Channel turbulent heat transfer

Choi, J.M., and Anand, N.K, Turbulent Heat Transfer in a Serpentine Channel with a Series of Right-Angle Turns , Inter. J. of Heat and Mass Transfer, Vol. 38, No. 7, pp. 1225-1236, 1995. 

Lau, S.C., Kukreja, R.T., and McMillin. R.D., Effects of V-Shaped Rib Arrays on Turbulent Heat Transfer and Friction of Fully Developed Flow in a Square Channel , /nr. J. 

Liou, Tong Miin, Hwang, Jenn Jiang Chen, Shih Hui, Simulation and Measurement of Enhanced Turbulent Heat Transfer in a Channel with Periodic Ribs on One Principal Wall , Int. J. Heat and Mass Transfer. Vol. 36. No. 2, pp. 507-517, 1993. 

Turbulent Heat Transfer in Circular Tube and Plane Channel... 

M. D. Mikhailov, Finite Element Analysis of Turbulent Heat Transfer in Rod Bundles, Turbulent Forced Convection in Channels and Bundles, eds. S. Kaka< , and D. R Spalding, (1) 250-277,1979. 

Mesh or spiral brush inserts were used by Megerlin et al. [182] to enhance turbulent heat transfer in short channels subjected to high heat flux. The largest recorded improvements in turbulent heat transfer coefficients were obtained—up to 8.5 times however, the pressure drop was up to 2800 times larger. In general, it appears that these displaced enhancement devices are useful in very few practical turbulent situations, for reasons of pressure drop, plugging or fouling, and structural considerations. 

The dummy tubes do not pass through the tubesheets, and can be located close to the inside of the shell. The seating strips extend from baffle to baffle in a longitudinal direction and effectively channel the fluid across the tubes to minimize turbulence and heat transfer. On some fixed tubesheet designs, the outer tubes are in close proximity to the inside of the shell so that by-pass is minimal and no by-pass elimination is necessary. There are a number of... 

The heat transfer correlations are considered separately in the laminar and turbulent regimes in Figs. 2.21 and 2.22, respectively. The dependence of the Nusselt number on the Reynolds number is stronger in all the micro-channel predictions compared to conventional results, as indicated by the steeper slopes of the former Choi et al. (1991) predict the strongest variation of Nusselt number with Re. The predictions for all cases by Peng et al. (1996) also fall below those for a conventional channel. 

Acikalin T, Wait S, Garimella S, Raman A (2004) Experimental investigation of the thermal performance of piezoelectric fans. Heat Transfer Eng 25 4-14 Adams TM, Abdel-Khalik SI, Jeter SM, Qureshi ZH (1998) An experimental investigation of single-phase forced convection in micro-channels. Int J Heat Mass Transfer 41 851-857 Adams TM, Dowling ME, Abdel-Khalik SI, Jeter SM (1999) Applicability of traditional turbulent single phase forced convection correlations to non-circular micro-channels. Int J Heat Mass Transfer 42 4411 415... 

The problems of micro-hydrodynamics were considered in different contexts (1) drag in micro-channels with a hydraulic diameter from 10 m to 10 m at laminar, transient and turbulent single-phase flows, (2) heat transfer in liquid and gas flows in small channels, and (3) two-phase flow in adiabatic and heated microchannels. The smdies performed in these directions encompass a vast class of problems related to flow of incompressible and compressible fluids in regular and irregular micro-channels under adiabatic conditions, heat transfer, as well as phase change. 

Adams et al. (1998) investigated turbulent, single-phase forced convection of water in circular micro-channels with diameters of 0.76 and 1.09 mm. The Nusselt numbers determined experimentally were higher than those predicted by traditional Nusselt number correlations such as the Gnielinski correlation (1976). The data suggest that the extent of enhancement (deviation) increases as the channel diameter decreases. Owhaib and Palm (2004) investigated the heat transfer characteristics... 

Dwyer, O. E., G. Strickland, S. Kalish, and P. J. Schoen, 1973b, Incipient-Boiling Superheats for Sodium in Turbulent Channel Flow Effect of rate of Temperature Rise, Trans. ASME, J. Heat Transfer 95 159 165. (4)... 

Models may be one-, two-, or three-dimensional Of course, more advanced models describe the flow in the channels more accurately, but this is not required in all types of investigations. Section 2 in Chapter 8 provides an in-depth discussion of relevant flow phenomena that have to be taken into account when modeling monoliths. One-dimensional models can provide interesting information on mass and heat transfer effects in the washcoat [54]. However, if the development of a laminar flow in the monolith channels IS to be simulated, a two-dimensional model is needed. This is the case if multimonolith combustors are investigated [67]. This specific design, discussed in detail in Section IV.A, has a number of monoliths in senes, which enables vanation of monolith materials and cell density. Moreover, it leads to improved mass transfer by induced turbulence at the entrance of each monolith segment. 

Little has been published about heat transfer in narrow channels. Some attempts have been made to model heat transfer for segmented flow in small tubes (not capillaries) by Hughmark [28] and Oliver and Young Hoon [29,30]. The concept adopted by these authors is that heat transfer in a two-phase system may be approximated by heat transfer to a single fluid (the liquid phase) contained in a series of shorter tubes with some form of intermediate mixing. However, these studies have been carried out for larger tubes (2.54-cm ID) in which turbulent flow also occurs. Thus, they are not directly applicable to heat transfer monoliths. 

Because pressure drop measurements are much faster and cheaper than mass transfer or heat transfer measurements, it is tempting to try to relate the Sherwood and Nusselt numbers to the friction factor. A relation that has proved successful for smooth circular tubes is obtained from a plausible assumption that is known as the film layer model. The assumption is that for turbulent flow the lateral velocity, temperature, and concentration gradients are located in thin films at the wall of the channel the thickness of the films is indicated with 8/, 87, and 8., respectively. According to the film model, the lateral velocity gradient at the channel surface equals (m)/8/, the lateral temperature gradient equals (T/, - rj/87 and the lateral concentration gradient equals (c. /, - C , )/8,.. From these assumptions, and the theoretical knowledge that 8//8r Pr and 8//8e Sc (for... 

The value of depends both on the fraction of the gas flow that bypasses the structure in the gap between the structure and the tube wall and on the flow regime therein. The larger the ratio of the gap to the hydraulic diameter of the channels of the structure, the higher the bypass stream velocity and the less effective the interaction with the well-mixed, highly turbulent flow in the structure. This in turn leads to substantially reduced heat transfer. 

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