为验证多相流热泵蒸发系统的在线阻垢及强化换热性能,以蒸氨废液为液相工质、氧化铝及聚甲醛粒子为阻垢颗粒进行实验研究。结果表明,氧化铝颗粒的加入可有效去除蒸发器已有垢层,换热系数由结垢后的392.5 W/(m²·K)提升至 1 712.2 W/(m²·K),且连续运行130 h换热系数未降低;蒸发器换热系数受颗粒物性参数影响较大,随着颗粒直径、密度、体积分率增加换热系数逐渐增大,但增加过量时导致流动不畅,换热系数降低;颗粒自身材质导热系数越高强化换热效果越好;循环流量、颗粒分布形式对换热系数也有较大影响,提高循环流量有助于强化换热;不同分布形式在一定程度上均可提高换热系数,双层多孔分布器可实现颗粒逐级输运,增加其进入换热管比例,强化换热效果最佳。

The online scale inhibition and enhanced heat transfer performances of a set of multi-phase flow heat pump evaporation system is verified through employing ammonia-evaporated waste liquid as the liquid material,and using alumina and polyoxymethylene as the solid scaling particles.It is verified by results that the existing scale layer can be removed effectively after adding alumina particles,and the heat transfer coefficient of the evaporator is improved from 392.5 W/(m²·K) after scaling to 1 712.2 W/(m²·K).As descaling by alumina particles,the heat transfer coefficient remains unchanged after 130 h of continuous operation.The heat transfer coefficient of the evaporator is greatly affected by the property parameters of solid particles.With the increases of the diameter,density,type,and volume fraction of solid particles,the heat transfer coefficient increases as well.However,the fluidization state will be weakened and the heat transfer coefficient will decrease consequently when these parameters increase excessively.The higher the thermal conductivity of the particles,the better the heat transfer enhancement effect.Moreover,circulation flowrate and particle distribution form have also big impact on the heat transfer coefficient of the evaporator.Increasing the circulation flowrate contributes to enhancing the heat transfer effect.Different particle distribution forms are beneficial to improve the heat transfer coefficient,in which double-layer perforated plate distributor can also facilitate particle transportation,which is helpful to enhance the proportion of particles entering heat exchange tubes and hence presents a better heat transfer enhancement effect.

侯超(1991-),男,博士,助理研究员,研究方向为工业节能,ucas_hc@163.com;李伟钊(1990-),男,博士,助理研究员,研究方向为热力过程优化与节能,通讯联系人,wzli2022@mail.ipc.ac.cn。