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D. Wibowo Djamari - One of the best experts on this subject based on the ideXlab platform.

  • Theoretical study of a novel refrigeration compressor – Part II: Performance of a rotating Discharge Valve in the revolving vane (RV) compressor
    International Journal of Refrigeration-revue Internationale Du Froid, 2009
    Co-Authors: D. Wibowo Djamari
    Abstract:

    Abstract A new refrigeration compressor, named ‘Revolving Vane (RV) compressor’, has been introduced in Part I of this paper series. For a first time in refrigeration compressors, a rotating Discharge Valve is employed in the RV compressor mainly due to the rotation of the entire cylinder. This paper presents a theoretical investigation on the dynamic behavior of a reed-type Discharge Valve undergoing rotatory motion, with the primary objective of elucidating the applicability of such Valves in refrigeration compressors. Under the application of the Euler–Bernoulli beam theory, a mathematical model of the rotating Valve is formulated and the transient response of the Valve under centrifugal loads in addition to pressure forces is analyzed. Results have shown that under careful design considerations, the performance as well as the reliability of the rotating Discharge Valve can be enhanced as compared to a non-rotating Valve that has been used in all refrigeration compressors currently.

  • Theoretical study of a novel refrigeration compressor - Part II: Performance of a rotating Discharge Valve in the revolving vane (RV) compressor
    International Journal of Refrigeration, 2009
    Co-Authors: Y. L. Teh, Kim Tiow Ooi, D. Wibowo Djamari
    Abstract:

    A new refrigeration compressor, named 'Revolving Vane (RV) compressor', has been introduced in Part I of this paper series. For a first time in refrigeration compressors, a rotating Discharge Valve is employed in the RV compressor mainly due to the rotation of the entire cylinder. This paper presents a theoretical investigation on the dynamic behavior of a reed-type Discharge Valve undergoing rotatory motion, with the primary objective of elucidating the applicability of such Valves in refrigeration compressors. Under the application of the Euler-Bernoulli beam theory, a mathematical model of the rotating Valve is formulated and the transient response of the Valve under centrifugal loads in addition to pressure forces is analyzed. Results have shown that under careful design considerations, the performance as well as the reliability of the rotating Discharge Valve can be enhanced as compared to a non-rotating Valve that has been used in all refrigeration compressors currently. © 2008 Elsevier Ltd and IIR.

Ziwen Xing - One of the best experts on this subject based on the ideXlab platform.

  • Experimental study of the swing compressor with no Valves
    Applied Thermal Engineering, 2019
    Co-Authors: Chengcheng Tian, Shuang Wu, Ziwen Xing
    Abstract:

    Abstract One of the challenges in swing compressor is how to mitigate or eliminate the impact of the Discharge Valve. In order to achieve this goal, the swing compressor with no Valves (SCNV) has been designed, fabricated, instrumented and tested. This compressor design eliminates the Discharge Valve and the Discharge close volume. A compressor prototype has been tested using R410a as the working fluid and operated at 1800–5400 rev/min. The volumetric efficiency, the isentropic efficiency, and the coefficient of performance (COP) of SCNV have been analyzed. The volumetric efficiency rises with the increase of the shaft speed. However, the isentropic efficiency and the COP increase firstly and then decrease. Additionally, the COP of SCNV is found to be greater than that of the conventional swing compressor when the shaft speed is 1800 rev/min and the reverse is true for the shaft speed at 3600 rev/min and 5400 rev/min.

  • experimental investigation of the Discharge Valve dynamics in a reciprocating compressor for trans critical co2 refrigeration cycle
    Applied Thermal Engineering, 2012
    Co-Authors: Zhilong He, Xueyuan Peng, Ziwen Xing
    Abstract:

    The self-acting Valve has a significant influence on the efficiency and reliability of the reciprocating compressor. In the trans-critical CO2 cycle, the large density and high pressure difference across the Valve cause serious bending and impact stresses in the Valve, offering great challenges for successful Valve design. Experimental investigation of the Valve dynamics is required in order to design a self-acting Valve with a high efficiency and long life span for the trans-critical CO2 compressor. A semi-hermetic reciprocating compressor was developed for application in CO2 refrigeration, and a test system was incorporated into the compressor performance test rig, with a focus on investigating the dynamics of the Discharge Valves. With the experimental results, the movement of the Valve was discussed in detail for the trans-critical CO2 compressor, allowing for the study of the thermodynamic performance of the compressor. While varying design parameters such as pressure ratio, Valve lift, spring stiffness and compressor speed, the movement of the Discharge Valve in the reciprocating CO2 compressor was measured in order to investigate the major factors that influence the Valve dynamics. The average Valve speed increased from 0.71 m/s to 0.81 m/s as the Discharge pressure changed from 7.8 MPa to 12 MPa. The experimental methods and results discussed in this paper could provide useful information for both Valve testing and the optimization of their reliability in trans-critical CO2 compressors.

Wibowo D Djamari - One of the best experts on this subject based on the ideXlab platform.

  • theoretical study of a novel refrigeration compressor part ii performance of a rotating Discharge Valve in the revolving vane rv compressor
    International Journal of Refrigeration-revue Internationale Du Froid, 2009
    Co-Authors: Wibowo D Djamari
    Abstract:

    Abstract A new refrigeration compressor, named ‘Revolving Vane (RV) compressor’, has been introduced in Part I of this paper series. For a first time in refrigeration compressors, a rotating Discharge Valve is employed in the RV compressor mainly due to the rotation of the entire cylinder. This paper presents a theoretical investigation on the dynamic behavior of a reed-type Discharge Valve undergoing rotatory motion, with the primary objective of elucidating the applicability of such Valves in refrigeration compressors. Under the application of the Euler–Bernoulli beam theory, a mathematical model of the rotating Valve is formulated and the transient response of the Valve under centrifugal loads in addition to pressure forces is analyzed. Results have shown that under careful design considerations, the performance as well as the reliability of the rotating Discharge Valve can be enhanced as compared to a non-rotating Valve that has been used in all refrigeration compressors currently.

Cesar J. Deschamps - One of the best experts on this subject based on the ideXlab platform.

  • Influence of break-in on the leakage through reed-type Valves of low-capacity refrigeration compressors
    International Journal of Refrigeration-revue Internationale Du Froid, 2019
    Co-Authors: Fernanda Dos Santos, Ernane Silva, Cesar J. Deschamps
    Abstract:

    Abstract Valve leakage can significantly decrease the efficiency of reciprocating compressors adopted in household refrigeration systems, especially in low-capacity and oil-free compressors. These leakages occur through the Valves due to geometric irregularities resulting from the manufacturing and assembly processes, which form leakage paths between the reeds and seats. Valve leakage is generally measured using completely new Valve systems, which may not represent the actual leakage in Valves after break-in. The aim of this study was to assess the influence of break-in on the leakage through reed-type Valves of low-capacity refrigeration compressors. The leakage was measured for the suction and Discharge Valves of a R600a compressor before and after the Valves were subjected to a break-in period. The Valve leakage was characterized by the geometric parameter edge gap, defined as the gap between the reed and seat at the internal border of the Valve orifice. The results indicate that the edge gap, and consequently leakage, is reduced with break-in. The leakage was reduced by up to 76% for the suction Valve and by up to 95% for the Discharge Valve after break-in, while the edge gap was reduced by up to 50% for the suction Valve and by up to 73% for the Discharge Valve. It should be mentioned that the reed and seat surfaces of the suction Valve had their maximum roughness reduced by 40% and 29%, respectively, after break-in, suggesting that the edge gap is related to the surface finishing.

  • Modeling of gas leakage through compressor Valves
    International Journal of Refrigeration, 2015
    Co-Authors: Leandro R. Silva, Cesar J. Deschamps
    Abstract:

    This paper describes a model developed to predict gas leakage in cases of incomplete sealing of the reed-type Valves of small reciprocating compressors adopted for household refrigeration. The model assumes a one-dimensional formulation for the flow, considering the effects of viscous friction, slip-flow regime and compressibility. Reed bending into the port due to the pressure load is also taken into account to characterize the Valve clearance. Computations are carried out during the compression cycle and the effect of leakage on both the isentropic and volumetric efficiencies is quantified for two operating conditions. It was found that leakage significantly reduces the compressor efficiency even for very small Valve clearances and that leakage in the Discharge Valve is of greater importance than that in the suction Valve.

  • a lumped thermodynamic model for scroll compressors with special attention to the geometric characterization during the Discharge process
    2010
    Co-Authors: Evandro L L Pereira, Cesar J. Deschamps
    Abstract:

    A numerical model based on an integral formulation for mass and energy conservation has been developed to simulate the thermodynamic performance of scroll compressors. Internal gas leakages are predicted via a quasi-onedimensional model that includes viscous and inertial effects. A one-degree of freedom model and a quasi-static model are tested to describe the dynamics of the Discharge Valve. Unlike most models proposed in the literature, mathematical expressions are written to accurately evaluate both the volume of the compression chamber and the available Valve port area during the Discharge process. Additionally, a new solution procedure is devised to simplify the code implementation and to improve the convergence of the iterative procedure. The paper analyzes the influence of the aforementioned approaches on the scroll modeling.

  • Large eddy simulation applied to reciprocating compressors
    Journal of The Brazilian Society of Mechanical Sciences and Engineering, 2006
    Co-Authors: João B. Rovaris, Cesar J. Deschamps
    Abstract:

    This paper considers the application of large-eddy simulation (LES) to predict the performance of hermetic reciprocating compressors utilized in refrigeration. In such devices the pressure difference between the suction/Discharge chamber and the cylinder, established by the piston motion, is responsible for the Valve opening. Once the Valves are open, the flow dictates the pressure distribution on the Valve reed surface and, consequently, the resultant force that will govern the Valve dynamics and its displacement from the seat. The methodology developed herein applies LES, combined with the Smagorinsky sub-grid model, to account for the compressible turbulent flow through the Discharge Valve. A one-degree of freedom model is adopted for the Valve dynamics, and a finite volume methodology to solve the flow field throughout the Discharge Valve. For the remainder of the compression cycle, an integral formulation is employed, with effective flow and force areas being used to evaluate the dynamics and mass flow rate for the suction Valve. Numerical results demonstrate that the methodology is capable of predicting important flow features in the Discharge process, at a reasonable computational cost.

Won Sik Oh - One of the best experts on this subject based on the ideXlab platform.

  • linear compressor Discharge Valve behavior using a rigid body Valve model and a fsi Valve model
    International Journal of Refrigeration-revue Internationale Du Froid, 2017
    Co-Authors: Il Sun Hwang, Sang Jun Park, Won Sik Oh
    Abstract:

    Abstract The Discharge Valve of a linear compressor commonly uses a circular plate Valve and research on such Valves is lacking. Thus, in this study, the rigid body model and the FSI model, widely used for the reed Valve, were used to examine the behavior of the Discharge Valve. Also, a comparison with experimental results was conducted to determine the characteristics of each Valve model. According to the results, only the Valve lift of the FSI model was in agreement with the experimental result. Moreover, the 3D rigid body Valve model could not predict the additional displacement fluctuations of the Valve that cause backflow during the expansion process of the compressor whereas the 3D FSI Valve model was able to predict the additional displacement fluctuations. Therefore, the FSI model was found to be advantageous in calculating the cooling capacity or EER of the linear compressor with the circular plate Discharge Valve.

  • A study on cycle performance variation of a linear compressor considering Valve behavior
    Journal of Mechanical Science and Technology, 2017
    Co-Authors: Sang Jun Park, Il Sun Hwang, Won Sik Oh
    Abstract:

    The suction Valve of a linear compressor is a reed Valve and the Discharge Valve is a circular plate Valve. The reed Valve moves in three dimensions while the Discharge Valve translates in one dimension. Thus, the reed Valve needs a FSI model but the Discharge Valve can use a rigid body model. In this study, both the FSI model and the rigid body model were applied to the suction Valve to find out if they are appropriate for the cycle analysis of the linear compressor. The effects of the Valve dynamics on the cooling capacity, the compression power, and EER were investigated for each Valve model. The results show that both models are in good agreement with the experiments although the FSI model is more appropriate for the prediction of the Valve lift or closing time. However, the computation time of the FSI model is approximately 10 times greater than that of the rigid body model. Therefore, if the structural analysis of the Valve is not necessary, the rigid body model can be effectively used to predict the cycle performance such as EER or compression work.