Abstract A low-temperature heat pump sludge drying system was constructed and experimentally studied in the present study. The initial and final moisture contents on dry basis of sludge are 1.53 and 0.2, and the drying duration is 5 h. Theoretical models for heat pump circulation and moist air circulation are established and validated with the experimental results. Based on the validated theoretical models, sensitivity analysis of evaporating temperature, condensing temperature, and air mass flow rate on the temperature and humidity of moist air at the outlet of drying closet, drying rate and specific power consumption (SPC) are carried out. The temperature of moist air at the outlet of drying closet increases with increasing evaporating temperature and condensing temperature, while decreases with increasing air mass flow rate. The drying rate decreases with increasing evaporating temperature while increases with increasing condensing temperature, and first increases and then decreases with increasing air mass flow rate. The appreciated air mass flow rate ranges between 0.8 and 1.0 kg/s, and the drying rate around 6.0 kg/10min can be achieved under these conditions. The relative humidity of moist air at the outlet of drying closet shares a similar trend with the drying rate while SPC shows a contrary trend.

中文翻译：

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低温热泵污泥干化系统的理论分析与试验研究

摘要 本研究构建了低温热泵污泥干燥系统并进行了实验研究。污泥干基初含水率和终含水率分别为1.53和0.2，干燥时间为5 h。建立了热泵循环和湿空气循环的理论模型，并用实验结果进行了验证。基于经过验证的理论模型，进行了蒸发温度、冷凝温度、空气质量流量对干燥柜出口湿空气温湿度、干燥速率和比功耗（SPC）的敏感性分析。干燥柜出口处的湿空气温度随着蒸发温度和冷凝温度的升高而升高，而随着空气质量流量的增加而降低。干燥速率随着蒸发温度的升高而减小，随着冷凝温度的升高而增大，并且随着空气质量流量的增大先增大后减小。在这些条件下，可欣赏的空气质量流量范围在 0.8 到 1.0 kg/s 之间，干燥速度约为 6.0 kg/10min。干燥柜出口潮湿空气的相对湿度与干燥速率呈相似趋势，而SPC则呈相反趋势。