Experimental study of heat transfer and pressure drop of supercritical CO2 cooled in metal foam tubes

An experiment was conducted to investigate the forced convective heat transfer and pressure drop characteristics of supercritical CO2 cooled in tubes partially filled with metal foam. The effects of CO2 inlet pressure, mass flow rate and mean bulk temperature on the heat transfer and pressure drop were analyzed. Moreover, the parametric study was performed with different porosities (void fraction, 0.85/0.9/0.95) and pore densities (number of pores per inch, 20/40/60). The heat transfer coefficient decreases at first and then increases as porosity increases, and decreases as pore density decreases and finally approaches to a near constant value. The pressure drop monotonously increases as porosity decreases and finally approaches to a near constant value, and increases at first and then decreases as pore density increases. Based on the experimental data, both correlations for heat transfer and friction factors were proposed. The maximum error between the results predicted by new correlations and measured is ±15%.