## 5 Results and Discussion
After this moment, the temperature and relative humidity of the room increase depending on the disturbing effects. When the differences between instantaneous values and set values exceed the determined critical values, the cooler is operated in active control mode (Mode-3 for fans and desiccant wheel). The room temperature and relative humidity, which reach the set values again, remain at the set  
Figure 3: (**a**) The variations in the room temperature. (**b**) The control input of a fan. (**c**) The variations in the room relative humidity. (**d**) The control input of the desiccant wheel. values until the automatic Stop/Run process, which will be repeated after a certain period. The control inputs for the fans and desiccant wheel are shown in Figure 3b,d, respectively. Figure 3b shows the control input signal generated by the controller for the fans. The fans regulate the flow rate of the air by changing their speed by working in line with the orders (voltage values) coming from the controller. There is an inverse relationship between the operating speed of the fans and the cooling performance of the cooler. The slowing down of the airflow passing through the cooler increases the amount of heat transfer from the dry channels to the wet channels. The air that loses more heat by passing more slowly will be fed into the room in a cooler way. For rapid cooling of the room air, the cooler outlet air also needs to be cooled as much as possible. For this reason, after the cooler is switched to active control mode, the operating speed of the fans should be reduced to obtain more cooling performance. According to the results obtained, when the cooler switches to active control mode (Mode-3) the control input, which starts around 15 V, drops to 8 V until it reaches the first set value. Thus, the fan speed is reduced to reach the first set value, and the necessary cooling is provided by slowing the airflow. With the set value change occurring at the 800 th second, cooler air is needed at the cooler outlet. For this reason, it is necessary to reduce the fan speed further after this moment. As can be seen from the figure, the control input signal determined for the fans decreased to 7 V. Thus, the fan speed is further reduced compared to the first case, and the rate of heat transfer within the cooler has increased. With this control input value, the room temperature reached the second set value of 21 \({}^{\circ}\)C. The cooler was stopped after the automatic Stop/Run mode was activated at 1650 s. For this reason, 0 V was sent to the fans to stop the fans during this period. Later, after the cooler was turned ON again, the fans started to work with a 7 V supply again. The variations in the speed of the fans are shown in Figure 4a, in detail. In accordance with the physical condition described above, it can be seen that the fan's rotation speed was 1200 rad/sec for the first set point, while it was reduced to 1000 rad/sec to reach the second set point. The control input of the desiccant wheel is obtained as in Figure 3d. The operation modes of the desiccant wheel are shown in Figure 4b and these modes are similar for the fans. In order to reach the initial set value of the room, 43%, the dehumidification in the cooler must be increased. The dehumidification in the cooler and the speed of the desiccant wheel work in direct proportion. This means creating a higher mass (vapor) transfer rate to increase dehumidification. A higher mass transfer rate is made possible by moving the wheel faster. Considering that the desiccant wheel's speed is directly proportional to the supply voltage, the desiccant wheel's supply input was increased to 18 V by the controller in the time it took to reach the first set value. Since the second set value is lower than the first set value, the air at the cooler outlet needs to be further dehumidified. For this reason, it is necessary to increase the speed of the DW.