استفاده از چرخه ام جهت تحليل سامانه آب شيرين‌كن رطوبت¬زني -رطوبت¬گيري

In arid an‎d semi-arid regions, particularly in countries such as Iran where freshwater resources are decreasing, the use of water desalination processes is of great importance. One of these processes is the humidification–dehumidification (HDH) process based on the Maisotsenko (M) cycle. In this study, air first passed through a compressor an‎d a heater an‎d then entered a humidification system based on the M-cycle. A portion of the cooled air in the dry channel was directed into a bubble column humidifier, where the air humidification process took place. The performance of the M-cycle-based humidification system was investigated an‎d compared with a humidification system without the M-cycle. In this study, instead of directly measuring the produced freshwater, after the system reached steady-state conditions, temperature an‎d relative humidity were measured an‎d the corresponding absolute humidity values were calculated to compare the results. The main objective of this research was to investigate the effect of operational variables including inlet air velocity at three levels (1.6, 2.4, an‎d 3.2 m/s), water height in the humidifier at three levels (45, 75, an‎d 105 cm), an‎d inlet air temperature at three levels (50, 65, an‎d 80 °C), an‎d to compare the performance of the two systems. For each experiment, air temperature an‎d humidity data were collected at 10-minute intervals for 120 minutes, an‎d performance indicators including gained output ratio an‎d specific energy consumption were calculated. With the increase in air velocity from 1.6 to 3.2 m/s, due to the reduction in air–brine contact time, the absolute humidity of the air leaving the humidifier slightly decreased an‎d the overall system performance declined. In the system with the M-cycle, the gained output ratio decreased from 0.896 to 0.864 an‎d the specific energy increased from 17706.15 to 17996.58 kJ/kg. In contrast, in the system without the M-cycle, the gained output ratio decreased from 0.869 to 0.835 an‎d the specific energy increased from 18427.80 to 18948.55kJ/kg. Increasing the water height from 45 to 105 cm improved heat an‎d mass transfer between the saline water an‎d air. Accordingly, in the system with the M-cycle, the average absolute humidity of the air leaving the humidifier increased from 0.02109 to 0.02297 kg water vapor per kg dry air. The gained output ratio in the system with the M-cycle increased from 0.834 to 0.898 an‎d the specific energy decreased from 19034.96 to17445.26 kJ/kg. In the system without the M-cycle, the average absolute humidity of the outlet air increased from 0.02065 to 0.02218 kg water vapor per kg dry air, the gained output ratio increased from 0.787 to 0.864, an‎d the specific energy decreased from 19852.18 to 18135.06 kJ/kg. By increasing the inlet air temperature from 50 to 80 °C, the absolute humidity of the outlet air from the humidifier in the M-cycle system increased from 0.01095 to 0.02284 kg water vapor per kg dry air. Within this temperature range, the gained output ratio increased from 0.861 to 0.899 in the M-cycle system an‎d from 0.808 to 0.87 in the system without the M-cycle, while the specific energy decreased from 36532.95 to 17512.74 kJ/kg in the M-cycle system an‎d from 38039.18 to 18080.27 kJ/kg in the system without the M-cycle. Overall, the results showed that the system based on the M-cycle had a higher gained output ratio an‎d lower specific energy consumption than the system without the M-cycle under all operating conditions. The best thermodynamic performance was obtained at an inlet air temperature of 80 °C, a water height of 105 cm in the humidifier, an‎d an inlet air velocity of 1.6 m/s.

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