Heat transfer enhancement in a counter-flow sinusoidal parallel-plate heat exchanger partially filled with porous media using metal foam in the channels' divergent sections.

This is a numerical study of heat transfer and flow in a counter-flow sinusoidal parallel-plate heat exchanger using metal foam in the channels' divergent sections. The cold water fluid with Reynolds number of 100 and hot oil fluid with Reynolds number of 2 enter the downer and upper channels of the heat exchanger, respectively. The sinusoidal heat exchanger is investigated with two-wave amplitudes (0.3 and 0.6 cm), two wavelengths (6 and 12 cm) inserting the porous media with three particle diameters (0.1, 0.05 and 0.01 mm) and three thicknesses (A/3, 2A/3, and A). Darcy–Brinkman–Forchheimer and local thermal non-equilibrium models are used. To evaluate the increased heat transfer versus the increased pumping power, a dimensionless number called performance evaluation criteria (PEC) has been defined in the current study. The obtained results showed that the heat transfer rate, effectiveness and overall heat transfer coefficient of the heat exchanger are increased up to 19.2%, and the PEC number is enhanced to 1.171 in the optimum case with wave amplitude, wavelength, metal foam particle diameter and thickness equal to 0.6 cm, 6 cm, 0.01 mm and 2A/3, respectively. Moreover, since the metal foam is embedded in the wake region of the heat exchanger or channels' divergent sections, its effect on pumping power is subtle, which is an advantage of using the porous medium at these regions. [ABSTRACT FROM AUTHOR]