The New KRISS Low Frost-Point Humidity Generator
- 96 Downloads
A new low frost-point humidity generator (LFPG) has been designed, and its performance has been tested, in order to extend the calibration capabilities to the low frost-point range at KRISS. The water vapor–gas mixture is generated by saturating air with water vapor over a surface of an ice-coated saturator under the conditions of constant temperature and pressure. This LFPG covers a range of frost point from − 99 °C to − 40 °C. The temperature of the saturator, which is controlled by thermoelectric devices and a two-stage mechanical refrigeration system, is stable within 5 mK, and the difference between the saturator temperature and the frost point generated at the saturator outlet is less than 20 mK. This stability is achieved by using oxygen-free high-conductivity copper materials as the saturator body, and applying a precision PID temperature control system. The performance of this new LFPG system is compared with the KRISS standard two-temperature generator in the frost-point range ( − 80 to − 40) °C, and its performance is tested with a quartz crystal microbalance (QCM), which was built at KRISS, to − 91 °C.
KeywordsDew point Frost point Humidity standard Low frost-point generator Quartz crystal microbalance Thermoelectric device
Unable to display preview. Download preview PDF.
- 1.G.E. Scace, D.C. Hovde, J.T. Hodges, P.H. Huang, J.A. Silver, J.R. Whetstone, in Proceeedings of 3rd International Symposium on Humidity and Moisture, vol. 1 (NPL, 1998)Google Scholar
- 2.G.E. Scace, P.H. Huang, J.T. Hodges, D.A. Olson, J.R. Whetstone, in Proceedings of NCSL 1997 Workshop and Symposium (Atlanta, 1997), p. 657Google Scholar
- 3.G.E. Scace, J.T. Hodges, in Proceedings of TEMPMEKO 2001, 8th International Symposium on Temperature and Thermal Measurements in Industry and Science, ed. by B. Fellmuth, J. Seidel, G. Scholz (VDE Verlag, Berlin, 2002), p. 597Google Scholar
- 4.Sonntag D.: Z. Meteorol. 40, 340 (1990)Google Scholar
- 5.Greenspan L.: J. Res. NBS 80, 41 (1976)Google Scholar