In this paper, a heat exchange system using cooling dehumidification and mixing process was proposed as an experimental study for a white smoke reduction heat exchanger system under winter condition. The white smoke reduction heat exchange system is divided into an EA part, SA part, W part and mixing zone. For the operating conditions, three types (Cases 1, 2, and 3) were selected depending on whether EA fan, SA fan, and A-W heat exchanger were operated. In addition, in order to visualize the white smoke exhausted from the mixing zone, it was photographed using CCTV. In order to investigate the performance of the white smoke reduction heat exchange system, the temperature reduction rate and absolute humidity reduction rate of EA and the heat recovery rate of W were calculated. The temperature change of EA and SA according to operating conditions was most effective in Case 3, and the temperature and absolute humidity at the outlet of the mixing zone were greatly reduced. From the results of the white smoke visualization, it was confirmed that the white smoke generation mechanism was different depending on the operating conditions, and the amount of white smoke generation was greatly reduced.

In this study, a white smoke reduction simple prediction model of white smoke reduction heat exchange system was developed by using EES. In order to verify the reliability of the EES model, it was compared with the computational results. The developed EES predictive model was used to calculate the temperature and absolute humidity of the mixed SA and EA according to the change of cooling water capacity, flow rate ratio of SA/EA, and SA inlet temperature. The difference between final temperature and absolute humidity at the outlet of the mixer calculated by computational analysis and EES was within 1.4% and 3.6%. As the cooling water capacity and the inlet flow rate ratio increased, and as the inlet air temperature decreased, the temperature and absolute humidity of the mixer decreased. The most influential factor in the white smoke reduction effect among the design variables of the white smoke reduction heat exchange system was the flow rate ratio of SA/EA.

In this study, the temperature, the absolute humidity, and the turbulent flow characteristics of exhaust air and supply air in the mixer were studied while changing the shape of the mixer of the white smoke reducing heat exchange system. Using Solidworks, the mixer of the white smoke reduction heat exchange system was created by 3-D model. Also, the mixed flow of supply air and exhaust air inside the mixer under the uniform inlet conditions was computed, using the solidworks flow simulation. Two types of improvement models were selected by using a perforated plate and a guide vane as a turbulent mixing flow control method of the mixer. The mean temperature and mean absolute humidity of the mixture were greatly decreased according to the internal shapes of Case 1, 2, and 3. The temperature difference between the inlet and outlet of the mixer Case 3 was 26℃. The exit temperature and absolute humidity reduction rates of Case 3 were 26.2% and 48.1%, respectively, compared with Case 1.

An enthalpy exchange element (EEE) is frequently made of papers, and a concern exists on growth of fungus or bacteria. This concern may be eliminated if polymer membrane is used instead of paper. Furthermore, most existing enthalpy exchangers have cross-flow configuration, which yields lower performance than counter-flow one. In this study, a counter-flow enthalpy exchange element was made using PVDF and cellulose composite. Heat and moisture transfer tests were conducted changing the frontal air flow rate from 150 m 3 /h to 350 m 3 /h at both the heating and the cooling condition. Results showed that the temperature efficiencies were approximately the same independent of the weather condition. Humidity efficiencies at the heating condition, however, were higher than those at the cooling condition. Furthermore, the heat transfer coefficients approached the theoretical value as the flow rate increased. In addition, the vapor transmission rates at the heating condition were higher than those at the cooling condition, probably due to the higher humidity efficiency at the heating condition. Future research will be focused on moisture diffusion characteristics of the composite membrane, which requires further measurements of water holdup, equilibrium adsorption curve, etc.

In this study, the characteristics of the heat flow on SA(supply air) side of the white smoke reducing heat exchange system according to the change of SA velocity were analyzed in the winter condition (outside temperature 0℃). Also, the mixing process of SA and the EA(exhaust air) is presented in the psychrometric chart to confirm the possibility of reducing white smoke. Solidworks flow simulation was used to analyze the heat flow on the heat exchange system under uniform conditions. As the inflow velocity of SA increased, the temperature of SA decreased due to the convective heat transfer improvement due to the active flow in SA system. And the outlet temperature and absolute humidity of the mixing zone decreased significantly. At SA velocity 7 m/s, the outlet temperature and absolute humidity decreased to about 58% and 82%, respectively.

In this study, effects of reducing white smoke at a heat exchange system for white smoke reduction were studied in the winter season. For this purpose, the heat transfer processes on the exhaust air were investigated by Solidworks. Five wave heat exchangers of air-to-air and air-to-water type were applied for the exhaust air heat recovery. The analytical condition of the exhaust air was fixed and the computational analysis was performed according to the change of SA(supply air) inlet velocities. In order to evaluate the performance of the heat exchange system for white smoke reduction, W(water)/SA recovered capacities and the temperature/ absolute humidity reduction rate were calculated. As SA inlet velocity increased, the exit temperature and absolute humidity of the mixing zone were reduced by up to about 40℃ and 0.12kg/kg respectively. Also, W/SA recovered capacities increased linearly up to about 35%.

In the present study, the white reduction system was designed and manufactured to evaluate the performance of a heat exchange system using a wave heat exchanger. The reducing effect of white smoke and the amount of heat recovered from cooling water were investigated experimentally using the cooling and dehumidifying method. The white smoke reduction system consists of two parts; the generating part and the reducing part of white smoke. Experimental conditions on EA(exhaust air) and SW(supply water) were fixed. And the outlet temperature and absolute humidity of EA were measured according to inlet velocity of SA(supply air). The outlet temperatures and absolute humidities of EA gradually decreased as inlet velocities of SA increased. From the experimental results, we can see that the absolute humidity reduction rate of EA was max. 84%, and the heat recovery rate of SW was max. 42%.

최근 많은 시간을 실내에서 생활하는 현대인에게 실내 공기의 질은 매우 중요한 개념으로 자리 잡고 있으며, 이는 현재 새롭게 대두되어야 할 문제이다. 실내 공기질은 온도, 습도 등으로 결정이 된다. 따라서 현재 이러한 인자를 제어하여 실내 공기질을 개선하고 있지만, 실내 공기질 개선을 위해서는 에너지소비가 심하다는 단점이 있다. 그리하여 전열 교환을 적용한 문제를 해결하려는 방법에 대한 연구가 활발히 이루어지고 있고, 전열 교환막을 이용하여 효과적으로 제어하고자 하는 많은 연구가 이루어지고 있는 추세이다. 따라서, 본 연구에서는 전열 교환 분리막 적용을 위하여, poly(styrene-ethylene-butylene-styrene)고분자에 암모늄을 도입하여 친수성을 가지는 아민화된 SEBS 고분자를 합성 및 특성평가를 진행하였다.

온실의 난방부하 중 지중전열부하는 산정방법이나 적용여부가 제각각이고, 온실의 규모에 따라 각각의 방법에는 큰 차이가 있으므로 보다 정확히 국내에 적용할 수 있는 방법을 정립할 필요가 있다. 본 연구에서는 원예시설의 난방부하 산정방법 정립에 필요한 기초자료를 제공하기 위하여 위치와 규모가 다른 3개의 연동 플라스틱 온실에서 난방기간 동안 지온분포와 토양열류를 실측하였으며, 온실의 지중전열부하 산정방법을 검토하고 난방설계에 필요한 기준자료를 도출하였다. 난방중인 온실의 지온분포를 실측하여 실내기온과 비교한 결과 온실의 중앙 부분에서는 지온이 실내기온 보다 높고, 온실의 끝부분과 모서리 부분에서는 지온이 실내기온 보다 낮은 것으로 나타났다. 그러므로 온실의 중앙 부분에서는 지중열이 공급되고, 온실의 측면 부분에서는 외주부를 통해서 열손실이 발생하며, 온실의 규모에 따라 차이가 있는 것으로 판단된다. 건물의 외주부를 통한 열손실 개념을 도입하고, 온실의 규모를 반영하여 수정한 온실의 지중전열부하 산정방법은 타당성이 있는 것으로 평가된다. 토양열류센서를 이용하여 실측한 지중전열량은 실내외 기온차에 비례하여 직선적으로 증가하는 것을 확인할 수 있었다. 지중전열량 분석 결과로부터 지중전열의 방향이 바뀌는 기준온도차를 도출하였으며, 국내 온실의 난방설계에서 대규모 온실은 10oC 내외, 소규모 온실은 12.5 ~15oC를 적용할 것을 제안하였다. 또한 지중열류 실측 결과로부터 온실의 외주부 단위길이당 열손실계수를 도출하였으며, 대규모 온실은 7.5~10W·m-1·K-1, 소규모 온실은 2.5~5.0W·m-1·K-1를 설계기준 자료로 제안하였다.

Earth to air heat exchangers made by iron, aluminium, copper and poly-ethylene pipe for single greenhouse heating were experimented and blowers. Earth to air heat exchanger was installed by pipelines in earth tube at 70cm depths and air blower was the heating capacity 3kW/h, As the result, Temperature difference due to temperature history of the inlet and outlet air on the various type in earth tube in greenhouse showed that air temperature at the various type in earth tube, comparison tube were make no difference respectively. Under the experimental condition, heat fluxes and heating load were showed 6,800Kcal/h, 19,699kcal/h generally yield of Lactuca Sativa cultured during days of sowing 90day in greenhouse using copper pipe was 170% incleased.

In this study, an enthalpy exchanger was coated by silver nano particles via spark discharge method and its antimicrobial and heat exchange efficiencies were evaluated. A method utilizing thermophoretic force was used to improve coating efficiency. Four spark discharge systems were parallel connected and generated silver nano aerosol particles (number concentration of 1.65×10⁸ particles/cc, mode diameter of 31 nm). The coating efficiency was evaluated according to various face velocities (V=0.25~1 m/s) and temperature gradients ((T_hot-T_cold)/T_hot=0~0.09). The maximum coating efficiency was 90.8 % when the face velocity was 0.25 m/s and the temperature gradient was 0.09 (Thot=30℃, Tcold=2℃). Silver nano particles were coated onto the enthalpy exchange element and two different coating amounts of silver nano particles (0.11 ㎍/cm³ , 0.22 ㎍/cm³ ) were tested. For evaluation of antimicrobial efficiency, the suspension test method with E. coli was used. After the suspension test method, CFU(colony forming unit)s of each test sample were counted and colony ratio was calculated. The colony ratio was decreased more quickly when the amount of coated silver particles was increased. When the contact time between each sample and suspension was over 3 hours, antimicrobial efficiencies of coated samples were more over 99.9 % for both amount of silver nano particle(0.11 ㎍/cm³ , 0.22 ㎍/cm³ ). The coating of silver nano particles did not affect the heat exchange efficiency.

본 연구는 1993년부터 2003년 동안 겨울철 제주도 지방에 눈이 내린 경우를 대상으로 대기가 해양으로부터 얻은 열교환량을 계산하여 보웬비(현열속/잠열속)와 강설간의 관계를 분석한 것이다. 대상지역은 제주도 4개 관측지점인 제주, 서귀포, 성산포, 고산이다. 적설 예측의 신뢰도를 높일 수 있는 방법을 찾기 위하여 바람과 같은 기상의 영향이 가미된 보웬비와 적설과의 관계를 해기차와 적설과의 관계와 비교해 보았다. 그 결과 신적설 시, 지역별 최저 해기차는 제주시, 서귀포, 성산포, 고산에서 각각 10.9, 12.3, 11.5, 14.3˚C였고, 그 이상의 해기차에서 신적설 확률은 각각 26, 29, 13, 23%인데 비해, 신적설시 지역별 최저 보웬비는 각각 0.59, 0.60, 0.65, 0.65였고, 그 이상의 보웬비에서 신적설 확률은 33, 70, 31, 58%로 나타나 보웬비가 해기차보다 높은 확률을 보였다. 보웬비에 의한 확률이 해기차에 의한 확률보다 높게 나타나는 이유는 해기차에 의해 형성된 강설의 조건에 바람에 의한 열교환이 강설의 조건을 강화시킨 것이 보웬비에 나타났기 때문으로 생각된다. 10년(’93~’02)간 자료를 분석한 결과 각 지역별 신적설이 10.0~0.9cm 일 때 평균 보웬비는 0.63~0.67이고 신적설이 1.0~4.9cm 일때 평균 보웬비는 0.72 이상으로 조사되어 강설시 적설량과 보웬비는 비례관계가 있음을 알 수 있었다.

본 연구에서는 온실의 온풍식 난방시스템 연통에 장착할 수 있는 폐열 회수기의 성능 개선을 목적으로 기 설계된 세 가지 열교환 장치와 기존의 장치에서 열교환 면적과 파이프의 두께 및 공기흐름 방향을 개량한 새 열교환 장치에 대해 열회수 성능을 실험적으로 비교 분석하였다. 그 결과 기존의 열 교환장치인 A형, B형 및 C형의 열회수 성능은 동일 송풍전입에서 각각 42.2%, 40.6% 및 54.4% 정도였으나 , 새로 개량된 D형은 69.2%로써 가장 현저히 높게 나타났다. 그러나 열회수용 공기의 흐름방향 변화에 따른 열회수 성능 개선효과 (A형 대비 B형)는 없는 것으로 나타나 적정 송풍기 용량이라면 직선형이 공기의 흐름방향 180˚C 굴절시키는 헤어핀형보다 효과적인 것으로 판단된다. 결국 열회수 성능은 열회수 시스템의 열교환 면적과 열교환 파이프의 두께 및 풍속에 크게 좌우되는 것으로 나타났다. 따라서, 열교환 파이프의 내구성 등 을 고려하여 기능한 한 범위 내에서 열 교환면적을 증대시키거나 열교환 파이프의 두께를 앓게 하고 풍속을 증대시키는 것이 열회수 성능 개선효과와 직결됨을 알 수 있었다. 그리고 송풍기 용량이 필요이상으로 큰 경우, 소비전력이 많게 되는 등의 문제가 있기 때문에 적정용량 및 제품의 안정성을 고려하여 선택해야 할 것으로 판단되었다.

기상청에서 덕적도와 칠발도에 설치한 해양기상 관측부이 자료를 이용하여 해양 및 대기 특성과 해양-대기간의 열교환을 살펴보았다. 각 관측지점에서의 일평균 현열속 및 잠열속은 벌크공기역학법을 적용하여 계산하였다. 표층수온은 기온과 같이 뚜렷한 연주기를 보이지만, 1달 정도 시간지연을 가진다. 해면기압은 7월에 가장 낮았고 겨울에 가장 높았으며, 습도는 5-8월 사이 비교적 높았다. 풍속은 가을과 겨울에 평균 5m/s 이상으로 강한 편이었다. 현열속 분석결과 가을부터 겨울에 걸처 해양의 열손실이 두드러졌으며, 봄과 여름에는 반대로 대기에서 해양으로의 약한 열전달이 이루어져 연중 순현열속은 해양에서 대기로의 열전달을 보여주었다. 잠열속 분석결과 봄에서 여름까지 대기의 열손실이 나타나지만, 그 외 기간에는 해양의 열손실이 월등히 크게 나타났다. 현열속과 잠열속의 크기를 비교해 볼 때,1-2월을 제외하고는 전반적으로 현열속보다 잠열속에 의한 해양의 열손실이 우세함을 알 수 있었다. 관측지점별로 분석한 열속의 크기와 변동폭은 대체적으로 덕적도에서 더 크게 나타났다. 일정 기간을 선정한 사례연구에서, 1998년 5월사례의 경우 현열속과 잠열속 모두 칠발도에서 더 크고, 1996년 11월 사례의 경우에는 덕적도에서 훨씬 크게 나타났다.

Evapotranspiration is one of the important elements related water cycle and there is many kind of measurement method of evapotranspiration today. This study developed mini lysimeter for the purpose of direct measurement of evapotranspiration and installed on 5th, July, 2010 at the field of MRI which located at Tsukuba, Ibaraki, Japan for continuous measurement and understand relation between evapotranspiration and meteorological elements expecially radiation elements. And compared the evapotranspiration data of lysimeter with Bowen Ratio Method. The result of this study is as follows; There is high related with solar radiation and evapotranspiration with R2=0.947. and 46 % of solar radiation converted into evapotranspiration during clear 5 days. In net radiation also highly related with evapotranspiration, we can derive evapotranspiration is mainly controlled by radiation energy in clear days. From the 104 days data, there is only 9 % difference between Bowen Ratio Method and evapotranspiration of lysimeter which was developed from this study is very useful to estimate evapotranspiration at field site with simple and high accuracy. High accuracy and resolution measurement of evapotranspiration by lysimeter can give a chance further study of meteorological phenomena of on ground expecially in night time condensation which means abnormal energy flow.