The Problem
Innovative energy efficient kiln-based heat treatment (HT) techniques are urgently needed for manufacturers of timber products to comply with new international legislation aimed at the eradication of pests and pathogens.

Without these innovations the industry is likely to increase their energy use (and CO₂ emissions) or even worse switch to cheaper, yet more energy intensive alternatives, such as plastics. Currently many kilns operate without adequately accounting for the heat transfer properties of the individual batches being treated and as a result they tend to use significantly more energy than necessary. This inefficiency is compounded by the heating cycle taking much longer than needed because factors like the temperature inertia between heating the kiln and the bulk of the timber are not considered.

The Approach
BHR Group and Forestry Research are working together to develop a methodology to predict the optimum heating conditions for a heat treatment chamber (kiln) and the timber materials being heat treated. The method will calculate the rate of heat transfer through timber of different sizes. This will be based on a thorough understanding of the thermal diffusivity of timber (a function of tree species, dimensions, moisture content, densities, initial timber temperatures, etc) gained through data collected from extensive laboratory and industrial experiments.

The work will result in a modelling tool which potentially can be used to optimise the operation of industrial kilns in real time. Ultimately the aim is to integrate the software within the control technologies of kilns. Armed with this information, and knowledge of the heat flow within a kiln, kiln operators in future will be able to optimise their operations, reducing energy costs and CO₂ emissions by 25%.

The Work Programme
The specific challenges this work will address are to:

• Establish the heat transfer characteristics of a variety of timber species at small scale under controlled but varied heating conditions
• Develop a generic predictive model (TimberTherm) based on data from the small scale kilns
• Carry out measurements on industrial scale kilns to determine the sensitivity of the heat treatment cycle to kiln operation
• Establish scale-up rules for the model
• Validate the model by running a kiln using the heating cycle proposed by the model.

The proposed project brings together BHR Group and Forest Research, organisations with both the relevant technical track-record (e.g. heat treatment measurement of timbers in kilns, heat transfer modelling in complex materials, regulatory framework) and understanding of the potential market requirements. The work should be complete within 24 months and is being supported by the Carbon Trust, a publicly funded body funded by the UK government to support industrial development and uptake of energy efficient and low carbon technologies.

For more information about the project, please contact us.