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A dynamic model of ammonia production within grow -finish swine barns.

机译：生长肥育猪舍内氨产生的动态模型。

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摘要

The overall objective of this research project was to model ammonia formation and transmission processes in a grower-finisher swine barn, by first modelling the ammonia production and emission from urine puddles on the floor surface and the ammonia emission from the slurry pit, and then incorporating these emission rates in a dynamic model that separates the room and slurry pit headspace as two separate, but linked, control volumes.;The ammonia emissions from 36 simulated urine puddles under a variety of temperature, air velocity and initial urea concentration conditions were measured in a bench-scale experimental set-up. The measurements were used to calibrate and validate a dynamic, mechanistic, urine puddle emission model that considered the processes of evaporation, urea conversion, change in liquid concentration and puddle pH in order to simulate the amount of ammonia emitted from a puddle.;The impact of different slurry compositions on the ammonia emission rate from slurry pits was tested in another bench-scale experimental set-up with emission chambers. The emission chamber concentration data collected was used to calibrate and validate a developed slurry emission model. The collected slurry samples were concentrated mixtures of urine and feces from individually-housed animals fed different diets. An empirical equation was developed to express the amount of total ammoniacal nitrogen in the slurry that was in the form of ammonia (f) and thus volatile to the surroundings. Based on the empirical equation, the simulated value of f was between 0.03 and 0.08 and did not show the sensitivity to slurry pH that has been reported by other authors.;Using the information gained in the previous experiments, a mechanistic model describing the dynamic ammonia concentration in the room and in the slurry channel headspace of grower-finisher swine barns, as well as the ammonia emitted to the surrounding environment was developed. Data was collected from two grower-finisher rooms to use as input data to the model and for calibration and validation purposes. The model calibration procedure determined that the amount of emissions originating from the slurry for the simulated room conditions was generally less than 5% of the total room emissions, the air exchange rate through the slatted floor was approximately 4% of the room ventilation rate, and that in the first two weeks of animal activity in a room the urease activity at the floor surface will increase.;The first step in modelling the ammonia emission rate from the floor surface was to determine the frequency of urinations by grower-finisher pigs. Male and female pigs were observed three times during their finishing phase to determine their urination frequency over the course of a day. The average measured urination frequency was 0.62 +/- 0.11 urinations pig -1 h-1. A sinusoidal dromedary model was developed to describe the daily variation in urination frequency for male and female pigs between 51 and 78 kg.;The dynamic model was tested for its sensitivity to various input factors in terms of the floor emission rate, slurry emission rate and total emission rate. An interesting aspect of the simulations was that increases in either floor or surface emission rate were compensated to a small extent by decreases in the other emission rate as a result of a reduced concentration gradient for mass transfer. The ammonia emission rate from the floor was most sensitive to changes in urease activity, fouled floor area and puddle area. The ammonia emission rate from slurry was most sensitive to changes in slurry pH. The impact of input variables on the total emission rate was dependant on the simulated proportion of the total ammonia emission coming from either the floor surface or slurry channel. Three ammonia reduction techniques were tested and evaluated on their impact to the total ammonia emission rate from a room compared to a given set of control conditions. (Abstract shortened by UMI.).
机译：该研究项目的总体目标是通过首先模拟地板表面尿液坑中的氨产生和排放以及浆坑中的氨排放，来模拟生长猪场猪舍中氨的形成和传播过程。在一个动态模型中将这些排放速率分开，该模型将房间和矿浆坑的顶部空间分隔为两个独立但相互关联的控制体积。在以下条件下测量了36种模拟尿液在各种温度，空气速度和初始尿素浓度条件下的氨排放量：实验规模的实验装置。这些测量结果用于校准和验证动态，机械的尿液水坑排放模型，该模型考虑了蒸发，尿素转化，液体浓度变化和水坑pH值的过程，以模拟从水坑中排放的氨量。在另一个带有排放室的实验室规模实验装置中，测试了不同浆料组成对浆料坑氨排放速率的影响。收集的排放室浓度数据用于校准和验证开发的泥浆排放模型。收集的浆液样品是来自饲喂不同饮食的独立饲养动物的尿液和粪便的浓缩混合物。建立了一个经验方程式，以表示浆液中氨（f）形式的氨中总氮含量，因此对周围环境易挥发。根据经验方程，f的模拟值在0.03至0.08之间，并且没有显示其他作者所报告的对浆料pH的敏感性。;利用先前实验中获得的信息，描述了动态氨的机械模型养猪场和养猪场的浆液通道顶部空间的浓度以及排放到周围环境中的氨都得到了发展。数据是从两个育肥室收集的，用作模型的输入数据以及用于校准和验证目的。模型校准程序确定，在模拟的室内条件下，源自泥浆的排放量通常小于房间总排放量的5％，通过板条地板的空气交换率约为房间通风率的4％，并且；在房间的动物活动的前两周，地板表面的脲酶活性将增加。;对地板表面的氨排放速率进行建模的第一步是确定生长肥育猪的排尿频率。在肥育阶段对雄性和雌性猪进行了三遍观察，以确定它们在一天内的排尿频率。平均测得的排尿频率为猪-1 h-1排尿0.62 +/- 0.11。建立了正弦曲线的单峰骆驼模型，以描述雄性和雌性猪每天排尿频率在51至78公斤之间;动态模型测试了其对各种输入因子的敏感性，包括地板排放率，泥浆排放率和总排放率。模拟的一个有趣的方面是，由于降低了传质的浓度梯度，其他排放速率的降低在一定程度上补偿了地板排放速率或地面排放速率的增加。地板的氨气排放速率对脲酶活性，污染的地板面积和水坑面积的变化最敏感。浆料的氨排放速率对浆料pH的变化最敏感。输入变量对总排放量的影响取决于来自地板表面或泥浆通道的总氨排放量的模拟比例。与给定的一组控制条件相比，测试并评估了三种氨还原技术对房间总氨排放速率的影响。 （摘要由UMI缩短。）。

著录项

  • 作者

    Cortus, Erin Lesley.;

  • 作者单位

    The University of Saskatchewan (Canada).;

  • 授予单位 The University of Saskatchewan (Canada).;
  • 学科 Agricultural engineering.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 287 p.
  • 总页数 287
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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