Sousa E.F., Santolin M.A., Do Frédéric. (2020). Estimation of steady water flux density in a porous medium by Fourier analysis of temperature variations in a cyclic heat pulse system. In :
Hölttä T. (ed.), Salmon Y. (ed.). Proceedings of the XI international workshop on sap flow. Louvain : ISHS, 187-192. (Acta Horticulturae ; 1300). International Workshop on Sap Flow, 11., Hyytiälä (FIN), 2019/10/07-11. ISBN 978-94-6261-298-3.
Titre du document
Estimation of steady water flux density in a porous medium by Fourier analysis of temperature variations in a cyclic heat pulse system
International Workshop on Sap Flow, 11., Hyytiälä (FIN), 2019/10/07-11
We tested a novel theoretical model that determines the steady water flux density in a porous medium from Fourier analysis of temperature variations induced by a cyclic heat pulse system. The model depends on the thermal diffusivity of the medium and on the relative spatial variation of the amplitude and phase of the first order sinusoidal component of the heat wave. The model was tested by using a hydraulic column made of a PVC pipe filled with sawdust. The sensor consisted of two hypodermic needles spaced 7 mm apart. One needle contained a heater and a thermocouple while the other contained only a thermocouple. Different combinations of heating and cooling cycles were tested. The flow was controlled by pressure head and volumetrically measured at the outlet of the tube. The experimental results supported the theoretical model. In particular, the convective index defined in terms of the variations of amplitude and phase of the first component of the heat wave was linearly related to the measured flux density, as predicted. The model was independent of the different combinations of heating and cooling cycles. The estimated water flux density was strongly related to the measured flux density (R2>0.99), having the same slope for the different combinations. The first results of this new approach of cyclic heat pulse system are very promising and suggest further studies and field applications.
Plan de classement
Mathématiques appliquées [020MATH01]
;
Etude du micro et phytoclimat / Modélisation [072BCLIGE04]
