which solved the immediate problem and be confident that it would perform adequately throughout the specified range of conditions.

Valve and In-Cylinder Flow Generated by a Helical Port in a Production Diesel Engine

1987 ◽  
Vol 109 (4) ◽  
pp. 368-375 ◽  
Author(s):  
C. Arcoumanis ◽  
C. Vafidis ◽  
J. H. Whitelaw
Keyword(s):  
Diesel Engine ◽  
Laser Doppler Anemometry ◽  
Operating Conditions ◽  
Valve Lift ◽  
Valve Closure ◽  
Rapid Decay ◽  
Inlet Valve ◽  
Compression Stroke ◽  
Axial Velocity Distribution ◽  
Cylinder Flow

The flow generated by the helical port of a production Diesel engine has been investigated by laser Doppler anemometry under steady flow and operating conditions at ∼ 900 rpm and compression ratio of 8. The flow around the valve periphery was found to be non-uniform with the axial velocity distribution being more sensitive to valve lift. The in-cylinder swirl distribution at inlet valve closure exhibited an axial stratification in the disc-chamber while turbulence intensity remained constant in the clearance volume during the rest of the compression stroke with levels of 0.5 vp and a minimum of about 0.4 vp at top-dead-center following a rapid decay at θ=340°.

scholarly journals Influence of compressible medium on the operation of a reciprocating compressor

2018 ◽  
Vol 245 ◽  
pp. 04009
Author(s):  
Andrey Kotlov ◽  
Leonid Kuznetsov ◽  
Boris Hrustalev
Keyword(s):  
Piston Compressor ◽  
Compressible Medium ◽  
Reciprocating Compressor ◽  
Flow Area ◽  
Suction System ◽  
Piston Velocity ◽  
Number Of Factors ◽  
Valve Dynamics ◽  
Pressure Changes ◽  
Oscillatory Processes

A reciprocating compressor is a volumetric machine. Consequently, the motion of gas in communications always is of non-stationary or pulsating character. The diagram of oscillatory processes in communications is complex because a number of factors affect the nature of the flow: cyclical gas supply, valve dynamics, change in the flow area of pipelines, variable cylinder volume, variable piston velocity, temperature gradients, etc. The analysis of non-stationary processes in the suction stage of a household refrigeration compressor is considered. A mathematical model of the flow of real gas in the suction system of a household refrigeration piston compressor has been developed. We performed a calculation study of the motion diagram of the suction valve, gas velocities in the suction pipe and pressure changes in the suction chamber. The results of a reciprocating compressor study while compressing various gases are given. The influence of the properties of refrigerants on the operation of the compressor and the suction system is considered.

An Experimental Investigation on Hysteresis in a Wet Gas Compressor

2017 ◽  
Author(s):  
Martin Bakken ◽  
Tor Bjørge
Keyword(s):  
Liquid Phase ◽  
Multiphase Flow ◽  
Open Loop ◽  
Operating Conditions ◽  
Test Facility ◽  
Centrifugal Impeller ◽  
Compression Process ◽  
Wet Gas ◽  
Liquid Load ◽  
Compressor Performance

Performance monitoring of wet gas compressors is challenging due to the liquid phase impact on performance. Introduction of a liquid phase alters both the thermodynamics as well as the fluid dynamics of the compression process. Hence, understanding the flow interaction between the impeller, diffuser and volute is pivotal. Previous investigations have detected occurrence of compressor hysteresis at certain wet gas operating conditions, resulting in temporary deviations from the steady state compressor characteristics. This kind of behavior influences both the compressor stability and performance. Thus, being able to understand the onset of hysteresis and its impact on the compressor is paramount. An experimental test campaign has been performed at the Norwegian University of Science and Technology (NTNU). The test facility is an open loop configuration consisting of a shrouded centrifugal impeller, a vaneless diffuser and a circular volute. The current investigation document the compressor performance shift and the occurrence of compressor hysteresis when gradually increasing the liquid load on a centrifugal compressor. Emphasis was put on the compressor performance and its correlation to the diffuser multiphase flow regime. The investigation revealed that there is a clear dependence between the diffuser multiphase flow characteristics and the compressor performance.

Mathematical Modeling of the Polytropic Process Using the Sequential Cubic Polynomial Approximation

2021 ◽  
Author(s):  
Matt Taher
Keyword(s):  
Performance Testing ◽  
Operating Conditions ◽  
Solution Technique ◽  
Polynomial Method ◽  
Compression Process ◽  
Energy Degradation ◽  
Cubic Polynomial ◽  
Compressor Performance ◽  
Path Dependent ◽  
Polytropic Process

Abstract The polytropic process is used to signify the effect of “energy degradation” associated with the equipment losses, which is as an inherent irreversibility in a compression process. The polytropic process is path dependent, which entails the irreversibility associated with the system. The change of gas composition and operating conditions affect the energy degradation. In this paper the polytropic process of real gas is explained and thermodynamics and mathematical model used in Taher-Evans Cubic Polynomial Method [1], [2] is presented. The elegance of Taher-Evans Cubic Polynomial Method is its rapid solution technique and high precision for calculating polytropic efficiency as required for compressor performance testing by the ASME PTC-10 [3].

The Theory of Spring-Loaded Valves for Reciprocating Compressors

1950 ◽  
Vol 17 (4) ◽  
pp. 415-420
Author(s):  
Michael Costagliola
Keyword(s):  
Natural Frequency ◽  
Reciprocating Compressor ◽  
Important Criterion ◽  
Flow Area ◽  
Main Design ◽  
Design Variables ◽  
Flow Test ◽  
Piston Speed ◽  
Valve Dynamics ◽  
Static Flow

Abstract The inlet and discharge processes of a reciprocating compressor equipped with spring-loaded valves of the automatic type have been analyzed to determine the effects of the main design variables on performance. The most important criterion is found to be a parameter involving effective flow area through the valves and piston speed. Valve dynamics is a secondary consideration. For optimum valve dynamics, the valve would have no weight and a very small spring constant, giving an infinite natural frequency of the valve system. If certain valve characteristics are known (or measured by static-flow test), the performance of a compressor using these valves can be predicted with fair accuracy.

Study on Characteristics of the Linear Air-Conditioner Compressor at Varied Operating Conditions

2011 ◽  
Vol 201-203 ◽  
pp. 632-636 ◽  
Author(s):  
Jie Fei Xie ◽  
Xin Hua Li ◽  
Hong Zhang
Keyword(s):  
Engineering Application ◽  
Axial Direction ◽  
Operating Conditions ◽  
Air Conditioner ◽  
Design Development ◽  
Runge Kutta Method ◽  
Moving Body ◽  
Cylinder Piston ◽  
Compressor Performance ◽  
Intake Pressure

This paper mainly introduces a novel linear air conditioner compressor which is driven by the linear oscillatory motor with two divided moving body, of which the Cylinder-piston assembly presents symmetrical distribution along the axial direction. The compressor dynamics equations were built and solved numerically with the fourth order Runge-Kutta method. in the meantime, this paper emphatically analyzes the influence of those factors, such as the intake pressure, the exhaust pressure, the suction gas superheat, the cooling degree, on the compressor performance at varied operating conditions. These works shows that improving the suction gas pressure and reducing the exhuast pressure can help to increase the refrigeration capacity and energy efficiency ratio of the air conditioner compressor. Those analysis results provide theory foundation for design,development, and engineering application of this linear air-conditioner compressor.

Break-Up of Threads From Laminar Open Channel Flow Influenced by Cross-Wind Gas Flow

2014 ◽  
Author(s):  
Jens Kamplade ◽  
Tobias Mack ◽  
Andre Küsters ◽  
Peter Walzel
Keyword(s):  
Size Distribution ◽  
Channel Flow ◽  
Gas Flow ◽  
Drop Size ◽  
Open Channel ◽  
Open Channel Flow ◽  
Drop Size Distribution ◽  
Operating Conditions ◽  
Breakup Process ◽  
Breakup Length

The breakup process of threads from laminar operating rotary atomizer (LamRot) is in the scope of this investigation. A similarity trail is used to investigate the influence of the thread deformation within a cross-wind flow on the thread breakup process. The threads emerge from laminar open channel flow while the liquid viscosity, the flow rate, the pipe inclination towards the gravity as well as the cross-wind velocity is varied. The breakup length and drop size distribution are analyzed by a back-light photography setup. The results thus obtained are compared with results of previous examination by Schröder [1] and Mescher [2]. It is found that the breakup length decreases and that the drop size grows with rising cross-wind intensity, while the width of the drop size distribution increases. At the same operating conditions, the breakup length for laminar open channel flow is smaller compared to completely filled capillaries. In contrast to this observation, the drop size distribution remains nearly unchanged. The critical velocity for the transition from axisymmetric to wind-induced thread breakup was found to be smaller than for completely filled capillaries.

Behavior of Radial Incompressible Flow in Pneumatic Dimensional Control Systems

2003 ◽  
Vol 125 (5) ◽  
pp. 843-850 ◽  
Author(s):  
G. Roy ◽  
D. Vo-Ngoc ◽  
D. N. Nguyen ◽  
P. Florent
Keyword(s):  
Gas Flow ◽  
Flow Behavior ◽  
Pressure Gauge ◽  
Axisymmetric Flow ◽  
Low Pressure ◽  
Industrial Applications ◽  
Nozzle Geometry ◽  
Machined Surface ◽  
Flow Area ◽  
Simpler Algorithm

The application of pneumatic metrology to control dimensional accuracy on machined parts is based on the measurement of gas flow resistance through a restricted section formed by a jet orifice placed at a small distance away from a machined surface. The backpressure, which is sensed and indicated by a pressure gauge, is calibrated to measure dimensional variations. It has been found that in some typical industrial applications, the nozzles are subject to fouling, e.g., dirt and oil deposits accumulate on their frontal areas, thus requiring more frequent calibration of the apparatus for reliable service. In this paper, a numerical and experimental analysis of the flow behavior in the region between an injection nozzle and a flat surface is presented. The analysis is based on the steady-state axisymmetric flow of an incompressible fluid. The governing equations, coupled with the appropriate boundary conditions, are solved using the SIMPLER algorithm. Results have shown that for the standard nozzle geometry used in industrial applications, an annular low-pressure separated flow area was found to exist near the frontal surface of the nozzle. The existence of this area is believed to be the cause of the nozzle fouling problem. A study of various alternate nozzle geometries has shown that this low-pressure recirculation area can be eliminated quite readily. Well-designed chamfered, rounded, and reduced frontal area nozzles have all reduced or eliminated the separated recirculation flow area. It has been noted, however, that rounded nozzles may adversely cause a reduction in apparatus sensitivity.

Sign in / Sign up

Export Citation Format

Share Document