基于有机质降解产热模型的堆肥过程热平衡动态特性研究

Mathematical model provides a comprehensive method to gain better understandings of composting processes, which leads to insights of upgrading composting engineering. Respiratory heat drives the temperature variations for most self-heating composting practices but the thermal balancing principles are not yet well understood. Systematic analysis with mathematical model can be a feasible manner to optimize temperature control. In this proposal, modeling of respiratory heat production is based on degradation kinetics of soluble substrates and insoluble substrates. Lab-scale reactor composting trails will be conducted. Samples will be collected to analysis substrate degradation, supplying information to format more mechanism-oriented degradation models and heat production simulation. Kinetics of hydrolysis and liquid-gas transfer equations are introduced to unfold their effects on degradation and heat production. To understand thermal balances as a dynamic system, an integrated mass and heat transfer model should be developed, considering multiple factors such as aeration velocity, aeration pressure, temperature, degradation ability and thermal characteristics. The simulation of gas thermodynamics will be included in the thermal balance models. The modeling and simulations, solved with numerical software, will be validated with observed composting results, vice versa. It is expected to conclude more sophisticated strategy of heat preservations in terms of systematic thinking and experimental results.

基于有机质降解产热模型研究堆肥过程热平衡动态特性。首先，采集代表性堆肥样本进行降解特性试验分析，研究不可溶性有机质水解转化规律，并引入氧相态传递数学模型，发展有机质降解动力学模型，基于有机质降解动力学深入研究降解产热机理，完善堆肥热量平衡过程的产热部分。其次，分析并模拟计算堆肥过程气体（氧气、水蒸汽等）的物性状态变化（比体积、焓变等），研究氧气在气液两相态间的传递规律，并为对流换热模型和蒸发潜热模型构建奠定基础，完善热量积累模型、传导与对流换热模型、辐射换热模型等堆肥热量平衡过程的散热或热量积累部分。最后，基于数值计算仿真平台构建求解热量平衡数学模型，使用堆肥试验测量结果交互验证数学模型，利用系统动力学方法研究堆肥过程热平衡动态特性。依据堆肥过程有机质降解产热模型和热平衡动态特性规律的分析，揭示堆肥产热、散热机理，探索堆肥温度控制新方法。

系统热量平衡是重要的堆肥过程要素，是保障有效堆肥和实现畜禽粪便“三化利用”的基本控制指标。第一，堆肥系统热量平衡的直接结果是堆肥过程温度的变化，堆肥高温阶段维持时间是评价堆肥腐熟度的重要指标，也是实现畜禽粪便废弃物无害化利用的重要前提条件，研究堆肥系统热量平衡对控制延长堆肥高温时间具有重要指导意义。第二，堆肥系统热量散失的形式主要包括通风对流、传导、辐射散热和水蒸发潜热，研究热量散失的机理可指导减轻堆肥对外部环境温度的依赖，并对实现高寒地区低温堆肥具有重要的实际意义。第三，堆肥过程产生了大量的热量，这些热量最终通过不同形式散失到大气中，造成了能量的浪费，研究堆肥系统热量平衡有助分析堆肥余热的产出和指导堆肥余热的收集，对堆肥余热的循环利用具有重要的工程实际意义。.基于现有研究对堆肥系统热平衡动态特性认识不足的前提，提出了基于数学模型系统动力学方法的堆肥过程热平衡动态特性，量化了堆肥系统热平衡动态特性规律，为生物反应器温度控制奠定了完备的理论基础。