Humidity measurements at high temperatures and transient conditions
The aim of this project was to significantly improve the accuracy and efficiency of industrial humidity measurements at high temperatures up to 180 °C and under transient conditions by developing improved humidity measurement and calibration techniques.The project succeeded in developing humidity calibration methods and procedures for industrial use for air temperatures above 100 °C and absolute pressures up to 6 bar with an uncertainty of less than 2 %. Calibration methods for non-static humidity conditions were developed – also with an uncertainty of less than 2 %. Humidity measurement techniques and procedures for the accurate monitoring of temporal and spatial humidity variations were successfully developed and demonstrated in the temperature range up to 100 °C. Above 100 °C, it was not possible to achieve the desired uncertainty of 5 %.SI traceable in-line water activity measurement (equilibrium relative humidity) techniques, as well as methods for establishing the traceability link between water activity and water mass fraction measurements, were developed. In-line water activity measurements provide a direct feedback to the drying, baking or roasting process. The achieved uncertainty in the water activity measurements was 2 %. The methods developed in this project were demonstrated in relevant industrial applications.