77th Annual Meeting of the Southeastern Section of the APS
Volume 55, Number 10
Wednesday–Saturday, October 20–23, 2010;
Baton Rouge, Louisiana
Session JA: Microfluidics: Computational and Experimental Challenges
3:45 PM–5:45 PM,
Friday, October 22, 2010
Nicholson Hall
Room: 119
Chair: Michael Martin, Louisiana State University
Abstract ID: BAPS.2010.SES.JA.1
Abstract: JA.00001 : Counter-flow Microfluidics for Stable Flow Thermodynamics
3:45 PM–4:15 PM
Preview Abstract
Abstract
Author:
Niel Crews
(Louisiana Tech University)
Microfluidic thermal reactors are able to achieve high
temperature ramping
rates due to their low thermal mass. Of these, the most
thermodynamically
efficient are flow systems that rely on a steady-state temperature
distribution to induce temperature change of the moving fluid.
Rather than
inserting or extracting heat at controlled time intervals, the
fluids are
heated and cooled only through local heat transfer with the
substrate
material in which the microchannels are embedded. In addition to
accelerated
ramping and reduced energy consumption, such systems have the
potential to
provide greater control of the heating rates. This is because the
temperature change is simply a function of the fluid velocity
vector with
respect to the stable temperature distribution within the
material. However,
the operation of such a system is complicated by the thermal
perturbation
that the fluid flow introduces into the system.
When predicting the temperature change of the fluid, it is common
to ignore
the effect of the fluid flow on the original temperature
distribution within
the substrate. However, this has been shown to be the dominant
behavior in
many scenarios. This behavior is particularly problematic in
polymeric
microfluidic devices, where thermal conductivities are on the
order of 0.2
W/m-K. This presentation will address a powerful solution to this
thermal
instability. By implementing a counter-flow microfluidic
geometry, it will
be shown how the temperature smearing common to microflow thermal
reactors
can be virtually eliminated. The deleterious effect of the
insulative
properties of popular polymer substrates is minimized, allowing
for higher
flow rates and temperature ramp rates. This is achieved by
creating a
preferred heat path for the thermal energy that is being driven
into or out
of the fluid during flow. Theory will be presented; experimental
data will
be discussed; application to lab-on-a-chip systems will be
demonstrated.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2010.SES.JA.1