15-23: Wet Bulb Measurement with Psychrometers and Hygrometers Field Test

Worldwide, the air moisture content entering a cooling tower may be measured either with a relative humidity sensor, a psychrometer, or a capacity hygrometer. Some European standards, dedicated to cooling tower thermal tests such as EN 14705, historically recommend hygrometers for cooling tower acceptance tests for more than 20 years now, while the CTI-ATC 105 (and also 140 ; 150) standard only recommends the use of mechanically-aspired psychrometers. The goal of this paper is to compare the measurement results of these two technologies with CTI-approved psychrometers and commonly used hygrometers for cooling tower tests.