Open AccessOn the damping of temperature fluctuations in a circular tube relevant to the eddy covariance measurement technique
Author(s) -
Rannik Üllar,
Vesala Timo,
Keskinen Raimo
Publication year - 1997
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/97jd00362
Subject(s) - tube (container) , mechanics , eddy covariance , heat exchanger , nusselt number , heat flux , flow (mathematics) , materials science , physics , reynolds number , thermodynamics , heat transfer , turbulence , ecology , ecosystem , composite material , biology
A semiempirical model for the heat exchanger design to find out a minimum length to dampen temperature fluctuations is presented. Stationary heat transport processes through the tube wall are analyzed by means of Nusselt numbers. The conservative treatment of the problem reveals that the tube length should be of the order of 1000 times the inner diameter of the tube to neglect the corrections due to sensible heat flux in eddy covariance measurements of trace gases. The model is analytical and easy to use regarding the choice of tube and flow characteristics. Teflon tube is found to be practically as good a heat conductor as metals. The minimum length required for the damping is not affected by the possible heating of the tube outer surface.