This paper presents an automation design on evaporative cooling air conditioning unit. The evaporative cooling air conditioning unit includes indirect stage （heat pipe） and direct stage （pads）. The unit and air conditioning room build up a single-chamber VAV (Variable Air Volume) air conditioning system. First, Siemens S7-200 PLC controller is used to control the air conditioning system. Then, KingView software is used to design the HMI (Human Machine Interface). The HMI can monitor all equipment's operation clearly. Monitoring data is accurate and real-time. The HMI can also conduct the animation demonstration.
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