Pyrolysis model sensitivity on temperature dependent thermal parameters of EWP? + Vertical density profile.
Thermal properties
Research question? Motivation?
Sensitivity studies were reported in the literature for noncharring materials, but the char makes the interpretation of data difficult. We need to come up with a systematic way how to interpret the influence of char formation and its properties
Bulk Density
Thermal conductivity
Specific heat capacity
Evaluated from ambient temperature up to decomposition, in air
Dry samples versus moist samples
In case of moist samples, effective cp is evalauted
Cannot be evaluated in Netzsch software, because the mass is changing
Vojta prepared a Python script to calculate cp when mass is changing due to evaporation. How we will apply this to our 1D models?
Is it worth to apply it to pyrolysis models? Does it get lost in the complexity of the model or it actually improves the model in terms of important MLR characteristics?
Take the ambient data, calculate 1D model and compare to nitrogen cone data - do we get at least a decent fit, when all the thermal and kinetic parameters were measured?
Take the "most accurate - temperature dependant + VDP" measured values and compare to cone nitrogen data. Does it perform better? is any in particular more pronounced than others and need to be incorporated in the pyrolysis models?
How does the temperature dependence or vertical profile influence the heat transfer in 1D model?
First change only one parameter, the rest will be taken at the room temperature or bulk density, Compare the significant characteristics on the MLR/temperature profile curve - in a similar way to IAFSS poster
How accurately can the temperature dependence be measured?
Simple 1D heat conduction analysis, no pyrolysis?
Report values of both virgin and char! Experimental data are valuable, especially for char. How to interpret influence of thermal properties when char originates? Thermal properties of char are constant?
Dry samples? STA furnace or standalone furnace.
Moist samples? They are not climatized...
With cp based on the nature of the sample, there is no effect of nonhomogenity of EWP?
thermal inertia - cp and k should be changing when rho is changing in the VDP? Thermal conductivity should be independent of thickness, but nonhomogenity?
Why bulk density and not density is used in the pyrolysis models?
We have measured density profiles of EWPs for various thicknesses - can we find a correlation that would describe VDP as a function of thickness? Or is the VDP the same regardless of the thickness if the VDP - correlation is nondimensionless?
Present EWP char bulk density data measured by Ondra -> cite OSB and publish the rest.
VDP was done for MDF for IAFSS (mass loss rate only)
Validation using nitrogen/oxygen cone data?
Maybe the influence on the heat transfer will fall to experimental error or nonhomogenity of EWPs? Thermal conductivity data suggest that.
Can we combine VDP and temperature dependent thermal conductivity?
How does "improving" thermal properties change temperature profile? problem is - char...so composition of the material is changing over time.
Does the sample preparation and technique of measurement influence the data with nonhomegeneous materials like EWP?
Does the thermal properties change significantly with temperature up to decomposition?
Virgin EWP from 25 to 150 °C in 25 °C steps is measured for moist wood, dry wood, wood stored in climatic chamber.
Can we measure thermal conductivity when the sample is decomposing? Not for now.
Can we measure thermal conductivity of char? No!
Can we combine them? k, rho, cp
Temperature profile? Surface temperature? Back side temperature? MLR? Only up to ignition temperature.
Efective values of k, rho, cp after ignition. Dependent on layer composition (virgin/char). Unable to measure for virgin. Measurable for char. Effective value is dependent on thermal decomposition scheme.
Software
3D heat transfer possibility in FDS?
FDS simple 1D cone model?
GPyro?
Self-made code, problems to define boundary condition.
Materials
Model time to ignition for all materials?
Include char properties if possible.
Publish material data for OSB, DTD, PLY, MDF
Is the 1D simplification valid?
click to edit
Only dry samples were measured successfully.