设计参数对蒸发式冷凝器管外传热传质的影响

Influence of design parameters on heat and mass transfer of outside tube of evaporative condenser

结合DPM离散模型与组分输运模型,考虑液滴在换热盘管壁面形成液膜以及气-液两相传热传质,建立蒸发式冷凝器气-液两相热质耦合传递模型,分析影响蒸发式冷凝器换热性能的主要设计参数。结果表明:在侧进侧出的送风方式下,进口风速不宜大于3 m/s;喷淋角度对蒸发式冷凝器换热性能会产生一定影响,在本模型中喷淋角度宜取15°;在一定喷淋流量范围内,当流量从0.001 kg/s增加到0.005 kg/s时,出口水蒸气质量分数平均值由0.0015增加至0.0032;蒸发式冷凝器的传热性能主要受水膜与空气间传质驱动力变化影响,当进口空气相对湿度由30%增大至90%时,出口水蒸气质量分数平均值从0.00114减少至0.00096。本文的研究工作可为蒸发式冷凝器的设计提供理论参考。

Combined with the discrete model of DPM and the component transport model,considering the formation of liquid film on the wall of heat exchange coil and the heat and mass transfer of gas-liquid two-phase,a coupled heat and mass transfer model of gas-liquid two-phase in evaporative condenser is established,and the main design parameters affecting the heat transfer performance of evaporative condenser are analyzed.The results show that under the air supply mode of lateral inlet and outlet,the air inlet velocity should not be greater than 3 m/s;the spray angle will also have a certain impact on the heat transfer performance of evaporative condenser,and the spray angle should be 15°in this model;in a certain spray flow range,when the flow rate increases from 0.001 kg/s to 0.005 kg/s,the average value of outlet steam mass fraction increases from 0.0015 to 0.0032;when the relative humidity of inlet air increases from 30%to 90%,the average value of outlet steam mass fraction decreases from 0.00114 to 0.00096.The research work can provide a theoretical reference for the design of evaporative condenser.