杂质与不完善粒含量对进口玉米粮堆自发热过程中热量与CO2传递特性的影响

    Effect of impurity and content of imperfect grains on heat and carbon dioxide transfer characteristics during self-heating process of imported corn grain bulk

    • 摘要: 为研究不同杂质与不完善粒含量的进口玉米粮堆局部发热时热量与CO2的传递特性,在实验室条件下对不同杂质与不完善粒含量(1%+8%,3%+11%,5%+15%)的进口玉米粮堆(湿基水分含量14.0%)中心点加入高水分进口玉米(湿基水分含量20.0%),在20~25℃室内环境储藏40 d。结果表明:各监测点温度均呈现先上升后下降的趋势;随着与中心发热点距离的增加,各监测点温度升高速率降低,最高粮温与最终粮温降低;随着粮堆中杂质与不完善粒含量的升高,中心发热点温度升高速率降低,最高粮温与最终粮温升高,其余监测点的温度升高速率降低,最高粮温也降低,但最终温度升高;粮堆整体CO2扩散速率由大到小的顺序为中层、下层、上层,随着粮堆中杂质与不完善粒含量的升高,各监测点的CO2体积分数升高速率变快,最高体积分数升高;储藏40 d后中心发热点的脂肪酸值和霉菌数随着粮堆杂质与不完善粒含量的升高而上升,水分含量反而下降。研究结果可以进一步为粮堆发热点的发现、监测和控制提供基础数据,对进口玉米储藏过程中的异常粮情监控和预防做出指导。

       

      Abstract: To study the transfer characteristics of heat and carbon dioxide during local heating of imported corn piles with different content of impurities and imperfect grains, imported corn with high moisture (water content of wet base 20.0%) was added to the center of imported corn piles (water content of wet base 14.0%) with different content of impurities and imperfect grains (1%+8%, 3%+11%, 5%+15%) under laboratory conditions to simulate the mildew and heat of grain caused by high moisture in local grain piles, and stored in indoor environment at 20-25℃ for 40 days. The experimental results showed that the temperature of each monitoring point increased first and then decreased. With the increase of the distance from the center hot spot, the temperature rise rate of each monitoring point decreased, and the maximum grain temperature and the final grain temperature decreased. With the increase of the content of impurities and imperfect grains in the grain heap, the increase rate of the central hot spot temperature decreased, and the maximum grain temperature and the final grain temperature increased. The temperature rise rate of other monitoring points decreased, and the maximum grain temperature also decreased, but the final temperature increased. The overall CO2 gas diffusion rate of the grain pile was:middle layer > lower layer > upper layer. With the increase of the content of impurities and imperfect particles in the grain pile, the CO2 concentration of each monitoring point increased faster and the highest concentration increased. After 40 days of storage, the fatty acid value and mold number of the central hot spot increased and the moisture content decreased with the increase of the content of impurities and imperfect grains in the grain pile. The research results can further provide basic data for the discovery, monitoring and control of grain stacking hotspots, and provide guidance for the monitoring and prevention of abnormal grain conditions during the storage of imported corn.

       

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