Analyzing ventilation efficiency using age of air theory and CFD technology

In agricultural-buildings like livestock houses and greenhouses, environmental conditions are controlled by ventilation-systems. Comprehension of ventilation is important to improve the internal growth conditions. Notable researchers in the field of architectural-science have been using "Age-of-air" theory to investigate ventilation-efficiencies. However, this has not yet been applied in agricultural fields. The concepts of LMA and LMR were used to evaluate the-distribution of fresh air and the potential for eliminating-contaminants. However, experiments had been limited due to a shortage of experimental-devices and unstable tracer-gas. In this study, the Age-of-air concept and CFD were employed to address the mentioned limitations. A 3-dimensional chamber was designed to accurately implement and verify the Age-of-air concept via simulation analysis. The simulation results were compared with the results of the experiment which was conducted via the tracer-gas approach. In validating the computations of the LMAs and LMRs, the results showed similar tendencies of distribution and average errors of 9 and 13%, respectively. It was concluded that the simulation for implementation of the Age-of-air was designed reasonably. The results showed that when the ventilation rate increased, the Age-of-air values decreased; however, when comparing air exchange efficiencies, the values had an opposite tendency. Based on the results, the research could be upgraded to quantitatively detennine the overall or local ventilation-efficiencies in agricultural-facilities using the Age-of-air theory.