Research on operating characteristics of single slide valve capacity control mechanism of the single screw refrigeration compressor

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 obtained. All of this work can provide the basis for the later optimization design for the slide valve.

Theoretical and Experimental Research on Thermal Dynamic Characteristics of Single-Screw Compressor with a New Composite SLIDE Valve

“…In order to obtain the effective discharge and bypass area, the equation of profile VL, VR, and the boundary curves surrounding the bypass port should be set up. The equation of VL can be obtained according to the literature [19]:…”

“…Following this, Zhou et al investigated the capacity adjustment mechanisms of the slide valve and the performance of compressors utilizing this single-control slide valve device [18]. Wang et al [19] presented a mathematical calculation method to study the capacity control mechanism of single-slide valve. Variable frequency technology can regulate compressor capacity by altering the compressor's rotational speed.…”

A Review of Recent Research and Application Progress in Screw Machines

“…It suggested that the slide valve installation angles should be as large as the installation space permits, and the fixed type slide should stop with a length of 20-25% of the rotor length when the external pressure ratio was single or else the moveable type. Wang et al [106] adopted a similar method to investigate the effects of slide valve structure parameters on the operation process of a refrigeration SSC under part-load conditions and compared the capacity control process with the built-in volume ratio control process. Further, they [107] studied the thermal dynamic characteristics of a refrigeration SSC with the single slide valve capacity control and the frequency conversion control under part-load conditions.…”

Development of single screw compressor technologies and their tendency

“…However, it is difficult to apply these results directly to other occasions due to the lack of mechanism analysis. Through geometric research, Wang et al 94 found that the adjustment range of displacement increased when the initial position of the bypass orifice is closer to the exhaust side. Moreover, the ratio of internal volume increases as the initial position of valid exhaust port approaches the exhaust side.…”