• 한국유체기계학회 논문집
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• 제3권4호
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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.

• 소음진동
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• 제10권6호
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• pp.963-970
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• 2000

The turbo chiller uses centrifugal compressor, which operates at about 14,500 rpm. Due to the high rpm of the impeller, the noise of chiller males one of the serious problems. The possibility of the sound reduction by using absorbing material is studied in this paper. The generated sound propagates through the duct and then radiates to the outer field. So, the use of sound absorption material inside the duct is one of the effective methods. To study the effect of location of the material, we use Boundary Element Method to analyze the sound field inside the duct system. Numerical study shows the highest sound pressure region is near the elbow of curved duct. From the numerical study, it is also shown that appropriate use of sound absorbing material at this region makes 8dB reduction of the highest noise level.

• 한국유체기계학회 논문집
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• 제7권3호
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• pp.7-13
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• 2004

In this paper, we identify the noise source and the path of a chiller. This chiller is newly developed for R-l34a refrigerant and 250 RT cooling capacity. The measured overall SPL of the developed turbo-chiller is about 100 dBA. Due to the high rotating speed of the centrifugal impeller, the nun noise source of the chiller is the blade passing frequency and its higher harmonics of the centrifugal impeller. This generated soundpropagates through the duct, and then transmits and radiates to the outer field. From the experiment, it is found that the high frequency noise is mostlytransmitted and radiated through the elbow duct, but the low frequency noise is transmitted and vadiated through the condenser wall. Therefore applying the absorbing material is an effective way of reducing the high and low frequency noise simultaneously. Measurement results show that the application of the sound absorbing material to the elbow duct reduced the overall sound pressure level by 4 dB compared to the 9 dBA reduction for the case of full enclosure. In order to control the generated noise, a dissipativetype silencer is also designed and tested. The silencer reduced the radiated noise about 7.5 dBA.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.184-188
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• 2001

Severe vibration was detected during test operation in motor frame of the Turbo Chiller (300RT). To identify the vibration problem, vibration measurement and modal test were carried out. From the test results, it is concluded that the severe vibration occurred due to the resonance between the motor frame horizontal mode and the motor excitation frequency. Therefore the horizontal mode of the frame could be controlled by the sensitivity analysis results for the length of the supporting plate.

• 소음진동
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• 제9권5호
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• pp.1042-1049
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• 1999

In the Part I has been reported a rotordynamic analysis of the driving motor-bull gear rotor-bearing system of a turbo-chiller. In this study, Part II, a rotordynamic analysis is performed with the turbo-chiller compressor pinion-impeller rotor system supported on two fluid film bearings. The pinion-impeller rotor system is driven to a rated speed of 14,600 rpm through a speed-increasing pinion-bull gear. It is modeled utilizing the finite element method for analysis. As loadings on the bearings due to the gear action are significant in the system considered, each resultant bearing load is calculated statically by considering the generalized forces of the gear action as well as the rotor itself. The two support bearings, the generalized forces of the gear action as well as the rotor itself. The two support bearings, partial and 3-axial groove bearings, are designed to take their varying loads along with their varying load angles, and they are also analyzed to give their rotordynamic coefficients. Then, a complex rotordynamic analysis of the compressor pinion-impeller rotor-bearing system is carried out to evaluate its stability, whirl natural frequencies and mode shapes, and unbalance responses under various loading conditions. Results show that the bearings and entire rotor system are well designed regardless of operating conditions, i.e., loads and operating speeds.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.125-131
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• 2000

The turbo chiller uses centrifugal compressor, which operates at about 14500 rpm. Due to the high rpm of the impeller, the noise of chiller makes one of the serious problems. The possibility of the sound reduction by using absorbing material is studied in this paper. The generated sound propagates through the duct and then radiates to the outer field. So, the use of sound absorption material inside the duct is one of the effective methods. To study the effect of location of the material, we use Boundary Element Method to analyze the sound field inside the duct system. Numerical study shows the highest sound pressure region is near the elbow of curved duct. From the analysis, it is also shown that the elbow duct is the main radiator of noise and sound absorption treatment of this duct results noise reduction of the highest noise level at BPF and high frequency region.

• 한국유체기계학회 논문집
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• 제10권4호
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• pp.29-38
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• 2007

In this study, flow structure in a two-stage centrifugal compressor for a turbo-chiller with the refrigerant, R134a, was numerically investigated at the design point of the compressor using a commercial code. Flow characteristics in the passages of impeller, diffuser and return channel were analyzed in detail including velocity vector, secondary flow, Mach number and pressure contours in blade spanwise and meridional plane for each stage. The estimation on the one-dimensional output from the preliminary design and three-dimensional shape of the impeller blade and the meridional shape of the return channel were performed through the flow analysis, while some numerical schemes and techniques including Multiple Frames of Reference technique, real gas property data and inlet boundary condition changes, which were used in CFD, were compared with their features. The results will be used as reference data for a new design of 3-D impeller shape to improve R134a compressor performance.

• 소음진동
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• 제9권3호
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• pp.593-599
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• 1999

A rotordynamic analysis is performed with a motor-bull gear rotor system supported on two partial bearings, which is intended to drive a high-speed turbo-chiller compressor impeller shaft through its built-in pinion gear. The motor-bull gear rotor system has a rated speed of 3,600 rpm, and is modeled utilizing the finite element method for analysis. As loadings on the bearings due to the gear action are significant in the system considered, each resultant bearing load is calculated statically by considering the generalized forces of the gear action as well as the rotor itself. The two support partial bearings are designed to take their varying loads along with their varying load angles, and they are also analyzed to give their rotordynamic coefficients. Then, a complex rotordynamic analysis of the motor-bull gear rotor-bearing system is carried out to evaluate its whirl natural frequencies and mode shapes and unbalance responses under various loading conditions. Results show that the bearings and entire rotor system are well designed regradless of operating conditions, i.e., loads and operating speeds.

• 한국가스학회지
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• 제18권5호
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• pp.85-90
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• 2014

대용량의 공기조화용으로 널리 사용되는 터보냉동기는 냉매로 HCFC-123 가스를 주로 사용하며, HCFC-123은 CFC계 프레온의 대체 냉매제로 독성은 낮으나 환기가 원활하지 않는 밀폐공간이나 작업공간에서 산소결핍으로 인한 질식재해를 유발할 수 있는 것으로 보고되고 있다. 본 연구에서는 2011년 대형할인마트 기계실 내부 터보냉동기 냉매 누출로 인해 작업자 4명이 질식 등의 사유로 사망한 재해 사례를 대상으로 전산유체역학을 이용하여 HCFC-123 누출에 따른 산소농도를 예측함으로써 프레온 가스 누출사고에 대한 원인을 조사하고 대응책을 제시하여 동종 재해의 재발 방지에 도움이 되고자 한다.

• 한국수소및신에너지학회논문집
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• 제33권4호
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• pp.437-445
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• 2022

This paper presents an experimental study on the main management factors of the condenser contamination such as fouling and corrosion for the R-134a turbo-chiller to save energy, reduce corrosion rates, and reduce maintenance costs through the application of condenser non-cleaning water treatment chemical. The series of experiment is conducted using combining oxidative microbial sterilizers, non-oxidizing microbial sterilizers, and anti-corrosion agents. The leaving temperature difference and corrosion rates for three different combination of chemicals are collected and analyzed. The experimental results show that the cost reduction (4,066,000 Won/year) of the disinfectant (FT-830) can be achieved by adding the oxidative disinfectant (NaOCl) and the non-oxidizing disinfectant (NX-1116). The LTD value is maintained at 1.9℃, and the corrosion rates of copper and carbon steel specimens are 0.07 mpy and 1.61 mpy, respectively.