Ko, Kang-Hoon (2004-12). Heat transfer enhancement in a channel with porous baffles. Doctoral Dissertation. | Thesis individual record

An experimental and numerical investigation of heat transfer enhancement in a

three dimensional channel using wall mounted porous baffles was conducted. The

module average heat transfer coefficients were measured in a uniformly heated

rectangular channel with staggered positioned porous baffles. A numerical procedure

was implemented, in conjunction with a commercially available Navier-Stokes solver, to

model the turbulent flow in porous media. The Brinkman-Forchheimer-Extended Darcy

model was used for modeling fluid flow through the porous baffles. Conventional, oneequation,

and two-equation models were used for heat transfer modeling. The accuracy

and characteristics of each model were investigated and discussed. The results were

compared with experimental data.

Baffles were mounted alternatively on the top and bottom walls. Heat transfer

coefficients and pressure loss for periodically fully developed flow and heat transfer

were obtained for different pore densities (10, 20, and 40 pores per inch (PPI)) with two

different baffle heights ( / h h B D = 1/3 and 2/3), and two baffle thicknesses ( / t h B D = 1/3

and 1/12). The Reynolds number (Re) was varied from 20,000 to 50,000. To compare

the effect of foam metal baffles, the data for conventional solid-type baffles was

obtained for ( / t h B D =1/3). The maximum uncertainties associated with the module

Nusselt number and friction factor were 5.8% and 4.3%, respectively. The experimental

procedure was validated by comparing the data for the straight channel without baffles

( / h h B D = 0) with those in the literature.

The use of porous baffles resulted in heat transfer enhancement as high as 300%

compared to heat transfer in straight channels without baffles. However, the heat transfer

enhancement per unit increase in pumping power was less than one for the range of

parameters studied in this work. Correlation equations were developed for the heat

transfer enhancement ratio and the heat transfer enhancement per unit increase in

pumping power in terms of Reynolds number.

The conventional theoretical model, the dispersion conductivity model, and the

modified two-phase model using the local thermal non-equilibrium theory were

considered. The results from each model were compared against the experimental data,

and compared to each other to investigate the efficiency of each model. Also, the

characteristics of each model were discussed.

etd chair
publication date