Peter M. Martin

Microchannel devices for efficient contacting of liquids in solvent extraction

ABSTRACT Microchannel devices were designed and tested for efficient contacting of two liquids in solvent extraction, and the results are presented. This study is part of an overall effort to produce and demonstrate efficient compact devices for chemical separations. Engineering these devices at the microscale offers many technical advantages. Achieving high contact area per unit system volume, thin-film contacting, and establishing uniform flow distribution result in substantially higher throughput per total system volume over conventional technologies. Theoretical calculations are presented that provide insight into the relative importance of various resistances to mass transfer, as well as their relationship to overall performance of the microchannel devices. Experimental results are presented for device performance using both commercial polymeric membranes and micromachined contactor plates for stabilizing the liquid-liquid interface. These results indicate that current-generation micromachined plates...

Microchannel heat exchangers for advanced climate control

This paper presents details of fabrication and performance testing of prototype microchannel heat exchangers. The microchannel heat exchangers are being developed for advanced cooling and climate control applications, and are designed for heat loads of 100 W/cm2. Bulk and surface micromachining techniques are used to fabricate the test devices. Each heat exchanger section consists of over 150 microchannels etched in silicon substrates by either chemical etching or ion milling processes. The channels are 100-micrometers deep, 100-micrometers wide, and spaced 50- to 100-micrometers apart and connected with headers. Other heat exchangers have also been fabricated in copper and aluminum using machining and ion milling processes. Process steps involved photolithographic patterning, deposition of etch masks, ion or chemical etching, electrostatic bonding of the silicon to glass, insulator deposition, lamination of silicon to metals, application of thin heater coatings with busbars, and installation of the inlet/outlet hardware and valves. Recent hear exchangers have the silicon laminated to copper substrates. Performance testing focuses on determining the performance characteristics of the microchannel heat exchangers over a wide range of flow and heat transfer conditions. The working fluid for heat transfer is restricted to water or SUVA refrigerant HCFC-124 (R-124). Testing with water is run under single-phase conditions. The tests with R-124 are run under single-and two-phase flow conditions.

Vacuum-deposited polymer/silver reflector material

Weatherable, low cost, front surface, solar reflectors on flexible substrates would be highly desirable for lamination to solar concentrator panels. The method to be described in this paper may permit such reflector material to be fabricated for less the 50

Photolytically driven generation of dissolved oxygen and increased oxyhemoglobin in whole blood.

CNT per square foot. Vacuum deposited Polymer/Silver/Polymer reflectors and Fabry-Perot interference filters were fabricated in a vacuum web coating operation on polyester substrates. Reflectivities were measured in the wavelength range from .4 micrometers to .8 micrometers . It is hoped that a low cost substrate can be used with the substrate laminated to the concentrator and the weatherable acrylic polymer coating facing the sun. This technique should be capable of deposition line speeds approaching 1500 linear feet/minute2. Central to this technique is a new vacuum deposition process for the high rate deposition of polymer films. This polymer process involves the flash evaporation of an acrylic monomer onto a moving substrate. The monomer is subsequently cured by an electron beam or ultraviolet light. This high speed polymer film deposition process has been named the PML process- for Polymer Multi- Layer.

Properties of reactively deposited SiC and GeC alloys

The severely debilitating nature of chronic lung disease has long provided the impetus for the development of technologies to supplement the respiratory capacity of the human lung. Although conventional artificial lung technologies function by delivering pressurized oxygen to the blood through a system of hollow fibers or tubes, our approach uses photolytic energy to generate dissolved oxygen (DO) from the water already present in blood, thus eliminating the need for gas delivery. We have previously demonstrated that it is feasible to generate dissolved oxygen from water based on UVA illumination of a highly absorbent TiO2 thin film. In the current study, we extend this work by using photolytic energy to generate DO from whole blood, thus resulting in an increase of oxyhemoglobin as a function of back side TiO2 surface film illumination. Initial experiments, performed with Lockes Ringer solution, demonstrated effective film thickness and material selection for the conductive layer. The application of a small bias voltage was used to conduct photogenerated electrons from the aqueous phase to minimize electron recombination with the DO. Mixed arterial-venous bovine blood was flowed in a recirculating loop over TiO2 nanocrystalline films illuminated on the side opposite the blood (or “back side”) to eliminate the possibility of any direct exposure of blood to light. After light exposure of the TiO2 film, the fraction of oxyhemoglobin in the blood rapidly increased to near saturation and remained stable throughout the trial period. Last, we evaluated potential biofouling of the DO generating surface by scanning electron microscopy, after photolytically energized DO generation in whole blood, and observed no white or red blood cell surface deposition, nor the accumulation of any other material at this magnification. We conclude that it is feasible to photolytically oxygenate the hemoglobin contained in whole blood with oxygen derived from the bloods own water content without involving a gaseous phase

Photocatalytic generation of dissolved oxygen and oxyhemoglobin in whole blood based on the indirect interaction of ultraviolet light with a semiconducting titanium dioxide thin film

Thin-film silicon carbide (SiCi) and germanium carbon (Ge,Ci) alloy coatings with low Üifrared optical absorption have been fabricated by DC- and RF-reactive magnetron sputtering. The optical and mechanical properties of the coatings depend on composition determined by deposition conditions. The refractive index and optical absorption coefficient of SiCi. alloys were varied from those of amorphous Si to those near diamond-like carbon (DLC) by increasing C content. The band edge shifted below 1.2 eV with C content as high as 0.8. The useful range of the SiCi coatings was extended to wavelengths as low as 1 jim. The useful transparency range of GeCi coatings is from 3 to 12 jim. The refractive index of GeCi coatings was varied from 4.2 of amorphous Ge to near 3.4 by increasing x from 0 to 0.5. The optical absorption coefficient was a complex function of composition and C-H, Ge-H, and Ge-C bonding. Mechanical stress in both materials was generally moderate, and increased with increasing C content for the GeC alloys and decreased with increasing C for the SiC alloys. The wide range of optical properties obtainable for both coating types makes them useful in many types of multilayer designs. Abrasion-resistant infrared (IR) multispectral antireflection coatings on zinc sulfide (ZnS) were demonstrated using Geij•9C and DLC layers.

Use of Photolytic Technology to Maintain Breathing Gases in Confined Spaces While Regenerating Fuel Hydrocarbons Recycled From CO 2 and H 2 O Byproducts

Most current artificial lung technologies require the delivery of oxygen to the blood via permeable hollow fibers, depending on membrane diffusivity and differential partial pressure to drive gas exchange. We have identified an alternative approach in which dissolved oxygen (DO) is generated directly from the water content of blood through the indirect interaction of ultraviolet (UV) light with a semiconducting titanium dioxide thin film. This reaction is promoted by photon absorption and displacement of electrons from the photoactive film and yields a cascading displacement of electron “holes” to the aqueous interface resulting in the oxidation of water molecules to form DO. Anatase TiO2 (photocatalyst) and indium tin oxide (ITO) (electrically conductive and light transparent) coatings were deposited onto quartz flow-cell plates by direct current reactive magnetron sputtering. The crystal structure of the films was evaluated by grazing incidence x-ray diffraction, which confirmed that the primary crystal...

Coatings for large-area low-cost solar concentrators and reflectors

Photolytically-Driven Electrochemistry (PDEC) is a bio-inspired technology that uses energy from light to mimic photosynthesis (PS-II). Green plants use light energy to oxidize water to oxygen and hydrogen ions. Concurrently, carbon dioxide is reduced to form carbohydrates. Electrons for this reduction come from the water. Similarly, through a UV light-activated thin-film metal-oxide photocatalyst, PDEC converts water to oxygen, electrons and hydrogen ions. This technology is based fundamentally on the convergence of several synergistic physical systems: (1) photolytic energy providing electron-hole charge separation, (2) electrical energy to drive cathodic (reduction) reactions, and (3) photolytically driven anodic (oxidation) chemical reactions. Potential applications of this technology are diverse and include generation of oxygen and sequestration of carbon dioxide through formation of reduced carbon products, including products suitable for fuels. Nomenclature

Microchannel laminated mass exchanger and method of making

Large-optics coating facilities and processes at Pacific Northwest Laboratory (PNL) that were used to develop large-area high-performance laser mirrors for SDIO are now being used to fabricate a variety of optical components for commercial clients, and for novel applications for other DoD clients. Emphasis of this work is on technology transfer of low-cost coating processes and equipment to private clients. Much of the technology transfer is being accomplished through the CRADA (Cooperative Research and Development Agreement) process funded by the Department of Energy (DOE).