印刷烘干用热泵系统的管板式回热装置设计及性能分析

Design and Performance Analysis of Tube-sheet Heat Recovery Device for Heat Pump System in Printing Drying

介绍了一种回热式空气能热泵系统,其回热装置采用管板式结构,在回收利用废气余热的同时避免了废气中墨料杂质和水蒸气对新风的污染。CFD数值模拟了新/回风在回热装置中的流动换热过程,结果显示:新风管道沿程压降和表面换热系数基本保持恒定,回热装置稳定连续工作;新/回风出口温度随环境温度线性变化,回风入口温度变化则会整体改变出口温度变化幅度。极端环境温度-20℃时,新风通过回热装置预热后温度可达272.7K以上,可保证热泵系统的正常工作。热泵系统COP计算结果显示:回热装置大幅提升了印刷烘干用热泵系统的COP值。对应热风烘干最优工作温度50℃,此时热泵COP值在2.81~7.94。

A heat pump with heat recovery device was introduced in this paper.Through adopting the tube-plate structure for the heat recovery device,the pollution to fresh air incurred by the ink impurities in offgas and vapors can be avoided while the waste heat in fumes was reclaimed.Numerically simulating both flow and heat transfer process of fresh/hot air in the heat recovery device showed that,the pressure drop and surface heat transfer coefficient are almost constant,which means the recovery device can work stably and continuously and the fresh/hot air temperatures at the outlet of the device change linearly with the fresh air temperature at its inlet.The linear relationship could be altered by varying the inlet temperature of the hot air.Regarding a-20℃ environment temperature,the temperature of fresh air at the outlet of the device can rise to-0.3℃ to ensure a normal operation of the heat pump system.Calculating COPs of the heat pump system with or without the heat recovery device indicated that,the recovery device can make great contribution to increasing the COP of the heat pump system in the printing drying.When a working temperature is 50℃,the COP of the heat pump system can stay at 2.81 to 7.94.