본 연구에서는 대류 및 복사열전달에 따른 단동온실 내 열유동 특성을 예측하기 위해 3차원 정상상태 열유동해석을 수행하였다. 넓은 파장대역폭에서 연속적으로 방사되는 태양복사에너지를 수치해석적으로 모사하기 위해 특정 파장영역대를 기준으로 복사에너지를 유한한 영역으로 구분하는 다중대역모델 적용하였다. 또한 비회체 특성을 갖는 비닐의 물성을 해석상에 적용하기 위해 파장영역대별 투과율(또는 흡수율)을 변화하여 적용하였고 유속, 온도, 복사에너지의 경계조건을 변화시켜 추가적인 해석을 수행하였다. 이러한 수치해석기법을 검증하기 위해 수치해석 결과를 실제 온실에서 측정된 온도 값과 비교분석한 결과 평균오차가 12.2∼14.2 % 정도에 차이를 보이지만 유사한 경향성을 나타내고 있어 해석기법의 타당성을 확인하였다. 또한 복사에너지는 파장영역대별 비닐 투과율에 따라 온실 내에서 복사강도가 현저히 감소하고, 온실 내 열유동은 환기팬에 의한 강제대류에 의해 크게 영향을 받고 있음을 확인하였다.
Recently, there are lots of increasing interest in smart farming that represents application of modern Information and Communication Technologies (ICT) into agriculture since it has a real potential to deliver a more productive and sustainable agricultural production based on a more precise and resource-efficient approach. In order to obtain high performance and stability for smart greenhouse, it is important to identify the effect of various working parameters such as capacity of ventilation fan, vent opening area and etc. In the present study, a 3-dimensional CFD(Computational Fluid Dynamics) simulation for single-span greenhouse was conducted using the commercial program, Ansys CFX 18.0. The numerical simulation for single-span greenhouse was implemented to figure out the internal thermal and flow characteristics. In order to numerically model solar radiation that spread over a wide range of wavelengths, the multiband model that discretizes the spectrum into finite bands of wavelength based on Wien’s law is applied to the simulation. In addition, absorption coefficient of vinyl that is varied with the band s of wavelength is also applied based on Beer-lambert law. To validate the numerical method applied herein, the numerical results of the temperature at specific monitoring points were compared with the experimental data. The average error rates (12.2∼14.2 %) between them was shown and numerical results of temperature distribution are in good agreement with the experimental data. The results of the present study can be useful information for the design of various greenhouses.
