Abstract The need for renewable sources of energy has fueled interest in harvesting the heat produced by composting. Pilot-scale compost reactors were built with in-vessel heat exchangers to test the effect of heat extraction on the composting process. Water was passed through copper tubes embedded in the compost-filled barrels and the temperatures of the compost and the inlet and outlet water were monitored. More heat could be extracted with higher water flow rates. Compost temperatures were especially sensitive to the water flow rate during the thermophilic stage. The data from this experiment was then used to update a computational model of the composting process. COMSOL Multiphysics™ (v. 5.2, COMSOL AB, Stockholm, Sweden) was used to create a three-dimensional, finite-element simulation of mass and energy balances in the compost barrels. The model was validated against empirical data from the experiment. Simulated and empirical data were in general agreement from the start of composting until peak thermophilic temperatures, at which point they diverged, likely due to inappropriate heat transfer boundary conditions in the model. This work is a step in the development of empirically validated computational tools for the optimal design of compost heat extraction systems.

中文翻译：

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优化堆肥的热量提取

摘要 对可再生能源的需求激发了人们对收集堆肥产生的热量的兴趣。中试规模的堆肥反应器是用容器内的热交换器建造的，以测试热提取对堆肥过程的影响。水通过嵌入堆肥桶中的铜管，并监测堆肥和进出水的温度。更高的水流速可以提取更多的热量。在嗜热阶段，堆肥温度对水流量特别敏感。然后使用来自该实验的数据来更新堆肥过程的计算模型。COMSOL Multiphysics™（第 5.2 版，COMSOL AB，斯德哥尔摩，瑞典）用于创建堆肥桶中质量和能量平衡的三维有限元模拟。该模型根据实验的经验数据进行了验证。从堆肥开始到高温峰值，模拟数据和经验数据大体一致，此时它们出现分歧，这可能是由于模型中的传热边界条件不合适。这项工作是开发经过实证验证的计算工具以优化堆肥排热系统设计的一步。