Cylinder-piston Assembly Research Articles

OPERATION OF PISTON-CYLINDER ASSEMBLY IN GAS ENGINE COMPRESSORS

Gas engine compressors are indispensable components in a wide array of industrial processes, serving to compress gases for various applications such as power generation, manufacturing, and refrigeration. The efficient operation of these compressors is contingent upon the meticulous orchestration of their internal mechanisms, with the cylinder piston assembly standing as a pivotal nexus of functionality. Comprising a dynamic interplay of precision-engineered components—including the cylinder, piston, piston rings, and connecting rod-the assembly plays a foundational role in facilitating the compression process with reliability and efficacy. This article embarks on a comprehensive exploration of the vital elements constituting the cylinder piston assembly, aiming to unravel the intricate nuances of its design, operation, and optimization. By delving into the nuanced functionalities and structural intricacies of each component, this study endeavors to offer a nuanced understanding of the assembly's significance within the broader context of gas engine compressor technology. Furthermore, the article endeavors to dissect the manifold challenges encountered by the cylinder piston assembly during operation, ranging from issues of thermal management to mechanical wear and misalignment. Through a meticulous examination of these challenges, coupled with an analysis of contemporary methodologies and best practices, this study seeks to unearth actionable insights for enhancing the functionality and longevity of gas engine compressors. By distilling complex engineering concepts into practical insights, this article aims to equip industry practitioners, researchers, and stakeholders with the knowledge and tools necessary to navigate the complexities of gas engine compressor technology with confidence and proficiency. Keywords: cylinder piston assembly, piston rings, crankshaft, connecting rod, gas.

Transient heat transfer and deformation characteristics of a bidirectional compressor cylinder block-piston assembly under multi-field coupling

This paper established a multi-field coupling model for the air-cooled cylinder-piston assembly of a bidirectional compressor, proposed a transient calculation method, studied the temperature and deformation characteristics of each component in a single working cycle, constructed five evaluation indexes, analyzed the internal temperature and deformation characteristics of the cylinder block-piston assembly, explored the effect of different loads on the deformation, and verified the reasonableness of the method through tests. The results show that the research method of this paper is relatively accurate, and the calculation error is within 7 %; during a single working cycle, the temperature of each component shows a “W”-type change, and the maximum deformation shows a “folding” type change; the average temperature and maximum deformation of each component are highest at crank angles of 184° and lowest at crank angles of 101°; under extreme working conditions, the temperature and deformation of all parts are distributed in a “tilted” manner, with the percentage of the hot zones in the cylinder block as high as 54.6 %, and the thermal load plays a dominant role in the deformation of the cylinder-piston assembly; the average abnormal deformation at the position of support ring 1 reached 0.039 mm, which is very likely to cause wear and air leakage.

Learning Sparse Kernel CCA With Graph Priors for Nonlinear Process Monitoring

Process monitoring (PM) is important for improving product quality and ensuring plant safety in industrial systems. Recently, canonical correlation analysis (CCA)-based PM has shown excellent performance. The core idea is to first seek the relationship between two sets of process variables via CCA, then construct a residual generator and determine test statistics, and finally achieve the best monitoring. However, the global and local structure of process variables is not fully exploited. In this article, we propose a new nonlinear PM approach called joint sparse constrained kernel CCA and graph learning (JSKCCA-GL) by incorporating joint sparse kernel CCA (JSKCCA) and graph priors. Technically, imposing the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\ell _{{2},{0}}$ </tex-math></inline-formula> -norm joint sparse constraints can capture the global row-wise structure, and embedding the graph Laplacian priors can preserve the local structured variable correlation information. Furthermore, an efficient alternating minimization algorithm is developed by integrating least squares and iterative hard thresholding (IHT). The superiority of the proposed JSKCCA-GL is extensively verified on the benchmark Tennessee Eastman process (TEP) and a practical cylinder-piston assembly (CPA) of marine diesel engines. In particular, the fault detection rate (FDR) values for unknown-type faults in the TEP have been improved by around 16.10% on average.

Fault Detection Using Structured Joint Sparse Nonnegative Matrix Factorization

Nonnegative matrix factorization (NMF) is an efficient dimension reduction technique, which has been extensively used in the fields, such as image processing, automatic control, and machine learning. The application to fault detection (FD) is still not investigated sufficiently. To improve the performance of NMF-based FD approaches, this article proposes a novel FD approach using the structured joint sparse NMF (SJSNMF) for non-Gaussian processes. The basic idea of SJSNMF is to incorporate the graph Laplacian to preserve the relationship between process variables and operation units and introduce the joint sparsity to exploit row-wise sparsity of the latent variables. Technically, an optimization algorithm based on the alternating direction method of multipliers (ADMM) is established. To detect the fault, two test statistical metrics are adopted and the kernel density estimation (KDE) is calculated to estimate the control limit. The effectiveness of the proposed SJSNMF is verified on the benchmark Tennessee Eastman process (TEP) and the cylinder-piston assembly of diesel engines.

Malfunctions of Aviation Hydraulic Pumps

Abstract Hydraulic pumps are among the most complex and responsible units from the point of view of aircraft flight safety. One of the most important scientific and technical problems in improving the reliability of hydraulic pumps is to understand the physical nature of the cause of damage in them and on this basis to develop measures and recommendations to ensure their reliability. The article discusses the characteristics of hydraulic piston pairs of hydraulic pumps according to the kinematics of their movement and load conditions. Selected actual damages of axial piston pumps are discussed. The paper presents a simplified 3D solid model of the cylinder-piston assembly and the mechanism for adjusting the inclination of the piston cylinder block, the axial hydraulic pump, and the model of breaking loads for selected elements of this pump. The digital solid model and element load analysis were developed in SolidWorks Simulation.

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

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.

Defect Levels in n-Type Gallium Arsenide and Gallium Aluminum Arsenide Layers

Capacitance-voltage/time measurements have been made on Au-Schottky barrier diodes to LPE, VPE, bulk, OMVPE-GaAs, GaAlAs and MBE-GaAs/GaAlAs quantum wells to detect and characterize deep levels. LPE-GaAs was-grown by varying the degree of melt under- and super-saturation to study the effect on traps. Cylinder-piston assembly and Bridgman anvil systems were employed to observe the emission of carriers from deep levels up to a pressure of 50 x 10 8 Pa. The effect of annealing on traps in VPE-GaAs has also been investigated. It has been shown that emission from the 0.83 eV (EL-2) level in GaAs is not dependent on electric field in the range of about 60-125 kV/cm. The energy pressure coefficient of this level in GaAs has been measured as 4.0 × 10 8 meV/Pa by extending measurements, for the first time, to 15 × 10 8 Pa. From emission studies at 50 x 10 8 Pa, it has been shown that the level EL-2 is coupled to the L minima and the r-L energy separation of 0.282 eV accounts for most of the experimental data. The 0.83 eV level has also been found to exist in LPE-GaAs and it has been concluded that Ga vacancy and As Ga antisite defect complex are responsible as the most likely source of its origin. It has been concluded that the absolute position of the level in the band gap remains almost invariant with pressure and that there is no need to assume a pressure dependent Franck-Condon shift. However, for a similar level found in GaAs/GaAlAs MBE quantum wells, the energy pressure coefficient has been measured to be as high as (13.8 ± 0.8) x 10 8 meV/Pa. In some samples, 0.83 and 0.76 eV electron levels exist together, clearly showing that these are two different levels. The 0.64 eV hole trap level has not only been found in LPE-GaAs, GaAlAs, heat treated VPE but also in as-grown' VPE-GaAs. The present results have discounted the pure Ga and As vacancy model for the 0.83 and 0.64 eV levels in VPE and LPE-GaAs, respectively. We attribute the 0.64 eV hole level to a Ga vacancy-Cr complex.

Modelling Spray/Wall Interaction in Swirling Flows for DI Diesel Engines

A mathematical model for predicting spray/wall interaction in swirling flows of a direct-injection (DI) diesel engine is developed using a centre-line velocity vector/continuum approach. Generalization of the integral method for solving continuity and momentum equations for both free and wall regions of spray motion is demonstrated. The compression-induced swirl is estimated taking into consideration the wall friction and the exact moment of inertia of cylinder-piston assembly. The predictions are found in general agreement with the results of other workers.

Transient heat transfer analysis in an internal combustion engine piston

Numerical calculations based on finite difference approximations are carried out to assess the transient thermal response of an aluminium alloy piston of a semi-adiabatic diesel engine having a 1-cm-thick cast iron cylinder wall. The engine cylinder wall is coated externally by a 2-mm thin layer of oxide based ceramic insulating material. The non-ideal thermal contacts between the piston circumference and the cylinder wall are also considered. A detailed analysis is given for estimating the boundary conditions of the cylinder-piston assembly of an internal combustion engine. The isothermic distribution in the piston body and heat flow rates to cooling water and air below the piston at four different engine loads are depicted for cases both with and without insulation coating. The results indicate a 6% reduction in heat loss through the piston with the use of an insulation coating on the cylinder wall.

Investigation of heat transfer in an oil cooled piston with and without ceramic insulation on crown face

A numerical method is presented for calculating the temperature fields in a semi-adiabatic diesel engine piston having a cooling oil canal. The crown face of the piston is coated by a 2 mm thick oxide based ceramic insulating material. The non-ideal thermal contacts between the piston circumference and cylinder wall are also considered. A detailed analysis has been given for estimating the boundary conditions of the cylinder-piston assembly of an internal combustion engine. The isothermic distribution in the piston body and the heat flow rate through the different cooling media at four different engine loads have been depicted both for the cases with and without insulation coating. The results indicate a reduction (12–30%) in heat loss through the piston by use of an insulation coating at the piston crown face, assuming that both the heat transfer process from and the temperature of the combustion products remain unchanged.

Method and apparatus for seismic exploration

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Well serving system employing sonic energy transmitted down the pipe string

A well servicing system in which sonic energy is transmitted down a pipe string to a down hole work area a substantial distance below the surface. The sonic energy is generated by an orbiting mass oscillator and coupled therefrom to a central stem to which the piston of a cylinder-piston assembly is connected. The cylinder is suspended from a suitable suspension means such as a derrick, with the pipe string being suspended from the cylinder in an in-line relationship therewith. The fluid in the cylinder affords compliant loading for the piston while the fluid provides sufficiently high pressure to handle the load of the pipe string and any pulling force thereon. The sonic energy is coupled to the pipe string in a longitudinal vibration mode which tends to maintain this energy along the string.

A versatile hydraulically operated respiratory servo system for ventilation and lung function testing.

A description is given of the design and performance of a microcomputer-controlled respiratory servo system that incorporates the characteristics of a mechanical ventilator and also allows the performance of a multitude of test procedures required for assessment of pulmonary function in paralyzed animals. The device consists of a hydraulically operated cylinder-piston assembly and solenoid valves that direct inspiratory and expiratory gas flow and also enable switching to different test gas sources. The system operates as a volume-flow-preset ventilator but may be switched to other operational cycling modes. Gas flow rates may be constant or variable. The system operates as an assister-controller and, combined with a gas analyzer, can function as a "demand" ventilator allowing for set-point control of end-tidal PCO2 and PO2. Complex breathing maneuvers for a variety of single- and multiple-breath lung function tests are automatically performed. Because of the flexibility in selection and timing of respiratory parameters, the system is particularly suitable for respiratory gas studies.

Vortex sheet approximation of boundary layers

A grid free method for approximating incompressible boundary layers is introduced. The computational elements are segments of vortex sheets. The method is related to the earlier vortex method; simplicity is achieved at the cost of replacing the Navier-Stokes equations by the Prandtl boundary layer equations. A new method for generating vorticity at boundaries is also presented; it can be used with the earlier vortex method. The applications presented include (i) flat plate problems, and (ii) a flow problem in a model cylinder-piston assembly, where the new method is used near walls and an improved version of the random choice method is used in the interior. One of the attractive features of the new method is the ease with which it can be incorporated into hybrid algorithms.

Pattern Oversweep In Nine-Spot Waterflood Pilots

Abstract A laboratory study has been conducted on isolated and partially confined five- and nine-spot water/load patterns. The results show that both isolated patterns continue to produce oil with continued injection, but that each pattern, when surrounded by a single ring of like patterns, behaves as if it were confined provided the injection rate is sufficiently high to ensure a stabilized flood. Introduction Although the five-spot is popular in test pilots, there are occasions where the nine-spot is used so as to increase the total injection rate into the pivot and thereby decrease the duration of the test. It was therefore decided to extend the above study to the nine-spot pattern. As the Rapoport, Carpenter and Leas scaling criterion(2) was developed for the five-spot pattern and its validity for the nine-spot was not established, it was decided to vary the injection rate for both the five- and nine-spot and to compare the results. Equipment The model studied was the same one used and described in the previous study. A new injection system was designed and built. This system was modelled after the old one, but was built to permit simultaneous injection into as many as forty wells. It consisted of 41 cylinder-pistonassemblies positioned between two 3/4-inch-thick steel plates. As in the previous study, the center cylinder-piston assembly was double acting and was used toctuate the remaining 40. Injection pressures were measured by means of manometers, as was the case in the earlier study. However, in order that up to 40 injectors could be used, the manometer anks had to be modified and extended. Model &amp; Fluid Properties Although the model and beads used in the present study were the same as in the previous work, the system was cleaned and repacked. This resulted in a pack with a porosity of 36.4 percent and a permeability of 6.60 darcys. The fluids employed had the properties shown in Table 1 and were essentially identical to those used in the previous study. Procedure The experimental procedure used was identical to that in the earlier stuoy, except that a different constant injection rate was used in each run. In each case, the range of rates was chosen so as to straddle the value required by the scaling criterion or its equivalent. Observations Flood tests were carried out on an isolated five-spot, a five-spot surrounded by eight other fivespots, an isolated nine-spot and a nine-spot surrounded by eight other nine-spots, as shown in Figure 1. Isolated five-spot tests were conducted at constant injection rates ranging from 42.9 to 514.3 cc/hr well, as is indicated in Figure 2. From the, results, it may be seen that in each case the flood oversweeps the pattern, but that an increased injection rate tends to increase the degree of confinement. In the case of the isolated ninespot, tests were conducted at five different constant injection rates in the range of 21.4 to 257.1 cc/hr well.

Operating temperature regime of the cylinder-piston assembly of a drilling pump

Operating temperature regime of the cylinder-piston assembly of a drilling pump