• The KSFM Journal of Fluid Machinery
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• v.3 no.2 s.7
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• pp.36-43
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• 2000

This study presents the centrifugal compressor performance for three different vane stagger angles and wall pressure distribution within vaned diffuser channels, and is also discussed about the stability with respect to the compressor components. As the vane stagger angle decreases, the flow rate for the stall onset decreases, and higher pressure can be obtained at the low flow rate region, however, the effective operation range of the compressor decreases because of the blockage effect of the diffuser vane. Low pressure pocket within the vaned diffuser channel moves from the pressure side of leading edge to the suction side as the flow rate decreases. The compressor system stability mainly depends on that of the diffuser.

• The KSFM Journal of Fluid Machinery
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• v.5 no.1 s.14
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• pp.42-48
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• 2002

In this study, the instability of a centrifugal compressor with vaned diffuser was investigated. During unstable operation of the test compressor, pressure fluctuations at different diffuser radius ratios were measured by using high frequency pressure transducers. Two different types of stall, mild and deep stalls, were observed alternately and irregularly at some flow rates where the compressor performance was steeply deteriorated. In this transient zone, the size of rotating stall cell was estimated through the wavelet transform analysis. It was about 45 percents of rotor circumferential space at 300 rpm and not dependent on flow rate.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.99-105
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• 2001

In this study, the instability of a centrifugal compressor with vaned diffuser was investigated. During unstable operation of the test compressor, pressure fluctuations at different diffuser radius ratios were measured by using high frequency pressure transducers. Two different types of stall, mild and deep stall, were observed alternately and irregularly at some flow rate where the compressor performance was steeply deteriorated. In this transient zone, the size of rotating stall cell was estimated through the Wavelet transform analysis. It was about 45 percents of rotor circumferential space at 3000 rpm and not dependent on flow rate.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.136-141
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• 2010

This study describes effects of width contraction in vaneless diffuser on the performance of centrifugal compressors using commercial CFD code. Numerical analysis for three different diffusers such as Parallel, half contraction, and full contraction was performed. The results show that the performance of the centrifugal compressor is improved through the use of the diffusers with width parallel in high flow rate. The width contraction of diffusers is influenced static pressure rises. Comparison with the experimental data shows agreement.

• 유체기계공업학회:학술대회논문집
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• 1999.12a
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• pp.55-60
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• 1999

A centrifugal compressor was tested with three different diffusers with plate vanes. The vane inlet angle was varied from 15 to 30 dog. The higher static pressure rises are obtained with lower vane stagger angle. In the stable region the static pressure field in vaneless space is very sensitive to flow rate. The impeller has a stabilizing effect over the whole stable operating range. The diffuser has a stabilizing effect at high flow rate but is destabilizing at low flow rate.

• Food Science and Preservation
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• v.11 no.2
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• pp.250-256
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• 2004

The objectives of this study were to develop a new commercial grain cooler suited to domestic weather and post-harvesting conditions for paddy, and to evaluate the performance. A prototype grain cooler capable of cooling paddy of 200 tons within 24 hours was developed. The grain cooler was designed to control the refrigeration capacity from 0 to 100% by controlling the capacity of compressor with unloading solenoid valve and by changing the flow rates of hot refrigerant gas flowing into reheater and evaporator from compressor. And a controller with one chip microprocessor was developed to control temperature and relative humidity of cooling air. The maximum cooling capacity of the grain cooler was 35,284㎉/hr at condensing/evaporating pressure of 16.5/3.6 kgf/$\textrm{cm}^2$. Maximum flow rate of cooling air was 120 ㎥/min at static pressure of 279 mmAq. The total maximum required power was 22.8㎾, and total required energy was saved from 26.7 to 33.3% of maximum power depending on operating conditions. The coefficient of performance of refrigeration devices and total coefficient of performance of the grain cooler were 4.71 and 1.8, respectively.