• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.171-176
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• 2008

As one way of design optimization of two-stage two-cylinder rotary compressor used for R410A heat pump application, displacement volume ratio, being defined by the ratio of the second stage cylinder volume to that of the first stage, has been varied and its effect on the compressor performance has been investigated by a computer simulation program. For simplicity, only the cylinder height of the second stage was varied to change the volume ratio. With increasing the volume ratio in the range of VR=$0.55{\sim}0.9$, volumetric efficiency increased monotonically, but adiabatic efficiency showed a maximum at around VR=0.6. Mechanical efficiency was little influenced by the volumetric ratio. As a consequence, maximum improvement of the compressor performance was found at around VR=0.7. Compared to a one-stage two-cylinder rotary compressor with about the same cooling capacity, COP improvement was about 6.96%.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.533-539
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• 2004

The rotary compressor is widely used for the air conditioner because it is efficient and compact. In recent, the need for silent and efficient compressors is much stronger than the past. The new type muffler was invented to reduce noise level and to improve efficiency. The new type muffler that has two side discharge holes and dome shape represents much lower overall noise level, especially noise levels around 1kHz than the old type one that has one center discharge hole In acoustic spectra. Also it has higher air conditioner efficiency by lower oil discharging amount of a compressor than old type one that has rectangular shape and two side discharge holes. The noise reduction and efficiency improvement effects of the new type muffler were verified by tests for rotary compressors and air conditioners.

• The KSFM Journal of Fluid Machinery
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• v.3 no.4 s.9
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• pp.44-51
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• 2000

The present study has been conducted to design the high efficiency centrifugal compressor for a R134a turbo-chiller. The centrifugal compressor consists of an impeller with splitters, two vaneless diffusers, a low-solidity vaned diffuser and a volute. A cycle analysis program for a turbo-chiller was developed to obtain compressor design parameters and requirements. We have designed the high efficiency centrifugal compressor by applying the repeated design procedure including a meanline design, a 3D geometry generation and fluid dynamic loading calculations.

• The KSFM Journal of Fluid Machinery
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• v.14 no.2
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• pp.11-16
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• 2011

This paper presents a numerical study of casing treatments on a centrifugal compressor stage to improve stability and the surge margin. High efficiency, a high pressure ratio, and a wide operating range are required for a high performance centrifugal compressor. In the present study, a ring groove arrangement was applied to the transonic centrifugal compressor. According to the numerical analysis using a commercial code ANSYS-CFX, the unstable phenomena limiting the range of the centrifugal compressors were compared with and without a ring groove. Although the ring groove decreased the efficiency, but increased the operating range by suppressing a flow separation at the leading-edge of the impeller especially near shroud part. Newly designed ring groove arrangement improved the compressor performance and increased the operating range of the compressor.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.570-575
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• 2005

An efficiency of a refrigeration cycle and a reliability of a compressor can be reduced if a refrigerant including excessive lubricating oil is exhausted from a rotary compressor. Thus, the oil behavior inside the compressor should be analyzed to improve the efficiency. A tested rotary compressor has been manufactured with visualization windows at upper parts in this study to investigate the oil behavior using developed visualization techniques. Discharge pipe with level gage has been visualized to investigate discharged oil amount. The oil behaviors inside the compressor and discharging pipe at various operating conditions have been analyzed. The results of the visualization for the discharging pipe have been compared with those of the upper part to confirm the accuracy.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.3
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• pp.63-69
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• 2022

Compressor efficiency must be improved to reduce refrigerator power consumption. In this study, the heat dissipation rate through the compressor housing is increased via gap flow passages between the compressor body and housing. Four types of gap flow passages are considered for achieving the maximum heat-dissipation rate. In addition, thermal analysis is performed to examine the effect of increased heat dissipation rate on the energy efficiency ratio (EER). The results show that the heat dissipation rate, compressor superheat, and compressor EER increased by up to approximately 52%, 3 ℃, and approximately 1%, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.1
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• pp.65-69
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• 1977

The characteristics of two stage compressor which is constituted of two separated reciprocating compressors was tested measuring the volumetric efficiency of each compressor at suction of both bighandlowpressdresideusillgorificetypeflolrmeters. The volumetric efficiency of low pressure side compressor was lower than that of the high side when they were operating under the same compression ratio. And it tended to reduce obviously by lowering evaporating temperature resulting in a markable reduction of refrigerating capacity at the same time. It is assumed that the falling of volumetric efficiency at low side compressor was directed by the decrease in evaporating temperature which derives the falls of gas pressure at suction, increase in compression ratio, and gas flow resistance at suction and discharge valves.

• The KSFM Journal of Fluid Machinery
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• v.3 no.4 s.9
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• pp.22-29
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• 2000

Numerical analysis using three dimensional finite volume method for the discretization, adaptive grid method for the numerical accuracy, multiple rotating frame method for the rotating body and the standard $k-{\epsilon}$ model for the turbulent flow was performed to understand the heat transfer phenomena and to improve the efficiency of the scroll compressor. The temperature measurement was carried out under ARI condition. It was found that the fluid temperature in the compressor was predicted accurately while the temperature of the motor coil showed large discrepancy between the calculation and experiment due to the large anisotropy of the conductivity and non homogeneity. We found that the efficiency of the compressor depends on the inlet temperature of the compressing part and the flow pattern around the inlet region of the compressing part influences the inlet temperature due to high surface temperature of the main frame. The efficiency of the compressor using Coanda effect is higher than the previous one because the smooth suction at the inlet region of the compressing part leads to low heat transfer to the refrigerant of the compressor.

• International Journal of Air-Conditioning and Refrigeration
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• v.17 no.4
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• pp.115-122
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• 2009

Numerical simulations for scroll, two-stage twin rotary, and two-cylinder reciprocating compressors have been carried out to understand the effectiveness of each type compressor for heat pump water heater application using $CO_2$ as refrigerant. For suction pressure of 3.5 MPa and discharge pressure of 9 MPa, clearance volume ratio of the reciprocating compressor needs to be about 5% or less to have the volumetric efficiency comparable to that of the scroll compressor with tip clearance of $5\;{\mu}m$. Volumetric efficiency of the scroll compressor is quite sensitive to tip clearance. Adiabatic efficiency of the twin rotary compressor was calculated to be the lowest among the three types, and the most severe drawback of the $CO_2$ scroll compressor was a significant increase in the mechanical loss at the thrust surface supporting the orbiting scroll member. While the scroll compressor showed very smooth torque load variation, peak-to-peak torque variations of the twin rotary and two-cylinder reciprocating compressors were about 50% and 250%, respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.2
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• pp.164-173
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• 2012

To study the applicability of a scroll type compressor to small capacity refrigerators, a R600a scroll compressor with algebraic scroll wrap has been designed. Its size and performance have been compared to a reciprocating type of the same displacement volume. By employing scroll wrap based on algebraic curve, high compression ratio can be accomplished without increasing the wrap angle much so that compact scroll may be obtained. Compared to a reciprocating one, the designed scroll compressor has diameter and height reduced by about 50% and 80%, respectively. By numerical simulation, it has been estimated that the scroll compressor provides 38.6% more cooling capacity than reciprocating type with 8.9% more power consumption, resulting in 27.3% increase in COP for ASHRAE low back pressure condition. With increasing the operating pressure ratio from 9.5 to 15.3, the overall compressor efficiency of the scroll compressor decreases from 72.6% to 65.2%, while that of the reciprocating compressor increases from 55.7% to 59.8%.