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Eric Winandy - One of the best experts on this subject based on the ideXlab platform.
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Semi-empirical modelling of a variable speed scroll Compressor with vapour injection
International Journal of Refrigeration, 2015Co-Authors: Laurent Dardenne, Enrico Fraccari, Luca Proserpio, Luca Molinaroli, Alessandro Maggioni, Eric WinandyAbstract:Vapour injection scroll Compressors are nowadays gaining attention in vapour compression systems, especially in high temperature lift application, due to the advantages they provide. To date, proposed models of this kind of Compressor are mainly deterministic models, requiring a detailed description of Compressor geometry and allowing, in turn, minute calculation of the refrigerant state as function of orbiting angle. Semi-empirical models are largely proposed for standard scroll Compressors in order to accurately compute Compressor performance without the need of the knowledge of Compressor geometrical feature. In this paper, a semi-empirical model of a variable speed scroll Compressor with vapour injection is introduced and validated over a set of 63 experimental data finding that 89%-98% of calculated suction and injection refrigerant mass flow rates, Compressor electrical power and refrigerant temperature at Compressor discharge agree within ±5%, ±10% or ±5 K with respect to the experimental values.
Rainer Kurz - One of the best experts on this subject based on the ideXlab platform.
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The Impact of Reciprocating Compressor Pulsations on the Surge Margin of Centrifugal Compressors
Journal of Engineering for Gas Turbines and Power, 2017Co-Authors: Klaus Brun, Sarah Simons, Rainer KurzAbstract:Pressure pulsations into a centrifugal Compressor can move its operating point into surge. This is concerning in pipeline stations where centrifugal Compressors operate in series/parallel with reciprocating Compressors. Sparks (1983, “On the Transient Interaction of Centrifugal Compressors and Their Piping Systems,” ASME Paper No. 83-GT-236); Kurz et al. (2006, “Pulsations in Centrifugal Compressor Installations,” ASME Paper No. GT2006-90700); and Brun et al. (2014, “Impact of the Piping Impedance and Acoustic Characteristics on Centrifugal Compressor Surge and Operating Range,” ASME J. Eng. Turbines Power, 137(3), p. 032603) provided predictions on the impact of periodic pressure pulsation on the behavior of a centrifugal Compressor. This interaction is known as the “Compressor dynamic response” (CDR) theory. Although the CDR describes the impact of the nearby piping system on the Compressor surge and pulsation amplification, it has limited usefulness as a quantitative analysis tool, due to the lack of prediction tools and test data for comparison. Testing of Compressor mixed operation was performed in an air loop to quantify the impact of periodic pressure pulsation from a reciprocating Compressor on the surge margin (SM) of a centrifugal Compressor. This data was utilized to validate predictions from Sparks’ CDR theory and Brun’s numerical approach. A 50 hp single-stage, double-acting reciprocating Compressor provided inlet pulsations into a two-stage 700 hp centrifugal Compressor. Tests were performed over a range of pulsation excitation amplitudes, frequencies, and pipe geometry variations to determine the impact of piping impedance and resonance responses. Results provided clear evidence that pulsations can reduce the surge margin of centrifugal Compressors and that geometry of the piping system immediately upstream and downstream of a centrifugal Compressor will have an impact on the surge margin reduction. Surge margin reductions of over 30% were observed for high centrifugal Compressor inlet suction pulsation.
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The Impact of Reciprocating Compressor Pulsations on the Surge Margin of Centrifugal Compressors
Journal of Engineering for Gas Turbines and Power, 2016Co-Authors: Klaus Brun, Sarah Simons, Rainer KurzAbstract:Pressure pulsations into a centrifugal Compressor can move its operating point into surge. This is concerning in pipeline stations where centrifugal Compressors operate in series/parallel with reciprocating Compressors. Sparks (1983), Kurz et al., (2006), and Brun et al., (2014) provided predictions on the impact of periodic pressure pulsation on the behavior of a centrifugal Compressor. This interaction is known as the “Compressor Dynamic Response” (CDR) theory. Although the CDR describes the impact of the nearby piping system on the Compressor surge and pulsation amplification, it has limited usefulness as a quantitative analysis tool, due to the lack of prediction tools and test data for comparison. Testing of Compressor mixed operation was performed in an air loop to quantify the impact of periodic pressure pulsation from a reciprocating Compressor on the surge margin of a centrifugal Compressor. This data was utilized to validate predictions from Sparks' CDR theory and Brun's numerical approach. A 50 hp single-stage, double-acting reciprocating Compressor provided inlet pulsations into a two-stage 700 hp centrifugal Compressor. Tests were performed over a range of pulsation excitation amplitudes, frequencies, and pipe geometry variations to determine the impact of piping impedance and resonance responses. Results provided clear evidence that pulsations can reduce the surge margin of centrifugal Compressors and that geometry of the piping system immediately upstream and downstream of a centrifugal Compressor will have an impact on the surge margin reduction. Surge margin reductions of <30% were observed for high centrifugal Compressor inlet suction pulsation.
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analysis of the effects of pulsations on the operational stability of centrifugal Compressors in mixed reciprocating and centrifugal Compressor stations
Journal of Engineering for Gas Turbines and Power-transactions of The Asme, 2010Co-Authors: Klaus Brun, Rainer KurzAbstract:Mixed operation with both centrifugal and reciprocating Compressors in a compression plant poses signifcant operational challenges as pressure pulsations and machine mismatches lead to centrifugal Compressors' instabilities or poor performance. Arrangements with reciprocating Compressors placed in series with centrifugal Compressors generally lead to higher suction/discharge pulsations on the centrifugal Compressor than conventional parallel operation. This paper demonstrates that by properly analyzing and designing the interconnecting piping between the Compressors, utilizing pulsation attenuation devices, and matching the Compressors' volumetric-flow rates, a satisfactory functional compression system design can be achieved for even the worst cases of mixed centrifugal and reciprocating Compressor operation. However, even small analysis errors, design deviations, or machine mismatches result in a severely limited (or even inoperable) compression system. Also, pulsation attenuation often leads to a significant pressure loss in the interconnect piping system. Utilizing analysis tools in the design process that can accurately model the transient fluid dynamics of the piping system, the pulsation attenuation devices, and the Compressor machine behaviors is critical to avoid potentially costly design mistakes and minimize pressured losses. This paper presents the methodology and examples of such an analysis using a 1D transient Navier-Stokes code for complex compression piping networks. The code development, application, and example results for a set of mixed operational cases are discussed. This code serves as a design tool to avoid critical piping layout and Compressor matching mistakes early in the Compressor station design process.
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analysis of the effects of pulsations on the operational stability of centrifugal Compressors in mixed reciprocating and centrifugal Compressor stations
Volume 7: Education; Industrial and Cogeneration; Marine; Oil and Gas Applications, 2008Co-Authors: Klaus Brun, Rainer KurzAbstract:Mixed operation with both centrifugal and reciprocating Compressors in a compression plant poses significant operational challenges as pressure pulsations and machine mismatches lead to centrifugal Compressors’ instabilities or poor performance. Arrangements with reciprocating Compressors placed in series with centrifugal Compressors generally lead to higher suction/discharge pulsations on the centrifugal Compressor than conventional parallel operation. This paper demonstrates that by properly analyzing and designing the interconnecting piping between the Compressors, utilizing pulsation attenuation devices, and matching the Compressors’ volumetric-flow rates, a satisfactory functional compression system design can be achieved for even the worst cases of mixed centrifugal and reciprocating Compressor operation. However, even small analysis errors, design deviations, or machine mismatches result in a severely limited (or even inoperable) compression system. Also, pulsation attenuation often leads to a significant pressure loss in the interconnect piping system. Utilizing analysis tools in the design process that can accurately model the transient fluid dynamics of the piping system, the pulsation attenuation devices and the Compressor machine behaviors is critical to avoid potentially costly design mistakes and minimize pressured losses. This paper presents the methodology and examples of such an analysis using a 1-D transient Navier-Stokes code for complex compression piping networks. The code development, application, and example results for a set of mixed operational cases are discussed. This code serves as a design tool to avoid critical piping layout and Compressor matching mistakes early in the Compressor station design process.Copyright © 2008 by ASME and Solar Turbines Incorporated
Eckhard A. Groll - One of the best experts on this subject based on the ideXlab platform.
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Two-phase injected and vapor-injected compression: Experimental results and mapping correlation for a R-407C scroll Compressor
International Journal of Refrigeration, 2018Co-Authors: Domenique R. Lumpkin, Ammar M Bahman, Eckhard A. GrollAbstract:Vapor compression systems in hot climates tend to operate at higher pressure ratios, leading to increased discharge temperatures, higher irreversibilities during compression, lower specific enthalpies differences across the evaporator, and possibly a reduction in the Compressor life due to the breakdown of the oil. To counter these effects, the use of economized, vapor injection Compressors is proposed for vapor compression systems in high temperature climates. Such Compressors are commercially available however an accurate method for mapping single-port injection Compressors is unclear. This paper establishes Compressor maps for a single-speed R-407C scroll Compressor with two-phase injection and vapor-injected compression. A dimensionless-PI correlation for mapping the injection ratio, refrigerant discharge temperature, Compressor power consumption, overall isentropic and volumetric efficiencies, and the heat loss ratio for these Compressor maps and a variable speed R-410A Compressor with vapor injection is presented. The mapping results are compared to the AHRI 10-coefficient polynomial and another proposed correlation.
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Modeling and Testing of a Two-Stage Rotary Compressor
2008Co-Authors: Margaret M. Mathison, James E. Braun, Eckhard A. GrollAbstract:While previous research studies have analyzed the compression process of single-stage rotary Compressors, little information is available on two-stage rotary Compressors. However, two-stage Compressors provide opportunities for energy savings through modifications such as intercooling and economizing. This paper presents a computer model of a hermetic two-stage rotary Compressor that was developed to provide design engineers with the means to optimize the Compressor design. The computer model considers the effects of leakages and heat transfer in its calculations to estimate the Compressor power input and refrigerant mass flow rate. The model can be operated both with and without intercooling between the stages. External measurements were conducted using a prototype Compressor to validate the model. The intermediate temperature and pressure, discharge temperature, power consumption, and mass flow rate were recorded for seventeen different operating conditions. The model predicts the Compressor power consumption and mass flow rate within ±5% of the experimental results.
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Analysis of liquid-flooded compression using a scroll Compressor.
2008Co-Authors: Ian H. Bell, James E. Braun, Vincent Lemort, Eckhard A. GrollAbstract:ABSTRACT One possible means of decreasing the work of compression of a scroll gas Compressor is by injecting, or flooding, high specific heat liquid into the inlet gas stream of the Compressor. The high specific heat liquid can then absorb the heat of compression of the gas and offer the possibility of a reduction in the net power of the Compressor. The particular application of interest for this flooded-compression technology is the Liquid-Flooded Ericsson cycle as proposed by Hugenroth et al. (2007), a gas refrigeration cycle. Adequate performance of the Ericsson cycle is contingent on designing scroll Compressors that can efficiently compress high heat of compression gases. A detailed model of the flooded scroll Compressor has been constructed which allows prediction of the Compressor performance over a wide range of operating conditions. The detailed flooded scroll Compressor model has been validated with experimental data, for which good agreement was found. 1. INTRODUCTION A vapor-compression scroll Compressor has been modified to run on a mixture of gas and oil. Originally the Compressor was an automotive R134a Compressor, but due to its semi-hermetic design it could easily be modified for use with liquid flooding. The radial compliance and discharge valve were removed, but otherwise the Compressor was off-the-shelf. Previous investigators (Li 1992, Hiwata 2002, Oku 2006) have experimentally researched flooded compression in scroll Compressors, though their studies were based on vapor compression systems, and the Compressors were not optimized for liquid flooding.
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Measurement of performance of carbon dioxide Compressors. Final report.
2002Co-Authors: B Hubacher, Eckhard A. GrollAbstract:The aim of this project was to measure the performance of two carbon dioxide prototype Compressors using a Compressor load stand and to develop Compressor performance maps based on the experimental data. A Compressor load stand was specifically designed and constructed for this purpose, which is based on a hot-gas bypass design and uses an oil-separator in the discharge line. The measured Compressors were a semi-hermetic, two-piston, single-stage, reciprocating Compressor with an estimated cooling capacityof 10.6 kW (3 tons of refrigeration) and a hermetic, two-stage, rotary Compressor with an estimated cooling capacity of 2.8 kW (0.8 tons of refrigeration). A test matrix of 48 operating conditions was established. Extract from the table of contents: CO2-Compressor background; test stand (design and performance, instrumentation, oil measurements); carbon dioxide grades; lubrication; analysis; single-stage, semi-hermetic Compressor; two-stage, hermetic Compressor. The report can be downloaded from the Web site: www.arti-21cr.org/research/completed/index.html.
Jose Gonzalvezmacia - One of the best experts on this subject based on the ideXlab platform.
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semi empirical model of scroll Compressors and its extension to describe vapor injection Compressors model description and experimental validation
International Journal of Refrigeration-revue Internationale Du Froid, 2019Co-Authors: Fernando M Tellooquendo, Emilio Navarroperis, Francisco Barceloruescas, Jose GonzalvezmaciaAbstract:Abstract This paper presents a semi-empirical model of scroll Compressors and proposes a methodology in order to extend this model to vapor-injection scroll Compressors. The model takes into account the ideal evolution of the refrigerant throughout the Compressor and considers the main sources of losses in the compression process. The model is able to predict the Compressor and volumetric efficiencies in terms of ten empirical parameters, which have a direct physical interpretation. For the model validation, a series of four non-injected scroll Compressors of different capacities were tested using R-290 and a scroll Compressor with vapor-injection (SCVI) was characterized using R-407C. Results show a correct agreement between the experimental and calculated Compressor efficiencies, with a maximum deviation of ±5%. Furthermore, the model estimates accurately the discharge temperature of the refrigerant, Compressor power input, and refrigerant mass flow rate in the suction and injection port. Finally, the SCVI model response was evaluated by varying the intermediate pressure and the injection superheat.
Laurent Dardenne - One of the best experts on this subject based on the ideXlab platform.
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Semi-empirical modelling of a variable speed scroll Compressor with vapour injection
International Journal of Refrigeration, 2015Co-Authors: Laurent Dardenne, Enrico Fraccari, Luca Proserpio, Luca Molinaroli, Alessandro Maggioni, Eric WinandyAbstract:Vapour injection scroll Compressors are nowadays gaining attention in vapour compression systems, especially in high temperature lift application, due to the advantages they provide. To date, proposed models of this kind of Compressor are mainly deterministic models, requiring a detailed description of Compressor geometry and allowing, in turn, minute calculation of the refrigerant state as function of orbiting angle. Semi-empirical models are largely proposed for standard scroll Compressors in order to accurately compute Compressor performance without the need of the knowledge of Compressor geometrical feature. In this paper, a semi-empirical model of a variable speed scroll Compressor with vapour injection is introduced and validated over a set of 63 experimental data finding that 89%-98% of calculated suction and injection refrigerant mass flow rates, Compressor electrical power and refrigerant temperature at Compressor discharge agree within ±5%, ±10% or ±5 K with respect to the experimental values.
