A research team led by Ri Hyok Min, a researcher at the Nano Physics Engineering Institute, has developed an auto control system and a dehumidification device for ozone disinfection and applied it to the practice.
The system manages overall ozone disinfection processes for different types of objects to be disinfected, so that disinfection processes can go in a scientific way.
The system consists of a central control unit, a human-machine interface (HMI) with a touch screen, an exhausting unit, an alarm unit and other electric contactors and relays. The central control unit receives data including limiting cumulative CT, limiting ozone concentration, temperature and humidity in disinfection rooms from HMI and drives the ozone generator.
During the disinfection process, the central control unit constantly receives ozone concentration in disinfection rooms through the RS-485 communication interface from the sensor located in the room, and calculates the cumulative CT automatically. When the calculated cumulative CT reaches the limit value, it stops the ozone generator and starts the exhausting unit. Then, the ozone concentration of the room decreases rapidly. If the ozone concentration of the room is below 0.6ppm (safety value to human), the exhausting process stops and the alarm device starts ringing. It indicates to the operator the finish of the disinfection process. Also, it stops the ozone generator when the ozone concentration reaches the limit value. It prolongs the lifetime of the ozone generator and prevents deterioration of objects to be disinfected.
A dehumidification device is necessary to protect the ozone generator from damage and increase the quantity of ozone. In general, the input gas of the ozone generator is air. But the air includes vapor, which decreases the amount of ozone generation and, more dangerously, it creates nitrous acid.
Thus, they designed and manufactured a dehumidification device which is based on freezing and absorption. The freezing device drops the dew point to 4℃ and the absorbent dehumidifier drops it to －55℃. As a result, they could achieve twice as much ozone as before.
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