Louisiana State University and Agricultural & Mechanical College

University of Kentucky Research Foundation

Agricultural and Mechanical College

International Mezzo Technologies, Inc.

Kevin W Kelly

Chad R Harris

Mircea S Despa

Lyndon S Stephens

Philip J Coane

Jost S G&ouml;ttert

Lyndon Scott Stephens

David Craig

This invention relates to a light weight microtube heat exchanger that meets all the performance requirements of more conventional plate-fin heat exchangers (thermal performance, shock and vibration, and weight, etc.) while providing significant improvements with respect to air-side fouling due to sand and dirt or weight reduction.

Microtube heat exchanger

A seal assembly for a machinery housing includes a seal ring having a micro heat exchanger and a gland plate for securing the seal ring to the machinery housing. The gland plate includes a cooling fluid port in communication with the micro heat exchanger.

Seal assembly for machinery housing

An extremely high efficiency, cross flow, fluid-fluid, micro heat exchanger and novel method of fabrication using electrode-less deposition is disclosed. To concurrently achieve the goals of high mass flow rate, low pressure drop, and high heat transfer rates, the heat exchanger comprises numerous parallel, but relatively short microchannels. Typical channel heights are from a few hundred micrometers to about 2000 micrometers, and typical channel widths are from around 50 micrometers to a few hundred micrometers. The micro heat exchangers offer substantial advantages over conventional, larger heat exchangers in performance, weight, size, and cost. The heat exchangers are especially useful for enhancing gas-side heat exchange. The use of microchannels in a cross-flow micro-heat exchanger decreases the thermal diffusion lengths substantially, allowing substantially greater heat transfer per unit volume or per unit mass than has been achieved with prior heat exchangers.

Crossflow micro heat exchanger

A method is disclosed for producing x-ray masks on graphite substrates inexpensively and rapidly. The method eliminates the need for an intermediate x-ray mask, instead using a less expensive intermediate UV lithography step. The absorber structures are electroplated directly onto the graphite. The capability to economically produce x-ray masks is expected to greatly enhance the commercial appeal of x-ray lithography in processes such as LIGA. The x-ray mask produced by this process comprises a graphite substrate that supports an absorber such as gold-on-nickel. The thickness of the absorber structures can be varied as needed to supply sufficient contrast for the particular application. A layer of a deep UV resist such as SU-8 is spin-coated directly onto a graphite substrate. The resist is then patterned with an UV mask using a UV radiation source. After developing the exposed resist, gold-on-nickel or other absorber structures are electroplated directly into the resist-covered graphite, and the resist is then removed.

Graphite mask for x-ray or deep x-ray lithography

An extremely high efficiency, crossflow, fluid-fluid, micro heat exchanger is disclosed. To concurrently achieve the goals of high mass flow rate, low pressure drop, and high heat transfer rates, the heat exchanger comprises numerous parallel, but relatively short microchannels. The performance of these heat exchangers is superior to the performance of previously available heat exchangers. Typical channel heights are from a few hundred micrometers to about 2000 micrometers, and typical channel widths are from around 50 micrometers to a few hundred micrometers. The micro heat exchangers offer substantial advantages over conventional, larger heat exchangers in performance, weight, size, and cost. The heat exchangers are especially useful for enhancing gas-side heat exchange. Some of the many possible applications include aircraft heat exchange, air conditioning, portable cooling systems, and micro combustion chambers for fuel cells. The use of microchannels in a cross-flow micro-heat exchanger decreases the thermal diffusion lengths substantially, allowing substantially greater heat transfer per unit volume or per unit mass than has been achieved with prior heat exchangers. The cross-flow micro-heat exchanger have performance characteristics that are superior to state-of-the-art designs, as measured on a per-unit-volume or per-unit-mass basis.

Properties of mechanical bearings and mechanical seals can be significantly improved by covering the load-bearing surfaces with fields of high aspect ratio microstructures (HARMs), such as microchannels or microposts. The HARMs can substantially enhance heat transfer capability and lubricant flow. The present invention uses microstructures and micro-channels manufactured by a modified LIGA process to enhance the performance of load bearing surfaces. Benefits include reduced operating temperatures, precise metering of lubricant flow to all affected surfaces, increased reliability, increased life, higher maximum rotational speed, and the ability of the seal or bearing to run &ldquo;dry,&rdquo; that is, without periodic re-application of lubricant. The invention may be used with a variety of bearings and mechanical seals, including for example ball bearings, roller bearings, journal bearings, air bearings, magnetic bearings, single mechanical seals, double mechanical seals, tandem mechanical seals, bellows, pusher mechanical seals, and all types of rotating and reciprocating machines. Improved cooling jackets are also disclosed, for use with bearings, seals, or other applications.

Bearings and mechanical seals enhanced with microstructures

The performance of many macroscopic structures (those whose dimensions are on the order of centimeters, meters, or even larger) can be greatly improved by covering their surfaces with microstructures. There are several applications in which &ldquo;large,&rdquo; microstructure-covered sheets are useful. An apparatus and method are disclosed for forming high aspect ratio microstructures (&ldquo;HARMs&rdquo;) on planar and non-planar surfaces, using a modification of the LIGA microfabrication process. A free-standing polymer sheet is lithographically patterned with through-holes. The polymer sheet is then pressed against, clamped to, or otherwise attached to a conductive substrate in such a way that the patterned holes in the sheet are not blocked. Subsequent electroplating produces well-defined HARM structures on the planar or non-planar surface, in shapes that are complementary to the lithographically patterned through-holes in the polymer. The polymer may then be removed (e.g., by melting, dissolution, or burning). Various planar and non-planar surfaces have been covered with microstructures. Where the metal surface is non-planar, the polymer sheet may be heated or otherwise made sufficiently flexible to conform to the metal surface, preferably by heat-shrinking to assure firm contact. The process may be used to electroplate microstructures directly onto metal surfaces generally&mdash;not just onto metal surfaces that have been specially prepared for LIGA processes, as has previously been the case.

High aspect ratio, microstructure-covered, macroscopic surfaces

Properties of mechanical bearings and mechanical seals can be significantly improved by covering the load-bearing surfaces with fields of high aspect ratio microstructures (HARMs), such as microchannels or microposts. The HARMs can substantially enhance heat transfer capability and lubricant flow. The present invention uses microstructures and micro-channels manufactured by a modified LIGA process to enhance the performance of load bearing surfaces. Benefits include reduced operating temperatures, precise metering of lubricant flow to all affected surfaces, increased reliability, increased life, higher maximum rotational speed, and the ability of the seal or bearing to run 'dry,' that is, without periodic re-application of lubricant. The invention may be used with a variety of bearings and mechanical seals, including for example ball bearings, roller bearings, journal bearings, air bearings, magnetic bearings, single mechanical seals, double mechanical seals, tandem mechanical seals, bellows, pusher mechanical seals, and all types of rotating and reciprocating machines. Improved cooling jackets are also disclosed, for use with bearings, seals, or other applications.

Mechanical seals enhanced with microstructures

The performance of many macroscopic structures (those whose dimensions are on the order of centimeters, meters, or even larger) can be greatly improved by covering their surfaces with microstuctures. There are several applications in which 'large,' microstructure-covered sheets are useful. For example, dissimilar sheets of material that otherwise would not bond well to one another (such as a polymer and a metal) can be more strongly bonded with microstructures extending from one of the sheets and embedded into the other sheet. Such products make valuable laminate composites. As another example, the rate of heat transfer between an object and the surrounding medium can be dramatically changed (up or down) by covering the surface of the object with high aspect ratio microstructures, without significantly changing the component's size or weight. As compared to prior thermal barrier coatings, when microstructures are thus used to cover turbine blades the turbines can operate at substantially higher temperatures (as much as 290.degree. C. higher than otherwise possible) and substantially higher pressures, while simultaneously reducing thermal stresses. Yet another application is the use of microstructures as acoustic absorbers, to reduce the amplitude of sound transmitted through a surface.

Growing community of inventors

Baton Rouge, LA, United States of America

Kevin W Kelly