Numerical analysis on the performance of mechanical vapor recompression system for strong sodium chloride solution enrichment

Highlights: • MVR system is used to evaporate a type of anti-frozen solution in HVAC fields. • Regeneration performance of anti-frozen solution of heat-source tower is studied. • Influence factors on evaporating performance of input parameters are modelled. • An experimental plant of is established to validate the mathematical model. Mechanical Vapor Recompression (MVR) system is an efficient system for evaporation, which has been employed in extensive fields. Solution regeneration in HVAC fields is significant. In this paper, MVR system is used to regenerate a type of anti-frozen solution of heat-source tower heat pump, the sodium chloride solution with high concentration. A system model has been built to analyze the stable operating performance of regeneration. Meanwhile, an experiment plant of MVR system has been established to monitor the actual operating performance of the system to validate the model. Operating parameters of the system are calculated based on the system model. Performance indicators are analyzed according to the parameters calculated above. The influence of the input parameters on the evaporating performance of the system is studied, including the frequency of compressor, temperature of inlet weak solution, concentration of inlet weak solution. With the increase of frequency of compressor or the increase of inlet solution temperature, evaporation rate, quantity of heat transfer and power consumption of compressor increase accordingly. Power consumption of the compressor to evaporate per ton of water reaches 16.8 kWh, when the suction pressure is 25 kPa, the concentration of the inlet weak solution is 18%, and the frequency of compressor is 100 Hz. Concentration of solution has a great effect on the boiling point elevation of the solution. Therefore, when the concentration of solution is high, power consumption of compressor increases significantly, and COP decreases sharply. When the inlet concentration increases 1%, the power consumption of the compressor to evaporate per ton of water increases 8.2%, and COP decreases 2.7%.