Simultaneous measurement of temperature and velocity fields using thermographic phosphor tracer particles

In this article, an unsteady free convection flow of MHD viscous fluid over a vertical rotating plate with Newtonian heating and heat generation is analyzed. The dimensionless governing equations for temperature and velocity fields are solved using the Laplace transform technique. Analytical solutions are obtained for the temperature and components of velocity fields. The obtained solutions satisfy the initial and boundary conditions. Some physical aspects of flow parameters on the fluid motion are presented graphically.

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Analysis Tools for Thermally Driven Microfluidics

Volume 10: Micro and Nano Systems ◽

10.1115/imece2010-40822 ◽

2010 ◽

Author(s):

M. Sigurdson ◽

C. D. Meinhart

Keyword(s):

Heat Pipe ◽

Electronics Cooling ◽

Velocity Fields ◽

Microfluidic Systems ◽

Infrared Thermometry ◽

Analysis Tools ◽

Thermally Driven ◽

Temperature And Velocity Fields ◽

Fluorescence Thermometry

Thermally driven microfluidics, that is, flow that is driven by a temperature gradient, has applications from lab-on-a-chip to electronics cooling. Development of such devices requires tools to predict and probe temperature and velocity fields. We have developed analytical, numerical, and experimental analysis tools for design and characterization of thermally driven microfluidic systems. We demonstrate these tools through the analysis of two different systems: an electrothermal microstirring biochip, and a high aspect heat pipe for cooling. First, a numerical model is developed for temperature and velocity fields, in a hybrid electrothermal-buoyancy microstirring device. An analytical tool, the electrothermal Rayleigh number, is used to further explore the relative importance of electrothermal and buoyancy driven flow. Finally, two experimental thermometry techniques are described: fluorescence thermometry and infrared thermometry. These analytical, numerical, and experimental tools are useful in the design of thermally driven microfluidic systems, as demonstrated here through the development and analysis of microstirring and heat pipe systems.

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Natural Convective Characteristics of an Oblique Heat Source Module in the Closed and Ventilated Cabinets

ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, Volume 2 ◽

10.1115/esda2010-24154 ◽

2010 ◽

Author(s):

Yeong-Ley Tsay ◽

Jen-Chieh Cheng ◽

Yong-Lin Zhuang

Keyword(s):

Heat Source ◽

Hot Spot ◽

Velocity Fields ◽

Thermal Interaction ◽

Surrounding Area ◽

The Difference ◽

Conjugate Conduction ◽

Temperature And Velocity Fields ◽

Air Streams ◽

Spot Temperature

A numerical analysis is performed to study the characteristics of heat transfer from a block heat source module at different angles in two-dimensional cabinets. Great efforts are carried out to conduct the effects of thermal interaction between the air steams inside and outside the cabinet on the conjugate conduction–natural convection phenomena. Moreover, the enhancement of cooling performance of the heat source module through the construction of air vents on cabinet wall is rigorously examined. The computation domain covers the cabinet and the surrounding area, and the temperature and velocity fields of the cabinet and surrounding area are solved simultaneously. Results show that the thermal interaction between the airs inside and outside the cabinet, the module angle and vent position can significantly affect the transfer characteristics. Comparing the results for cases with and without the consideration of thermal interaction between the air streams, the difference in hot spot temperature of module can be up to 26% for Pr = 0.7, Kbf = Kpf = Kwf = 100, 105 ≦ Ra ≦ 107 and φ = 0°, 90°, 270°. The maximum reduction in hot spot temperature is about 41% when two air vents are constructed on cabinet wall. The variation of module angle results in the maximum difference of the hot spot temperature is 15% for closed cabinet, and 10% for ventilated cabinet.

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Free Convection Thermal Interaction Between 2D Components Mounted on a Vertically Oriented PCB

Heat Transfer, Volume 7 ◽

10.1115/imece2002-33003 ◽

2002 ◽

Cited By ~ 2

Author(s):

D. Newport ◽

T. Dalton ◽

M. Davies

Keyword(s):

Boundary Layer ◽

Effective Conductivity ◽

Ball Grid Array ◽

Velocity Fields ◽

Two Dimensional ◽

Thermal Interaction ◽

Trade Off ◽

Layer Flow ◽

Digital Moiré ◽

Temperature And Velocity Fields

In this paper, measurements are presented of the temperature and velocity fields about two PCBs, with an array of five equally spaced two dimensional ribs. The ribs are two dimensional approximations of the Super Ball Grid Array (SuperBGA) package from Amkor electronics. The temperature and Nusselt number distributions are measured using Digital Moire´ Subtraction Interferometry and PIV is used to measure the velocity field. The effect of substrate conductivity is examined, and the level of thermal interaction is quantified. It is found that substrate conductivity significantly alters the induced boundary layer flow and also the recirculating vortex structure external to it. It is also found that there is a trade-off between a downstream component being heated by the thermal energy of the plume from a lower component, and cooled by the kinetic energy of that plume. The spacing to length ratio, above which the cooling effect is greater, is three for components mounted on a board with a high effective conductivity (15 W/m K). The ratio is greater than three for PCBs with lower effective conductivities. Previous work in the literature indicates a ratio greater than four for components mounted flush with an adiabatic substrate.

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