• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.862-865
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• 2004

The system air conditioner has an outdoor unit and a number of indoor units, which connected by several long pipes. In comparison with building HAVC system, the system air conditioner doesn't need lots of facilities, such as control of room, cooling tower, etc. At the beginning stage for the market of the system air conditioner, its main application was a school which size is small to use the building HAVC and large to use home air conditioning system, such as PAC (package air conditioner), RAC (room air conditioner). Therefore, because of the advantages of the system air conditioner mentioned above, the market is expanded rapidly. Since it is difficult to evaluate the noise caused by the system air conditioner because it has to be implemented before the finish of construction, the prediction or estimation of the noise by using CAE technology should be very important. In this research, using a commercial code, RAYNOISE, the noise is estimated to improve the design of building.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.609-614
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• 2008

The heating and cooling performance of system multi-air conditioner under high-head and long-line conditions are experimentally investigated. The maximum head and tube length were 110 m and 1000 m, respectively. The experimental system was composed of 4 outdoor units with module systems, and 13 indoor units which were joined with the mode change unit by single-tube circuit. Field tests without indoor and outdoor temperature control were performed in a general office building with 22 different working conditions. Experimental results were prepared on the p-h diagram. Also the oil level in the compressor was normally maintained at the safety zone for the system multi-air conditioner with high-head and long-line conditions.

• 한국태양에너지학회 논문집
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• 제32권6호
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• pp.141-148
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• 2012

Ceiling cassette type air conditioner has been a main stream as a heating/cooling system recently in school, Korea. In this study, indoor thermal environments made by ceiling cassette type air conditioner were investigated by CFD simulation. Concentrations of $CO_2$ were investigated by a field measurement. Indoor thermal environment with the velocity inlet angle of $45^{\circ}$ from the ceiling in heating season was very ununiform so that thermal area was divided into two parts those the one is window side which is cold, and the other is corridor side which is hot. In cooling season under the same condition, there are areas too hot or too cold. If the velocity inlet angle is set in $30^{\circ}$ from the ceiling, indoor thermal environments was improved greatly in cooling season and heating season, too. Also, from the field measurement of $CO_2$ concentrations, it was suggested to install ventilators with proper air volume considered the number of class students.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.330-333
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• 2008

The hybrid air-conditioner, where air is cooled both by convection and radiation, is developed. The indoor unit of the air-conditioner consists of radiation panel and dehumidification coil, where refrigeration R-134a is supplied by independent refrigeration cycles. Optimum refrigerant charge was 750g for both cycles. Optimum evaporation pressure was 3.7 bar for the radiation panel cycle and 3.9 bar for the dehumidification cycle. The cooling capacity of the radiation panel was 1.01 kW and that of the dehumidification coil was 0.94kW, which yielded COP of 3.3.

• 태양에너지
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• 제20권4호
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• pp.45-52
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• 2000

Multi A/C is consisted of one outdoor unit and several indoor units. When the Multi Air conditioner is installed, we have to be cautious of the length of pipe arrangements. When the pipe arrangement is installed with unbalance or too long, there can be cooling capacity losses and low EER. An experimental study was carried out about the operation characteristic of Multi Air conditioner varying the length of pipe arrangements. If the pipe arrangement of the system is 15m, the cooling capacity and EER were decreased 0.8% and 1.3% respectively compared to the case when pipe arrangement is 5m. In case of 25m, the cooling capacity and EER were decreased 10.7% and 12.2% respectively compared to the case of 5m. When the length of pipe is not same each other, it is profitable to make the pipe length of highest capacity indoor unit shortest.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.304-309
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• 2008

The heating and cooling performances of system multi-air conditioner for various refrigerant flow rates with high-head and long-line conditions are experimentally investigated. The maximum head and tube length were 110 m and 1000 m, and the two different adjustments of refrigerant flow rates were +20 % and -20 %, respectively. The experimental system was composed of 4 outdoor units with module systems, and 13 indoor units which were joined with the mode change unit by single-tube circuit. Field tests without indoor and outdoor temperature control were performed in a general office building with two different refrigerant flow rates. Especially, the oil level in the compressor was normally maintained at the safety zone. Experimental results were prepared on the p-h diagram.

• 한국전산유체공학회지
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• 제17권4호
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• pp.81-86
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• 2012

The objective of the present study is to investigate the effects of various turbulence models on the aerodynamic noise of an air-conditioner (AC) indoor unit. The results from URANS (unsteady Reynolds-averaged Navier-Stokes) simulations with the standard k-$\varepsilon$, k-$\omega$ shear stress transport (SST) and Spalart-Allmaras (S-A) turbulence models were analyzed and compared with the noise data from the experiments. The frequency spectra of the far-field acoustic pressure were computed using the Farrasat equation derived from the Ffowcs Williams-Hawkings (FW-H) equation based on the acoustic analogy model. Two fixed fan casings and the rotating cross-flow fan were used as the source surfaces of the dipole noise in the Farrasat equation. The result with the standard k-$\epsilon$ model showed a much better agreement with the experimental data compared to the k-w SST and S-A models. The differences in the pressure spectra from the different turbulence models were discussed based on the instantaneous vorticity fields. It was found that the over-estimated power spectra with the k-w SST and S-A models are related to the emphasized small-scale vortices produced with these models.

• 설비공학논문집
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• 제22권1호
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• pp.26-32
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• 2010

This paper is suggesting a new technology for refrigerant amount detection of a system air-conditioner installed under various installation conditions. System air-conditioner was introduced to domestic market first in 2000. It consists of one or a series of outdoor units and a number of indoor units connected with single pipe line to the outdoor unit. The system can vary the capacity from 2.0 kW to 186 kW. For the system Installed under long and high-elevated condition, about 100 kg of refrigerant is charged in the whole system. In this paper, the new technology RAD (Refrigerant Amount Detection) with edge technology of refrigerant cycle control and measurement of a system air conditioner was developed and investigated for its application for the various installation conditions.

• 설비공학논문집
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• 제23권8호
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• pp.580-586
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• 2011

In this study, 3 cooling systems of apartment which are air-cooled air conditioner with indoor unit, water-cooled air conditioner with indoor unit and small capacity absorption chiller-heater with FCU have been evaluated by Multi-Criteria Decision Making Analysis. Weights of 7 selected factors which are economics, space, billing, constructability, human comfort, visibility and reliability are determined by expert group of 30 system designers and 30 construction engineers. Final weights were derived for 101 and 166 $m^2$ apartments. Analysis shows that small capacity absorption chiller-heater with FCU is the most favorable system for apartment cooling system.

• 설비공학논문집
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• 제18권11호
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• pp.874-880
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• 2006

The power density and heat dissipation rate per unit area of the telecommunication equipment have been increased with the technology development in the footprint of telecommunication hardware. A proper heat dissipation method from the PCB module is very important to allow reliable operation of its electronic component. In this study, a hybrid air-conditioner for the telecommunication equipment room was designed to save energy and obtain system reliability. For high outdoor temperatures, the hybrid system operates in the vapor compression cycle, while, for low outdoor temperatures, the hybrid system works in the secondary fluid cooling cycle with no operation of the compressor. The performance of the hybrid air-conditioner was measured by varying outdoor and indoor temperatures. The hybrid air-conditioner yielded 50% energy saving compared with the conventional refrigeration system when the mode switch temperature was $8.3^{\circ}C$.