Articles
SAP FLOW AND HEAT CONDUCTIVITY MEASUREMENT AND THEIR INTERACTION
Article number
951_10
Pages
95 – 100
Language
English
Abstract
There are many different methods for sap flow measurement.
Quantitative output of such methods is a precondition of their application.
However it is not easy to quantify, if not all needed input parameters are known.
Heat conductivity is one of them.
Introducing a constant value into corresponding equations has usually solved this problem, although this means introducing an unknown error.
We have been working with two approaches: trunk heat balance method, THB, giving total flow rate per tree and the heat field deformation method, HFD, giving total, but also particular flows in different sapwood depths.
There was a tendency to unify both these useful approaches, which led to development of intermediate (stationary at present), linear heat balance method, LHB. The applied main equation (LHB formula) is derived from fundamental partial differential equation describing convective-conductive heat flow.
A new approach was developed most recently, capable to calculate both parameters (sap flow and heat conductivity) at the same time, which is being applied and gradually improved now.
This approach is based on two equations with the above-mentioned parameters.
One includes heat balance around a heater; the other one includes deformation the heat field around a heater.
The LHB method is illustrated on the example of a series of diurnal courses of sap flow calculated on the basis of different principles.
Quantitative output of such methods is a precondition of their application.
However it is not easy to quantify, if not all needed input parameters are known.
Heat conductivity is one of them.
Introducing a constant value into corresponding equations has usually solved this problem, although this means introducing an unknown error.
We have been working with two approaches: trunk heat balance method, THB, giving total flow rate per tree and the heat field deformation method, HFD, giving total, but also particular flows in different sapwood depths.
There was a tendency to unify both these useful approaches, which led to development of intermediate (stationary at present), linear heat balance method, LHB. The applied main equation (LHB formula) is derived from fundamental partial differential equation describing convective-conductive heat flow.
A new approach was developed most recently, capable to calculate both parameters (sap flow and heat conductivity) at the same time, which is being applied and gradually improved now.
This approach is based on two equations with the above-mentioned parameters.
One includes heat balance around a heater; the other one includes deformation the heat field around a heater.
The LHB method is illustrated on the example of a series of diurnal courses of sap flow calculated on the basis of different principles.
Publication
Authors
M. Trcala , J. Cermák
Keywords
sap flow, heat conductivity, linear heat balance, heat field deformation, trunk heat balance
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