破损青贮牧草氧气与温度原位观测及变质预测模型研究
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中央高校基本科研业务费专项资金项目(2015QC002)、北京市自然科学基金项目(6164036)和中德科学中心项目(GZ888)


In-situ Sensing and Modeling Dynamics of Oxygen and Temperature in Grass Silage Bale of Suffering Aerobic Deterioration
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    摘要:

    裹包式青贮饲料因塑封膜破损或开包饲喂致使空气(氧气)侵入,激活微生物消耗营养物质产生热量,引起异常温升,最终导致饲料营养成分损失,腐败变质。为此,本文提出了一种基于Clark电极原理的溶解氧传感器,用于原位观测有氧胁迫下青贮裹包饲料内部氧动态与温度变化。在此基础上,构建了基于偏微分-常微分方程系统的有氧胁迫下青贮饲料内部氧动态、温升以及微生物繁殖耦合模型,并检验了模型的适用性。采用CLAAS公司生产的Rollant455型打包机打出的青贮裹包饲料在2个干物质含量(DM-1:39.0%±1.3%和DM-2:31.4%±2.1%)下进行有氧变质过程实验,对比分析实验原位观测值与模型预测值的差异。结果表明:模型预测结果与实验测定结果总体上有较好的一致性,两者差异产生的原因是青贮饲料内部容重(孔隙)分布不均。此外,有氧变质过程产生的水分会改变模型的初始参数(氧气扩散速率降低,比热容提高等),导致模型后期预测精度降低。

    Abstract:

    Aerobic deterioration of bale silage due to puncturing plastic cover by accident or feeding animals results in the nutrition and energy losses. The invasive oxygen that activates the aerobic microorganism to consume nutrition in silage, producing heat that raises the silage temperature, is a key factor being in charge of aerobic deterioration of silage. However, thus far, the in-situ sensing and modeling the dynamics of oxygen diffusion and temperature rising in bale silage has seldom been reported. For this, a Clark-electrode-based dissolved oxygen sensor was applied for in-situ measurement of oxygen concentration and temperature in bale silage. Based on the measurement data, a mathematical model coupling two-dimensional oxygen diffusion, microorganism growth and temperature rising was presented and validated. The tested grass silage was baled by using a baler from CLAAS company (Baler type: Rollant455) with two levels of dry matter contents (DM-1:39.0%±1.3%;DM-2:31.4%±2.1%). Each level had three replications. The results showed that the model simulations generally agreed with the in-situ measurements. The uncertainties between measurement and simulation were mainly due to the heterogeneity of silage density distribution. Moreover, a great quantity of water produced during aerobic deterioration changed the parameters in model such as decline of the diffusion rate of oxygen, increase of the heat capacity, resulting in lower predicting accuracy. Thus, the heterogeneity of silage density distribution and water-induced parameter variation should be included in proposed model for achieving higher predicting accuracy.

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程强,周海洋,单桂林,李梦华,BUESCHER W,孙宇瑞.破损青贮牧草氧气与温度原位观测及变质预测模型研究[J].农业机械学报,2018,49(3):138-143. CHENG Qiang, ZHOU Haiyang, SHAN Guilin, LI Menghua, BUESCHER W, SUN Yurui. In-situ Sensing and Modeling Dynamics of Oxygen and Temperature in Grass Silage Bale of Suffering Aerobic Deterioration[J]. Transactions of the Chinese Society for Agricultural Machinery,2018,49(3):138-143.

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  • 收稿日期:2017-09-08
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  • 在线发布日期: 2018-03-10
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