The Experts below are selected from a list of 156 Experts worldwide ranked by ideXlab platform

Murat Hosoz - One of the best experts on this subject based on the ideXlab platform.

  • Comparative performance of an automotive air conditioning system using fixed and variable capacity Compressors
    International Journal of Refrigeration-revue Internationale Du Froid, 2010
    Co-Authors: Alpaslan Alkan, Murat Hosoz
    Abstract:

    Abstract This study investigates the experimental performance of an automotive air conditioning (AAC) system for the Cases of employing fixed and variable capacity Compressors (FCC and VCC). For this aim, an experimental system consisting of original components from an HFC134a AAC system has been set up and instrumented. For each Compressor Case, the system has been tested under steady-state operating conditions by varying the Compressor speed, temperatures of the air streams entering the condenser and evaporator as well as the velocities of these air streams. The energy and exergy analysis has been applied to the experimental system, and its performance for both Compressor operations has been evaluated. The results show that the operation with the VCC usually yields a higher COP than the operation with the FCC in expense of a lower cooling capacity. Furthermore, the cooling capacity and the rate of total exergy destruction in the VCC operations remain almost constant after a certain Compressor speed, while both parameters increase continually with the Compressor speed in the FCC operations.

  • Comparative performance of an automotive air conditioning system using fixed and variable capacity Compressors
    International Journal of Refrigeration, 2010
    Co-Authors: Alpaslan Alkan, Murat Hosoz
    Abstract:

    This study investigates the experimental performance of an automotive air conditioning (AAC) system for the Cases of employing fixed and variable capacity Compressors (FCC and VCC). For this aim, an experimental system consisting of original components from an HFC134a AAC system has been set up and instrumented. For each Compressor Case, the system has been tested under steady-state operating conditions by varying the Compressor speed, temperatures of the air streams entering the condenser and evaporator as well as the velocities of these air streams. The energy and exergy analysis has been applied to the experimental system, and its performance for both Compressor operations has been evaluated. The results show that the operation with the VCC usually yields a higher COP than the operation with the FCC in expense of a lower cooling capacity. Furthermore, the cooling capacity and the rate of total exergy destruction in the VCC operations remain almost constant after a certain Compressor speed, while both parameters increase continually with the Compressor speed in the FCC operations. ? 2009 Elsevier Ltd and IIR.

  • Experimental performance of an automobile air conditioning system using a variable capacity Compressor for two different types of expansion devices
    International Journal of Vehicle Design, 2010
    Co-Authors: Alpaslan Alkan, Murat Hosoz
    Abstract:

    This study investigates the experimental performance of an automotive air conditioning (AAC) system for the Cases of employing fixed and variable capacity Compressors (FCC and VCC). For this aim, an experimental system consisting of original components from an HFC134a AAC system has been set up and instrumented. For each Compressor Case, the system has been tested under steady-state operating conditions by varying the Compressor speed, temperatures of the air streams entering the condenser and evaporator as well as the velocities of these air streams. The energy and exergy analysis has been applied to the experimental system, and its performance for both Compressor operations has been evaluated. The results show that the operation with the VCC usually yields a higher COP than the operation with the FCC in expense of a lower cooling capacity. Furthermore, the cooling capacity and the rate of total exergy destruction in the VCC operations remain almost constant after a certain Compressor speed, while both parameters increase continually with the Compressor speed in the FCC operations. ?? 2009 Elsevier Ltd and IIR.

Alpaslan Alkan - One of the best experts on this subject based on the ideXlab platform.

  • Comparative performance of an automotive air conditioning system using fixed and variable capacity Compressors
    International Journal of Refrigeration-revue Internationale Du Froid, 2010
    Co-Authors: Alpaslan Alkan, Murat Hosoz
    Abstract:

    Abstract This study investigates the experimental performance of an automotive air conditioning (AAC) system for the Cases of employing fixed and variable capacity Compressors (FCC and VCC). For this aim, an experimental system consisting of original components from an HFC134a AAC system has been set up and instrumented. For each Compressor Case, the system has been tested under steady-state operating conditions by varying the Compressor speed, temperatures of the air streams entering the condenser and evaporator as well as the velocities of these air streams. The energy and exergy analysis has been applied to the experimental system, and its performance for both Compressor operations has been evaluated. The results show that the operation with the VCC usually yields a higher COP than the operation with the FCC in expense of a lower cooling capacity. Furthermore, the cooling capacity and the rate of total exergy destruction in the VCC operations remain almost constant after a certain Compressor speed, while both parameters increase continually with the Compressor speed in the FCC operations.

  • Comparative performance of an automotive air conditioning system using fixed and variable capacity Compressors
    International Journal of Refrigeration, 2010
    Co-Authors: Alpaslan Alkan, Murat Hosoz
    Abstract:

    This study investigates the experimental performance of an automotive air conditioning (AAC) system for the Cases of employing fixed and variable capacity Compressors (FCC and VCC). For this aim, an experimental system consisting of original components from an HFC134a AAC system has been set up and instrumented. For each Compressor Case, the system has been tested under steady-state operating conditions by varying the Compressor speed, temperatures of the air streams entering the condenser and evaporator as well as the velocities of these air streams. The energy and exergy analysis has been applied to the experimental system, and its performance for both Compressor operations has been evaluated. The results show that the operation with the VCC usually yields a higher COP than the operation with the FCC in expense of a lower cooling capacity. Furthermore, the cooling capacity and the rate of total exergy destruction in the VCC operations remain almost constant after a certain Compressor speed, while both parameters increase continually with the Compressor speed in the FCC operations. ? 2009 Elsevier Ltd and IIR.

  • Experimental performance of an automobile air conditioning system using a variable capacity Compressor for two different types of expansion devices
    International Journal of Vehicle Design, 2010
    Co-Authors: Alpaslan Alkan, Murat Hosoz
    Abstract:

    This study investigates the experimental performance of an automotive air conditioning (AAC) system for the Cases of employing fixed and variable capacity Compressors (FCC and VCC). For this aim, an experimental system consisting of original components from an HFC134a AAC system has been set up and instrumented. For each Compressor Case, the system has been tested under steady-state operating conditions by varying the Compressor speed, temperatures of the air streams entering the condenser and evaporator as well as the velocities of these air streams. The energy and exergy analysis has been applied to the experimental system, and its performance for both Compressor operations has been evaluated. The results show that the operation with the VCC usually yields a higher COP than the operation with the FCC in expense of a lower cooling capacity. Furthermore, the cooling capacity and the rate of total exergy destruction in the VCC operations remain almost constant after a certain Compressor speed, while both parameters increase continually with the Compressor speed in the FCC operations. ?? 2009 Elsevier Ltd and IIR.

P.b Bianchi - One of the best experts on this subject based on the ideXlab platform.

  • Rotordynamic analysis of a large industrial turboCompressor including finite element substructure modeling
    Journal of Engineering for Gas Turbines and Power, 2010
    Co-Authors: J.j.a Moore, G.b Vannini, M.b Camatti, P.b Bianchi
    Abstract:

    A rotordynamic analysis of a large turboCompressor that models both the casing and supports along with the rotor-bearing system was performed. A 3D finite element model of the casing captures the intricate details of the casing and support structure. Two approaches are presented, including development of transfer functions of the casing and foundation, as well as a fully coupled rotor-casing-foundation model. The effect of bearing support compliance is captured, as well as the influence of casing modes on the rotor response. The first approach generates frequency response functions (FRFs) from the finite element Case model at the bearing support locations. A high-order polynomial in numerator-denominator transfer function format is generated from a curve fit of the FRF. These transfer functions are then incorporated into the rotordynamics model. The second approach is a fully coupled rotor and casing model that is solved together. An unbalance response calculation is performed in both Cases to predict the resulting rotor critical speeds and response of the casing modes. The effect of the Compressor Case and supports caused the second critical speed to drop to a value close to the operating speed and not compliant with the requirements of the American Petroleum Institute (API) specification 617 7th edition. A combination of rotor, journal bearing, casing, and support modifications resulted in a satisfactory and API compliant solution. The results of the fully coupled model validated the transfer function approach. Copyright © 2010 by ASME.

W C Maier - One of the best experts on this subject based on the ideXlab platform.

  • An Approach to Compact, Wet Gas Compression
    Volume 5: Industrial and Cogeneration; Microturbines and Small Turbomachinery; Oil and Gas Applications; Wind Turbine Technology, 2010
    Co-Authors: L R José Gilarranz, H A Kidd, Gocha Chochua, W C Maier
    Abstract:

    In recent years, several papers have been written regarding the use of centrifugal compression technology to handle applications in which the process gas entering the equipment contains a significant amount of liquids, and can therefore be considered a wet gas. One such application that is currently being considered by many oil and gas operators is the installation of processing and compression equipment on the sea bed, to directly handle the process gas stream in close proximity to the wellhead. Other applications also exist topside, in which the operator would benefit from the installation of additional compression and processing capabilities at brown field facilities. Most of these existing installations have limited space for expansion and have strict size and weight limitations that have to be met by the additional equipment. This, in many Cases, hinders the utilization of traditional compression and processing equipment, which is typically arranged using the large and heavy multi deck approach. A novel integrated compression system (ICS) has recently been developed to address the current need for compact compression systems that can handle wet process gas. The ICS makes use of centrifugal Compressor stages driven directly by a high-speed, close-coupled electric motor, and incorporates a proprietary integrated centrifugal gas-liquid separation unit within the Compressor Case. This compact compression unit is packaged with process gas coolers in a single-lift module, providing a complete compression system that can be applied to all markets — upstream, midstream and downstream. With this integrated approach, the total footprint and weight of a conventional module or equipment layout can be greatly reduced. This paper is part of a series of publications that will describe the attributes of the new integrated compression system, and will serve to introduce the ICS and the benefits associated to the integration of the centrifugal separator into the Compressor casing. The paper will focus on the OEM’s approach to Wet Gas Compression, with emphasis on the benefits of handling the liquid and vapor phases as separate streams, making the system more efficient and reliable than alternate solutions, including the ones that handle the wet gas directly. Finally the paper will provide a comparison between a traditional compression train and the new ICS to show how the latter system offers significant size and weight advantages.

  • PROCEEDINGS OF THE ASME TURBO EXPO 2010, VOL 5
    AN APPROACH TO COMPACT WET GAS COMPRESSION, 2010
    Co-Authors: José L. Gilarranz, H A Kidd, Gocha Chochua, W C Maier
    Abstract:

    In recent years, several papers have been written regarding the use of centrifugal compression technology to handle applications in which the process gas entering the equipment contains a significant amount of liquids, and can therefore be considered a wet gas. One such application that is currently being considered by many oil and gas operators is the installation of processing and compression equipment on the sea bed, to directly handle the process gas stream in close proximity to the wellhead. Other applications also exist topside, in which the operator would benefit from the installation of additional compression and processing capabilities at brownfield facilities. Most of these existing installations have limited space for expansion and have strict size and weight limitations that have to be met by the additional equipment. This, in many Cases, hinders the utilization of traditional compression and processing equipment, which is typically arranged using the large and heavy multi deck approach. A novel integrated compression system (ICS) has recently been developed to address the current need for compact compression systems that can handle wet process gas. The ICS makes use of centrifugal Compressor stages driven directly by a high-speed, close-coupled electric motor, and incorporates a proprietary integrated centrifugal gas-liquid separation unit within the Compressor Case. This compact compression unit is packaged with process gas coolers in a single-lift module, providing a complete compression system that can be applied to all markets upstream, midstream and downstream. With this integrated approach, the total footprint and weight of a conventional module or equipment layout can be greatly reduced. This paper is part of a series of publications that will describe the attributes of the new integrated compression system, and will serve to introduce the ICS and the benefits associated to the integration of the centrifugal separator into the Compressor casing. The paper will focus on the OEM's approach to Wet Gas Compression, with emphasis on the benefits of handling the liquid and vapor phases as separate streams, making the system more efficient and reliable than alternate solutions, including the ones that handle the wet gas directly. Finally the paper will provide a comparison between a traditional compression train and the new ICS to show how the latter system offers significant size and weight advantages.

Philippe Moser - One of the best experts on this subject based on the ideXlab platform.

  • Computability and Complexity - Bounded Pushdown Dimension vs Lempel Ziv Information Density
    Computability and Complexity, 2016
    Co-Authors: Pilar Albert, Elvira Mayordomo, Philippe Moser
    Abstract:

    In this paper we introduce a variant of pushdown dimension called bounded pushdown (BPD) dimension, that measures the density of information contained in a sequence, relative to a BPD automata, i.e. a finite state machine equipped with an extra infinite memory stack, with the additional requirement that every input symbol only allows a bounded number of stack movements. BPD automata are a natural real-time restriction of pushdown automata. We show that BPD dimension is a robust notion by giving an equivalent characterization of BPD dimension in terms of BPD Compressors. We then study the relationships between BPD compression, and the standard Lempel-Ziv (LZ) compression algorithm, and show that in contrast to the finite-state Compressor Case, LZ is not universal for bounded pushdown Compressors in a strong sense: we construct a sequence that LZ fails to compress significantly, but that is compressed by at least a factor 2 by a BPD Compressor. As a corollary we obtain a strong separation between finite-state and BPD dimension.

  • Bounded Pushdown dimension vs Lempel Ziv information density
    arXiv: Computational Complexity, 2007
    Co-Authors: Pilar Albert, Elvira Mayordomo, Philippe Moser
    Abstract:

    In this paper we introduce a variant of pushdown dimension called bounded pushdown (BPD) dimension, that measures the density of information contained in a sequence, relative to a BPD automata, i.e. a finite state machine equipped with an extra infinite memory stack, with the additional requirement that every input symbol only allows a bounded number of stack movements. BPD automata are a natural real-time restriction of pushdown automata. We show that BPD dimension is a robust notion by giving an equivalent characterization of BPD dimension in terms of BPD Compressors. We then study the relationships between BPD compression, and the standard Lempel-Ziv (LZ) compression algorithm, and show that in contrast to the finite-state Compressor Case, LZ is not universal for bounded pushdown Compressors in a strong sense: we construct a sequence that LZ fails to compress signicantly, but that is compressed by at least a factor 2 by a BPD Compressor. As a corollary we obtain a strong separation between finite-state and BPD dimension.