Digitized Heat Transfer

Digitized heat transfer is the use of translating, discrete microdroplets to remove heat from a source. The heat transfer rate is dependent on droplet size, velocity, thermal conductivity, and residence time. 

Digitized Heat Transfer, Fig. 1 Digitized flow in a circular microchannel... 

Digitized Heat Transfer, Fig. 2 Digitized flow on a planar surface using EWOD or DEP actuation. Droplets rest on a grid of electrodes that can be activated to induce... 

Digitized Heat Transfer, Table 1 Eorces and velocity for various droplet actuation methods. P is the applied voltage, c is the capacitance per unit area, d is the thickness of the dielectric layer, R is the radius, p is the viscosity, h is the channel height, L is the droplet length, q is the charge per unit area. A is the potential difference, is the dielectric constant, y is the surface tension, T is the temperature, and 0 is the contact angle. For additional information, please refer to Ref. [7]... 

Digitized Heat Transfer, Fig. 4 Droplet velocity profiles in a translating droplet from a stationary reference frame [1]. H is the channel height, x is the wall tangential axis, y is the wall-normal axis, u is the velocity, and U is the mean velocity... 

Digitized Heat Transfer. Fig. 5 Flow field in a translating droplet on a planar surface. Colors denote relative velocity magnitude, x-y plane is the solid surface, z-axis is ptnptaidicular to surface, v is the velocity, and Vt, is the bulk velocity... 

Digitized Heat Transfer. Fig. 6 (a) Nusselt number for DHT in a circular microchannel with respect to nondimensional axial distance. The flow is hydrodynam-ically fully developed and subject to a constant wall... 

Baird E, Mohseni K (2008) Digitized heat transfer a new paradigm for thermal management of compact micro systems. IEEE Trans Compon Packag Technol 31(1) 143-151... 

Zhang P, Mohseni K (2014) A unified model for digitized heat transfer in a microchannel. hit J Heat Mass Transf 78 393 07... 

Baird ES (2008) Hydrodynamic and thermal modeling of two-dimensional microdroplet arrays for digitized heat transfer. Ph.D. Thesis. University of Colorado, USA... 

The large amount of calorimetric data, which can be conveniently stored in a digital form, may, of course, be used in a computer to solve the general equation for the heat transfer in a heat-flow calorimeter (Section IV.B) ... 

This is Fick s second diffusion equation [242], an adaptation to diffusion of the heat transfer equation of Fourier [253]. Technically, it is a second-order parabolic partial differential equation (pde). In fact, it will mostly be only the skeleton of the actual equation one needs to solve there will usually be such complications as convection (solution moving) and chemical reactions taking place in the solution, which will cause concentration changes in addition to diffusion itself. Numerical solution may then be the only way we can get numbers from such equations - hence digital simulation. 

It should be obvious to the reader by now that finite-difference techniques may be applied to almost any situation with just a little patience and care. Very complicated problems then become quite easy to solve when large digital computer facilities are available. Computer programs for several heat-transfer problems of interest are given in Refs. 17, 19, and 21 of Chap. 3. Finite-element methods for use in conduction heat-transfer problems are discussed in Refs. 9 to 13. A number of software packages are available commercially for use with microcomputers. 

Gray (39) developed a program which accepts the DSC sample and baseline data, matches the isothermal, performs cumulative and total area integrations in units of cal/g, corrects the temperature for thermal lag, and tabulates and plots ordinate values in specific-heat units as well as cumulative area in enthalpy units. The analog data from the DSC instrument are digitized and transferred to paper tape with the use of the Perkin-Eimer ADS VI Analytical Data System for Thermal Analysis. The data are digitized every two seconds or every 0.133°. A computer plotter then plots the DSC curve and also the cumulative peak area in specific enthalpy units, cal/g. 

Son, S. R, Queiroz, M., and Wood, C. G. "Compensation of Thermocouples for Thermal Inertia Effects Using a Digital Deconvolution." In Heat Transfer Phenomena in Radiation, Combustion, and Fires, edited by R. K. Shah, 515-22. New York ASME HTD-Vol. 106, 1989. 

Thermal mass flow meter. The meter s probe is inserted into a duct of known dimensions. Flowing gases pass through the sensing element at the bottom of the probe. The sensing element consists of two rods. The heat transfer between these rods is correlated to flow. An electrical transmitter and digital display is located in the head of this instrument. 

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