水润滑双螺杆空压机工作过程传热传质特性研究

Research on Heat and Mass Transfer Characteristics of Water Lubricated Twin-screw Air Compressor

水润滑双螺杆空压机由于能够提供绝对无油的洁净空气而引起了广泛的关注,为研究水润滑双螺杆空压机内部的传热传质特性,建立考虑干空气-水蒸气-液态水三相流动与传热传质的工作过程模型,并采用p-V图试验数据对计算结果进行验证。经对比发现,模拟结果和试验结果吻合良好,进而通过该模型,研究三相流体传热传质特性。结果表明,大量的水喷入转子腔仍未实现与湿空气的充分换热,使得湿空气在压缩过程仍有较大温升。而液态水的最大温升也不超过15 K,证明了液态水的蒸发是由于液态水表面与湿空气中水蒸气的密度差驱动的对流传质现象。并且,压缩和排气过程的大部分时间对流传质现象为湿空气中的水蒸气冷凝为液态水。因此,压缩过程中湿空气远未达到饱和状态,且随着压缩过程的进行更接近干空气。

The water-lubricated twin-screw air compressor has attracted wide attention because it can provide absolutely oil-free clean air.In order to study the heat and mass transfer characteristics of the water-lubricated twin-screw air compressor,a working process model considering the flow,heat and mass transfer of dry air,water vapor and liquid water is established,and the calculated results are verified by the experimental data from the perspective of p-V diagrams.By comparison,it can be found that the simulation results are in good agreement with the experimental results,and then the heat and mass transfer characteristics of three-phase fluids are studied.The results show that a large amount of water injected into the rotor cavity still does not achieve the full heat exchange with the wet air,so that the wet air still has a large temperature rise in the compression process.The maximum temperature rise of liquid water is less than 15 K,which proves that the evaporation of liquid water is caused by the convective mass transfer phenomenon driven by the density difference between liquid water surface and wet air.Moreover,the convective mass transfer phenomenon is that the water vapor in the wet air condensed into liquid water in most of the compression and exhaust process.Therefore,the wet air is far from saturated state in the compression process,and it is closer to the dry air as the compression process goes forward.