The Experts below are selected from a list of 2952 Experts worldwide ranked by ideXlab platform
Eric Winandy - One of the best experts on this subject based on the ideXlab platform.
-
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.
-
Scroll Compressors for dedicated heat pumps development and performance comparison
2008Co-Authors: Olivier Liegeois, Eric WinandyAbstract:Heat pump systems have to operate at high efficiency levels to be an economical alternative to the traditional heating systems. The requirements for the Compressors are derived from the heating system design parameters (air or ground source) as well as from the ambient conditions which are not uniform through-out Europe. Therefore dedicated Compressors were developed with adaptations to the standard air conditioning models to achieve the required coefficients of performance as well as the necessary operating range. Two types of Scroll Compressors for dedicated heat pumps are described in this paper. The first type is developed based on basic Scroll design for an increased operating map and performance at high condensing. The second type of compressor for high condensing and low evaporation operation integrates an injection port to allow the heat pump to use a cycle with economizer. The main advantages are then a higher COP, increased operating map and higher capacity at low evaporation. These dedicated compressor designs make it possible to achieve the required high condensing temperatures. A performance comparison with the standard compressor designs is finally presented.
-
analysis of the oil return in a pair of Scroll Compressors working in parallel at part load
Applied Thermal Engineering, 2003Co-Authors: Eric Winandy, Cristian B CuevasAbstract:Abstract Condensing units working with a pair of Scroll Compressors working in parallel (tandem) could be an interesting product since this configuration allows one to use these Compressors at higher outputs and to modulate load more easily and efficiently. Nevertheless, this configuration can present serious troubles linked to oil return, especially at part load. In this paper, an analysis of a condensing unit working with a pair of Scroll Compressors working in parallel is presented. First the test bench is described. The problems linked to the oil return when using two Compressors in parallel at part load are described. The configuration tested was equipped with a special connecting pipe to avoid the use of an oil level regulating system. The tests carried out over the range of the condensing unit are discussed. Emphasis is put on the oil circulation in the refrigerant network at part load when one compressor is cycling.
-
Scroll Compressors using gas and liquid injection experimental analysis and modelling
International Journal of Refrigeration-revue Internationale Du Froid, 2002Co-Authors: Eric Winandy, Jean LebrunAbstract:The first part of this paper presents an experimental analysis of different hermetic Scroll Compressors using different methods of injection: the first one is without injection, the second one uses vapor injection and the third one liquid injection. The analysis reveals the influence of these methods on the compressor behavior. A simplified model of the Scroll compressor is then proposed that takes into account not only the different internal processes but also the refrigerant injection. It assumes that the refrigerant mass flow rate is affected by a heating-up due to a uniform wall temperature. This fictitious wall is supposed to gain heat from the electromechanical losses and from the discharged gas and to loose heat to the suction and to the ambient. The compression step is considered isentropic up to the adapted pressure and then at constant volume until the discharge pressure. The model is able to compute variables of first importance like the mass flow rate, the electric power and the discharge temperature, as well as secondary variables as suction heating-up, discharge cooling-down, and ambient losses. The validation based on 45 experimental results shows excellent results.
Cesar J. Deschamps - One of the best experts on this subject based on the ideXlab platform.
-
data from the numerical analysis of radial and tangential leakage of gas in Scroll Compressors
Data in Brief, 2020Co-Authors: Evandro L L Pereira, Vitor M Braga, Cesar J. DeschampsAbstract:Abstract The data presented herein are related to the simulations and correlations reported in the article entitled “Numerical analysis and correlations for radial and tangential leakage of gas in Scroll Compressors” [1]. The numerical simulations were carried out using the ANSYS FLUENT 12.1.4 CFD code, which is based on the finite volume method. Details of the numerical modeling setup and data collection are provided to allow reproducibility. The datasets include predicted values of radial and tangential leakage carried out using ANSYS FLUENT 12.1.4 CFD code for different gases, operating conditions and geometries expressed as dimensionless parameters. The scripts in C++ for the correlations of radial and tangential leakages developed based on the numerical predictions are also provided together with experimental and numerical data used to validate the correlations.
-
numerical analysis and correlations for radial and tangential leakage of gas in Scroll Compressors
International Journal of Refrigeration-revue Internationale Du Froid, 2020Co-Authors: Evandro L L Pereira, Cesar J. DeschampsAbstract:Abstract Scroll Compressors are positive displacement machines of orbital motion that compress a gas by means of two interfitting spiral-shaped Scroll members. Gas leakage is an important source of inefficiency in Scroll Compressors and it therefore needs to be estimated. Currently, correlations for leakage required in simulation models are based on simplified flow conditions. Thus, a high degree of uncertainty is associated with leakage predictions for the wide range of operating conditions found in actual applications. This paper reports a numerical analysis of radial and tangential leakage in Scroll Compressors considering different gases, operating conditions and geometries expressed as dimensionless parameters. Numerical models were developed to analyze the aforementioned phenomena in detail, including the geometry of the wraps. Based on the predicted values, correlations for the radial and tangential leakage of gas particularly suitable for comprehensive simulation models were developed and validated through comparison with experimental data and other models available in the literature.
-
A heat transfer correlation for the suction and compression chambers of Scroll Compressors.
International Journal of Refrigeration, 2017Co-Authors: Evandro L L Pereira, Cesar J. DeschampsAbstract:Heat transfer in the suction and compression chambers of Scroll Compressors has not been sufficiently studied and typical correlations available in the literature are based on simplified flow conditions. This paper presents the results of a model developed to predict fluid flow and heat transfer inside the suction and compression chambers of Scroll Compressors. Due to the particular geometry of Scroll Compressors, an algorithm was developed to adapt the computational mesh automatically for each orbiting angle. Convective heat transfer is strongly affected by the flow in the near-wall region and for this reason a low-Reynolds-number turbulence model was adopted in the simulations. The study covered a wide range of operating conditions and geometric parameters, allowing the proposal of a characteristic velocity for the flow inside the suction and compression chambers and a new heat transfer correlation for Scroll Compressors, which is compared with other correlations adopted in the literature.
-
a lumped parameter thermal model for Scroll Compressors including the solution for the temperature distribution along the Scroll wraps
International Journal of Refrigeration-revue Internationale Du Froid, 2015Co-Authors: Marco C Diniz, Evandro L L Pereira, Cesar J. DeschampsAbstract:Abstract A lumped-parameter thermal model is presented to predict the temperature in different chambers and components inside Scroll Compressors with particular attention to gas superheating in the suction process. Thermal resistances between the components are based on global heat transfer conductances, whereas conduction heat transfer through the Scroll wraps is solved via a one-dimensional finite volume method. The thermal model was coupled to a thermodynamic model of the compression cycle and then applied to simulate the compressor performance under different conditions of speed and pressure ratio. The model was able to correctly predict the compressor temperature for operating conditions within the range of those adopted for its calibration. The results showed a strong coupling between the compressor thermal profile and the temperatures of the motor and lubricating oil. It has also been found that heat conduction through the Scroll wraps reduces slightly the discharge temperature.
-
a ntu based model to estimate suction superheating in Scroll Compressors
2014Co-Authors: Marco C Diniz, Cesar J. DeschampsAbstract:Suction superheating plays a major role in determining the efficiency degradation of hermetic Scroll Compressors. Current models to predict superheating are usually experimentally calibrated and therefore can only be applied to existing Compressors. This paper presents a thermal model to estimate suction superheating in Scroll Compressors, based on the NTU method for heat exchangers design. The model considers an isothermal surface exchanging heat with the gas in the suction path and in the discharge plenum. Compared to other models, the new approach described herein has the advantage of not requiring any experimental input data. The thermal model is coupled to a thermodynamic model and applied to evaluate the performance of a Scroll compressor. The model was capable to predict the suction gas temperature in good agreement with experimental data, making it particularly useful for compressor design.
Jose Gonzalvezmacia - One of the best experts on this subject based on the ideXlab platform.
-
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.
-
new characterization methodology for vapor injection Scroll Compressors
International Journal of Refrigeration-revue Internationale Du Froid, 2017Co-Authors: Fernando M Tellooquendo, Emilio Navarroperis, Jose GonzalvezmaciaAbstract:Abstract This paper presents a characterization methodology for vapor-injection Scroll Compressors (SCVI). An SCVI was characterized in a modified calorimetric test bench, which is able to control the intermediate pressure and the injection superheat independently. Based on the characterization results, the injection mass flow rate was correlated with the intermediate pressure through a linear expression, and a modified AHRI polynomial was proposed to estimate the compressor power input. The correlations were used in a simple model to predict the intermediate conditions of the SCVI installed in a heat pump prototype with an economizer. The deviations obtained for the evaporator mass flow rate, injection mass flow rate, intermediate pressure, and compressor power input were lower than 5% in all cases. The proposed methodology allows evaluating SCVI in a wide range of operating conditions, being only dependent on compressor characteristics and totally independent of the system in which it is installed.
Eckhard A. Groll - One of the best experts on this subject based on the ideXlab platform.
-
performance of the use of plastics in oil free Scroll Compressors
2012Co-Authors: Bryce Shaffer, Eckhard A. GrollAbstract:Manufacturing cost of high precision Scroll compressor parts remains a dominating factor in determining the overall production cost. Traditionally, Scroll Compressors are made of metallic parts which require high tolerances to avoid leakage. Precision is even more important when the compressor is designed for oil-free operation and metal to metal contact can potentially be detrimental to the overall performance. With implementation of non-metallic compressor parts such as plastics, various avenues such as injection molding can be taken to reduce production cost. In addition, various polymer blends can be chosen to alleviate the danger of contact through the use of self-lubricating materials. In the present study, a new compressor concept has been designed and built from both plastic and metallic materials. Performance tests have been conducted on the compressor concept and comparison between plastic and metallic compressor performance have been made.
-
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.
-
Modeling of Hermetic Scroll Compressors: Model Validation and Application
Hvac&r Research, 2004Co-Authors: Yu Chen, Eckhard A. Groll, James E. BraunAbstract:A detailed model for hermetic Scroll Compressors was presented in a companion paper. The current paper presents validation results for this model based upon detailed experimental measurements and application of the model to study the impact of design changes. The experimental study included a range of operating conditions that were controlled using a hot gas bypass compressor load stand. The model was validated in terms of overall performance predictions (refrigerant mass flow rate, discharge temperature, and compressor power consumption) and predictions of internal measurements (refrigerant pressures within the Scrolls as a function of orbiting angle, temperatures along the Scroll wraps, and temperatures at various points within the shell). The model performed very well in terms of predicting overall performance and was adequate in predicting the internal measurements. The parametric modeling study identifies some areas for potential improvement. Most significantly, a relative improvement of about 5% in ...
-
modeling of hermetic Scroll Compressors model development
Hvac&r Research, 2004Co-Authors: Yu Chen, James E. Braun, Eckhard A. GrollAbstract:This paper presents a comprehensive model for a hermetic Scroll compressor. The model combines models of the compression process including leakage and local heat transfer within the Scrolls, frictional losses, motor inefficiencies, and heat transfer within the shell and to the ambient. The model is useful for investigating the impact of design changes on compressor performance. Some sample results are presented in this paper. Detailed validation and an investigation of compressor design improvements are described in a companion paper.
-
mathematical modeling of Scroll Compressors part ii overall Scroll compressor modeling
International Journal of Refrigeration-revue Internationale Du Froid, 2002Co-Authors: Yu Chen, James E. Braun, Nils P. Halm, Eckhard A. GrollAbstract:Abstract This paper presents the development of a comprehensive simulation model of a horizontal Scroll compressor, which combines a detailed compression process model (Chen Y., Halm N., Groll E., Braun J. Mathematical modelling of Scroll Compressors — part I: compression process modeling, International Journal of Refrigeration 2002;25(6):731–750) and an overall compressor model. In the overall model, compressor components are analyzed in terms of nine different elements. Steady state energy balance equations are established applying the lumped capacitance method. In combination with the detailed compression process model, these equations were implemented into computer code and solved recursively. In this way, the temperature and pressure of the refrigerant in different compressor chambers, the temperature distributions in the Scroll wraps, and the temperatures of the other compressor elements can be obtained. Thereafter, power consumption and efficiency of the compressor can be calculated. Tests were used to verify the overall model on a macroscopic basis. Using the simulation program based on the overall compressor model, a parametric study of the Scroll compressor was performed, and the effects of internal leakage and heat transfer losses were investigated and some preliminary results were obtained. These results indicate that the comprehensive Scroll compressor model is capable of predicting real compressor behavior and useful to the design and optimization of Scroll Compressors.
Fernando M Tellooquendo - One of the best experts on this subject based on the ideXlab platform.
-
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.
-
new characterization methodology for vapor injection Scroll Compressors
International Journal of Refrigeration-revue Internationale Du Froid, 2017Co-Authors: Fernando M Tellooquendo, Emilio Navarroperis, Jose GonzalvezmaciaAbstract:Abstract This paper presents a characterization methodology for vapor-injection Scroll Compressors (SCVI). An SCVI was characterized in a modified calorimetric test bench, which is able to control the intermediate pressure and the injection superheat independently. Based on the characterization results, the injection mass flow rate was correlated with the intermediate pressure through a linear expression, and a modified AHRI polynomial was proposed to estimate the compressor power input. The correlations were used in a simple model to predict the intermediate conditions of the SCVI installed in a heat pump prototype with an economizer. The deviations obtained for the evaporator mass flow rate, injection mass flow rate, intermediate pressure, and compressor power input were lower than 5% in all cases. The proposed methodology allows evaluating SCVI in a wide range of operating conditions, being only dependent on compressor characteristics and totally independent of the system in which it is installed.