• 설비공학논문집
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• 제27권5호
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• pp.233-240
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• 2015

This paper discusses compressors operating number control strategy using cooperative logic to cope with variable partial load for high efficiency of a centrifugal water chiller. The cooperative logic is composed of a speed-up and speed-down controller, enabling smooth operation of compressors and equivalent distribution of thermal load in each compressor. This centrifugal water chiller design can be operated with high efficiency without incurring excessive energy waste and large transient phenomena at partial load states. Simulations in MATLAB and experiments in a real chiller system were conducted and verified the high efficiency control of a centrifugal water chiller achieved by the suggested strategy.

• 설비공학논문집
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• 제16권9호
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• pp.881-888
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• 2004

Control algorithms for a dual source chiller air conditioning system were developed. These are control algorithms for the supply air temperature control, the supply header chilled water temperature control, the chiller chilled water temperature control, and the cooling tower water temperature control. These algorithms were analyzed by using a dynamic simulation program. Simulation results showed the energy savings and the satisfactory controls of an absorption and centrifugal chiller air conditioning system. Therefore, control algorithms developed for this study may effectively be used for the improved controls of the dual source chiller air conditioning system.

• 대한기계학회논문집B
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• 제26권3호
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• pp.482-490
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• 2002

This paper presents modelling and analyzing method of centrifugal chiller which has a rated capacity of 200 RT(703 kW) through on-site performance test. Field performance data of a chiller installed in a research building of KIST have been collected. Simple models were developed for predicting the heat exchanger and system performances by regression of chiller operation data during 5 days in August. The models proposed here account for the effect of variations of cooling capacity, temperatures and flew rates of secondary fluids. The proposed models can predict the actual performance data from June to September within $\pm$ 5% error. The COP of centrifugal chiller are estimated under the standard rating conditions and reduced mass flow rates of chilled and cooling water.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.83-88
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• 2001

This paper presents modelling and analyzing method of centrifugal chiller which has a rated capacity of 200 RT(703 kW) through on-site performance test. Field data of chiller installed in the clean-room building of KIST have been collected, Simple models were developed for predicting the heat exchangers and system performances by regression of chiller operation data during 5 days in August. The models proposed here account for the effect of variations of cooling capacity, temperatures and flow rates of secondary fluids. The models are consistent with real performance data from June to September within ${\pm}5%$ error. The COP of centrifugal chiller are estimated under the standard rating conditions and reduced mass flow rate of chilled and cooling water.

• International Journal of Air-Conditioning and Refrigeration
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• 제10권2호
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• pp.97-105
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• 2002

A centrifugal water chiller using alternative refrigerant R134a has been developed. The prototype was designed to have refrigerating capacity of 300RT. Its compressor employs a single high-speed impeller, airfoil diffuser and collector. Newly developed, enhanced tubes were installed in the evaporator and the condenser to reduce the required head for the compressor. Off-design characteristics at various conditions, performance test of the compressor and analysis of the refrigeration cycle were performed. So the probability of use in part load condition was checked and the direction for revision was suggested.

• 설비공학논문집
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• 제13권5호
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• pp.333-340
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• 2001

A centrifugal water chiller using alternative refrigerant R134a have been developed. The prototype was designed to have refrigeration capacity of 300RT. Its compressor employs a single high-speed impeller, airfoil diffuser and collector. Newly developed enhanced tubes were installed in the evaporator and the condenser to reduce the required head for the compressor. Off-design characteristics at various conditions, performance test of the compressor and analysis of the refrigeration cycle were performed. So the probability of use in part load condition was checked and the direction for revision was suggested.

• 설비공학논문집
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• 제27권4호
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• pp.187-194
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• 2015

This paper describes the PI controller design based on a practical transfer function model for centrifugal water chillers. The rotational speed of a compressor and the opening angle of an electronic expansion valve were simultaneously regulated as manipulated variables to maintain temperature reference and to ensure high efficiency of the chiller. The COP according to the change in each variable was investigated by performing some static experiments, and it was reflected in the PI controller design to accomplish the high efficiency control. Especially, the practical transfer function model of the chiller was built based on the dynamic experimental data considering the strong inherent non-linearity and complexity of the chiller system. The validity of the designed PI controller was proven by some experimental results using the test facility and the results were also compared to the conventional evaporating pressure control results.

• Journal of Mechanical Science and Technology
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• 제19권8호
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• pp.1670-1681
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• 2005

In-situ diagnosis of chiller performance is an essential step for energy saving business. The main purpose of the in-situ diagnosis is to predict the performance of a target chiller. Many models based on thermodynamics have been proposed for the purpose. However, they have to be modified from chiller to chiller and require profound knowledge of thermodynamics and heat transfer. This study focuses on developing an easy-to-use diagnostic technique that is based on adaptive neuro-fuzzy inference system (ANFIS). The effect of sample data distribution on training the ANFIS is investigated. It is found that the data sampling over 10 days during summer results in a reliable ANFIS whose performance prediction error is within measurement errors. The reliable ANFIS makes it possible to prepare an energy audit and suggest an energy saving plan based on the diagnosed chilled water supply system.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 하계학술발표대회 논문집
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• pp.18-18
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• 2007