In this study, flow analysis was performed using ANSYS CFX to evaluate the performance of the 30kg hydrogen fuel cell hexa-copter drone in hovering flight. In the case of a hydrogen fuel cell hexa-copter drone, a total of four cooling fans are mounted on the drone's body in two pairs on the left and right to cool the fuel cell module. In order to evaluate the effect of the air flow from the cooling fan on the aerodynamic properties of the hydrogen fuel cell drone as the mounted cooling fan operates, the change in thrust for the case where the cooling fan operates and does not operate was compared and analyzed. Looking at the analysis results, it was found that the presence or absence of the drone's cooling fan had little effect on the drone's thrust through the thrust results for the six wings.

For this study, we established a system for the CPU cooling performance evaluation and conducted performance tests on air-cooling and water-cooling to understand the effect of the CPU cooling method on performance. For the performance evaluation, the test chamber and water-cooling system were set up, the workload S/W was selected, and a case file was created. In the case of the air-cooling, the CPU temperature is sensitively affected by the outside air temperature, the direction of the board installation, and the influence of the airflow formed around it, and may cause a lot of fluctuations in the CPU temperature. When the water-cooling system was applied, the CPU temperature decreased from 75℃℃ to 37℃ compared to the air-cooled type under the test conditions of 28.5℃ and 3LPM cooling water supply temperature and flow rate. As the CPU clock speed increased due to the decrease in temperature, it was found that the job execution time was reduced by 15~23%. In the future, it is expected that using this performance evaluation environment established through this study will enable us to easily conduct test evaluations for various processors, cooling methods, and changes in operating conditions.

In this study, heat exchangers used in data center and building air-conditioners were tested according to the type of heat exchangers to select them for commercial use. The experiment was performed three samples, one micro channel heat exchanger, the same volume oval coil and the same performance oval coil. The experiment conducted under actual operation conditions in the data center and building. Micro-channel heat exchanger has lower air side pressure drop and higher capacity per volume than oval coil. It may be advantageous when the installation small space or the little design static pressure in the fan, such as in-row systems or CRAC installed in data center.

The cooling operating characteristics of the 3 room air conditioner are experimentally investigated for the number of the indoor units (A, B, C) and the operating conditions (standard, overload) under the cooling operation. The cooling capacity and COP were calculated using a multi-type calorimeter. Also, EEV opening, compressor frequency, and superheat degree were obtained when the compressor started. From the experimental results, we can see that the performance and operation characteristics of the air conditioner depend on the indoor unit operation method. In case of simultaneous and single operation, the cooling overload performance was measured lower than the standard condition. Also, in the overload operation, the power consumption of the compressor was greatly increased and the COP was also decreased.

The Air-shiter is a new product possible ventilation at the same time cooling or heating with combined refrigerator and heat recovery ventilator. And a key device of this system is the air shifter. The air shifter device is to convert the outdoor air, room air, supply air and exhaust air flow. Therefore, an experimental study has been carried out to investigate the operating performance for this system. The results, it is possible to ventilate at the same time of heating by outside air above 30℃ in summer. and of heating by outside air within 3℃ in winter. The indoor discharge temperature is over 40℃, and the coefficient of performance is 3.4 in winter.

근권부 공기순환 덕트 냉방이 온도 및 생육에 미치는 영향을 구명하고자 고온기 파프리카((Capsicumannum.L. ‘Veyron’)을 코이어배지에서 수경재배하였다. 냉방시간 처리는 24시간 연속 가동한 연속냉방(All-day), 17시부터 다음날 1시까지 8시간 냉방한 야간냉방(Night), 대조구인 냉방 무처리(Control) 등 3 처리하여 온실 상·하부 온도, 근권온도, 엽온, 과실 특성 및 기관 분배율을 측정하였 다. 근권부 덕트 냉방하였을 때, 고온기(6월 ~8월) 온실 하부(바닥으로부터 40cm)와 상부(바닥으로부터 180cm) 온도, 근권온도는 하강되었다. 대조구와 비교하여 온실 하부/상부 온도 차이가 연속냉방에서는 4.4~5.1oC/ 2.1~3.1oC 하강을, 야간냉방 처리에서는 3.4~3.8oC/ 2.2~2.7oC 하강되었다. 근권온도는 온실 하부 온도 결과와 유사했으며, 연속냉방(22.8oC)> 야간 냉방(24.1oC) > 대조구(27.7oC) 순으로 온도가 낮았다. 연속냉방 처리에서 덕트 위치(통로, 베드하단)와 송풍 방향(45o, 90o, 180o)에 따른 온도 변화를 측정한 결과 덕트의 위치가 통로에 위치하고 송풍방향이 상향(45o) 또는 수평(180o) 인 처리는 지상부 100cm까지의 수직 위치에 따른 온도 차이가 크지 않지 않으면서, 근권부위 온도인 지상 50cm 온도가 낮은 특징을 보였고 베드와 베드 공간 사이로 덕트 송풍 방향이 직각(90o)이였을 때는 바닥과 지 상 50cm 부위의 온도가 높고, 지상 100cm 이상 200cm 부위 온도가 상대적으로 낮았다. 연속냉방 또는 야간냉방 처리했을 때 파프리카 엽온은 오후 7시가 오전 9시 보다 엽온 하강이 컸다. 과실 분배율은 대조구(24.4%)에 비해 연속냉방(48.6%)과 야간냉방(45.6%)에서 높았으며, 평균과중, 과수 및 수량도 연속냉방 처리에서 가장 높았다. 한편 야간냉방 처리에서도 고온기 평균 지상부 및 근권온도를 낮추었으나, 누적된 평균온도가 가장 낮은 연속냉방처리에서 과실로의 동화산물 분배율을 높여 파프리카 수량을 증가시킨 것으로 보인다.

The Air-shiter is a new products possible ventilation at the same time cooling or heating with integrated refrigeration and ventilation units. and is a key component of the air shifter devices and bypass damper. The air shifter devices are to convert the outdoor air, room air, supply air and exhaust air flow. And the bypass damper is device to determine a ventilation. After research and development of these systems were as follows. It is confirmed that the Air-shiter is possible ventilation at the same time cooling or heating, and outdoor air cooling in the spring or fall.

외부공기 유입방식에 따른 느타리버섯의 생육특성을 조사하기 위하여 3가지 처리구를 두어 실험한 결과 모든 처리구에서 재배기간 중 온도편차가 발생하였고, 처리구 모두 1, 2, 8월에 가장 높았으며, T2(열교환기)와 T3(기밀실)에서 T1(외부공기 직접유입) 보다 온도편차가 작은 경향이었다. 재배기간 중 냉방시간은 T1(외부공기 직접유입)은 1,090.3시간, T2(열교환기)는 661.1시간, T3(기밀실)은 865.0시간이었고,평균 냉방절감율은 T1(외부공기 직접유입) 대비 T2(열교환기)는 21%, T3(기밀실)은 11%이었다. 재배기간 동안 난방기의 년중 가동시간은 T1(외부공기 직접유입)은 1,506.9시간, T2(열교환기)는 875.6시간,T3(기밀실)은 1,054.2시간으로 T2의 가동시간이 가장 작았고, 년중 평균 난방절감율은 T1(외부공기 직접유입) 대비 T2(열교환기)는 22%, T3(기밀실)은16%이었다. 외부공기 유입방식에 따른 냉방정도(CD-H)는 T1(외부공기 직접유입)>T3(기밀실)>T2(열교환기)의 순이었고, 난방정도(HD-H)도 냉방정도(CD-H)의 경우와 동일하였다. 수량은 T2(열교환기)와 T3(기밀실)에서 T1(외부공기 직접유입) 보다 4,9, 10월을 제외한 전 기간에서 높았다.이와 같은 결과로 시설재배사에서 느타리버섯 병재배시 열교환기 또는 기밀실을 설치하여 재배할 경우에너지를 절감할 수 있고, 수량 및 고품질의 느타리버섯을 수확할 수 있어 농가소득증대에 기여할 것으로 판단되었다.

여름철 고온기 온실 내 효율적 증발냉방을 위하여 다량 포그 분무가 가능하고 설치비용이 저렴하도록 한 터보팬 2류체 노즐로 포그 분무장치를 구성하고 소형 유리온실에 2.2 m 높이로 설치하여 냉방시험을 실시하였다. 이 장치의 분무시험 결과 평균분무입경이 29 ㎛이고 1대당 포그 분무량은 160 ㎖/min로 비산반경 2 m이내에서 입자들이 모두 증발하는 것으로 나타났다. 이 장치를 평면적 228 ㎡인 단동 유리온실에 2대를 설치하여 냉방실험한 결과, 외기의 온도 30.2℃, 상대습도 81.2%인 때 온실 내 공기의 온도 28.8℃, 상대습도 87.5%의 낮은 냉각효과를 나타내었다. 문헌 조사와 냉방실험 결과로부터 여름철 우리나라 남부지역의 외기온 35℃를 기준으로 단동온실은 50% 차광에서 증발냉각에 의해 온실 내 공기온도를 외기온보다 2∼3℃ 낮추려면 환기회수 1회/분, 물분무량은 10 ㎖/min/㎡인 것으로 추정되었다.

In the study, space cooling performance of air source heat pump(ASHP) was evaluated in a pilot house. The ASHP, which provide for floor heating, domestic water heating and space cooling/heating, shows cooling capacity of 14.0 kW, when COP of ASHP was 3.21 based on test performance of KS C 9306. Test results shows that cooling capacity was depended on frequency of the compressor. The variable refrigerant flow rate for cooling were supplied into diverse room by using LEV. The COP at setting room temperature of 26℃ was 6.3% higher than the COP at that of 24℃, when the spending time in operation was decreased as 21.2%.

The diesel engine uses the intercooler for cooling of charging air by the turbo-charger. But the cooling efficiency of the intercooler which is influenced by the vehicle speed is decreased in low vehicle speed. If the vortex tubes are substituted for the intercooler due to their many intrinsic benefits in many industrial fields as parts for refrigerating machines, the cooling efficiency could be advanced in the low speed range. In this study, a counter-flow type of vortex tube is employed to investigate the temperature separation characteristics with various geometric configurations for optimization of charging air cooling. A parametric study was conducted to evaluate the performance of the vortex tube with various geometric structures and operating inlet pressures. The results show that variation of the cold exit orifice hole diameter significantly influences the energy separation between two exits.

온실의 한쪽 벽에 패드를 설치하고 반대쪽 벽에 팬을 설치하여 가동하는 팬 앤 패드 냉방 온실의 온도 경사 문제를 극복하기 위한 목적으로 일체형 팬 앤패드 시스템과 에어 덕트를 설치한 온실의 냉방 실험을 통하여 냉방성능을 분석하였다. 일체형 팬 앤 패드 증발냉각기의 효율은 1단 가동시 75.7%, 2단 가동시 88.6%로 나타나 대체로 우수한 냉각효율을 보이는 것으로 판단된다. 온실의 냉방성능 실험 결과 무차광 조건에서 온실 냉방 시스템을 가동할 경우 대조구 온실에 비해서 5.7~7.6℃ 정도의 냉방효과가 있으며 차광 조건에서는 7.4~9.7℃ 정도의 냉방효과가 있는 것으로 나타났다. 본 시스템을 적용할 경우 여름철 온실의 최고기온을 37℃ 정도로써 외기온 대비 5℃ 이내로 유지할 수 있으며, 적절한 차광을 실시할 경우에는 33℃ 정도에 2℃ 이내로 유지하는 것이 가능하여 고온기 작물재배에 큰 도움을 줄 수 있을 것으로 생각한다. 한편, 본 냉방 실험에서 온실의 온도 분포를 분석한 결과 18m 길이의 온실 내 최대 온도 편차는 차광시 1.6~1.7℃, 무차광시 2.3~2.7℃ 정도로 나타났다. Kittas 등(2003)과 Nam 등(2005)의 자료와 비교한 결과 본 연구에서 구상한 일체형 팬 앤 패드 시스템과 에어 덕트를 이용한 온실 냉방시스템은 기존의 팬 앤 패드 냉방 온실의 최대 단점인 온도 편차를 40~50% 정도 개선할 수 있는 것으로 나타났다. 본 시스템은 자연환기 상태에서 가동할 수 있으므로 단동 온실에 적용하기가 쉬우며, 일체형 증발냉각기 출구로부터 온실 내 에어 덕트 시점까지의 연결 덕트 부분을 철저하게 단열하면 냉방성능을 더욱 향상시킬 수 있을 것으로 판단된다.

In recent European telecommunication base transceiver stations(BTS), a membrane laminated air filter is reported to replace a heat exchanger in order to cool internal digital units of BTS. The concept of using the air filter is for the direct ambient cooling (DAC) of BTS without heat loss generally found in the heat exchanger type BTS. In the present study, a performance evaluation experiment was conducted to investigate the pressure drop characteristics with dust loading and the particle collection efficiency of the air filter for the DAC of BTS. Finally, the long term operation lifetime of the air filter for BTS was suggested with a given fan rotation speed.

This study was carried out to investigate the presence of L. pneumophila in indoor air and water collected from 692 air conditioning cooling towers at different public facilities. For these 4 years (2001～2004) of investigation, water samples were collected in high air conditioner operating month (from July to September) at department stores, hotels, offices, hospitals, discount stores, and public agencies. It was found that L. pneumophila was present in water samples from 47 air conditioning cooling towers. The detection rate of L. pneumophila was 7.6% in 2001, 10.7% in 2002, and 9.5% in 2003, respectively. When we compared the 4 air conditioner operating months, the highest rate of L. pneumophila detection was obtained in the water samples of July. The detection rate of L. pneumophila differed among different facilities. The highest detection rate of 17.9% was found in samples from department stores. L. pneumophila was detected similarly in water samples from hospitals (8.3%) and offices (8.2%). pH, temperature, and turbidity in the 47 L. pneumophila positive water samples ranged from pH 7 to 9, from 25℃ to 38℃, and from 1.0 to 3.5, respectively.