Progress 09/01/20 to 08/31/23
Outputs
Target Audience:The target audience includes 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 invasive species around the world through shipping materials. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Our project has provided the postdoc (Dr. Karolina Szymona) opportunity to learn about the pallet industry: its needs, challenges, and business models. She was mentored by other project participants learning about dielectric heating wood treatment and ISPM-15 regulation. Working closely with Kiln Tech Limited and its CEO and founder, Mark Hamelin, she acquired specific skills related to preparing and operating an RF unit for dielectric heating of wood in compliance with ISPM-15. She also gave a presentation about our research at the International Forest Quarantine Research Group virtual annual meeting in late September 2021 and in 2022. How have the results been disseminated to communities of interest?We presented our results during the virtual International Forest Quarantine Research Group (IFQRG-18) meetings in 2021, 2022, and 2023 which was attended by scientists, national regulators, and industry representatives from around the world. The following presentations were introduced to the audience: Gagnon M., Szymona K., Hoover K., Mack R. & Hamelin M., Janowiak J., (September 30, 2021),Progress update: Radio frequency heating of wood to meet ISPM-15 requirements. Moreover, we presented our results during the Processing Technologies for the Biobased Products Industries conference by Forest Products Society, held on November 1-3, 2021, on St. Simons Island. The following presentation was provided to an audience of primary forest products manufacturers, academics, and industry trade representatives. Gagnon, M.A., Szymona, K., Hoover, K., Mack, R., Hamlin, M. and Janowiak, J. 2021. Pressurized radio frequency heating of wood to meet ISPM-15 requirements. Processing Based Technologies for the Forest and Biobased Industries Conference. Forest Products Society. St. Simons Island, GA. Hoover et al. 2023. Approach to Validate ISPM-15 Compliance for Commercial Equipment Certification of Dielectric Standard Heating of Solid Wood Packing Materials using Radio Frequency. IFQRG Virtual Meeting, Nov. 21, 2023. Our project's website includes technical brief encouraging pallet manufacturers and treaters to contact us with any questions about the technology. In the past, we initiated and now have ongoing contact with several pallet manufacturers, including our long-term industry partner Penn Pallet in St. Marys, PA, that are the source of industry perspective on the wood packaging sanitation process. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Our experiments to accomplish our goals always involved bulk treatment of raw wood cut into pallet components (stringers and decking boards) that can be used to construct crates and pallets or shipping dunnage. We completed multiple commercial-scale experiments, in the first two years of the study using a RF with pressurization with a fully integrated pressure/vacuum and RF system built by a Canadian company (RF Kiln Technology). In 2022-23 we used the same RF kiln after upgrading to a solid state power supply and a 3-plate winged electrode; using the upgraded unit, we did not need to add pressurization. The ~3.0 cubic meter prototype (6.86 MHz, 50-kW heating output capacity) can bulk treat up to 1200 bd ft. at one time, representing a real-world commercial operation. Each treating cycle represents the rough equivalent of ISPM-15 sanitized raw material sufficient to build 82 standard pallets widely used for international shipping. We systematically tested different approaches to the RF heating process, including wood modification using salt water, to enhance dielectric properties and responsiveness to the RF treatment. We developed and performed tests to collect data on pre-soaking of wood material in ocean salt and NaCl water solutions to improve the interaction of the RF electromagnetic field with wood components. By increasing the salt concentration of the soak solution, this effectively reduced electrical impedances within the material and increased the RF heating rate to reduce treatment duration. This approach would be especially useful for treating dunnage, which are large pieces of wood used to brace containers in the hold of ships. After converting our RF unit to a solid-state power supply, we characterized the dielectric heating pattern and options for monitoring wood temperatures over a wide-ranging test matrix on wood packaging material that varied by wood species (single and mixed species of oak, yellow poplar and pine), dimension, moisture content, and loading configuration. During our experiments we also tested several temperature monitoring systems (infrared imaging, fiber optic probes, and pop-out devices described below). We collected data on temperature increase in real time, treatment time, and power consumption. The main objective was to provide insight into our efforts to optimize RF heat treatment technology for North American certification, and the methods that we used to verify compliance with ISPM-15. Our preliminary experiments on yellow poplar using the older 5-plate design took an average of 104 min to complete, while with the 3-plate winged electrode, we obtained shorter heating times for poplar of 79 ± 11 (SEM) min. Similarly, we noted significant improvement for pine wood; the older unit took 163 min to complete the treatment while using the new design system required 90 ± 9 min, which is 45% faster. IR images taken after the material was unloaded showed that the load heated more uniformly, which confirmed the advantages of using the 3-plate, winged-electrode. In addition to two fiber optic probes in the wood for monitoring temperature in wood in real time, we also tested disposable pop out devises (PODs) as a potential treatment verification for industrial application using a conventional oven. All the PODs that were supposed to trigger at 62.8 °C performed above the designed temperature threshold, with the lowest temperature noted of 63.4 °C. Thus, triggering temperatures tend to be higher than as designed, which provides an additional margin of confidence in using PODs for wood material. In general, when we used deployment of PODs during RF exposure as indicators of treatment termination, we obtained consistent and predictable heating patterns in the wood. This is an inexpensive, viable option for monitoring temperatures. The average treatment time varied from 63 ± 2 min for red oak stringers to 147 ± 9 min for eastern white pine dunnage, with an overall average of 86 ± 6 min for all stringer trials. The average final temperature registered by fiber optics sensors was 86.2 ± 1.24?C with an average heating rate of 0.75 ± 0.04 ?C/min and an average moisture loss of 4.4 ± 0.56%, and low coefficients of variation (1.9%-8.2 %), indicating low variability in final temperatures. RF is competitive with conventional heating with respect to price/pallet, and in fact has additional economic advantages in terms of overall heating efficiency. RF heating of dielectric materials such as wood, which has poor electrical and thermal conduction properties, heats wood directly wit
Publications
- Type:
Journal Articles
Status:
Under Review
Year Published:
2023
Citation:
Karolina K. Szymona, John J. Janowiak, Ron Mack, Mark Hamelin, Mark Gagnon, and Kelli Hoover. Approach to Validate ISPM-15 Compliance for Commercial Equipment Certification of Dielectric Standard Heating of Bulk Solid Wood Packing Materials using Radio Frequency. Forest Products Journal.
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Progress 09/01/21 to 08/31/22
Outputs
Target Audience:The target audience includes the International Plant Protection Convention technical panel on phytosanitary treatments and its Implementation Committee, and all participating National Plant Protection Organizations, the wood products industry, international shipping companies, USDA/APHIS, ports of entry, and the wood science community. Additional audiences include scientists and the public concerned with preventing or mitigating the spread of invasive species worldwide through shipping materials. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Our project has provided the postdoc (Dr. Karolina Szymona) opportunity to learn about the pallet industry: its needs, challenges, and business models. She was mentored by other project participants learning about dielectric heat wood treatment and ISPM-15 regulation. Working closely with Kiln Tech Limited and its CEO and founder, Mark Hamelin, she acquired specific skills related to preparing and operating RF units for dielectric heating of wood in compliance with ISPM-15 and gave 2 presentations about our research at the International Forest Quarantine Research Group meetings in 2021 and 2022. She assisted with designing and performing RF phytosanitary treatment experiments, collecting data during experiments, and preparing data analysis after each experiment. How have the results been disseminated to communities of interest?Our research results were presented during the virtual International Forest Quarantine Research Group (IFQRG-18) meeting, attended by scientists and industry representatives from around the world, in the form of PowerPoint presentations. The following talks were presented: Heffernan B., Mack R., Szymona K., Janowiak J., Hoover K., Innovative Temperature Monitoring Used in Alternative Heat Treatment Technologies for Logs and WPM, International Forestry Quarantine Research Group virtual meeting (IFQRG-18), September 30, 2021. Gagnon M., Szymona K., Hoover K., Mack R., Hamelin M., Janowiak J., Progress update: Economics of radio frequency heating of wood to meet ISPM-15 requirements, International Forestry Quarantine Research Group virtual meeting (IFQRG-18), October 7, 2021. Szymona, K., J.J. Janowiak, R. Mack, M. Gagnon, M. Hamelin, and K. Hoover. 2022. Radio Frequency (RF) Phytosanitation of Wood Packaging Material (WPM); Update on Development of Certification Protocols and Advancements for RF Technology. International Forestry Quarantine Research Group virtual meeting (IFQRG-19), September 16, 2022. Another presentation was given during the National Wooden Pallets and Container Association Leadership Conference in Carlsbad, CA, in March 2022: Gagnon M., Szymona K., Hoover K., Janowiak J., Mack R., Hamelin M., Pressurized Radio Frequency Heating of Wood: Review of Current Work, National Wooden Pallets and Container Association Leadership Conference, Carlsbad, CA, USA, March 8-11, 2022. What do you plan to do during the next reporting period to accomplish the goals?We will continue to perform replicated runs of wood packaging material on spruce/pine/fir to complete the trials needed to certify our RF unit as in compliance with ISPM-15 for Canada and the US. Now that we have optimized the RF system with solid state power supply to obtain markedly improve heating uniformity and reductions in time, energy and labor costs, our final objective is to optimize temperature monitoring to ensure compliance with 60 degrees C through the workload for 1 min. Our most recent trials with oak (worst case scenario), yellow poplar and ash revealed that we may be able to model air temperature in relation to wood surface temperature to deliver an easy, more affordable method for monitoring temperature during treatments. We intend to accomplish this task in the next few months. We also have scheduled meetings with port authorities on the East coast to discuss the use of this technology for untreated dunnage that arrives at ports. We now have the data we need to finalize economic analyses for our industry partners and for publication/outreach to market this technology. We will provide details to the IPPC Implementation Committee as they work to finalize the manual on how to use DH for radio frequency as stipulated in ISPM-15.
Impacts
What was accomplished under these goals?
Penn State University's research team is developing a radio frequency (RF) sanitizing method for wood packaging material (WPM). We upgraded the RF unit with solid-state amplifiers (50-ohm rectified field generation) to maximize heating uniformity and minimize treatment duration for pallet components and provide more constant power operation and winged edge electrode applicators. We performed a set of initial experiments using red oak and yellow poplar cut into stringers to tune the RF unit power settings and better understand the practical use and limitations of the current equipment configuration and the optimal way of preparing the workload. We are in the final stages of development, focusing on optimizing the process to provide reliable and cost-effective methods of monitoring the temperature of the workload to verify that it reaches 60 °C for 1 min per the ISPM-15 treatment standard. We invited representatives from the Canadian Lumber Standards Accreditation Bureau (CLSAB) and American Lumber Standards Committee (ALSC) to witness the experiments performed on green oak and yellow poplar dunnage. They assisted and provided feedback as we progressed on developing protocols to certify RF treatment units in compliance with ISPM-15. We observed reduced treatment times and increased heating uniformity compared to the previously used RF system. Pop-out disposable temperature indicators in the center of every piece of wood in the chamber provided evidence of sufficient heating throughout the workload. The next step is to provide data replicating our results from the initial experiments and present it to CLSAB and ALSC to proceed with the ISPM-15 certification of the RF unit.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Janowiak, J.J., K.K. Szymona, M.K. Dubey, R. Mack, and K. Hoover. 2022. Forest Products Journal 72(2): 1-7.
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Progress 09/01/20 to 08/31/21
Outputs
Target Audience:The target audience includes 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 invasive species around the world through shipping materials. Changes/Problems:The Covid-19 pandemic had marked impacts on our productivity. Penn State University was shut down from mid-March 2020 to mid-summer 2020. It was very difficult to obtain wood materials once campus reopened on a limited basis; we were limited to 2 people at a time in the shop where the RF unit is located, making experiments difficult and taking longer to complete. USDA personnel were required to work remotely for most of 2020 and ports were operating with reduced staff, so it wasn't possible for us to carry out the port visits we had intended in 2020 to set up a study on RF treatment of dunnage. Now we are being asked to wait again for port visits because they are so far behind schedule in unloading containers. Moreover, most of our experiments require using the upgraded RFP unit with a solid state power supply that was constructed and needs to be installed by our collaborator in Ontario, Canada. The US border with Canada was closed to all but essential business from March of 2020 until just a few weeks ago. The US CBP and Canadian Border Patrol did not consider this project essential. However, now with the border open the upgrades to our RF unit will be completed this week so we can get back on track. Visits to wood packaging facilities started up again last month and we hope to visit a selected ports to discuss treatments for dunnage by early January. What opportunities for training and professional development has the project provided?Our project has provided the postdoc (Dr. Karolina Szymona) opportunity to learn about the pallet industry: its needs, challenges, and business models. She was mentored by other project participants learning about dielectric heating wood treatment and ISPM-15 regulation. Working closely with Kiln Tech Limited and its CEO and founder, Mark Hamelin, she acquired specific skills related to preparing and operating RF unit for dielectric heating of wood in compliance with ISPM-15 gave a presentation about our research at the International Forest Quarantine Research Group meeting. She also participated heavily in writing the grant that this project is funded by. How have the results been disseminated to communities of interest?Some of our research results were presented during the virtual International Forest Quarantine Research Group (IFQRG-18) meeting in late Sept. 2020, which was attended by scientists and industry representatives from around the world, in the form of PowerPoint presentations. The following presentations were given: Gagnon M., Szymona K., Hoover K., Mack R. & Hamelin M., Janowiak J., (September 30, 2021),Progress update: Radio frequency heating of wood to meet ISPM-15 requirements. Hoover, K. (Sept. 30, 2021), Impacts of spotted lanternfly on the wood products industry. Our project's website was further updated with more information about RFP technology for wood treaters. We continue to stay engaged with our long-term industry partner Penn Pallet in St. Marys, PA. Our research group, collaborating with Dr. Brad Gething, the Director of Science & Technology Integration at National Wooden Pallet & Container Association (NWPCA), is still participating in developing the Guidance Document on RF DH heating for the Implementation Committee of the International Plant Protection Convention. This will result in an appendix with operational guidance for dielectric heating of wood packaging materials under Annex 1 of ISPM-15. The document is under development and is expected to be finalized in 2022. What do you plan to do during the next reporting period to accomplish the goals?Following installation of the new solid state power supply and winged electrodes, we will first conduct RFP experiments on pre-cut wood packaging materials with representatives of the US and Canadian certification entities to obtain certification of our commercial scale RFP unit for compliance with ISPM-15. Then we intend to work on Objectives 1-4 as outlined in our proposal. We will also repeat the experiments using salt solutions with the upgraded RF unit. We are working on a manuscript for publication as well from our insulation of the RF unit trials. We expect to achieve heating uniformity equal to or better than was obtained with the existing five electrode plate design. Reducing the number of plates from five to three has multiple benefits. Having only three plates is expected to eliminate heating variations between inner and outer zones, as was experienced in the five-plate design. The associated reduction in kiln input current of the three-plate system will allow more power into a wider range of wood species and moisture content conditions before the limits of the matching network components are reached. The treatment chamber with material loads will be easier and quicker to fill since the load is only divided into two equal stacks.
Impacts
What was accomplished under these goals?
Our experiments to accomplish our goals involved bulk treatment of raw wood that can be used to construct crates and pallets or used as shipping dunnage. We completed multiple commercial-scale experiments, using a radio frequency with pressurization unit (RFP) with a fully integrated pressure/vacuum and RF system built by a Canadian company (RF Kiln Technology). The ~3.0 cubic meter prototype (6.86 MHz, 50-kW heating output capacity) can bulk treat up to 1200 bd ft. at one time, representing a real-world commercial operation. Each treating cycle represents the rough equivalent of ISPM-15 sanitized raw material sufficient to build 82 standard pallets widely used for international shipping of commerce goods. We investigated the heating behavior of mixed wood species components, which is common in the pallet industry. We systematically tested different approaches to the process, including wood modification, to enhance its dielectric properties and responsiveness to the radio frequency treatment. We started a set of experiments that included data collection on direct treating and post-treating heating behavior to establish the influence of ionic modification of wood on the dielectric treatment process. PSU and USDA researchers developed and performed tests to collect data on pre-soaking of wood material in ocean salt and NaCl water solutions to improve the interaction of the RF electromagnetic field with wood components. By increasing the salt concentration of the soak solution, this effectively reduced electrical impedances within the material and increased the RF heating response to reduce treatment duration. The first experiments focused on the effects of dissolved mixed metal ion (sea) salt concentrations on treatment time reduction. The results showed this approach did enhance the heating rates of the wood materials. Later experiments focused on less costly sodium chloride (NaCl) presoak treatments. Hydration properties (lower water hydration constant for Na+) suggested this lower cost salt could have better ion mobility to penetrate the wood material with shorter soak schedules. Additional experimentation included the use of a weak organic 2-hydroxypropane-1,2,3 tricarboxylic acid (citric acid) addition to adjust soak solution pH to improve sodium metal cation mobility for time-dependent heat absorption of the wood material. Use of an organic acid as opposed to a stronger mineral acid was hypothesized to avoid further oxidative corrosion to any shipping container constructions involving installed metal fasteners. We examined RFP heating responses using increased dissolved salt concentrations under several different soak durations with and without pH adjustments (control = untreated tap water with slightly alkaline 7.6 pH). We subjected two wood species to pH modification by submerging them in water with added citric acid, bringing the pH level of the solution to ~4.0. The highest salinity soak test included 150 g/gal of sodium chloride with heavy dimension (4"x6") wood cants soaked for 1 to 4 h. We collected samples of the wood for salinity (content and concentration values) and then performed electrical conductivity measurements on these wood samples during RFP treatment. We observed a slight improvement in the salinity and conductivity for oak material soaked in lowered pH solution and a more significant difference in the case of oak material soaked in the solution with the addition of citric acid and sodium chloride. Compared with control samples, the results were more pronounced for maple cants, for citric acid with sodium chloride soak. For the test series, where we tested the time of soaking for oak, the experiments revealed good improvement for 1h soak, then adverse effect for 2h, with the best results for 4h soak. We observed higher temperatures and more rapid heating for the material soaked in solutions than the control samples; heating rates significantly improved, by 72% for 2h soaked oak and by 48% for 4h soaked oak material. Salt testing with wood may have direct implications for improving RF treatment of wood dunnage at port facilities. RF unit power upgrade: A three-plate configuration (one driven plate, two ground plates) was proposed by our collaborator RF Kiln Technology in Ontario, Canada to reduce stress on the vacuum feedthrough on our RF equipment and remove the requirement for high-power RF switches on the feed lines. This upgrade was included in our current project objectives for the RF unit that would be used for our objectives. With the current 5 plate RF system applicator configuration, stress on the feedthrough is relatively large and diminishes the service life of the of the RF field generator. Further upgrading to solid-state amplifiers (50-ohm rectified field generation) should provide more constant power for the frequency 6.78 MHz operation. In contrast, the legacy vacuum tube free-running oscillator power RF unit we have been using typically operates at a less consistent frequency. In addition to the solid state amplifiers, our research RFP unit will operate a three-plate configuration with double winged design, and an active middle electrode applicator; this upgraded RF unit will be fully operational in late-November 2021 now that the border with Canada is open to perform tests of RF heating for wood pallets components. The cooling across the inductor coil and vac capacitors were also increased due to the increased power outcome.Winged edge applicators can serve to reduce electromagnetic energy variations and provide better power delivery to avoid excess heating differences within the treated volume of wood material. Thus, we will now be using higher amperage and lower voltage to achieve the same outcome, and it is the amperage affecting the cables that needed to be updated.
Publications
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