• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.217-222
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• 2005

Building energy consumption according to the ventilation has been considered to be an important subject. The purpose of this study is to investigate the cooling loads in a test space with a forced ventilating system. In the test space, on/off controlled air-conditioning and forced ventilating facility were operated between 8:30 to 21:00 during 4 days and some important data like temperatures and energy consumption were measured to obtain actual cooling loads. The simulation was carried out in a mode of temperature level control using a TRNSYS 15.3 with a precisely measured air change amount and performance data of air-conditioner. Cooling loads including sensible and latent were compared between by experiment and by simulation. Both of cooling loads associated with ventilation show a close agreement within an engineering tolerance.

• 한국정밀공학회지
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• 제15권9호
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• pp.25-32
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• 1998

The forced cooling system is designed to shorten the overhaul time of steam turbine, which is important in view of economic concern of utility companies, Forced cooling of the hot turbine is achieved by suction of air flow into the turbine after the turbine shuts down. The heat transfer process by suction of air flow can cause thermal stress due to the thermal gradients. In this paper, the analysis of heat transfer is performed to calculate the air flow rate. Based on the prediction of cyclic fatigue damage and the experience, the cooling equipment is designed for shortening the cooling time of steam turbine.

• 설비공학논문집
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• 제18권12호
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• pp.947-954
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• 2006

Building energy consumption according to the ventilation has been considered to be an important subject. The purpose of this study is to investigate the cooling and heating loads in a test space with a forced ventilating system. In the test space, on/off controlled air-conditioning and forced ventilating facility were operated between 8 : 30 to 21 : 00 during 4 days and some important data like temperatures and energy consumption were measured to obtain actual thermal loads. The simulation was carried out in a mode of temperature level control using a TRNSYS 15.3 with a precisely measured air change amount and performance data of air-conditioner. Heating load and cooling load including sensible and latent were compared between by experiment and by simulation. Both of thermal loads associated with ventilation show a close agreement within an engineering tolerance.

• 생물환경조절학회지
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• 제19권4호
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• pp.360-365
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• 2010

본 연구는 예냉처리가 치콘의 MA저장에 미치는 영향을 알아보고자 실시하였다. 치콘의 예냉은 강제송풍 예냉처리에 빠르게 진행되어 품온이 예냉 목표 온도인 $2{\pm}1^{\circ}C$까지 저하되는데 소요시간이 강제송풍예냉이 자연통풍식의 1/6 수준이었다. 반냉각시간은 자연예냉이 3시간 21분, 강제통풍식이 1시간 17분이었다. 저장중 치콘의 생체중은 $5^{\circ}C$와 $10^{\circ}C$ 저장에서 모든 처리구가 0.5% 미만의 감소로 극히 적었으며 예냉시간이 짧았던 강제송풍예냉이 가장 높게 유지되었다. 저장중 포장재내 산소와 이산화탄소 그리고 에틸렌의 농도변화는 $5^{\circ}C$에 비해 $10^{\circ}C$에서 변화폭이 컸다. 예냉에 의한 호흡 억제 효과는 $5^{\circ}C$에서 나타나지 않았으나, $10^{\circ}C$에서 저장 9일 이후 대조구보다 낮은 이산화탄소와 높은 산소 농도로 확인되었다. 에틸렌은 예냉처리구가 저장 3일까지 대조구에 비해 다소 낮았으나 저장 6일부터는 처리간에 차이를 보이지 않았다. 저장 15일째 조사한 외관상 품질은 $5^{\circ}C$와 $10^{\circ}C$ 모두에서 대조구에 비해 예냉처리구에서 높게 유지되었는데, 예냉처리별로는 예냉기간이 휠씬 짧았던 강제송풍예냉에서 품질저하가 자연예냉 보다 더 컸다. 이는 6.0m/sec의 강한 송풍으로 치콘의 외옆 일부가 물리적 상처를 입었기 때문이라 판단되어 송풍속도 등에 대한 세밀한 추가 실험이 요구된다.

• 한국식품저장유통학회지
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• 제11권4호
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• pp.448-454
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• 2004

본 연구에서는 열전반도체를 사용한 강제송풍식과 기계식냉동시스템을 사용한 정지공기식 냉각저장고를 이용하여 냉각방식에 따른 백미의 냉각특성과, 저장중 백미의 품질특성을 구명하였다. 강제송풍식과 정지공기식에서 냉각속도는 각각 $0.30^{\circ}C/hr,\;0.21^{\circ}C/hr$으로 강제송풍식이 빨랐으나, 냉각공기의 편차와 저장고 각 위치별로 백미의 온도편차가 정지공기식에 비해 크게 나타났으며, 상대습도는 낮게 나타났다. 14주간의 백미저장실험 결과, 강제풍통식에 저장한 백미의 함수율은 저하하였지만 백미의 지방산가, b값과 밥의 관능적 품질은 정지공기식에 저장한 경우에 비해 유의적인 차이가 없었다. 따라서, 강제송풍식의 경우 냉각공기 편차를 감소시킬 필요가 있는 것으로 나타났다. 반면, 대조구로서 $25^{\circ}C$ 상온챔버에 저장한 경우는 냉각저장구에 비해 백미의 함수율, b값 및 지방산가와 밥의 관능적품질에서 현저하게 빨리 품질이 저하하였다. 특히, 지방산가는 저장 6주 이후에 안전저장한계인 20 mL KOH/100g-dry matter를 초과하였으며, 밥의 관능적 품질도 저장 4주후부터 냉각저장구에 비해 유의적으로 낮게 나타났다.

• 설비공학논문집
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• 제2권1호
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• pp.49-62
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• 1990

The forced cooling system has been widely applied to passing more electric current in the underground power transmission cable technology. In this paper, the optimum cooling span of the in-trough-indirect water cooling method within an electric tunnel was investigated. A parametric study was performed for the cable currents, the coolant flow rates, and the coolant inlet temperatures. As a result, the temperature of the inlet air has been found as the most important parameter in determination of the optimum cooling span.

• Journal of Power Electronics
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• 제16권4호
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• pp.1598-1611
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• 2016

In some special occasions with strict size requirements, such as mine hoists, improving the design accuracy of the forced-air cooling systems of NPC three-level inverters is a key technology for improving the power density and decreasing the volume. First, a fast power-loss calculation method was brought. Its calculation principle introduced in detail, and the computation formulas were deduced. Secondly, the average and dynamic power losses of a 1MW mine hoist acting as the research target were analyzed, and a forced-air cooling system model based on a series of theoretical analyses was designed with the average power loss as a heat source. The simulation analyses proves the accuracy and effectiveness of this cooling system during the unit lifting period. Finally, according to an analysis of the periodic working condition, the maximum power-loss range of a NPC three-level inverter under multi cycle operation was obtained and its dynamic power loss was taken into the optimized cooling system model as a heat source to solve the power device damage caused by instantaneous heat accumulation. The effectiveness and feasibility of the optimization design based on the dynamic power loss calculation of the maximum power-loss range was proved by simulation and experimental results.

• 원예과학기술지
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• 제33권2호
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• pp.233-241
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• 2015

강원도 강릉에 위치한 고랭지 지역에서 재배된 배추 '춘광' 품종은 수확 직후 차압식예냉, 통풍식예냉, 예건 처리를 하였고, 전처리 후 각각 처리에 대해 0.02mm HDPE film으로 liner 처리 유무에 따라 분류한 다음 $2^{\circ}C$에 저장을 하면서 품질 조사를 실시하였다. 저장 중 무게 손실은 liner 처리구에서 차압예냉이 3% 미만의 손실률을 보였고, 통풍예냉 또한 4% 미만의 손실률을 보였다. 그러나 liner 무처리 구에서는 통풍예냉이 10% 미만의 손실률을 보였고, 차압예냉의 경우 15% 이상으로 가장 많은 손실률을 보였으며, 오히려 대조구가 손실률이 가장 적었다. 가용성고형물의 경우 $2-4^{\circ}brix$ 정도로 나타났으며, 색도는 CIE $L^*$ 값은 50 내외로 큰 차이를 보이지 않았고, hue angle 값은 조금씩 감소하였으나 $120{\pm}2^{\circ}C$ 사이 녹색의 범위 안에 분포하여 색의 변화에 대한 차이는 없었다. Chroma 값의 경우에도 28-32 사이에 분포하였다. 경도는 22N 정도로 나타났으며, 처리에 따른 유의적 차이는 보이지 않았다. 관능 평과 결과, 외관과 아삭거림 정도의 경우 차압예냉을 실시한 후 liner를 적용한 배추에서 가장 좋은 결과가 나타났으며, 나머지 항목에서는 유의적 차이가 없었다. 저장 6주 경과 후 liner 무처리구에서 외관이 많이 손상되었고, 7주 경과 후 liner 처리구에서 통풍예냉과 예건에서 내부 갈변이 심하게 발생하였다.

• International Journal of Air-Conditioning and Refrigeration
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• 제8권1호
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• pp.1-13
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• 2000

A numerical study for performance analysis of a crossflow-type forced draft cooling tower has been performed based on the finite volume method with non-orthogonal body fitted, and non-staggered grid system. For solving the coupling problem between water and air, air enthalpy, moisture fraction, water enthalpy, and water mass balance equations are solved with Navier-Stoke's equations simultaneously. For the effect of turbulence, the standard k-$\varepsilon$ turbulent model is implied in this analysis. The predicted result of the present analysis is compared with the experimental data and the commercial software result to validate the present study. The predicted results show good agreement with the experimental data and the commercial software result. To investigate the influence of the cooling tower design parameters such as approach, range and wet bulb temperature, parametric studies are also performed.

• 설비공학논문집
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• 제8권2호
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• pp.230-239
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• 1996

A multi-faceted experimental investigation has been carried out to study the cooling performance for stacked modules in arrays of heat generating rectangular modules deployed along PCB's in the enclosed cabinet. The main parameters which have an important effect on cooling characteristics are flow velocity, channel spacing, installation of fan unit, attachment of heat sink, and acoustic noise. The results of individual effect are very helpful for the electronic packaging designer. In order to improve the cooling performance, it is certain that the enlargement of channel space is obviously effective, while this id disadvantageous in high density electronic packaging. Each of the paameters is quantitatively examined as cooling performance and the correlation of Reynolds number to Nusselt number is compared with previous study.