Progress 09/01/13 to 08/31/14
Outputs
Target Audience: Target audiences include the International Plant Protection Convention and all participating NPPO’s, the wood products industry, international shipping companies, USDA/APHIS, and the wood science community. Additional audiences include scientists concerned with preventing or mitigating the spread of exotic species around the world through shipping materials. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? One graduate student was involved in the collection and modeling of the RF and Conventional heat treatment data as a component of her PhD research. A postdoctoral scholar was involved in designing experiments, conducting experiments, and writing grants and manuscripts (in progress). The graduate student also attended the National Wooden Pallet and Container Association conference to learn about industry needs. Based on the recent cooperative agreement with an industrial RF oven and continued work to test commercial scale oak and ash pallet materials, PSU investigators have been asked by the American Softwood Lumber Committee (ASLC) for their representatives to attend these data collection activities. ASLC is the primary oversight authority for phytosanitary certification of US certified pallet treaters with respect to quality assurance issues e.g. ISPM-15 compliance. The goal is train key personal to better understand the systematic application of RF dielectric heating with recent adoption of the dielectric heating under ISPM-15. How have the results been disseminated to communities of interest? Several presentations were given at the International Forestry Quarantine Research Group (IFQRG) meeting held in Australia in 2013. Results of the cost analysis were delivered via presentation at the IFQRG meeting held at FAO in Rome in September, 2014. The team also provided technical expertise to the Capacity Development Committee of the International Plant Protection Convention to assist with development of training materials on the newly adopted Annex 1 of ISPM on dielectric heating and in the development of a guidance document. The guidance document is designed to help dielectric equipment developers and National Plant Protection Organizations to produce/certify that the equipment can meet the schedule as indicated in ISPM-15, Annex 1 for phytosanitary treatment of wood packaging. Research results have been shared with industry leaders in North America via a 2-day booth presentation at the Annual Leadership Conference of the National Wooden Pallet and Container Association. As major accomplishments occur, they are covered in the blog by co-PI Ray called GoWood. What do you plan to do during the next reporting period to accomplish the goals? Research is planned to collect depth of heat penetration data with respect to power input requirements with comparative evaluations of RF to MW treatment performance. The purpose of this study is to make the case that the 20 cm dimension limit on WPM that can be treated using dieletric heating is unnecessary and should be removed. The cost model developed in the last reporting period will be refined and implemented in a new website that is under development for use by industrial users considering investment in the technology or NPPOs interested in learning about dielectric heating. More data will be collected for verification and validation of the cost curves that have been generated thus far. This verified cost information will be used in an economic study using GTAP Economic software to determine the potential changes in GDP and economic trade balances due to adaptation of dielectric heat treatment of wooden packaging at various levels of implementation around the world. An extensive website will be developed to deliver results of our research in a manner that is understandable to all stakeholders and end users that will also take advantage of social media as a method for informing interested parties in developments as the technology moves towards implementation.
Impacts
What was accomplished under these goals?
Our first goal to facilitate final approval of dielectric heating technology by the Commission on Phytosanitary Measures of the IPPC as a new treatment for wood packaging materials under ISPM-15 was accomplished. This is the first new technology to be approved as an alternative to methyl bromide fumigation (and conventional heat treatment) and was adopted under both ISPM-15 (Annex 1) and ISPM-28. The treatment schedule adopted based on our results requires that treated material research 60 degrees C through the profile of the wood for at least 1 minute. Initial commercial-scale RF heating trials for bulk treatment of WPM were performed to investigate volumetric heat development. This study was performed under an equipment lease agreement with Ben Aaron Lumber, Inc (Forestville, NY), which gave the team access to an industrial capacity (1200 bd ft volume) RF (4.6 MHz oven frequency, 150 kW heating power) vacuum kiln to study the heating behavior of hardwood sawlog cants commonly used as the primary raw material source for domestic and international shipping pallet construction. The initial trials included only mixed white oak material to investigate compliance with the Annex 1 for dielectric heating under ISPM-15. The schedule requires that the treatment be completed within 30 minutes. White oak was selected due it is high weight to volume (density), which represents a worse case scenario for hardwoods. The study was been expanded to further examine the heating behavior for mixed red oak and mixed ash cant materials. Results showed that RF effectively heats large bulk packs, but the ability to complete treatment of large bulk volumes within a 30-minute time limit will be problematic without substantially higher input power density to reduce the heating rate. The higher the power density needed (via the generator), the greater the cost of the RF equipment. This problem is being addressed in a new funding cycle started Oct. 1. In addition we have initiated studies to develop a database on the complex dielectric properties that describe relative permittivity and loss factors of mixed white oaks, red oaks and ash as hardwood cant material. These data combined with the commercial-scale experimental trials shall serve as a basis to explore the development of standard RF volumetric treatment schedules for other WPM. The first step of an economic analysis was initiated. The cost of energy input in the dielectric (RF) treatment process was calculated based on laboratory-observed treatment times and fundamental energy engineering equations. These trials and calculations provided the team with an energy-cost estimate of 25 cents per pallet for phytosanitary treatment using RF. Cost data were collected from actual heat-treating operations to establish a statistical sample from which a more general population of heat-treating costs could be developed through computer simulation. This simulation was performed and distributions were developed for individual cost components of electricity, chamber fuel, and maintenance. These were then added to result in a total cost curve for conventional heat treatment of wooden pallets in North America. A graphical chart was developed to aid in the comparison and evaluation of RF treatment chamber investment versus conventional heat treatment at variable electricity cost rates.
Publications
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Progress 09/01/12 to 08/31/14
Outputs
Target Audience: Target audiences include the International Plant Protection Convention and all participating National Plant Protection Organizations, the wood products industry, international shipping companies, USDA/APHIS, and the wood science community. Additional audiences include scientists and the public concerned with preventing or mitigating the spread of exotic species around the world through shipping materials. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Two post-doctoral researchers appointed (in different periods) attained greater proficiency and career advancement including: new knowledge about technical and policy aspect of phytosanitary treatment of wood and wood packaging materials; obtained professional skills e.g. operate DH ovens, wood specimens preparation for DH and subsequent analysis; optical-temperature measurements techniques; IR image analysis; participated in grant writing, reporting and manuscript preparation; networking opportuniies through project partners (USDA APHIS, FPI Canada, PSC Inc); IFQRG members and other post-doctoral fellows through Penn State Post-Doctoral Society; received training on measurement of dielectric properties of wood at different frequencies, moisture content and temperature at the state-of-art facility of Centre of Dielectric Studies, Penn State University. The postdocs also participated in a series of professional development seminars and training programs for the post-doctoral researchers organized by Office of Postdoctoral Affairs, PSU; IT department and Schreyer Institute for Teaching Excellence. One postdoc participated as a judge and presenter in poster competitions for graduates and post-doctoral at the PSU. One graduate student was involved in the collection and modeling of the RF and Conventional heat treatment data as a component of her PhD research. The graduate student also attended the National Wooden Pallet and Container Association conference to learn about industry needs. Based on the recent cooperative agreement with an industrial RF oven and continued work to test commercial scale oak and ash pallet materials, PSU investigators have been asked by the American Softwood Lumber Committee (ASLC) for their representatives to attend these data collection activities. ASLC is the primary oversight authority for phytosanitary certification of US certified pallet treaters on quality assurance issues e.g. ISPM-15 compliance. The goal is train key personal to better understand the systematic application of RF heating with recent adoption of the dielectric heating under ISPM-15. How have the results been disseminated to communities of interest? Several presentations were given at the International Forestry Quarantine Research Group (IFQRG) meeting held in Australia in 2013. Results of the cost analysis were delivered via presentation at the IFQRG meeting held at FAO in Rome in September, 2014. The team also provided technical expertise to the Capacity Development Committee of the International Plant Protection Convention to assist with development of training materials on the newly adopted Annex 1 of ISPM on dielectric heating and in the development of a guidance document. The guidance document is designed to help dielectric equipment developers and National Plant Protection Organizations to produce/certify that the equipment can meet the schedule as indicated in ISPM-15, Annex 1 for phytosanitary treatment of wood packaging. Research results have been shared with industry leaders in North America via a 2-day booth presentation at the Annual Leadership Conference of the National Wooden Pallet and Container Association. As major accomplishments occur, they are covered in the blog by co-PI Ray called GoWood. A manuscript for publication on the MW vs. RF comparison of heating uniformity and heating depth is in review for the European Journal of Wood Wood Science. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Approval of dielectric heating technology by the International Plant Protection Convention occurred in 2013 under Annex 1 of ISMP-15 and ISPM-28. This is the first new technology to be approved as an alternative to methyl bromide fumigation (and conventional heat treatment). The treatment schedule for dielectric heating under the new standard is based on our results, which requires that treated material research 60 degrees C through the profile of the wood for at least 1 minute. Initial commercial-scale RF heating trials for bulk treatment of WPM were performed to investigate volumetric heat development. This study was performed under an equipment lease agreement with Ben Aaron Lumber, Inc (Forestville, NY), which gave the team access to an industrial capacity (1200 bd ft volume) RF (4.6 MHz oven frequency, 150 kW heating power) vacuum kiln to study the heating behavior of hardwood sawlog cants commonly used as the primary raw material source for domestic and international shipping pallet construction. The initial trials included only mixed white oak material to investigate compliance with the Annex 1 for dielectric heating under ISPM-15. The schedule requires that the treatment be completed within 30 minutes. White oak was selected due it is high weight to volume (density), which represents a worse case scenario for hardwoods. The study was been expanded to further examine the heating behavior for mixed red oak and mixed ash cant materials. Results showed that RF effectively heats large bulk packs, but the ability to complete treatment of large bulk volumes within a 30-minute time limit will be problematic without substantially higher input power density to reduce the heating rate. The higher the power density needed (via the generator), the greater the cost of the RF equipment. This problem is being addressed in a new funding cycle started Oct. 1. In addition we have initiated studies to develop a database on the complex dielectric properties that describe relative permittivity and loss factors of mixed white oaks, red oaks and ash as hardwood cant material. These data combined with the commercial-scale experimental trials serve as a basis to explore the development of standard RF volumetric treatment schedules for other WPM. The first step of an economic analysis was initiated. The cost of energy input in the dielectric (RF) treatment process was calculated based on laboratory-observed treatment times and fundamental energy engineering equations. These trials and calculations provided the team with an energy-cost estimate of 25 cents per pallet for phytosanitary treatment using RF. Cost data were collected from actual heat-treating operations to establish a statistical sample from which a more general population of heat-treating costs could be developed through computer simulation. This simulation was performed and distributions were developed for individual cost components of electricity, chamber fuel, and maintenance. These were then added to result in a total cost curve for conventional heat treatment of wooden pallets in North America. A graphical chart was developed to aid in the comparison and evaluation of RF treatment chamber investment versus conventional heat treatment at variable electricity cost rates.
Publications
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Progress 09/01/12 to 08/31/13
Outputs
Target Audience: Target audiences include the International Plant Protection Convention and all participating National Plant Protection Organizations, the wood products industry, international shipping companies, USDA/APHIS, and the wood science community. Additional audiences include scientists concerned with preventing or mitigating the spread of exotic species around the world through shipping materials. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? A postdoctoral researcher and a Ph.D. student received training on this project. The postdoc was heavily involved in the modeling and heating uniformity experiments, while the Ph.D. student has been working on the economic analysis of RF compared with conventional heat treatment and methyl bromide fumigation. Also, the postdoc attended the 2012 International Forestry Quarantine Research Group meeting in Cardiff, Wales where he learned a great deal about the science and policy of phytosanitation of wood products. How have the results been disseminated to communities of interest? Outreach and extension efforts included presentations at the International Forestry Quarantine Research Group annual meeting in 2012 in Cardiff, Wales; the National Wooden Pallet and Container Recycler's and Leadership Annual Conferences in 2013; and the Forest Products Society Annual Meetings in 2012 and 2013. In addition, a booth was set up at the 3-day 2013 Leadership Conference of the National Wooden Pallet and Container Association to familiarize participants with advancement of the science of radio frequency. In response to the outreach effort at the 2013 National Wooden Pallet and Container Association Annual Leadership conference, 11 companies agreed to participate in economic analysis of the technology, and the results of this exercise will in large part determine industry efforts to adopt the new technology. What do you plan to do during the next reporting period to accomplish the goals? Work will continue on optimizing RF oven configurations to maximize heating uniformity. Using previously determined treatment times/temperatures, we will expand calculations on the preliminary scale-up work of 3x3 arrays to the RF heating of aspen, mixed maple, and red pine species. Using woods of different densities, specific gravity and moisture content, it is our goal to complete the temperature heating profile of different wood types during bulk treatment to inform the industry in the development and application of this technology to ensure adoption. We will also test our calculations of depth of penetration using different wood species and convey this information to the U.S., Canadian and European NPPOs to have the 20 cm size restriction eliminated for RF to ensure that the technology will be adopted commercially. In concert with adoption of RF and MW as a new treatment under ISPM-15, our team was consulted to assist with production of a guidelines document to assist equipment manufacturers and National Plant Protection Organizations around the world with information regarding how this technology works and what parameters need to be considered in designing and certifying DH equipment for phytosanitary treatment under IPSM-15. We will continue to participate in this effort. We will continue to work on the economic analysis to compare costs/benefits of RF with methyl bromide and conventional heat treatment for these applications. Several outreach programs for end users are planned for the next reporting period.
Impacts
What was accomplished under these goals?
Results from the projects funded by NIFA served as the basis for approval by Commission on Phytosanitary Measures of the IPPC of dielectric heating, both microwave (MW) and radio frequency (RF), as a new treatment under the International Standard of Phytosanitary Measures No. 15 (Annex 1 of ISPM-15). Thus, our primary goal was achieved. However, 20-cm restriction for wood sizes that can be treated using MW or RF was included in the Annex, which will significantly limit the commercial adoption of these treatments and heating uniformity has been of great concern. To address these issues, calculations of depth of penetration showed that this size restriction is appropriate for MW, especially 2.45 GHz, but not for RF. At RF frequencies between 10 MHz and 50 MHz (typical for RF), the depth of penetration is greater by meters, not just cm, with greater uniformity of heating. To improve heating uniformity throughout a consignment of treated material, the first step was to make primary modifications to the RF oven so that it could be used to treat a small stack of wood material rather than individual wood pieces, thus simulating a commercial treatment. We worked with PSC, Inc. engineers to fine-tune the RF oven to enhance its treating capabilities to a larger load of wood. During this development, several wood species were tested to ensure that they all could be treated in the future. An experimental design was developed for heating a stack of 4” x 4” (3.5 in nominal) oak wood in a 3x3 array in the RF oven replicated 10 times. These conditions were used as a baseline for comparison against treatments at optimized conditions. The optimized condition was determined by the computational modeling effort performed by PSC, Inc. A 3D model of the RF heating system and the sample of wood to be heated was developed.The physical system was modeled using 3D CAD software to define the physical boundaries of the system, and then transferred to 3DTLM, a modeling code that calculates the electric fields inside the system. The electric field data was then cut into slices in the x, y, and z planes, and the heating rates calculated based on the field intensities, dielectric loss factor and material properties. This gives a 3D sliced picture of the heating in the system. The results of the existing RF heating model were evaluated and potential solutions developed to further improve uniformity.An intermediate electrode was designed to improve uniformity and this new design was modeled showing a significant improvement in overall uniformity.Ten replicated experiments were performed in which temperature sensors were inserted into the center of each piece of wood and heating rates (degrees C/min) were determined. PSC manufactured this new intermediate electrode and modifications to the heating system to match the model.Additional tests were run with the modified RF heating system to verify the improved uniformity.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2012
Citation:
Uzunovic, A., A. Dale, B. Gething, R. Mack, J. Janowiak and K. Hoover. 2012. Lethal temperature for pinewood nematode, Bursaphelenchus xylophilus, in infested wood using radio frequency energy. J. Wood Science DOI 10.1007/s10086-012-1306-2.
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