• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.219-222
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• 2002

There are screw, reciprocating type turbo compressor by structure in an air compressor which is essential equipment on the industrial spot. Recently, the application range of a turbo compressor tend to be wide gradually. And this type of compressor needs high speed rotation of impeller in structure so high ratio gearbox and conventional induction motor driving required. This mechanical system have results of increased moment of inertia and mechanical friction loss. Recent studies of modern turbo compressor have been applied to developing super high speed BLDC motor and driver which remove gearbox that make its size small and mechanical friction loss minimum. To accomodate this tendency, we tried to develope a super high speed motor drive system for 150Hp, 70,000rpm direct drive Turbo compressor using DSP(Digital Signal Processor) and SVPWM(Space Vector Modulation PWM) technique. The results of this specific application show that super high speed driver and controller could be implemented well with digital electronics.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.237-243
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• 2002

A centrifugal compressor of 50HP for reverse brayton cryocooler using neon as a coolent has been developed. It has relatively low total-to-total pressure ratio but mass flow rate is very small and the voting gas, neon, has greater specific heat ratio than air. It was essential to have very high rotational speed of 100,000 RPM. The efficiency of compressor has great effects on overall system and the COP of cryocooler. To meet the design requirement of the compressor efficiency and to minimized the required rotational speed, highly efficiency impeller having low specific speed was designed. To maintain the overall system efficient high, gas bearing of bump type and high speed permanent magnet synchronus motor was developed and adopted. In this paper, design and performance prediction results of the compressor impeller is presented.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.3
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• pp.6-15
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• 2000

In this paper, we propose a high speed parallel multiplier with a hierarchical architecture using a fast 4-2 compressor and 6-2 compressor. Generally, the performance of parallel multiplier depends on the processing speed of partial products summation tree with CSA adder. In this paper we propose a new circuit of 4-2 compressor and 6-2 compressor which reduces the propagation delay time, compared with conventional one. We Propose a hierarchical multiplier architecture in order to improve the execution speed of 16$\times$16 parallel multiplier using proposed compressors in this paper and make layout design easily by regular structure. The propagation delay time of the proposed 4-2 compressor circuit was 14% reduced as a result of SPICE simulation, compared with the conventional 4-2 compressor. The total propagation delay time of proposed 16$\times$16 parallel multiplier was 12% reduced using proposed 4-2 compressor and 6-2 compressor.

• The KSFM Journal of Fluid Machinery
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• v.15 no.6
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• pp.51-57
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• 2012

Performance evaluation of a compressor is conducted to develop 500W class ultra-micro gas turbine (UMGT) for power generation. The performance evaluation is essential to check the performance of the components of UMGT, a radial turbine, a centrifugal compressor, an angular combustor and a shaft, which have been already designed in previous researches. The purpose of this study is to introduce the development process of the performance testing equipments of the UMGT and to present the results of compressor performance test. For the performance evaluation of the compressor, two test equipments are developed and the initial test equipment uses commercial static air bearings with long shaft. In the improved test equipment, static air bearing is improved to increase rotating speed and compressed nitrogen gas is used for utility gas of the static air bearing to supply compressed air in a stable and steady way. To increase rotating speed to 320,000 rpm, 80% speed of design speed, compressed air is provided to the turbine. The performance map of the compressor with the 50%, 60%, 70%, 80% speed of design point is presented. The results of the performance test of compressor show a good agreement with the results of 3D CFD.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.2
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• pp.193-204
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• 1999

Performance of a variable-speed, roller-type vane compressor was evaluated at low evaporating temperature. First, an experimental investigation was conducted to examine the performance variation as functions of both outdoor temperature and rotating speed. For this purpose, a typical heat pump was implemented as a test apparatus to measure mass flow rate and power input. Secondly, computational investigations corresponding to the heat pump test conditions were performed to predict compressor performance using ORNL Map-Based compressor model. Results obtained from the heat-pump experiments showed that both mass flow rate and power consumption were sensitively dependent on both evaporating temperature and compressor speed as was predicted from the computational results. From the comparisons of both experimental and computational results, it was well recognized that the ORNL model was subjected to larger error in the accuracy of prediction as outdoor temperature decreased. When the outdoor temperature was above $-5^{\cire}C$, errors of predicted values corresponding to both mass flow rate and power consumption were estimated as $\pm$10% and $\pm$ 15%, respectively. Finally, it is suggested that the ORNL model needs to be re-evaluated if compressor map data tested below $-5^{\cire}C$(in evaporating temperature) are available.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.258-263
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• 2002

A numerical analysis using 2-D unsteady compressible program is conducted to explain characteristics of rotating stall such as rotating speed and number of stall cells in an one-stage axial compressor. Unlike an axial compressor which has only a rotor, in one-stage axial compressor a rotating stall is generated by rotor/stator interaction and tack pressure rising without any artificial disturbance and modeling. As a back pressure is raised, the separation of suction side at blades is increased uniformly, but because of the discrepancy of blockage effect by stator, the disturbances are generated to form a stall cell. Once the stall cell is formed, regularly the stall cell are rotating through rotor blades. When the speed of rotor is design speed the rotating speed of stall cell is $83.3\%$ of rotor rotating speed. When the speed of rotor is $80\%$ of design speed, the speed of rotating stall is $88.2\%$ of rotor speed. The number of generated stall cell are also varied for rotor speed and back pressure.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.240-243
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• 2008

In this paper, the design of Centrifugal Compressor which is used in sizes 50 horse power has 8 pressure ratio and numerical analysis of the flow within compressor varying tip clearance length are performed. To get high pressure ratio with low power the exit height of impellers is low but compressor has very high speed of revolution. So compressor has high specific speed although mass flow rate is very small. The shape of impellers at the first stage is carried out. Flow and performance characteristics of impellers has been analyzed by using a commercial CFD program, $Fine^{TM}$/turbo. The result shows that loss coefficient is affected by tip clearance length and compressor has proper tip clearance length. It is possible to decrease loss by selecting apt tip clearance length.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.1
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• pp.50-58
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• 2003

An analytical study was carried out to investigate the performance of an oil pumping system of a variable speed compressor using a commercial CFD program. The simulations for the oil supplying system with the oil and air mixture were performed by varying compressor speed from 40 Hz to 90 Hz. Comparing the predicted with the measured data on the modified scroll compressor validated the simulation model. The predicted results were consistent with the test data with a maximum deviation of 12.8%. The oil flow rate significantly increased with a rise of compressor speed due to a higher oil flow rate from the swing pump and a greater centrifugal force on oil gallery.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.6
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• pp.879-884
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• 2002

There are screw, reciprocating and turbo compressor by structure in an air compressor, essential equipment on he industrial spot. Resently it is wide that the range of turbo compressor's use in gradual, turbo compressor needs high speed rotation of impeller in structure, high rated gearbox and conventional induction motor. This mechanical system increased the moment of inertia and mechanical friction loss. Resently the study of turbo compressor applied super high speed motor and drive, removing gearbox made its size small and mechanical friction loss minimum. In this study we tried to develope variable super high speed motor drive systems for 150Hp, 70,000rpm drect drive Turbo compressor. The result of study is applied to a 150Hp direct turbo compressor and makes it goods.

• New & Renewable Energy
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• v.7 no.4
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• pp.30-36
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• 2011

The objective of this study is to investigate the effects of the refrigerant charge amount on the performance of a water-to-water ground source heat pump with a variation of compressor speed and the secondary fluid flow rate. The water-to-water ground source heat pump was tested by varying refrigerant charge amount from -40% to 20% of full charge. Compressor speed was changed from 30 Hz to 75 Hz and the secondary fluid flow rate was adjusted from 6 LPM to 14 LPM. For all test conditions, EWTs of an indoor heat exchanger and an outdoor heat exchanger were maintained at standard conditions of ISO 13256-2. The slope of the COP with the variation of charge amount is much steeper at undercharged conditions than that at overcharged conditions. For all compressor speed, the variation of the system performance according to charge amounts showed the similar trends. However, the optimum charge amount of the system increased a little with an increment of compressor speed. When the secondary fluid flow rate decreased, the system was optimized at higher refrigerant charge amount conditions.