UMPQUA Research Company: Microwave Power Technologies
Workers in our laboratory have developed a variety of devices that exploit the unique benefits of microwave heating. Several of these are illustrated on this page. A microwave powered Single-Phase Space Laundry (SPSL) prototype, developed for NASA's Johnson Space Center (JSC), is shown below. This device is energized with 2.45 GHz microwave power via a magnetron which is located in the rectangular arm at the top, and attached to the top of the cylindrical washing/drying multi-mode cavity. Using water pumps, a pressure tank, water jets, a vacuum pump, an air blower, various control valves, and microwave power, all sequenced with a micro-controller in a systematic process, it was demonstrated that clothes can be washed and dried in a microgravity environment.
The Microwave Sterilizable Access Port (MSAP), also developed under funding from NASA-JSC, is shown below. The MSAP utilizes a custom built microwave generator to supply 2.45 GHz power to the sterile access port assembly via a flexible coaxial cable. The device is used for the aseptic transfer of materials between the environment and a bioreactor, or similarly microbially vulnerable system. Microwave induced superheated steam is used to effect a rapid thermal sterilization of all mating fixtures.
A photograph of the Microwave Regenerable Air Purification Technology Demonstrator developed under contract to NASA's Ames Research Center (ARC) is presented below. This technology represents an advanced microwave based thermally regenerable device employed to remove airborne contaminants using a variety of sorbents, including activated carbon and molecular sieves (zeolites). When the sorbents are fully loaded with contaminants such as CO2, water, and trace organics, the sorption capacity of the media is renewed by microwave powered thermal desorption. Potential applications of this technique include Atmospheric Revitalization, EVA, industrial solvent recovery, and ground-based environmental remediation.
The test stand used to demonstrate the Magnetically Controlled Microwave Powered Fluidized Bed Reactor concept, investigated under a grant from the National Science Foundation, is shown below. This work was conducted jointly with researchers within the Chemical Engineering Department at Oregon State University. Both rectangular and cylindrical waveguides are used in a novel configuration to effect microwave induced heating of microwave susceptible fluidization media housed within a vertical section of cylindrical waveguide. A series of electromagnets surrounding the fluidization column is used to achieve magnetic stabilization of the fluidization process. This allows much higher rates of mass transfer than would otherwise be possible. Hence, this device incorporates novel means for both improved heat transfer and mass transfer within the fluidized bed reactor.
A photo of the Microwave Powered Solid Waste Stabilization and Water Recovery test unit used in a recent Phase I effort for NASA-ARC is presented below. This apparatus employs a conventional magnetron and multimode cavity coupled with a condenser and sorbent bed for water recovery. Rapid efficient heating of the water present in waste material was demonstrated using this device, resulting in greater than 90 % water removal. In addition, it was shown that significant microbial reduction on both plastic surfaces in close proximity to the solids and within the bulk material occurs within the first few minutes of microwave heating. After microwave drying, not only is the product material left in a dry state, which promotes long term stability, but significant microbial reduction is also achieved, helping to assure a low microbial presence prior to storage. A Phase II SBIR effort is presently underway which will culminate in the delivery of a prototype device to NASA-ARC.
Following is a photograph of a Phase I proof of concept unit for the demonstration of Microwave Enhanced Freeze Drying (MEFD) of Solid Waste technology, also conducted on behalf of the Solid Waste Management group at NASA-ARC. Using microwave power in a closed microwave cavity, water-ice present in the frozen Solid Waste is selectively and rapidly heated. The prototype system recovers relatively pure water from that initially contained within solid waste and leaves a dry product that is stable with respect to microbial growth. Water activity levels below 0.65 (which prohibit microbial growth) have been demonstrated in the product at various microwave power levels and processing times. Compared to conventional freeze drying, which depends on conductive heat transfer through the drying product, the MEFD technology accelerates the drying rate via dielectric heating. Processing times which are 75% of those required for conventional freeze-drying have been demonstrated.
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Last Updated December 15, 2004