http://hdl.handle.net/1957/16183 2013-05-23T02:40:29Z 2013-05-23T02:40:29Z Hackleman, David Smith, Connor J. Lebsack, Jonathan http://hdl.handle.net/1957/38713 2013-05-22T23:22:53Z 2012-07-27T00:00:00Z

Microwave Extraction of Essential Oil from Peppermint - Field Trial Hackleman, David; Smith, Connor J.; Lebsack, Jonathan An in-field test of the solvent free microwave extraction of peppermint oil was held in mid-August 2009 at Butler Valley Farms in Stayton, Oregon. Results of the trial were limited due to rapid coalescence of the mint oil prior to entry into the separator. This resulted in no mint oil actually received at the normal receiving site. A small quantity of mint oil was discovered during take-down and laboratory analysis indicates it to be pure. For the Solvent Free Microwave Extraction (SFME) system to work effectively in the large scale (farm operation) condition, it is believed that a significant change in the condensation apparatus will be necessary. Work demonstrating a solution to that issue will be presented. The 100KW 915MHz microwave unit (normally used for drying) performed well in the farm environment and after significant modifications, feed systems were developed to take chopped mint hay from existing mint tubs and move it into the extractor. The results of this field trial were adequate to enable design improvements for future development. This is an author's manuscript. This paper was presented at the 2nd Global Congress on Microwave Energy Applications (2GCMEA). July 23-27, 2012. Hilton Long Beach. Long Beach, CA. USA Session D6.6.

2012-07-27T00:00:00Z Campbell, Travis J. (Travis James) http://hdl.handle.net/1957/38702 2013-05-22T15:56:12Z 2013-05-14T00:00:00Z

Photochemical reduction of carbon dioxide in aqueous and ionic liquid solutions in a microreactor with TiO₂ catalyst; experiment and modeling Campbell, Travis J. (Travis James) Microtechnology was used to study the chemical reduction of dissolved carbon dioxide into useful products. A novel TiO₂ photocatalyst was used to activate the reaction under ultraviolet irradiation. CO₂ was dissolved in aqueous and 50% BMIM-BF₄ (ionic liquid) solutions. The introduction of an ionic liquid increased the solubility of CO₂ by 60%. Both solutions were pumped through a continuous photochemical microreactor and analyzed for products. The aqueous photochemical microreactor process produced 5x10⁻⁸-1x10⁻⁶ moles of methane per liter of solution processed. These values vary with mean residence time within the 0.016 mL microreactor volume. Serial reduction intermediates are likely present in solution below the detection limits of our analytical instruments. The 50% ionic liquid process produced 4x10⁻⁸-1x10⁻⁷ moles of methane per liter of solution processed. Similarly, no intermediates were measured. Mathematical models for the kinetic mechanism, momentum transfer, and mass transfer within the reactor were developed. These models were added to a numerical simulation and compared to experimental values. An optimization scheme was executed to extract meaningful reaction rate constants from the simulation that best fit the experimental data. Reaction rate constants reflect the feasibility of operating these processes and the numerical models can be used as design tools. Graduation date: 2013

2013-05-14T00:00:00Z Widrlechner, Mark P. Daly, Christopher Keller, Markus Kaplan, Kim http://hdl.handle.net/1957/38293 2013-04-23T00:10:45Z 2012-02-01T00:00:00Z

Horticultural Applications of a Newly Revised USDA Plant Hardiness Zone Map Widrlechner, Mark P.; Daly, Christopher; Keller, Markus; Kaplan, Kim The accurate prediction of winter injury caused by low-temperature events is a key component of the effective cultivation of woody and herbaceous perennial plants. A common method employed to visualize geographic patterns in the severity of low-temperature events is to map a climatological variable that closely correlates with plant survival. The U.S. Department of Agriculture Plant Hardiness Zone Map (PHZM) is constructed for that purpose. We present a short history of PHZM development, culminating in the recent production of a new, high-resolution version of the PHZM, and discuss how such maps relate to winterhardiness per se and to other climatic factors that affect hardiness. The new PHZM is based on extreme minimum-temperature data logged annually from 1976 to 2005 at 7983 weather stations in the United States, Puerto Rico, and adjacent regions in Canada and Mexico. The PHZM is accessible via an interactive website, which facilitates a wide range of horticultural applications. For example, we highlight how the PHZM can be used as a tool for site evaluation for vineyards in the Pacific northwestern United States and as a data layer in conjunction with moisture-balance data to predict the survival of Yugoslavian woody plants in South Dakota. In addition, the new map includes a zip code finder, and we describe how it may be used by governmental agencies for risk management and development of recommended plant lists, by horticultural firms to schedule plant shipments, and by other commercial interests that market products seasonally. This is a scanned version of a published article. The original can be found at: http://horttech.ashspublications.org/. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work.

2012-02-01T00:00:00Z Bistrika, Alexander A. http://hdl.handle.net/1957/37935 2013-04-01T22:07:58Z 2013-03-27T00:00:00Z

Degradation of graphite electrodes in acidic bromine electrolytes Bistrika, Alexander A. As the world's power needs grow, the demand for power from renewable resources, such as wind or solar is increasing. One major drawback associated with these renewable resources is that the power output is dependent on environmental factors, such as cloud cover and wind speeds. This allows the possibility of either power output exceeding or falling short of forecast levels that may lead to grid instabilities. Therefore, Large Scale Energy Storage (LSES) systems are critical to store excess power when the output exceeds demand in order to supplement output power when it falls short of demand.¹ The Zinc/Bromine Redox Flow Battery (RFB) is a promising technology because of previously reported long cycle-life (CL) capability, high efficiencies, low cost materials, and scalable operating conditions.² The excellent energy storage performance of the Zinc/Bromine system was confirmed by measuring both Faradaic and Coulombic electrochemical cell efficiency dependence on temperature of a bench scale Zinc/Bromine flow cell. At room temperature, near 75% Faradaic efficiency was measured when cycling the system between 20% and 100% State of Charge (SOC), which is in good agreement with published values,³ and was measured to be over 80% efficient when operating at an elevated temperature of 50°C. To elucidate capital and operational costs, key system operation parameters especially focused on degradation mechanisms were investigated. Since deep discharge cycling is perceived as highly damaging to electrochemical systems, a system was cycled between 0% and 5% (SOC) 10,000 times. Performance was quantified by measuring the frequency factor (i[subscript 0]) and relative activation energy (α) for the reactions using Tafel scans. No statistically significant degradation or change to the electrodes was observed during the zero point cycling experiment. However, it was found that under conventional operation damage to the electrodes does accumulate, presumably due to the highly oxidative environment caused by the presence of high concentrations of dissolved bromine or tri-bromide. While the performance of both electrodes shows decreases in frequency factor attributed to the damage process, the bromide oxidation process seems to be more damaging (i.e., at the positive electrode during the charging process). Long term measurements show a degradation of the electrocatalytic parameters at an applied overpotential of 100 mV from ca. 40 mA/cm² to ca. 5 mA/cm² at the positive electrode and from ca. 20 mA/cm² to ca. 10 mA/cm² for the negative electrode. A degradation rate model was proposed to predict the service life expectancy of graphite electrodes in a bromine system based on processes showing a combined second order reaction rate coupled with a negative first order reaction rate. The model can be used to predict the cost of energy when operating any device using graphite electrodes, based on the operating power ratio, defined here as the quotient between operating power and system rated power. This damage could be partially reversed by exposing the electrode surfaces to concentrated potassium hydroxide dissolved in isopropanol, presumably due to exfoliation of the electrocatalytic surface leading to the exposure of a clean surface with electrocatalytic performance close to the original. Further, a chemical pretreatment for the graphite surface imparting enhanced stability in aqueous bromine systems was developed that shows negligible damage when similar amounts of current have passed through the electrode surface. After bromide oxidation equivalent to passing ca. 10 Ah/cm² the treated surface showed a change in steady state current density at an applied overpotential of 100 mV from ca. 50 mA/cm² to ca. 48 mA/cm². Graduation date: 2013; Access restricted to the OSU Community at author's request from April 1, 2013 - April 1, 2015

2013-03-27T00:00:00Z