Convection channel flow

The data presented in the previous chapters, as well as the data from investigations of single-phase forced convection heat transfer in micro-channels (e.g., Bailey et al. 1995 Guo and Li 2002, 2003 Celata et al. 2004) show that there exist a number of principal problems related to micro-channel flows. Among them there are (1) the dependence of pressure drop on Reynolds number, (2) value of the Poiseuille number and its consistency with prediction of conventional theory, and (3) the value of the critical Reynolds number and its dependence on roughness, fluid properties, etc. 

Peng XF, Wang BX (1993) Forced convection and flow boiling through micro-channels Int J Heat Mass Transfer 36 3421-3427... 

Interaction of void/reactivity coupling with flow dynamics and heat transfer Interaction among a small number of parallel channels Interaction of direct contact condensation interface with pool convection A flow excurision initiates a dynamic interaction between a channel and a compressible volume... 

Jiji, L. M.,andJ. A. Clark, 1964, Bubble Boundary Layer and Temperature Profiles for Forced Convection Boiling in Channel Flow, Trans. ASME, J. Heat Transfer 56 50 58. (4)... 

Tobias and Hickman (T2), the only investigators to date to study combined free and forced convection in horizontal channel flow, found a remarkably sharp separation between forced- and free-convection dominated mass transfer. In forced convection, the critical Grashof number, based on the diffusion layer thickness, is... 

The characteristics of laminar flow can allow mathematical prediction of the solution velocity and this has led to a range of hydrodynamic devices which use forced convection as a transport component under laminar flow conditions, examples include, the -> rotating disk electrode [i],-> wall jet electrode [ii], and channel flow cell (see -> flow cell). 

Flow profile is perturbed by electrodes which are not flush or smooth Generally steady state. Apart from RDE, models are two-dimensional due to convection EPR, spectroscopic and photochemical methods are easily incorporated into the small, transparent channel flow cell. RDE is less versatile... 

W. Nitsch, C. Kurthen, Convective Monolayer Compression in Channel Flow Behavior and Transfer of Soluble and Insoluble FUms , Thin Solid Films, 178, 145 (1989)... 

Cotta, R.M. and Ozisik, M.N. (1986) Transient Forced Convection in Laminar Channel Flow witii Stepwise Variations of Wall Temperature, CanJ. Chem. Eng., Vol. 64, pp. 734-742. 

Jarvis NL (1962) The effect of monomolecular films on surface temperature and convective motion at the air/water interface. J.Colloid Sci. 17 512-522 Kumar S, Gupta R, Baneijee S (1998) An experimental investigation of the characteristics of free surface turbulence in a channel flow. Physics of Fluids 10 437-456... 

F.G. Elmor, R.O.C. Guedes, and F.N. Scofano, Improved Lumped Solution for Conjugate Heat Transfer In Channel Flow with Convective Boundary Condition, Int. J. Heat Technology, pp. 78-88 (2005). 

The heat transfer mechanisms that are active in boiling in micro-channels can be summarized as follows (i) in bubbly flow, nucleate boiling and liquid convection would appear to be dominant, (ii) in slug flow, the thin film evaporation of the liquid film trapped between the bubble and the wall and convection to the liquid and vapor slugs between two successive bubbles are the most important heat transfer mechanisms, also in terms of their relative residence times, (iii) in annular flow, laminar or turbulent convective evaporation across the liquid film should be dominant, and (iv) in mist flow, vapor phase heat transfer with droplet impingement will be the primary mode of heat transfer. For those interested, a large number of two-phase videos for micro-channel flows from numerous laboratories can be seen in the e-book of Thome [22]. 

These interesting devices consist of a tube or duct within which static elements are installed to promote cross-channel flow. See Figure 8.5 and Section 8.7.2. Static mixers are quite effective in promoting radial mixing in laminar flow, but their geometry is too complex to allow solution of the convective diffusion equation on a routine basis. A review article by Thakur et al. (2003) provides some empirical correlations. The lack of published data prevents a priori designs that utilize static mixers, but the axial dispersion model is a reasonable way to correlate pilot plant data. Chapter 15 shows how Pe can be measured using inert tracers. 

J. P. Hartnett, Single Phase Channel Flow Forced Convection Heat Transfer, in 10th International Heat Transfer Conference, vol. 1, pp. 247-258, Brighton, England, 1994. 

D. E. Metzger and D. E. Larson, Use of Melting Point Surface Coating for Local Convection Heat Transfer Measurements in Rectangular Channel Flows with 90° Hirns, ASME J. of Heat Transfer, 108, pp. 48-54,1986. 

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