1,647 research outputs found
Study of Multilouvered Heat Exchangers at Low Reynolds numbers
Air Conditioning and Refrigeration Project 13
Manipulation of Spherical Droplets on a Liquid Platform Using Thermal Gradients
In the recent years, there has been a growing interest in droplet-based
(digital) microfluidics for which, reliable means of droplet manipulation are
required. In this study we demonstrate thermal actuation of droplets on liquid
platforms, which is ideal for biochemical microsystems and lab-on-chip
applications because droplets can be transported with high speed, good control
and minimal thermal loading as compared to using conventional solid substrates.
In addition, other disadvantages of using solid surfaces such as evaporation,
contamination, pinning, hysteresis and irreversibility of droplet motion are
avoided.
Based on the theoretical development and measurements, a silicon-based
droplet transportation platform was developed with embedded Titanium micro
heaters. A shallow liquid pool of inert liquid (FC-43) served as the carrier
liquid. Heaters were interfaced with control electronics and driven through a
computer graphical user interface. By creating appropriate spatio-temporal
thermal gradient maps, transport of droplets on predetermined pathways was
successfully demonstrated with high level of robustness, speed and reliability.
The video shows normal imaging of droplet manipulation accompanied by the
corresponding infrared thermal imaging showing the spatio-temporal temperature
maps and the outline of the drop as it moves towards hot spots.Comment: 63rd APS - Division of Fluid Dynamics - 201
Large-Eddy Simulations of Flow and Heat Transfer in Complex Three-Dimensional Multilouvered Fins
The paper describes the computational procedure and
results from large-eddy simulations in a complex three-dimensional
louver geometry. The three-dimensionality in the
louver geometry occurs along the height of the fin, where the
angled louver transitions to the flat landing and joins with the
tube surface. The transition region is characterized by a swept
leading edge and decreasing flow area between louvers.
Preliminary results show a high energy compact vortex jet
forming in this region. The jet forms in the vicinity of the louver
junction with the flat landing and is drawn under the louver in
the transition region. Its interaction with the surface of the
louver produces vorticity of the opposite sign, which aids in
augmenting heat transfer on the louver surface. The top surface
of the louver in the transition region experiences large velocities
in the vicinity of the surface and exhibits higher heat transfer
coefficients than the bottom surface.Air Conditioning and Refrigeration Project 9
Quantitative genetics of sleep in inbred mice
The timing and the organization of sleep architecture are mainly controlled by the circadian system, while sleep need and intensity are regulated by a homeostatic process. How independent these two systems are in regulating sleep is not well understood. In contrast to the impressive progress in the molecular genetics of circadian rhythms, little is known about the molecular basis of sleep. Nevertheless, as summarized here, phenotypic dissection of sleep into its most basic aspects can be used to identify both the single major genes and small effect quantitative trait loci involved. Although experimental models such as the mouse are more readily amenable to genetic analysis of sleep, similar approaches can be applied to humans
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