The Experts below are selected from a list of 39 Experts worldwide ranked by ideXlab platform
Vasko N. Šarevski - One of the best experts on this subject based on the ideXlab platform.
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Novel Combined Water (R718) Refrigeration Systems with Single-Stage Centrifugal Compressor and Two-Phase Ejectors
Water (R718) Turbo Compressor and Ejector Refrigeration Heat Pump Technology, 2020Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:A novel R718 refrigeration cycle with a single-stage centrifugal compressor and two-phase ejectors is theoretically investigated. A new compact R718 water chiller is proposed with integration of a centrifugal compressor stage and two-phase condensing ejectors as a second-stage compression device. The limitations of the R718 centrifugal stage pressure ratio, caused by the small molecular mass of the water and high isentropic exponent, result in high Impeller Peripheral Speed, high Mach number, and high discharge temperature. The Reynolds number is low and dimensions of the compressor are large. The complex thermal and flow phenomena inside the two-phase ejector flow field are discussed and performance characteristics are estimated. Although the efficiency of the concept of compression with a hydraulic pump and two-phase ejectors is lower, the integration of two-phase ejectors in an R718 centrifugal unit results in a low cost, high capacity refrigeration system with high energy efficiency, competitive with conventional refrigeration systems for environmental, technical, and economic reasons.
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Water (R718) Centrifugal Compressors
Water (R718) Turbo Compressor and Ejector Refrigeration Heat Pump Technology, 2020Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:Influence of the refrigerant thermodynamic properties on the characteristics of centrifugal compressors is investigated. Peculiarities of centrifugal compressors working with various refrigerants are defined and the range of priority application is determined. Interdependence between centrifugal stage pressure ratio, Peripheral Mach number and Impeller Peripheral Speed, as well as the influence of the refrigeration capacity on the dimensions of centrifugal compressors are determined to obtain the range of reasonable usage of R718 refrigeration/heat pump systems. Deep vacuum operating conditions, low specific volumetric cooling capacity of R718, and small molecular mass of water are the peculiarities that determine the main parameters of the water (R718) centrifugal compressors and the range of rational application of the R718 centrifugal refrigeration/heat pump systems. The high Peripheral Impeller Speed, high Mach number, and high pressure ratio cause separated jet-wake flow and transonic flow phenomena in the compressor flow field.
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Water (R718) Turbo Compressor Refrigeration/Heat Pump Systems
Water (R718) Turbo Compressor and Ejector Refrigeration Heat Pump Technology, 2020Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:R718 centrifugal refrigeration/heat pump systems are investigated to determine optimal schematic structure, to estimate performance characteristics, and to provide possibilities for wider application in the field of air-conditioning. Deep vacuum operating conditions, low specific volumetric cooling capacity, small molecular mass, and high isentropic exponent of the water are peculiarities which determine the main parameters of centrifugal compressors and the range of rational application of R718 refrigeration/heat pump systems. High Impeller Peripheral Speed, high Mach number, low Reynolds number, large dimensions, and high superheating at the compressor discharge are the features of R718 centrifugal refrigeration compressors. A two-stage centrifugal compressor and, respectively, two-stage refrigeration cycle are optimal technical solutions for refrigeration systems in the field of air-conditioning applications. Direct flash evaporation and condensation provide simplicity and the possibility of achieving a high COP. A comparison shows that R718 centrifugal refrigeration systems are competitive with traditional refrigeration systems.
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Preliminary study of a novel R718 refrigeration cycle with single stage centrifugal compressor and two-phase ejector
International Journal of Refrigeration-revue Internationale Du Froid, 2014Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:Abstract The paper describes the investigations of a novel R718 refrigeration cycle with single stage centrifugal compressor and two-phase ejector as a second stage compression device. The limitations of the R718 centrifugal stage pressure ratio, connected with small molecular mass of the water and high isentropic exponent, result on high Impeller Peripheral Speed, high Mach number and high discharge temperature. Reynolds number is low and dimensions of the compressor stage are large. The complex thermal and flow phenomena inside two-phase ejector flow field are investigated and performance characteristics are estimated. Although efficiency of the concept of compression with hydraulic pump and two-phase ejectors is lower, the integration of two-phase ejectors in the R718 centrifugal unit results in low cost high capacity refrigeration system with high energy efficiency, competitive with traditional refrigeration systems by environmental, technical and economical reasons.
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Preliminary study of a novel R718 refrigeration cycle with single stage centrifugal compressor and two-phase ejector
International Journal of Refrigeration, 2014Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:The paper describes the investigations of a novel R718 refrigeration cycle with single stage centrifugal compressor and two-phase ejector as a second stage compression device. The limitations of the R718 centrifugal stage pressure ratio, connected with small molecular mass of the water and high isentropic exponent, result on high Impeller Peripheral Speed, high Mach number and high discharge temperature. Reynolds number is low and dimensions of the compressor stage are large. The complex thermal and flow phenomena inside two-phase ejector flow field are investigated and performance characteristics are estimated. Although efficiency of the concept of compression with hydraulic pump and two-phase ejectors is lower, the integration of two-phase ejectors in the R718 centrifugal unit results in low cost high capacity refrigeration system with high energy efficiency, competitive with traditional refrigeration systems by environmental, technical and economical reasons. © 2013 Elsevier Ltd and IIR. All rights reserved.
Milan N. Šarevski - One of the best experts on this subject based on the ideXlab platform.
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Novel Combined Water (R718) Refrigeration Systems with Single-Stage Centrifugal Compressor and Two-Phase Ejectors
Water (R718) Turbo Compressor and Ejector Refrigeration Heat Pump Technology, 2020Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:A novel R718 refrigeration cycle with a single-stage centrifugal compressor and two-phase ejectors is theoretically investigated. A new compact R718 water chiller is proposed with integration of a centrifugal compressor stage and two-phase condensing ejectors as a second-stage compression device. The limitations of the R718 centrifugal stage pressure ratio, caused by the small molecular mass of the water and high isentropic exponent, result in high Impeller Peripheral Speed, high Mach number, and high discharge temperature. The Reynolds number is low and dimensions of the compressor are large. The complex thermal and flow phenomena inside the two-phase ejector flow field are discussed and performance characteristics are estimated. Although the efficiency of the concept of compression with a hydraulic pump and two-phase ejectors is lower, the integration of two-phase ejectors in an R718 centrifugal unit results in a low cost, high capacity refrigeration system with high energy efficiency, competitive with conventional refrigeration systems for environmental, technical, and economic reasons.
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Water (R718) Centrifugal Compressors
Water (R718) Turbo Compressor and Ejector Refrigeration Heat Pump Technology, 2020Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:Influence of the refrigerant thermodynamic properties on the characteristics of centrifugal compressors is investigated. Peculiarities of centrifugal compressors working with various refrigerants are defined and the range of priority application is determined. Interdependence between centrifugal stage pressure ratio, Peripheral Mach number and Impeller Peripheral Speed, as well as the influence of the refrigeration capacity on the dimensions of centrifugal compressors are determined to obtain the range of reasonable usage of R718 refrigeration/heat pump systems. Deep vacuum operating conditions, low specific volumetric cooling capacity of R718, and small molecular mass of water are the peculiarities that determine the main parameters of the water (R718) centrifugal compressors and the range of rational application of the R718 centrifugal refrigeration/heat pump systems. The high Peripheral Impeller Speed, high Mach number, and high pressure ratio cause separated jet-wake flow and transonic flow phenomena in the compressor flow field.
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Water (R718) Turbo Compressor Refrigeration/Heat Pump Systems
Water (R718) Turbo Compressor and Ejector Refrigeration Heat Pump Technology, 2020Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:R718 centrifugal refrigeration/heat pump systems are investigated to determine optimal schematic structure, to estimate performance characteristics, and to provide possibilities for wider application in the field of air-conditioning. Deep vacuum operating conditions, low specific volumetric cooling capacity, small molecular mass, and high isentropic exponent of the water are peculiarities which determine the main parameters of centrifugal compressors and the range of rational application of R718 refrigeration/heat pump systems. High Impeller Peripheral Speed, high Mach number, low Reynolds number, large dimensions, and high superheating at the compressor discharge are the features of R718 centrifugal refrigeration compressors. A two-stage centrifugal compressor and, respectively, two-stage refrigeration cycle are optimal technical solutions for refrigeration systems in the field of air-conditioning applications. Direct flash evaporation and condensation provide simplicity and the possibility of achieving a high COP. A comparison shows that R718 centrifugal refrigeration systems are competitive with traditional refrigeration systems.
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Preliminary study of a novel R718 refrigeration cycle with single stage centrifugal compressor and two-phase ejector
International Journal of Refrigeration-revue Internationale Du Froid, 2014Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:Abstract The paper describes the investigations of a novel R718 refrigeration cycle with single stage centrifugal compressor and two-phase ejector as a second stage compression device. The limitations of the R718 centrifugal stage pressure ratio, connected with small molecular mass of the water and high isentropic exponent, result on high Impeller Peripheral Speed, high Mach number and high discharge temperature. Reynolds number is low and dimensions of the compressor stage are large. The complex thermal and flow phenomena inside two-phase ejector flow field are investigated and performance characteristics are estimated. Although efficiency of the concept of compression with hydraulic pump and two-phase ejectors is lower, the integration of two-phase ejectors in the R718 centrifugal unit results in low cost high capacity refrigeration system with high energy efficiency, competitive with traditional refrigeration systems by environmental, technical and economical reasons.
-
Preliminary study of a novel R718 refrigeration cycle with single stage centrifugal compressor and two-phase ejector
International Journal of Refrigeration, 2014Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:The paper describes the investigations of a novel R718 refrigeration cycle with single stage centrifugal compressor and two-phase ejector as a second stage compression device. The limitations of the R718 centrifugal stage pressure ratio, connected with small molecular mass of the water and high isentropic exponent, result on high Impeller Peripheral Speed, high Mach number and high discharge temperature. Reynolds number is low and dimensions of the compressor stage are large. The complex thermal and flow phenomena inside two-phase ejector flow field are investigated and performance characteristics are estimated. Although efficiency of the concept of compression with hydraulic pump and two-phase ejectors is lower, the integration of two-phase ejectors in the R718 centrifugal unit results in low cost high capacity refrigeration system with high energy efficiency, competitive with traditional refrigeration systems by environmental, technical and economical reasons. © 2013 Elsevier Ltd and IIR. All rights reserved.
Mohammad Noaparast - One of the best experts on this subject based on the ideXlab platform.
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Estimation of diameter and surface area flux of bubbles based on operational gas dispersion parameters by using regression and ANFIS
International journal of mining science and technology, 2013Co-Authors: B. Shahbazi, Bahram Rezai, S. Chehreh Chelgani, S.m. Javad Koleini, Mohammad NoaparastAbstract:Abstract Adaptive neuro fuzzy inference system (ANFIS) procedure and regression methods were used to predict the Sauter mean bubble (bubble diameter) and surface area flux of the bubble in a flotation process. The operational conditions of flotation, Impeller Peripheral Speed, superficial gas velocity, and weight percent solids were used as inputs of methods. By using the mentioned operational conditions, the non linear regression results showed that Sauter mean, and surface area flux of the bubble are predictable variables, where the coefficients of determination (R2) are 0.57 and 0.74, respectively. To increase the accuracy of prediction an ANFIS model with cluster radius of 0.4 was applied. ANFIS model was capable of estimating both Sauter mean, and surface area flux of the bubble, where in a testing stage, satisfactory correlations, R2 = 0.78, and 0.86, were achieved for Sauter mean, and surface area flux of bubble, respectively. Results show that the proposed ANFIS model can accurately estimate outputs and be used in order to predict the parameters without having to conduct the new experiments in a laboratory.
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The Empirical Prediction of Gas Dispersion Parameters on Mechanical Flotation Cells
Engineering, 2012Co-Authors: B. Shahbazi, Bahram Rezai, Seyed Mohammad Javad Koleini, Mohammad NoaparastAbstract:Gas dispersion properties include bubble size ( ), gas holdup ( ) and bubble surface area flux ( ) and input power ( ) are effective parameters on flotation performance. During the last 10 years, some investigations have been carried out to measure these parameters in mechanical flotation cells. In this research, some models are created to estimate gas dispersion properties and input power by experimental data. Variables of models are Impeller Peripheral Speed ( ), superficial gas velocity ( ) and pulp density ( ) and final form of models are , , and . According to these equations, most effective variables are , and , respectively.
B. Shahbazi - One of the best experts on this subject based on the ideXlab platform.
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Estimation of diameter and surface area flux of bubbles based on operational gas dispersion parameters by using regression and ANFIS
International journal of mining science and technology, 2013Co-Authors: B. Shahbazi, Bahram Rezai, S. Chehreh Chelgani, S.m. Javad Koleini, Mohammad NoaparastAbstract:Abstract Adaptive neuro fuzzy inference system (ANFIS) procedure and regression methods were used to predict the Sauter mean bubble (bubble diameter) and surface area flux of the bubble in a flotation process. The operational conditions of flotation, Impeller Peripheral Speed, superficial gas velocity, and weight percent solids were used as inputs of methods. By using the mentioned operational conditions, the non linear regression results showed that Sauter mean, and surface area flux of the bubble are predictable variables, where the coefficients of determination (R2) are 0.57 and 0.74, respectively. To increase the accuracy of prediction an ANFIS model with cluster radius of 0.4 was applied. ANFIS model was capable of estimating both Sauter mean, and surface area flux of the bubble, where in a testing stage, satisfactory correlations, R2 = 0.78, and 0.86, were achieved for Sauter mean, and surface area flux of bubble, respectively. Results show that the proposed ANFIS model can accurately estimate outputs and be used in order to predict the parameters without having to conduct the new experiments in a laboratory.
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The Empirical Prediction of Gas Dispersion Parameters on Mechanical Flotation Cells
Engineering, 2012Co-Authors: B. Shahbazi, Bahram Rezai, Seyed Mohammad Javad Koleini, Mohammad NoaparastAbstract:Gas dispersion properties include bubble size ( ), gas holdup ( ) and bubble surface area flux ( ) and input power ( ) are effective parameters on flotation performance. During the last 10 years, some investigations have been carried out to measure these parameters in mechanical flotation cells. In this research, some models are created to estimate gas dispersion properties and input power by experimental data. Variables of models are Impeller Peripheral Speed ( ), superficial gas velocity ( ) and pulp density ( ) and final form of models are , , and . According to these equations, most effective variables are , and , respectively.
Bahram Rezai - One of the best experts on this subject based on the ideXlab platform.
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Estimation of diameter and surface area flux of bubbles based on operational gas dispersion parameters by using regression and ANFIS
International journal of mining science and technology, 2013Co-Authors: B. Shahbazi, Bahram Rezai, S. Chehreh Chelgani, S.m. Javad Koleini, Mohammad NoaparastAbstract:Abstract Adaptive neuro fuzzy inference system (ANFIS) procedure and regression methods were used to predict the Sauter mean bubble (bubble diameter) and surface area flux of the bubble in a flotation process. The operational conditions of flotation, Impeller Peripheral Speed, superficial gas velocity, and weight percent solids were used as inputs of methods. By using the mentioned operational conditions, the non linear regression results showed that Sauter mean, and surface area flux of the bubble are predictable variables, where the coefficients of determination (R2) are 0.57 and 0.74, respectively. To increase the accuracy of prediction an ANFIS model with cluster radius of 0.4 was applied. ANFIS model was capable of estimating both Sauter mean, and surface area flux of the bubble, where in a testing stage, satisfactory correlations, R2 = 0.78, and 0.86, were achieved for Sauter mean, and surface area flux of bubble, respectively. Results show that the proposed ANFIS model can accurately estimate outputs and be used in order to predict the parameters without having to conduct the new experiments in a laboratory.
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The Empirical Prediction of Gas Dispersion Parameters on Mechanical Flotation Cells
Engineering, 2012Co-Authors: B. Shahbazi, Bahram Rezai, Seyed Mohammad Javad Koleini, Mohammad NoaparastAbstract:Gas dispersion properties include bubble size ( ), gas holdup ( ) and bubble surface area flux ( ) and input power ( ) are effective parameters on flotation performance. During the last 10 years, some investigations have been carried out to measure these parameters in mechanical flotation cells. In this research, some models are created to estimate gas dispersion properties and input power by experimental data. Variables of models are Impeller Peripheral Speed ( ), superficial gas velocity ( ) and pulp density ( ) and final form of models are , , and . According to these equations, most effective variables are , and , respectively.
