Micro-fluid mixing is an important aspect of many of the various micro-fluidic systems used in biochemical production, biomedical industries, micro-energy systems and some electronic devices. Typically, because of size constraints and laminar flow conditions, different fluids may only have the opportunity to mix by diffusion, which is extremely rate limited....
Micro Energy and Chemical Systems (MIECS) are multi-scale microsystems, which rely
on embedded nano and micro-scale features to process bulk amounts of fluid in
applications ranging from man-portable heat pumps, distributed fuel reforming and insitu
waste remediation. Microlamination is a well-known process architecture for
fabricating the highly parallel, high aspect...
The effect of unsteady thermocapillary convection on the mass transfer rate of a solute between two immiscible liquids within a rectangular microscale channel with differentially heated sidewalls was numerically investigated. A computational fluid dynamic code in Fortran77 was developed using the finite volume method with Marker and Cell (MAC) technique...
Diffusion bonding has been widely used within microlamination architectures for the fabrication of Micro Energy and Chemical Systems (MECS). MECS are microsystems with the ability to process bulk amounts of fluid within highly-parallel microchannel arrays capable of accelerated heat and mass transfer. Thus far, diffusion bonding of the microchannel arrays...
Recent studies of flow boiling within microchannels have shown high heat fluxes, leading to successful design and testing of compact heat exchangers, cooling systems for electronics and other high efficiency, miniature components. An experimental study of flow boiling of a concentrated salt solution in microchannels is presented. Experiments examined flow...
Infrared (IR) thermography is applied to estimate heat transfer rates in external and internal microscale convective flows. The technique and analysis are developed in the context of external jet impingement flow and internal single-phase liquid flows. A heated-thin-foil thermography technique is applied to perform surface temperature visualization on a submerged...
Over the last decade, the miniaturization of analytical systems has become an increasingly important and interesting research area. Miniaturized systems offer many advantages, including reduced reagent and sample consumption, shorter analysis times, portability and disposability. This dissertation describes novel approaches in this direction, focusing on two areas: the miniaturization of...
The research is about developing a computerized design system for
microtechnology-based energy, and chemical systems (MECS). MECS devices are
a part of microfabrication, which primarily focuses on taking advantage of the
extremely high rates of heat and mass transfer available in microstructures. It
typically consists of intricate arrays of components...
Two-phase flow in a fractal-like branching microchannel heat sink may have
enhanced heat transfer capabilities over single phase flow in the same branching
channel network. In order to exploit this potential, a complete understanding
of flow boiling in this geometry is required. The fractal-like geometry is similar
to that of...
Microscale fluid processes are an increasingly important subgroup of fluid mechanics. Applications for heat transfer and micro-electro-mechanical devices use flows on the scale of less than one hundred microns. This study is part of a larger work in which a multiphase, high shear environment is studied in a microchannel that...
An experimental investigation into the behavior of micro-bubbles flowing
through a micro-channel has been conducted. Experiments were performed within a
rectangular micro-channel with dimensions of 5 cm x 13.2 mm x l30 jim. Bubbles
were generated in an electrolyte solution by electrolysis at the lower channel wall near
the inlet....
Micro Energy and Chemical Systems (MECS) devices enable at least two
areas of benefit due to the accelerated heat and mass transfer that can be
accomplished in microchannels. First, MECS devices enable process
intensification; the ability to reduce the volume of space needed to implement
systems of thermal and chemical...
An experimental study was performed in which an ammonia-water solution was desorbed within a branching fractal-like microchannel array. The solution entered in the center of a disk, and flowed out radially until discharging in to a gravity-driven separation chamber. Heat was added to the ammonia-water through a thin wall, above...
A unique channel surface enhancement technique via diffusion-bonding a layer of conductive fine wire mesh onto the heating wall was developed and used to experimentally study flow boiling enhancement in parallel microchannels. Each channel was 1000 μm wide and 510 μm high. A dielectric working fluid, HFE 7000, was used...
Diffusion bonding has been widely used within microlamination architectures for the
fabrication of Micro Energy and Chemical Systems (MECS). MECS are microsystems
with the ability to process bulk amounts of fluid within highly-parallel microchannel
arrays capable of accelerated heat and mass transfer. Thus far, diffusion bonding of
microchannel arrays is...
It is hypothesized that increases in pressure drop due to vapor generation during boiling in microchannels can be reduced by extraction of vapor at its point of inception. Ultimately, this local vapor extraction decreases the pressure drop required to drive the flow through a fractal-like branching, microchannel flow network within...
Dielectrophoresis (DEP) is a separation method in which a non-uniform electric
field is used to induce a dipole moment in a suspended particle. If the polarization
of the particle is greater than that of the suspending medium, the particle will move
towards the region of higher field strength (positive DEP);...
A PID controller was designed to control the performance of an oil-heated fractal-like branching microchannel desorber for use in an ammonia-absorption refrigeration system. Both the amount and concentration of ammonia refrigerant generated at the desorber can be controlled by choosing the rectified circulation ratio as the controlled variable in a...
A microfluidic nanofiltration module has been designed, fabricated and applied to the continuous-flow, pressure-driven, post-synthetic purification of macromolecules and nanoparticles via diafiltration using a commercially available organic solvent resistant nanofiltration membrane, STARMEM 122. This module will readily interface with other microscale components within a
"nanofactory" for the rapid synthesis, purification...
A non-intrusive measurement technique for direct quantitative thermal visualization of channel wall temperatures in two phase microchannel flows using infrared thermography (IRT) is presented. Specifically, the measurement of top channel wall temperatures in a fractal-like branching microchannel silicon heat sink during flow boiling is demonstrated and thoroughly documented. Obtaining quantitative...
Based on experimental investigations the present study evaluates flow instability and
void fraction in a fractal-like branching microchannel network with rectangular cross-section. The hydraulic diameter of the channels ranged from 308μm at the inlet to 143μm at the outlet. The flow network used is characterized by set branching ratios for...
Two-phase gas-liquid flows in microscale fractal-like branching channel flow networks were experimentally studied to assess the validity of existing void fraction correlations and flow regimes based on superficial gas and liquid velocities. Void fractions were assessed using two different methods. First, void fraction data were acquired using a High-Speed-High-Resolution (HSHR)...
The thermal wave technique has been explored for the use of liquid thermal conductivity measurement and flow property diagnostics in this dissertation. For liquid thermal conductivity measurements, an experimental technique based on the thermal wave approach is developed. A stainless steel strip functions as both a heating element and a...
Recent efforts show that microchannel technologies have much to offer the field of nanomanufacturing: the structuring of matter on the order of one billionth of a meter. During the synthesis of nanomaterials, microchannel reactors take advantage of large surface-to-volume ratios to accelerate heat and mass transport. This accelerated transport allows...
Single-layer and three-layer microchannel adsorption devices were fabricated by procedure that was newly developed. Aluminum was chosen for metal housing while the adsorption pair was silica gel and water. Each adsorption layer contained two layers of 250 μm-thick silica gel. Both silica gel layers opened to the same layer of...
The concept of reducing laboratory operations in scale such that they fit on a microfluidic chip has been met with great enthusiasm. Lab-on-a-chip devices promise to be cost effective to operate due to reduced reagent consumption, have the potential to offer shorter analysis times due to their short path lengths,...
The pressure drop of convective boiling flow may be reduced by extracting vapor locally since the entire generated vapor does not have to travel through the entire channel length. In this study, the theoretical model was developed to simulate a convective boiling flow through a fractal-like branching microchannel network with...
An experimental and numerical study of absorption of ammonia vapor bubbles into a constrained thin film of ammonia-water solution is presented in the context of a potential reduction in size of a heat-actuated heat pump component. A large-aspect-ratio channel with a depth of 600 µm restricts the thickness of the...
This study investigates the hydrodynamic characteristics of droplet impinging on heated surfaces using High Speed High Resolution (HSHR) imaging and evaluates the effect of surface temperature and using water and a nanofluid on a polished and a nano-structured surface. Three types of surfaces are used in the
study: polished silicon,...
This objective of this study is to investigate the capability of nanostructured surfaces on dissipating heat flux by performing pool boiling and convective flow boiling. The generation of ultra-high heat flux from high performance electric devices has motivated a number of investigations related to advanced heat transfer especially in two-phase...
Novel fluidic devices that utilize an array of microchannels to achieve their designed purpose are discussed. Examples of devices include: fuel reforming using Microreactors, chip cooling using microchannel heat sinks, and microchannel devices used for biological applications. The devices that have directly contributed to this research include: a microchannel water...
Continued interest in the development of miniaturized and portable analytical platforms necessitates the exploration of sensitive methods for the detection of trace analytes. Nanomaterials, on account of their unique physical and chemical properties, are not only able to overcome many limitations of traditional detection reagents but also enable the exploration...
This study lays the groundwork on potential techniques that could be employed to improve the post-thaw wash processing of cryopreserved human red blood cells. Transfusion of red blood cells is one of the most commonly practiced procedures in clinical medicine. Millions of red blood cell units are transfused to patients...
Methane is a flammable gas that is the main component of natural gas. It is a highly potent greenhouse gas, and accounts for about 20% of greenhouse gas emissions. Methane is routinely flared in many industrial processes without harnessing any of its energy. The environmental impact and wasted energy potential...
An inventor seeks to leverage his unique means in order to create and commercially exploit new technologies. Until new technologies are sufficiently developed, they have the theoretical potential for commercial exploitation in a wide range of markets. Those opportunities are limited by physical bounds that are often only discovered through...
Microfluidics is an evolving field that focuses on the manipulation of small fluid volumes. Because of its micron-sized features, it is the basis for many lab-on-chip and point-of-care diagnostic devices. The devices are predominantly molded from polydimethylsiloxane (PDMS); however, production is a multi-hour or multi-day process that typically requires clean...
The advent of 3D Printing has invigorated research into metamaterials, synthetic composite material that produce properties generally not found in natural materials, requiring further studies into understanding the fundamental properties of these materials. This dissertation proposes a novel imaging technique to investigate the surface interactions occurring in an unsaturated packed...