• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2005년도 추계학술대회논문집
• /
• pp.421-426
• /
• 2005

For the air-conditioner, refrigerant induced noise and vibration should be the problem when it reduced airflow rate in order to reduce the noise at low mode. With the test, it could be verified that one of the main reason for refrigerant induced noise were the velocity and flowing induced force of the refrigerant at the inlet of evaporator. So in order to reduce this velocity with same mass flow rate of refrigerant, quality at the evaporator inlet should be minimized. And in order to reduce flowing induced force of the refrigerant, flowing direction change should be eliminated. So in this paper, it would like to review the characteristics of refrigerating cycle at first and find how the quality and flowing induced force can be minimized.

• 설비공학논문집
• /
• 제22권6호
• /
• pp.361-368
• /
• 2010

Due to the insulation and the air-tightness requirement in modern buildings have resulted NBS(New Building Syndrome) and SBS(Sick Building Syndrome) of IAQ problems. Therefore, energy efficient way of solving such IAQ issues are of major concern in these days and building industries. This paper introduces a method to improve thermal performance with a DI(Dynamic Insulation) concept. The characteristic of the dynamic insulation is that the lower U-value as the higher air velocity through the DI in a micro level. A thermal performance monitoring study has been conducted to show the energy impact of porous DI over the static insulation material. The results show that up to 45% could be improved in the case with DI compared to the conventional insulation.

• 한국태양에너지학회 논문집
• /
• 제27권3호
• /
• pp.55-61
• /
• 2007

This paper has been conducted to estimate cooling capacity of the dehumidification tower using hot water from a solar water heating system as a energy source of regeneration process when the dehumidification and drying system is applied to room cooling. A solar water heating system was operated and indoor temperature distributions were simulated according to weather conditions when the concerned solution was used to dehumidify room air in the dehumidification tower. Through this simulation researches we found th following results ; It was found that air velocity through supply and return diffusers should be controlled because it can cause uncomfort in dwelling area. It was found that in the sunny morning temperatures of dwelling area 1 and 2 are higher than those of dwelling area 3 and 4. In this research all the calculation results of heating and cooling system supported by solar water heater have confirmed that its cooling capacity could not reach PMV 0, thermal comfort.

• 대한기계학회논문집B
• /
• 제36권7호
• /
• pp.683-687
• /
• 2012

본 연구는 CFD 해석을 이용하여 사각 천장형 루버 디퓨저의 토출각도와 토출 유량에 따른 실내 공기유동 특성에 관한 것이다. CFD 툴은 상용프로그램인 ANSYS 13.0의 CFX를 이용하였다. 연구에 사용된 디퓨저는 적은 유량에서도 충분한 도달거리를 확보할 수 있도록 모델링하였으며, 실내 크기는 $6{\times}6{\times}2.7m$로 디퓨저의 대각선 방향으로 원형 배기구를 모델링 하였다. 토출 공기의 체적유량은 5.1CMM, 7.4CMM이며, 디퓨저의 토출각도를 $30^{\circ}$에서부터 $60^{\circ}$까지 $10^{\circ}$씩 변화하여 실내의 유동특성에 대하여 고찰하였다.

• 설비공학논문집
• /
• 제20권4호
• /
• pp.274-279
• /
• 2008

In the perspective of saving energy in buildings, high performance of insulation and air tightness for improving the heating and the cooling efficiency has brought the positive effect in an economical view. However, these building energy saving technologies cause the lack of ventilation, which is the direct cause of increasing the indoor contaminants, and it is also very harmful to residents because they spend over 90% of their time in the indoor area. Therefore, the ventilation is important to keep indoor environment clean and it can also save energy consumption. In this study, a HEPA type breathing wall is designed as a passive ventilation system to collect airborne particles and to supply fresh outdoor air. To make fine porous structures, polymer nano fibers which were made by electro spinning method are used as a precursor. The nano fibers are coated with SiO2 nano particles and finally the HEPA type breathing wall is made by sintering in the electric furnace at $300\sim500^{\circ}C$. The pressure drops of nano ceramic structure are 8.2, 25.5 and 44.9 mmAq at the face velocity of 2.0, 5.9 and 8.8 cm/s, respectively. Also the water vapor permeability is $3.6g/m^2{\cdot}h{\cdot}mmHg$. In this research, the porous nano ceramic structures are obtained and the possibility for the usage of a material for HEPA type breathing wall can be obtained.

• 한국태양에너지학회 논문집
• /
• 제27권3호
• /
• pp.71-77
• /
• 2007

In past, parking lot was placed on the ground and for the reason air quality was not in problem. But recently parking lot has been placed under the ground and the air quality becomes problem. So in this study, the ventilation performance on the underground parking lot was estimated by using CFD software and alternative system was suggested. Three case studies are handled in this study. 1st case is just an underground parking lot. 2nd case is about an underground parking lot where has 4 fan rooms on each floor and 3rd case is about an underground parking lot where has 4 fan rooms and 30 guidance fans on each floor.

• 설비공학논문집
• /
• 제25권9호
• /
• pp.499-505
• /
• 2013

R744 has been appropriated for substitute refrigerant, because of its high stability, and environment-friendly nature as a natural refrigerant. To analyze the cooling performance of a refrigeration system in a refrigerator truck using R744 according to the blocking ratio, an analytical model of the refrigeration system was developed under frost conditions, using EES. The performance of the refrigeration system was predicted with the indoor and outdoor air temperature, outdoor air velocity, and compressor speed. As a result, the system performance decreased, with the increase of frost growth. When the blocking ratio was 40.4% in the basic condition, the refrigeration capacity was decreased by 27.1%, compared to the non-frost condition.

• 센서학회지
• /
• 제9권3호
• /
• pp.190-195
• /
• 2000

본 논문에서는 실내의 공기 흐름을 간단하게 측정할 수 있는 정온도형 디지털 열박막 풍속계를 개발하였다. 센서의 출력전압은 풍속에 대해서 4제곱근에 비례하므로 마이크로프로세서와 A/D 컨버터를 사용하여 선형화 하였다. 제작한 풍속계의 출력 풍속값은 기준 풍속계와 비교한 결과 오차는 ${\pm}2%$이내였다. 제작한 풍속계를 풍속이 10m/sec이고 공기 온도가 $23^{\circ}C{\sim}60^{\circ}C$ 범위에서 온도 실험한 결과에서 온도에 대한 오차는 약 ${\pm}1%$ 이었다.

• 설비공학논문집
• /
• 제17권4호
• /
• pp.333-340
• /
• 2005

Horizontal air-jet effect has been utilized in some air conditioning systems in order to control the contaminated air indoor. In the present study, the flow and heat transfer of the contaminated air from a range hood system has been investigated with or without horizontal air-jet effect when the hood fan is on or off. For the present numerical experiment, PAT Flow code has been used. From the present numerical simulations, it has been shown that the air jet of a range hood generates coanda effect confining the contaminated air in a certain region. Furthermore, the qualitative relation between the flow rate of the capture air jet and the distribution pattern of the contamination has been discussed.

• 한국입자에어로졸학회지
• /
• 제5권2호
• /
• pp.37-43
• /
• 2009

Particulate matter (PM) is one of the major indoor air pollutants especially in the subway station in Korea. In order to remove PM in the subway station, several kinds of PM removal system such as roll-filter, auto-washable air filter, demister, and electrostatic precipitator are used in the air handling unit (AHU) of subway stations. However, those systems are prone to operation and maintenance problems since the filter-regeneration unit consisting of electrical or water jet parts might malfunction due to the high load of particulates unless the filter medium is periodically replaced. In this study, the use of axial-flow cyclone was proposed for particulate filter unit in the AHU for its low operation and maintenance cost. Novel shape of axial-flow cyclone was designed by using computational fluid dynamics (CFD). The shape of vortex vane was optimized in terms of pressure drop and tangential velocity. In addition, CFD analysis was validated experimentally through the pressure drop measurement of mock-up model. We found that pressure drop and tangential velocity of fluid through the axia-flow cyclone was significantly affected by the rotating degree of vortex vane and the numerical prediction of pressure drop agreed well with experimental measurement.