Heat Transfer in MicroChannel Flow

Heat transfer in microchannel flow Single-phase convective flows in microchannels Single-phase forced convection in microchannels... 

In the course of the fast growing development of microfluidic devices like Lab-on-a-Chip, microreactors, and micro heat pipes, it is essential to develop effective systems for measuring the temperature distribution in the microscale. For example, for observing the heat transfer in microchannel flows, it is a matter of particular interest to know both the temperature distribution along the wall and the temperature distributirHi in the fluid flow. Conventional methods for temperature measurements are based on thermocouples and resistance thermometers which have a minimum size of about 10 pm and which always interfere with the system to be measured. Contactless methods for measuring temperature, e.g., infrared thermography, have many... 

Mala GM, Li D, Werner C (1997b) Flow characteristics of water through a micro-channel between two parallel plates with electro kinetic effects. Int J Heat Fluid Flow 18 491 96 Male van P, Croon de MHJM, Tiggelaar RM, Derg van den A, Schouten JC (2004) Heat and mass transfer in a square micro-channel with asymmetric heating. Int J Heat Mass Transfer 47 87-99 Maranzana G, Perry I, Maillet D (2004) Mini- and micro-channels influence of axial conduction in the walls. Int J Heat Mass Transfer 47 3993 004 Maynes D, Webb BW (2003) Full developed electro-osmotic heat transfer in microchannels. Int J Heat Mass Transfer 46 1359-1369... 

Samalam [43] modeled the convective heat transfer in water flowing through microchannels etched in the back of silicon wafers. The problem was reduced to a quasi-two dimensional non-linear differential equation under certain reasonably simplified and physically justifiable conditions, and was solved exactly. The optimum channel dimensions (width and spacing) were obtained analytically for a low thermal resistance. The calculations show that optimizing the channel dimensions for low aspect ratio channels is much more important than for large aspect ratios. However, a crucial approximation that the fluid thermophysical properties are independent of temperature was made, which could be a source of considerable error, especially in microchannels with heat transfer. 

Weisberg et al. [54] are among other researchers who all provided additional information and considerable evidence that the behavior of fluid flow and heat transfer in microchannels or microtubes without phase change is substantially different from that which occurs in large channels and/or tubes. 

Experimental investigations on convective heat transfer in liquid flows in microchannels have been in the continuum regime. Hence, the conventional Navier-Stokes equations are applicable. 

Rahman, M.M. and Gui, F., Experimental Measurements of Fluid Flow and Heat Transfer in MicroChannel Cooling Passages in A Chip Substrate, Advances in Electronic Packaging, ASME EEP-4-2, 1993, 685-692. 

Tunc, G (2002) Convective Heat Transfer in MicroChannel Gaseous Slip Flow, PhD. Thesis, Rice University, Houston, TX. 

CONDENSATION FLOW MECHANISMS, PRESSURE DROP AND HEAT TRANSFER IN MICROCHANNELS... 

The nature of boiling heat transfer in a channel with the gap less than the capillary is also studied and presented. The condensation flow mechanisms, pressure drop and heat transfer in microchannels, role of microscale heat transfer in augmentation of nucleate boiling and flow boiling heat transfer, binary-fluid heat and mass transfers in microchannel geometries for miniaturized thermally activated absorption heat pumps, evaporation heat... 

In this lecture, the effects of the abovementioned dimensionless parameters, namely, Knudsen, Peclet, and Brinkman numbers representing rarefaction, axial conduction, and viscous dissipation, respectively, will be analyzed on forced convection heat transfer in microchannel gaseous slip flow under constant wall temperature and constant wall heat flux boundary conditions. Nusselt number will be used as the dimensionless convection heat transfer coefficient. A majority of the results will be presented as the variation of Nusselt number along the channel for various Kn, Pe, and Br values. The lecture is divided into three major sections for convective heat transfer in microscale slip flow. First, the principal results for microtubes will be presented. Then, the effect of roughness on the microchannel wall on heat transfer will be explained. Finally, the variation of the thermophysical properties of the fluid will be considered. 

J.T. Liu, X.F. Peng, and B.X. Wang, Variable-property effect on liquid flow and heat transfer in microchannels. Chemical Engineering Journal 141, 346-353 (2008). 

F.V. Castelloes, C.R. Cardoso, P. Couto, and R.M. Cotta, Transient Analysis of Slip Flow and Heat Transfer in Microchannels, Heat Transfer Engineering, Vol. 28, 549-558 (2007). 

The smaller channel dimensions also shift the flow towards lower Reynolds number. In general, there is a lack of available experimental data for heat transfer in microchannels, and a need exists to generate new experimental data to cover the overall shift in the Reynolds numbers, heat flux, and mass flux in practical applications. 

Convective Heat Transfer in Microchannels, Table 3 Nusselt numbers Nut3 for laminar fully developed flow as a fimction of the dimensionless wall thermal resistance and of the Peclet number for the T3 honndary condition... 

Convective Heat Transfer in Microchannels, Tabie 5 Nusselt numbers Nuhs for laminar fully developed flow as a function of the m parameter defined by Eqs. 18 and 31 for the H5 boundary emidition ... 

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