沸点温升影响下机械蒸汽再压缩系统性能研究

Taking the evaporation and concentration of MgCl ₂ at low mass fraction as an example, a mathematical model of single-effect mechanical vapor re-compression system with vertical tube falling film evaporator and centrifugal compressor as the main components was established. The heat transfer area was calculated by logarithmic average temperature difference. The evaporation pressure, nominal heat transfer temperature difference and mass fraction of the material of the evaporator outlet were regarded as parameters. The influences of the parameters on heating coefficient COP and annual total cost were studied, when the material boiling point increased with the increase of mass fraction in evaporating of the evaporator. The results show COP decreases with the increase of evaporation pressure and mass fraction of material at the outlet when the nominal heat transfer temperature difference is constant. COP decreases with the increase of the nominal heat transfer temperature difference when the evaporation pressure is constant. The annual total cost increases with the increase of evaporation pressure when the nominal heat transfer temperature difference is 2-6 ℃. While the total annual cost decreases as the evaporation pressure increases when the nominal heat transfer temperature difference exceeds 6 ℃. When the evaporating pressure is constant, the annual total cost increases with the increase of the nominal heat transfer temperature difference. And when the nominal heat transfer temperature difference is constant, the annual total cost increases with the increase of the mass fraction of the material at the outlet.