It was difficult to make the set value stable for the first experiment. Especially, the relative humidity fluctuation ranged from 20 to 30% since the sensitivity of humidifier was not good. After knowing that both temperature and relative humidity sensors were not sensitive enough, those sensors were changed into more sensitive ones and the sensing time was adjusted from 10 to 5 s interval.Furthermore, each sensor was uncapped to get better sensitivity against the air flow. Fig. 5 shows the fluctuation of the temperature and relative humidity monitored at the evaporator inlet after the modification. This fluctuation was observed over 100 min and the same observations were carried out to check the cooling bench system. It is recommended that before testing evaporator, it is necessary to stabilize the test bench system at least for 20 to 30 min.