Determination of the mass transfer coefficient of ammonia emissions from dairy open lots using a scale model

文献类型： 外文期刊

第一作者： Ding, Luyu

作者： Ding, Luyu;Li, Qifeng;Jiang, Ruixiang;Yu, Ligen;Zheng, Wengang;Gao, Ronghua;Ma, Weihong;Zhang, Shirui;Ding, Luyu;Li, Qifeng;Jiang, Ruixiang;Yu, Ligen;Gao, Ronghua;Ma, Weihong;Wang, Chaoyuan;Shi, Zhengxiang;Wang, Chaoyuan;Shi, Zhengxiang;Zhang, Guoqiang;Zheng, Wengang;Zhang, Shirui

作者机构：

关键词： Two-film theory; Surface velocity; Vapour pressure deficit; Modelling

期刊名称：BIOSYSTEMS ENGINEERING （ 影响因子：4.123； 五年影响因子：4.508 ）

ISSN： 1537-5110

年卷期： 2020 年 190 卷

页码：

收录情况： SCI

摘要： Open lots are commonly used to provide outdoor free ranging spaces for dairy cows in many countries such as China and the USA. For this type of operation, the manure characteristics, floor types and environmental conditions, which potentially affect gaseous emissions from manure, are quite different from those of indoor systems. The estimation of NH3 emissions from manure depends greatly on the mass transfer coefficient, an empirical constant determined by environmental factors in the process-based emission model. Using a scale model, this study measured ammonia emissions to be expected from dairy open lots, based on different combinations of different surface air velocities (0.6 -2.2 m s(-1)), air temperatures (15-35 degrees C) and relative humidity values (20-60%). Based on the two-film theory, the overall mass transfer coefficient (K-OL) of NH3 was calculated from directly measured NH3 emission rates and the ammonium nitrogen content, temperature, and pH of manure. As an indicator of the driving potential of gaseous volatilisation, the vapour pressure deficit (VPD) was estimated using air temperature and relative humidity. As the VPD and surface air velocity increased, the measured NH3 emission rates ranged from 1.35 to 19.18 mg kg(-1) h(-1), and the estimated K-OL of NH3 from dairy open lots was within the range of 1.48 x 10(-6) - 7.86 x 10(-6) m s(-1). Using the air velocity and VPD as variables, a non-linear empirical model was developed to estimate the K-OL for NH3 emissions from manure on dairy open lots (R-2 = 0.69). The normalised mean error of the model was approximately 19.4%. (C) 2019 IAgrE. Published by Elsevier Ltd. All rights reserved.

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