School of Forestry

 

 

Project Number: 2019-40

Project Leader: Bill Heffernan/Nurzhan Nursultanov, Clemens Altaner, Shusheng Pang

Host Department: EPECentre (with School of Forestry and CAPE)

Project Title: Thermodynamic and economic evaluation of veneer log conditioning processes: a comparison of current and new heating methods

Project outline: The production of laminated wood products, such as plywood and LVL, is achieved by peeling logs on a lathe into thin sheets of veneer, which are subsequently dried, glued and laminated. The process is energy intensive with most of the energy being consumed in thermally conditioning the logs, to soften them before peeling, and then drying of the resulting sheets of veneer. The thermal energy is currently derived from burning wood waste (bark, sawdust, woodchips, veneer waste etc.) to produce hot water and/or steam. The green logs are heated either in hot water bath or in a steam chamber; however, it is observed that both processes have significant heat loss. In some overseas operations the waste wood boilers may also be used to produce electricity, which may be used within the plant, or exported to the grid.

The EPECentre has developed a process for heating freshly felled logs, employing Joule's effect, in which electric current-flow directly heats conductive parts within the timber with subsequent heat flow to less conductive parts. Computational models which predict and control the process reliably have been developed, validated experimentally on full-sized radiata pine logs and reported in the literature.

The result is an energy-efficient and relatively fast process (logs ready to peel for veneer in under 2 hours) compared to existing hot water bath (approximately 20 hours) or steam (of the order of 5 hours) processes. This results in time and energy savings, as well as changing the conditioning process from a batch to a continuous operation, which may also provide some logistical benefits. The energy savings result both from inherently reduced losses from the faster heating process and improved control of the individually tailored final temperature profile of each log.

The purposes of this project are:

  • to model both existing and new processes thermodynamically (heat and mass balance calculation) and economically,
  • to establish the net benefits that could be achieved from adopting this new technology,
  • to identify under what scenarios of equipment investment, electricity cost, alternative uses for currently-burned wood waste and carbon dioxide emissions pricing, economic benefits can be realized.

 

Specific Requirements: 3rd professional year student – ideally a student considering studying towards a higher degree.

Good knowledge of thermodynamics and process engineering (e.g. from ENCH292, ENCH392/393 and ENCH494, or from ENME215, ENME315 and ENME405/415)

Knowledge of process modelling techniques (heat and mass balance calculation is essential), process simulators (e.g. HYSYS), and scientific coding (e.g. MATLAB or Python)

 

 

Project Number: 2019-45

Project Leader: Nurzhan Nursultanov, Clemens Altaner

Host Department: EPECentre (with School of Forestry)

Project Title: Electrical characterization of green timber

Project outline: The electrical behaviour of recently felled timber, and indeed of living trees, is of significant scientific interest. It can be used, with suitable measuring instruments, to determine the proportions of the various wood regions inside a tree or log, such as heartwood, sapwood or intermediate wood. The content of these various wood regions has significant impact on the quality, value and best end use for the timber from a given tree and information on the growth rate of the various regions can influence the choice of the best genetics for propagation.

The electrical characteristics can also be used to predict the heating of logs using a process recently developed by the EPECentre, employing Joule's effect, in which electric current-flow directly heats the more conductive parts within the timber with subsequent heat flow to less conductive parts. Computational models which predict and control the process reliably have been developed, validated experimentally on full-sized radiata pine logs and reported in the literature. Logs used to produce veneers for decorative timber, plywood and laminated veneer lumber (LVL) are generally heated to soften the timber before peeling - the new process promises much faster heating than traditional methods.

In general the sapwood is more conductive than the heartwood, but the ratios between electrical conductivity (EC) vary between species, with grain orientation (axial, radial, and tangential), with temperature and with the soil the tree is growing/has been grown in. However, surprisingly little is known about this subject and for some species there is no information at all.

This project seeks to improve this situation, characterizing several thus far unstudied softwood and hardwood species, which are grown for timber in NZ and overseas, both with laboratory and field experiments.

Specific Requirements: 2nd or 3rd professional year student, probably in a science or an engineering discipline - perhaps a student considering studying towards a higher degree.

Prior knowledge of wood, forestry, chemistry or electrical engineering is not essential; knowledge and interest in statistics and the software packages R and/or MATLAB would be helpful but not essential. A positive attitude to practical work is far more important.

 

 

 

Project Number: 2019-130

Project Leader: Tara Murray

Host Department: Forestry

Project Title: Best practice monitoring techniques for threatened grasshoppers

Project outline: New Zealand has a quirky and unique insect fauna including flies that don’t fly, moths that jump, and grasshoppers that don't like grass. However, just like much of our better-known flora and fauna, many of our insects are threatened with extinction by introduced mammals, weeds, habitat loss and other changes in the landscape. Although invertebrates make a significant (but often unknown) contribution to land conservation values, particularly in alpine, dryland and semi-modified landscapes, there are very few best practice guidelines available for monitoring changes in insect populations. Monitoring is essential to detect population declines in responses to factors like increasing predator numbers or climate change, but also to detect responses to conservation management interventions to show if those actions are beneficial or not. Researchers at Canterbury University have previously developed and tested methods in collaboration with DOC and Environment Canterbury, for monitoring the cryptic braided river grasshopper Brachaspis robustus. This summer we are seeking a student to apply these methods to another cryptic grasshopper, the Nationally Critical species Sigaus homerensis that is only found around Homer Tunnel in Fiordland. The student will be based at the DOC research station at Knobs flat, Milford, where they will apply the monitoring protocols to Sigaus homerensis to determine if the monitoring methods are suitable for another species. They will investigate and provide recommendations on how the methods can be adapted to monitoring in an alpine habitat. If time permits the student will also test methods on two other threatened grasshoppers near Alexandra and Tekapo.

Specific Requirements: Students must have a drivers license and be willing to undertake field work outside of Christchurch over the summer months. Must be physically fit with some outdoors experience (such as tramping or field work)

 

 

 

Project Number: 2019 - 139

Project Leader: Campbell Harvey and Prof. Rien Visser

Host Department: Forestry

Project Title: Managing Harvesting Residue

Project outline: Managing harvesting residues during and after forest harvesting operations is important to avoid environmental risks. Harvest residues can also be recovered as a by product, for example bio-energy. This small research project will require considerable field work to visit harvesting operations and measure the actual quantity and distribution of residues. The project also lends itself to a final year dissertation project for Forest Eng or Forestry Science students.

Specific Requirements: Preference for a 2nd or 3rd year Forest Engineering or Forestry Science student, but open to any Engineering or Science student in 3rd year.