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Kim Tiow Ooi - One of the best experts on this subject based on the ideXlab platform.

  • theoretical study of a novel Refrigeration Compressor part iii leakage loss of the revolving vane rv Compressor and a comparison with that of the rolling piston type
    International Journal of Refrigeration-revue Internationale Du Froid, 2009
    Co-Authors: Yong Liang Teh, Kim Tiow Ooi
    Abstract:

    Abstract A new Refrigeration Compressor, named ‘Revolving Vane (RV) Compressor’, has been introduced in Part I of this paper series. The efficiency of the RV Compressor, alike other Refrigeration Compressors, is primarily affected by mechanical and leakage losses, amongst which the former has been investigated in Part I. In the present paper, the leakage loss in the RV Compressor which mainly occurs at the radial clearance between the rotor and the cylinder is analyzed theoretically. In comparison with the rolling piston type, the leakage loss at the radial clearance in the RV Compressor is typically found to be 40% lesser than that of the former. Furthermore, the leakage loss can be significantly reduced by selecting a shorter configuration of the Compressor, which is anticipated to yield good volumetric efficiencies of more than 95%. For a longer configuration, the leakage loss can be effectively minimized by employing the method of an eccentric cylinder.

  • theoretical study of a novel Refrigeration Compressor part i design of the revolving vane rv Compressor and its frictional losses
    International Journal of Refrigeration-revue Internationale Du Froid, 2009
    Co-Authors: Yong Liang Teh, Kim Tiow Ooi
    Abstract:

    Abstract This paper presents a new rotary type Compressor, named ‘Revolving Vane (RV) Compressor’, in which frictional losses are effectively reduced through the radical use of a rotating cylinder. The friction at various contact regions are formulated and analyzed, after which a parametric study is conducted to reveal configurations of the Compressor that achieves high mechanical efficiencies. Inadvertently, the rotating cylinder is also found to enhance the smoothness of the Compressor's operation by reducing its torque fluctuations. Besides good mechanical performance, the RV Compressor is also found to possess a high volumetric efficiency, as shown in Part III of this paper series ( Teh and Ooi, in press ). In further consideration of the small number of parts and simple geometries of its components, it is believed that the RV Compressor is well suited and can be readily adopted for Refrigeration and air-conditioning applications.

  • heat transfer study of a hermetic Refrigeration Compressor
    Applied Thermal Engineering, 2003
    Co-Authors: Kim Tiow Ooi
    Abstract:

    Abstract This paper presents an analytical study on heat transfer and temperature distribution for a hermetic reciprocating Refrigeration Compressor using the lumped thermal conductance approach. In this analysis, the intricate components of a hermetic Compressor were divided into 46 geometrically simplified discrete elements and each was assumed to be at a uniform temperature. The lumped thermal conductance method was then applied to all the components of the Compressor to form 46 simultaneous equations, which were then solved to get the components’ temperatures. The results obtained were in good agreement with measurement. The discrepancies in the prediction lie in the assumptions made in assigning various heat transfer correlations to model the convection heat transfer effects of the fluid and solid surface boundaries, and the simplification made in distributing the various components of the Compressor into discrete parts. The results of this study have been applied to actual Compressor design in industry and have resulted in improved Compressor performance.

Paul Bailey - One of the best experts on this subject based on the ideXlab platform.

  • The effect of clearance control on the performance of an oil-free linear Refrigeration Compressor and a comparison between using a bleed flow and a DC current bias
    International Journal of Refrigeration, 2016
    Co-Authors: Kun Liang, Richard Stone, Michael William Dadd, Paul Bailey
    Abstract:

    A moving magnet type oil-free linear Compressor has been designed for applications such as electronics cooling. A control system using a solenoid operated valve was developed for DC offset and axial clearance control. Operation of the linear Compressor with a fixed clearance of 0.8 mm was compared with a zero DC offset operation. The fixed clearance operation requires a higher power input. The mean piston position can be controlled by using a DC bias on the drive voltage or by using a bleed flow from the Compressor body to the suction side of the Compressor. Using a DC bias on the drive voltage induces a higher power loss than using a bleed flow when there is a small radial clearance between the piston and cylinder. This provides evidence that the piston control in a Refrigeration system with capacity control should be for a zero DC offset using a bleed flow.

  • A novel linear electromagnetic-drive oil-free Refrigeration Compressor using R134a
    International Journal of Refrigeration, 2014
    Co-Authors: Kun Liang, Richard Stone, Michael William Dadd, Paul Bailey
    Abstract:

    A new type of oil-free moving magnet linear Compressor with clearance seals and flexure springs has been designed for incorporation into a vapour compression Refrigeration system with compact heat exchangers for applications such as electronics cooling. A linear Compressor prototype was built with a maximum stroke of 14 mm and a piston diameter of 19 mm. An experimental apparatus was built to measure the Compressor efficiencies and coefficient of performance (COP) of a Refrigeration system with the linear Compressor, using R134a. The resonant frequency for each operating condition was predicted using the discharge pressure, suction pressure and stroke. Refrigeration measurements were conducted for different strokes under each pressure ratio with a fixed condenser outlet temperature of 50 �C and evaporator temperature ranging from 6 �C to 27 �C. The results show that the COPs are around 3.0 for tests with a pressure ratio of 2.5 (evaporator temperature of 20 �C).

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

  • Investigation of characteristics of discharge pressure pulsation in a twin-screw Refrigeration Compressor
    Archive: Journal of Mechanical Engineering Science 1959-1982 (vols 1-23), 2018
    Co-Authors: Wenqing Chen, Ziwen Xing, Xiaokun Wu, Xiaolin Wang
    Abstract:

    In this paper, characteristics of discharge pressure pulsation in a twin-screw Refrigeration Compressor are investigated. A thermodynamic model is developed and validated using data from a comprehensive experimental study. This validated model is then applied to investigate effects of key parameters including condensing temperature, Compressor rotational speed, super-feed pressure, part-load operation, and design parameters on the discharge pressure pulsation. The results showed that the discharge pressure pulsation was mainly due to periodic variations of mass and energy flow from the working volumes to the discharge chamber. As the condensing temperature increased or decreased from the design condition, the Compressor was in either over- or undercompression leading to an increase in the amplitude of the pressure pulsation. The gas super-feed pressure could increase the pressure pulsation at condensing temperatures below the design value and reduce the pressure pulsation at condensing temperatures above the design value. The analysis also demonstrated that the pressure pulsation was lower at part-load conditions. However, the Compressor rotational speed increased both the amplitude and frequency of the pressure pulsation. Theoretical analysis of design parameters indicated that a large discharge volume with a high number of lobes could lower the pressure pulsation. These analyses provide useful information for the Compressor design and optimization.

  • performance investigation of a pressure pulsation dampener applied in the discharge chamber of a twin screw Refrigeration Compressor
    International Journal of Refrigeration-revue Internationale Du Froid, 2018
    Co-Authors: Xiaokun Wu, Ziwen Xing, Wenqing Chen, Xiaolin Wang
    Abstract:

    Abstract Intermittent gas flow generates pressure oscillations in the twin-screw Refrigeration Compressor that cause serious problems such as structural vibration and noise. In order to reduce the amplitude of this pressure pulsation, a pressure pulsation dampener (PPD) applied in the discharge chamber of a twin screw Refrigeration Compressor was proposed based on the theory of Helmholtz resonator. A mathematical model was developed to design an optimal PPD by incorporating the R134-oil mixture sound speed model and the pressure pulsation simulation model. A comprehensive experimental study was then performed to validate the model and evaluate the effect of key parameters such as oil flow rate and cavity volume on attenuation performance of the PPD. Vibrational characteristics of the Compressor equipped with and without the PPD were also measured and compared. Under the design frequency of 250 Hz, the vibrational acceleration of Compressor under-chassis reduced by 36.2% to 41.1% when the Compressor was fitted with the proposed PPD.

  • Effects of lubricating oil on the performance of a semi-hermetic twin screw Refrigeration Compressor
    Applied Thermal Engineering, 2017
    Co-Authors: Xiaokun Wu, Ziwen Xing, Zhilong He, Xiaolin Wang, Wenqing Chen
    Abstract:

    Lubricating oil is often employed in a twin-screw Refrigeration Compressor for lubricating bearings, sealing leakage paths, cooling refrigerant gas and regulating capacity. In this paper, the effect of lubricating oil on the performance of a semi-hermetic twin-screw Refrigeration Compressor is investigated. A mathematical model is established and a comprehensive experimental investigation is performed for this purpose. The model is validated using experimental data and then used to investigate the effect on Compressor performance of lubricating oil supplied to the suction and discharge end bearings, and returned to the suction pipe. The results show that the Compressor performance is reduced as the compensation oil injection flow rate increases in the suction pipe. However, as the compensation oil injection position moves from the suction pipe to a proper compression chamber position, the Compressor efficiencies increase as the oil flow rate increases. The results also show that the Compressor performance decreases as the oil flow rate increases at the suction end bearing. But the effect on the Compressor performance of the lubricating oil supplied to the discharge end bearing depends on the oil temperature. Low temperature oil supplied to the discharge end bearing increases the Compressor performance, while high temperature oil lowers the Compressor performance. These analyses provide useful information for optimizing lubricating oil distribution to maximize energy efficiency in semi-hermetic twin screw Refrigeration Compressors.

  • theoretical and experimental research on the working process of screw Refrigeration Compressor under superfeed condition
    International Journal of Refrigeration-revue Internationale Du Froid, 2007
    Co-Authors: Ziwen Xing
    Abstract:

    Abstract In order to increase the Refrigeration capacity and improve the coefficient of performance (COP), an economizer arrangement is used in the Refrigeration system with screw Refrigeration Compressor. In this system, the mid-pressure refrigerant gas from the economizer is injected in the screw Refrigeration Compressor. So it affects the performance of the Compressor. In this paper, the working process of a twin screw Refrigeration Compressor with economizer under different superfeed pressures is studied. A mathematical model for simulating the working process of screw Refrigeration Compressor under superfeed condition with the economizer is presented; especially the flow coefficient of superfeed is obtained by the experimental research. To verify the model, the p – V diagrams (pressure–volume diagrams) of screw Refrigeration Compressor under different superfeed pressures with the economizer are recorded successfully by making use of a micro-type pressure sensor that embedded into the groove at the root of the female rotor on the discharge side. The p – V diagrams of theoretical calculation are in good agreement with the results of experimental recorded, which lead to conclusion that the model can be used as a powerful tool for performance prediction of screw Refrigeration Compressor, also, it is very helpful for Refrigeration system design.

  • experimental study on p v indicator diagrams of twin screw Refrigeration Compressor with economizer
    Applied Thermal Engineering, 2004
    Co-Authors: Huagen Wu, Xueyuan Peng, Ziwen Xing
    Abstract:

    This paper presents the experimental investigation on the effects of the superfeed pressure together with economizer type on the performance of the twin-screw Refrigeration Compressor by means of the indicator diagram. With a pressure sensor embedded into the groove at the root of the female rotor on the discharge side, the pressure within the working chamber of a semi-hermetic twin-screw Compressor with an economizer is recorded and then transformed into the indicator diagram. The results thus obtained are utilized to investigate the thermodynamic process of the Compressor. It is shown that the Compressor with an economizer has higher pressure during almost the whole compression process than without an economizer, resulting in the increase in the indicated power. Under different superfeed pressures, the pressure within the compression experiences different changes. This results in an optimal superfeed pressure for maximized Compressor efficiency, which can be identified from the calculated Compressor efficiency based on the indicator diagrams. It is also found that the pressure has a rapid increase at the beginning of superfeed process, and then a slow rise even a slight drop at the end of superfeed process, which is caused by the dynamic effect during superfeed process. Furthermore, if the superfeed pressure keeps the same, the pressure during compression in the Compressor with the heat exchanger economizer is slightly higher than with the flash tank economizer, due to the higher temperature of superfeed refrigerant gas in the former case.

Kun Liang - One of the best experts on this subject based on the ideXlab platform.

  • The effect of clearance control on the performance of an oil-free linear Refrigeration Compressor and a comparison between using a bleed flow and a DC current bias
    International Journal of Refrigeration, 2016
    Co-Authors: Kun Liang, Richard Stone, Michael William Dadd, Paul Bailey
    Abstract:

    A moving magnet type oil-free linear Compressor has been designed for applications such as electronics cooling. A control system using a solenoid operated valve was developed for DC offset and axial clearance control. Operation of the linear Compressor with a fixed clearance of 0.8 mm was compared with a zero DC offset operation. The fixed clearance operation requires a higher power input. The mean piston position can be controlled by using a DC bias on the drive voltage or by using a bleed flow from the Compressor body to the suction side of the Compressor. Using a DC bias on the drive voltage induces a higher power loss than using a bleed flow when there is a small radial clearance between the piston and cylinder. This provides evidence that the piston control in a Refrigeration system with capacity control should be for a zero DC offset using a bleed flow.

  • A novel linear electromagnetic-drive oil-free Refrigeration Compressor using R134a
    International Journal of Refrigeration, 2014
    Co-Authors: Kun Liang, Richard Stone, Michael William Dadd, Paul Bailey
    Abstract:

    A new type of oil-free moving magnet linear Compressor with clearance seals and flexure springs has been designed for incorporation into a vapour compression Refrigeration system with compact heat exchangers for applications such as electronics cooling. A linear Compressor prototype was built with a maximum stroke of 14 mm and a piston diameter of 19 mm. An experimental apparatus was built to measure the Compressor efficiencies and coefficient of performance (COP) of a Refrigeration system with the linear Compressor, using R134a. The resonant frequency for each operating condition was predicted using the discharge pressure, suction pressure and stroke. Refrigeration measurements were conducted for different strokes under each pressure ratio with a fixed condenser outlet temperature of 50 �C and evaporator temperature ranging from 6 �C to 27 �C. The results show that the COPs are around 3.0 for tests with a pressure ratio of 2.5 (evaporator temperature of 20 �C).

Quanke Feng - One of the best experts on this subject based on the ideXlab platform.

  • research of thermal dynamic characteristics for variable load single screw Refrigeration Compressor with different capacity control mechanism
    Applied Thermal Engineering, 2017
    Co-Authors: Zengli Wang, Zhenbo Wang, Jun Wang, Wenchun Jiang, Quanke Feng
    Abstract:

    In the single screw Refrigeration Compressor (SSRC), the capacity control mechanism is normally employed to meet the actual required cooling capacity under different load conditions. In this paper, theoretical calculation models describing the working process of the SSRC with the single slide valve capacity control mechanism (SVCCM) and SSRC with the frequency conversion regulating mechanism (FCRM) are established to research the thermal dynamic characteristics for variable load SSRC under part-load conditions. Experimental investigation on a SSRC under part-load conditions is also carried out to verify the theoretical calculation models. By using these validated models, the thermodynamic performances and dynamic characteristics of the SSRC with different capacity control mechanism under part-load conditions have been analyzed and compared. Through the comparison, the economical efficiency and reliability of the SSRC with different capacity control mechanism were obtained. All of these works can provide the basis for the later optimization design for the variable load single screw Refrigeration Compressor.

  • theoretical and experimental study on thermodynamic performance of single screw Refrigeration Compressor with multicolumn envelope meshing pair
    Applied Thermal Engineering, 2016
    Co-Authors: Zengli Wang, Zhenbo Wang, Ju Wang, Wenchu Jiang, Quanke Feng
    Abstract:

    Abstract In single screw Refrigeration Compressor (SSRC), the Multicolumn Envelope Meshing Pair (MEMP) was proposed to reduce the wear of the meshing pair. However, the application of this new type meshing pair will change the thermodynamic performance of SSRC. It is necessary to research the thermodynamic performance of the SSRC with MEMP to evaluate the value of the proposed MEMP. In this paper, a theoretical calculation model describing the working process of the SSRC with MEMP is established to predict the thermodynamic performance of the SSRC. Experimental investigations on the performance of a SSRC with MEMP under different conditions are also carried out to verify the theoretical calculation model. Obtained results show that the theoretical calculation results are in good agreement with the experimental ones, which means that the presented theoretical calculation model is a powerful tool for performance analysis of the SSRC with MEMP. With the validated model, thermodynamic performances of the SSRC with MEMP have been analyzed. The SSRC with MEMP is proved to have high volume displacement and volumetric efficiency but needs slightly more shaft power. The maximum increment of shaft power and volumetric efficiency of SSRC with MEMP is 5.06% and 3.7% respectively in all working conditions.

  • research on operating characteristics of single slide valve capacity control mechanism of the single screw Refrigeration Compressor
    Proceedings of the Institution of Mechanical Engineers Part A: Journal of Power and Energy, 2014
    Co-Authors: Zengli Wang, Zhan Liu, Feilong Liu, Quanke Feng
    Abstract:

    In the single screw Refrigeration Compressor (SSRC), the single slide valve capacity control mechanism (SVCCM) is the functional component used to achieve capacity control under different load conditions with cooperation of screw rotor and housing. In this paper, a new calculation model considering internal compression and leakage is presented to research the capacity control process and built-in volume ratio control process. By this model, the actual capacity and built-in volume ratio at different slide valve work locations can be determined using the calculated by-pass area and discharge area. The influences of structural parameters of the slide valve to the control characteristics of the capacity control process and the thermodynamic properties of the Compressor are analyzed. Through the comparison of the capacity control process and the built-in volume ratio control process, the axial displacements of the slide valve required in the capacity control and in the built-in volume ratio control were obtain...