International Compressor Engineering Conference
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Recent documents in International Compressor Engineering Conference
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Mon, 22 Dec 2014 09:57:57 PST
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Numerical Study on Rotor Deformation of Multiphase TwinScrew Pumps Under High Gas Volume Fraction Conditions
http://docs.lib.purdue.edu/icec/2249
http://docs.lib.purdue.edu/icec/2249
Tue, 12 Aug 2014 12:50:20 PDT
Multiphase pumping with twinscrew pumps is a relatively new technology that has been proven successful in a variety of field applications. It has three advantages such as less environment pollution, few separation equipments and more convenient operation than the conventional system. Despite many advantages of this technology, some problems have been encountered when operating under conditions with high gas volume fractions (GVF). While twinscrew multiphase pump is operating under high GVF conditions, the inner temperature of the pump increases obviously. The clearances between rotors change greatly and influence the volumetric efficiency of the twinscrew multiphase pumps. In some severe conditions, it may cause the pump damage. In this paper, the actual force and thermal boundary conditions are proposed through further investigations of pressure distributions and heat transfer. And then the screw rotor deformation and temperature field are calculated under different GVF conditions with ANSYS software. The results indicate that the main deformation of screw rotors is thermal deformation and the maximum radial deformation occurs on the top of the rotor in the discharge port. Through analyzing the influence of screw rotor deformation on the clearance, it can be realized that the greatest clearance changes are in the root of the rotor, followed by circumferential clearance, and there is no changes in flank clearance.
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Bin Hu et al.

An Investigation of Refrigerant Oil Retention in an Air Conditioning System with Two Inverter Compressors in Parallel
http://docs.lib.purdue.edu/icec/2248
http://docs.lib.purdue.edu/icec/2248
Tue, 12 Aug 2014 12:50:19 PDT
A VRF (variable refrigerant flow) air conditioning, having a number of air handling units connected to an external condensing unit, commonly uses two or more compressors in the system. The complicated piping system of the VRF air conditioning causes difficulties for refrigerant oils to return back to each compressor, especially for compressors operating in different frequencies. Compressors need lubrication in operation process, otherwise the compressor will burn out because of wearing and overheating. Therefore, whether refrigerant oils can successfully return back to each compressor has become a key issue in the VRF air conditioning system. To this regard, this report studied refrigerant oil retention of each compressor operating in different frequencies in an air conditioning system with two compressors in parallel and proposed a simple strategy for the refrigerant oil retention of compressors to keep lubricants balanced in two compressors.
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ChengShu Kuo et al.

CFD Modelling in Screw Compressors With Complex Multi Rotor Configurations
http://docs.lib.purdue.edu/icec/2247
http://docs.lib.purdue.edu/icec/2247
Tue, 12 Aug 2014 12:50:18 PDT
Computational Fluid Dynamics (CFD) of screw compressors is challenging due to the positive displacement nature of the process, existence of very fine fluid leakage paths, coexistence of working fluid and lubricant or coolant, fluid injection and most importantly the lack of methodologies available to generate meshes required for the full three dimensional transient simulations. In this paper, currently available technology of grid remeshing has been used to demonstrate the CFD simulations of complex multi rotor screw compressors like the twin screw compressor with parallel axis and single screw compressor with cylindrical main rotor and two planar gate rotors with perpendicular axis. Presently, methodology for grid generation of constant pitch twin screw machines is available through SCORG© (Kovacevic et al., 2007) but it is currently not suitable for different topologies like that of a single screw or variable pitch rotors. It is very challenging to handle the mesh deformation that happens in the compression chambers during operations of such machines. The methodology tested for this paper uses a technique called keyframe remeshing in order to supply pregenerated grids to the CFD solver as the solution progresses. In order to evaluate accuracy of such approach, an adiabatic compressionexpansion process in a reciprocating piston cylinder arrangement is studied and compared with a diffusion equation based mesh smoothing. It has been demonstrated, that although it is possible to simulate the complex configuration of screw compressors by keyframe remeshing technique, there are many limitations with respect to the time consumed in preprocessing, demand to computational resources, accuracy of results and general difficulty to include advanced modeling features like turbulence, multispecies or multiphase flows. Hence it was concluded that customized tools for generation of CFD grids for such complex screw machines still remain to be developed.
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Sham Ramchandra Rane et al.

Theoretical and Experimental Analysis of the Superheating in Heat Pump Compressors
http://docs.lib.purdue.edu/icec/2246
http://docs.lib.purdue.edu/icec/2246
Tue, 12 Aug 2014 12:50:16 PDT
In a conventional cooling system, refrigerant superheating inside the compressor is largely responsible for overall energy losses, increasing the compression specific work and decreasing the cooling capacity. In heat pump applications, superheating not only affects the compression loss, but also the specific heating capacity of the system, since the inlet temperature of the condenser depends on the final temperature of compression. Kremer et al. (2011) proposed a new approach to identify and understand the superheating losses in compressors submitted to heat pump applications. In this paper, a more accurate approach is proposed and the effects of refrigerant superheating are analyzed using a compressor thermal model. Different configurations of compressors are experimentally and numerically evaluated in order to validate the theoretical model. The obtained results follow the trend established by the theoretical purpose.
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Jose Nilton Fonseca et al.

A Numerical Simulation of FluidStructure Interaction for flow through valves of a hermetic compressor with Immersed Boundary Method.
http://docs.lib.purdue.edu/icec/2245
http://docs.lib.purdue.edu/icec/2245
Tue, 12 Aug 2014 12:50:15 PDT
The aim of the paper is to simulate numerically the FluidStructure Interaction for flow through valves of a hermetic compressor using immersed boundary method. The paper is primarily concerned with the mathematical structure and implementation of the Immersed Boundary Method which includes both the Immersed Boundary form of the equations of motion and also the Immersed Boundary numerical Scheme. The flow pattern of the fluid in the compressor is intimately connected with the performance of the valves, and this paper presents a solution of the NavierStokes equations in 2D of a Newtonian fluid under laminar regime, in the presence of moving immersed boundaries, being the fluid treated as isothermal. The immersed boundary method has evolved into a generally useful method for problems of Fluidstructure interaction. In this approach, the mathematical formulation employs a mixture of Eulerian and Lagrangian variables, the fluid is represented in a Eulerian coordinate frame and the structures or the interacting surfaces are considered in a Lagrangian coordinate frame. The two types of variables are linked by interaction equations that involve a smoothed approximation to the Dirac delta function, constructed according to the principles established in [1], which plays a prominent role. In the numerical scheme motivated by the Immersed Boundary formulation, the Eulerian variables are defined on a fixed Cartesian frame, and the Lagrangian variables are defined on a curvilinear mesh that moves freely through the fixed Cartesian mesh without being constrained to adapt to it in any way at all. Eulerian/Lagrangian identities govern the transfer of data from one mesh to another. A structured nonuniform staggered grid based two dimensional finite volume model is used to solve the equations of the fluid flow in laminar regime and a secondorder Adams BashforthCrank Nicholson scheme is used for temporal discretization and preconditioned Biconjugate gradient stabilized method is used to solve the derived system of equations. The numerical results presented show the average volumetric flow and the respective temporal valve displacements for different Laminar Reynolds numbers.
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Aditya Mushyam et al.

Properties of Refrigerant Affect Compressor Design
http://docs.lib.purdue.edu/icec/2244
http://docs.lib.purdue.edu/icec/2244
Tue, 12 Aug 2014 12:50:14 PDT
The paper examines selected thermodynamic properties of commonly used refrigerants and how they may affect design of a compressor. Among those properties are volumetric capacity, system pressure difference, system compression ratio, isentropic coefficient of performance, gas density, temperature of discharge gas, velocity of sound etc. The is made on the scale of evaporating temperatures from –40 oC to 30 oC, and condensing temperature 40.5 oC. The temperature of gas entering suction port is assumed constant and equal to 32.2 oC.
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Hubert Bukac

Modeling of a Novel Spool Compressor With Multiple Injection Ports
http://docs.lib.purdue.edu/icec/2243
http://docs.lib.purdue.edu/icec/2243
Tue, 12 Aug 2014 12:50:13 PDT
While models have previously been developed to investigate scroll compressor performance with a single injection port, the model described in this paper explores the effect of multiple injection ports on the performance of a novel rotary spool compressor. The model includes the effects of heat transfer and leakage and is numerically solved to predict the compressor power consumption and mass flow rate. The injection ports are modeled assuming that saturated vapor is injected at a specified pressure and the timing of the injection process can be controlled. Running at a speed of 1907 rpm with R22 as the working fluid, an evaporating pressure of 391 kPa, an inlet temperature of 7.6°C, and a discharge pressure of 1890 kPa, the model predicts that adding a single injection port will provide a 12% increase in the coefficient of performance (COP) of the cycle. Adding a second injection port increases the COP by an additional 4% compared to the cycle with a single port, or 16% over the baseline performance of the cycle without economization. The compressor model is also used to investigate the effect of injection pressure, injection port location, and injection port diameter on economized cycle performance.
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Margaret M. Mathison et al.

The Condition Monitoring of an Upstream Oil and Gas Dry Screw Compressor Drive Train and its Impact on the Control System.
http://docs.lib.purdue.edu/icec/2242
http://docs.lib.purdue.edu/icec/2242
Tue, 12 Aug 2014 12:50:12 PDT
Variable speed oil free screw compressors can be used in upstream oil and gas applications such as gas collection and flare gas recovery. The critical nature of these applications is such that the owners closely monitor the drive train of the package as long unplanned stoppages are extremely expensive. If any of the monitored parameters start to deviate from the norm then shutdowns and services can be scheduled in a timely manner preventing costly stoppages. This paper first describes the parameters monitored on the drive train as required by the international standards used by the oil and gas companies. The paper then leads onto an indepth description of the instrumentation mounted on and even within the drive train, incorporating the main drive motor, gearbox and compressor, and how the instrumentation is monitored by a package machine condition monitoring system that interfaces with the package control system. As the final location of the instruments is often in extremely hazardous environments such as highly corrosive offshore marine environments or abrasive hot desert environments, and the compressors themselves are often compressing highly combustible gas such as methane or even hydrogen, the protection methods employed by the instruments to prevent explosion is then discussed. The multiple communications networks that allow the condition monitoring system to send its values to the package control system and the client’s distributed control system are also discussed. This discussion includes how the measured values make their way from the stand alone machine condition monitoring system to the compressor control system and how the two systems integrate with each other to protect the package before annunciating the system status to the client's distributed control system. Finally a full description is given on how these measured values impact on the running of the package with respect to the compressors service life and the control systems ability to maintain the process setpoints. A solution to the presented problem is then offered.
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William James Milligan

Numerical Calculation and Analysis of Lubricating Water Film Cavitation of A Water Flooded Air Single Screw Compressor
http://docs.lib.purdue.edu/icec/2241
http://docs.lib.purdue.edu/icec/2241
Tue, 12 Aug 2014 12:50:11 PDT
Reynolds equations and onephase model with NS (Navier Stocks) equations are widely used to calculate pressure distribution in the liquid film. In most cases, negative pressure exits in the obtained results. In a waterflooded single screw compressor, it is necessary to investigate the pressure of water film along the whole tooth flank. A negative pressure may not be right, because that when the pressure is lower than the saturated vapor pressure, cavitation occurs. In this paper, we investigated the pressure distribution of the water film with cavitation model. Results were compared to the pressure distribution obtained by onephase model using NS equations. Results show that difference of pressure distribution obtained by the two models is very similar for the positive pressure distribution. For the negative pressure distribution, the saturated vapor pressure could be applied to replace the results obtained by onephase model with very small errors. Therefore, onephase model will be effective to simulate pressure distribution along the tooth flank by using the vapor pressure to replace the negative pressure.
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Rui Huang et al.

Theoretical and Experimental Study of Signal Processing Techniques for Measuring Hermetic Compressor Speed through Pressure and Current Signals
http://docs.lib.purdue.edu/icec/2240
http://docs.lib.purdue.edu/icec/2240
Tue, 12 Aug 2014 12:50:09 PDT
Measuring means extracting information from acquired signals. Either in the frequency or in the time, mathematical processing tools are applied to get information from measurement signals. It is usual, when processing measurement signals in the frequency domain, the application of Fourier analysis, mainly through Fast Fourier Transform (FFT) algorithms. Nevertheless, there are other digital signal processing tools that can overcome FFT performance in computation time or accuracy, and they can be very useful when extracting information from measurement signals. This paper presents some powerful mathematical tools and it shows how useful they can be, when measuring hermetic compressor speed through externallymeasurable quantities.
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Miguel Burg Demay et al.

Acoustic Calculation With the Free Solver Code_Aster
http://docs.lib.purdue.edu/icec/2239
http://docs.lib.purdue.edu/icec/2239
Tue, 12 Aug 2014 12:50:08 PDT
The aim of this article is to share our experience in compressor acoustic calculation using the free solver Code_Aster. We will review some typical compressor noise problem, how we modelize them and some results examples. Muffler transmission loss with different acoustic termination, acoustic field inside compressor cavity and rigid body motion of the shell, compressor shell acoustic radiation are some of the case study discussed in this article. Code_Aster is a free and powerful solver developed by EDF, the French electricity company. It is an attractive solution for all company that cannot afford the cost of a commercial acoustic code.
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David Leray et al.

Thermodynamic Design of Screw Motors for Constant Waste Heat Flow at Medium Temperature Level
http://docs.lib.purdue.edu/icec/2238
http://docs.lib.purdue.edu/icec/2238
Tue, 12 Aug 2014 12:50:07 PDT
This paper focuses on the interaction of the geometric parameters of screw motors and the fluid parameters of the system in compliance with the boundary condition of constant waste heat flow. Within the thermodynamic simulation the systematic variation of the geometric machine parameters include the number of lobes on male and female rotor and the internal volume ratio. The variation range of the system parameters consists of the dependent parameters of temperature and mass flow and of the pressure on the high pressure side of the machine. The conclusive assessment of the energetic efficiency and the operating behavior of the screw motor are demonstrated by the use of the internal power, the delivery rate and classification numbers for the inlet area and the gaps. The computed operational parameters and geometries of screw engines in applications of waste heat recovery differ significantly from the previously used machines.
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Jan Hütker et al.

Numerical Evaluation of Performance Curves of a High Frequency Microcompressor
http://docs.lib.purdue.edu/icec/2237
http://docs.lib.purdue.edu/icec/2237
Tue, 12 Aug 2014 12:50:06 PDT
This work presents a methodology for the numerical simulation of reed valves of a smallsize reciprocating compressor (approximately 200 mm in length, 60 mm in diameter), oil free and operating at high frequency. A fluidstructure interaction methodology is employed, where the fluid domain is modeled by the tridimensional transient NavierStokes equations, while the solid domain is governed by a beam model considering geometrical contacts between valves and stoppers (valve plate, piston, etc.) Results are shown for mass flow, pump power consumption and valve losses for evaporating temperatures ranging from 15 degrees Celsius to +40 degrees Celsius, and condensing temperatures from +45 degrees Celsius to +85 degrees Celsius. Finally, numerical results were compared to experimental data.
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Celso Kenzo Takemori et al.

Some Aspects of Estimating Geometric Characteristics of Screw Compressors
http://docs.lib.purdue.edu/icec/2236
http://docs.lib.purdue.edu/icec/2236
Tue, 12 Aug 2014 12:50:04 PDT
The methods used today for the calculation of screw compressor thermodynamic and fluid flow processes, from quasi onedimensional thermodynamic models to threedimensional computational fluid dynamics (CFD) procedures, require accurate identification and quantification of geometric parameters, such as volume, gradient and crosssection, leakage flow and blowhole areas. Historically, some of the geometric characteristics have been neglected, or approximated when calculation accuracy was not essential. However, more sophisticated models may lose some of their advantages if accurate geometric characteristics are not included in them. The work presented in this paper is aimed to enhance the accuracy of geometric calculations. The usual geometric calculation procedures are given and modified where necessary. The results are compared with models generated by 3D Computer Aided Design (CAD), software packages, from which improvements in the accuracy of predictions can be demonstrated.
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David Buckney et al.

Study on Iron Loss in Two Kinds of Movingmagnet Linear Motors
http://docs.lib.purdue.edu/icec/2235
http://docs.lib.purdue.edu/icec/2235
Tue, 12 Aug 2014 12:50:03 PDT
Linear motors are widely used in cryogenic fields to drive Stirlingtype cryocoolers. Generally the Joule heat loss associated with copper lead is considered as the main loss in motors while the iron loss is ignored at a lower frequency operation, not only because it’s regarded as small enough but also it’s difficult to measure or calculate. This paper introduces an experimental method to measure the iron loss for linear motors. Two kinds of movingmagnet linear motors have been tested, one is known as single coil and magnet linear motor, and the other as double coils and magnets linear motor. Dependence of iron loss on frequency and displacement are investigated. Results show that there is a 1.6 power exponent relation between iron loss and frequency in the singlecoil movingmagnet linear motor, and its iron loss come to be the same as copper loss at 75 Hz, it even grows to 1.65 times of copper loss at 100Hz. As for the double coils and magnets linear motor, there is a 1.3 power exponent relation between iron loss and frequency, and its iron loss percentage is only 15% at 120 Hz compared with 68% in the singlecoil linear motor. Iron loss is proved to be significant in linear motors especially at higher frequency.
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Longyi Wang et al.

Influence of Thermal Deformation on the Characteristic Diagram of a Screw Expander in the Automotive Application of Exhaust Heat Recovery
http://docs.lib.purdue.edu/icec/2234
http://docs.lib.purdue.edu/icec/2234
Tue, 12 Aug 2014 12:50:02 PDT
The present paper responds to the operating behavior of an exemplarily selected screw expander for exhaust heat recovery from combustion engines in the lower power range. The application in vehicles for the purpose of heat recovery, which is characterized by the small machine dimensions due to relatively low system mass flows, is a still unexplored area for the screwtype machine. The screw expander is to be used in an organic Rankine cycle (ORC). Compared to other expander designs in general screw expanders are characterized by high efficiency together with relatively low geometrical dimensions. Within the presented investigation mainly the performance characteristic of a screw expander, geometrically designed for a particular operating point, is determined as a function of the system parameters – inlet pressure and temperature – as well as the rotational speed of the expander. Here, based on an iterative coupling of thermodynamic and thermal simulations the influence of the thermal deformation on the machine performance in particular is analyzed. The results of the thermodynamic simulation, mainly based on socalled chamber models, represent the thermodynamic and fluid dynamic performance of the screw machine by means of mass and energy conservation. The information obtained in this way about the temperature distributions and the heat fluxes provides a basis for the subsequent thermal simulation using a finite element method (FEM) calculation. The resulting thermally deformed machine, whose performancerelated clearance heights are now changed, is used for the next iteration step within the thermodynamic simulation.
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Alexander Nikolov et al.

Calculated Optimal Mechanical Efficiency of a Large Capacity Reciprocating Compressor
http://docs.lib.purdue.edu/icec/2233
http://docs.lib.purdue.edu/icec/2233
Tue, 12 Aug 2014 12:50:01 PDT
In this study, calculations of the mechanical efficiency of a large reciprocating compressor, developed by Mayekawa MFG. Co., Ltd., with a per cylinder suction volume of 1300 cm3 were carried out. These calculations were used to confirm whether the empirical combination of major design parameters in the Mayekawa compressor delivers optimal mechanical efficiency. Initially, the theoretical equation of motion of the rotating crankshaft is developed. Subsequently, computer calculations are carried out to determine the mechanical efficiency for various combinations of the major design parameters for operating speeds of 800, 1000 and 1200 rpm. From these calculations, the optimal combination parameters yielding the maximum mechanical efficiency could be determined, and then compared with the empirical combination used in the Mayekawa compressor.
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Takuma Tsuji et al.

An Experimental Study of Lubrication in Thrust SlideBearings of Scroll Compressors  Effect of Thickness and Inside Form of Thrust Plate 
http://docs.lib.purdue.edu/icec/2232
http://docs.lib.purdue.edu/icec/2232
Tue, 12 Aug 2014 12:49:59 PDT
The present study focuses on the effect of the thickness and inner form of the thrust plate in a scroll compressor upon the lubrication features. A simplified model of a annular thrust slidebearing with thinner thrust plate submerged in a refrigerant oil VG56 was operated under pressure using R22 as the pressurizing gas, where the pressure difference was adjusted from 0 to 1.0 MPa. The friction force and coefficient of friction were measured over a wide range of orbiting speeds. The wedge angle due to elastic deformation is naturally increased with decreasing thrust plate thickness, resulting in a clear improvement in lubrication characteristics of the thrust slidebearing. Subsequently, similar lubrication tests were conducted for the thrust plate model with a realistic inner form, one as complicated as that in actual scroll compressors, while maintaining the thickness of the thrust plate as in the previous test. No significant change in lubrication features relative to those from the simplified annular model were identified, confirming the validity of using simplified annular model tests to assess the basic lubrication characteristics of the thrust slidebearing in scroll compressors.
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Takuma Tsuji et al.

ElastoHydrodynamic Lubrication Effect in ThrustSlide Bearings of Scroll Compressors
http://docs.lib.purdue.edu/icec/2231
http://docs.lib.purdue.edu/icec/2231
Tue, 12 Aug 2014 12:49:58 PDT
This paper presents the concept of the ElastoHydrodynamic Lubrication (EHL) effect for the thrust slidebearings in scroll compressors, which accounts for the superior lubrication characteristics of these bearings. The thrust plate undergoes elastic deformation due to axial loading, resulting in the formation of a fluid wedge between the orbiting and fixed thrust plates, a region with very high induced oil film pressure which, in turn, accounts for the remarkably good lubrication characteristics of the thrust slidebearing. Furthermore, the high oil film pressure induces further elastic deformation of the thrust plate, which forms a lubrication pocket with the thrust plate, more effectively increasing the oil film pressure between the sliding surfaces. The formation of the lubrication pocket was confirmed using FEM analysis and lubrication tests on the elastic deformation of the thrust plate. Subsequently a computer simulation flow chart to analyze the elastohydrodynamic lubrication of thrust slidebearing is presented.
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Noriaki Ishii et al.

Topology Optimization of Suction Muffler for Noise Attenuation
http://docs.lib.purdue.edu/icec/2230
http://docs.lib.purdue.edu/icec/2230
Tue, 12 Aug 2014 12:49:57 PDT
A topology optimization method is developed to optimally design suction mufflers in reciprocating compressors. Suction mufflers should be designed for high noise reduction. The suction mufflers are not easy to systematically design because their outer shape is so complicated and the center axes of the inlet/outlet do not coincide. Muffler researchers in industry have designed the internal configuration of suction mufflers intuitively and experientially. However, since our proposed muffler design method is not restricted to location of the inlet and outlet and to the outer shape of suction muffler, it could be applied to suction muffler design problems. A topology optimization problem is formulated for a finite element model simulating a suction muffler for a reciprocating compressor. Transmission loss value at a target frequency is selected as an objective function and partition volume is constrained. Design variables change continuously from zero to one during optimization process. The material filling one element is an intermediate material between fluid and solid in each iterative calculation and become fluid or rigid body at a final converged stage depending on the value of design variables. Rigid body elements build up partitions or flow path to increase transmission loss. The proposed muffler design method is applied to a suction muffler, which has been introduced at an international conference.
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Jin Woo Lee et al.