전산유체역학 기법을 이용한 공기연령 산정 방법의 개발
Development of Straightforward Method of Estimating LMA and LMR using Computational Fluid Dynamics Technology
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초록
Ventilation efficiency has an important role in agricultural facilities such as greenhouse and livestock house to keep internallyoptimum environmental condition. Age-of-air concept allows to assess the ventilation efficiency of an agricultural facility according toestimating the ability of fresh air supply and contaminants emission using LMA and LMR. Most of these methods use a tracer gasmethod which has some limitations in experiment like dealing unstable and invisible gas. Therefore, the aim of this study was todevelop a straightforward method to calculate age-of-air values with CFD simulation which has the advantage of saving computationaltime and resources and these method can solve the limitations in experiment using tracer gas method. The main idea of LMAcomputation is to solve the passive scalar transport equation with the assumption that the production of the time scalar throughout theroom is uniform. In case of LMR calculation, the transport of the time scalar was reversed compulsively using UDF. The methodologyto validate the results of this study was established by comparing with preceding research that had performed a computing LMAand LMR value by laboratory experiments and CFD simulations using tracer gas. As a result, the error was presented similarly levelof results of preceding research. Some big errors could be caused by stagnated area and incongruity turbulence model. while thecomputational time was reduced to almost one fourth of that by preceding research.
Abstract
Ventilation efficiency has an important role in agricultural facilities such as greenhouse and livestock house to keep internallyoptimum environmental condition. Age-of-air concept allows to assess the ventilation efficiency of an agricultural facility according toestimating the ability of fresh air supply and contaminants emission using LMA and LMR. Most of these methods use a tracer gasmethod which has some limitations in experiment like dealing unstable and invisible gas. Therefore, the aim of this study was todevelop a straightforward method to calculate age-of-air values with CFD simulation which has the advantage of saving computationaltime and resources and these method can solve the limitations in experiment using tracer gas method. The main idea of LMAcomputation is to solve the passive scalar transport equation with the assumption that the production of the time scalar throughout theroom is uniform. In case of LMR calculation, the transport of the time scalar was reversed compulsively using UDF. The methodologyto validate the results of this study was established by comparing with preceding research that had performed a computing LMAand LMR value by laboratory experiments and CFD simulations using tracer gas. As a result, the error was presented similarly levelof results of preceding research. Some big errors could be caused by stagnated area and incongruity turbulence model. while thecomputational time was reduced to almost one fourth of that by preceding research.
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