Experimental Characterization of Additively Manufactured Metallic Heat Exchangers

Abstract

In this study, three manifold-microchannel heat exchangers were additively manufactured by direct metal laser sintering. The heat exchangers were manufactured from stainless steel (SS17-4) with an overall dimension of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$64.2\times 46.0\times27.1$ </tex-math></inline-formula> mm. The thermal and hydrodynamic performance of the heat exchangers was experimentally evaluated at different air and water flow rates. The microchannel fins had a thickness of 0.48 mm which featured the smallest length scale used in these heat exchangers. While the overall dimensions of the heat exchangers were identical, their interior designs were slightly different. Heat exchanger A was based on the original manifold-microchannel heat exchanger design concept while heat exchangers B and C had pin fins on their air manifolds. Heat exchangers B and C were different in their microchannel orientations as the microchannels in heat exchanger C were along the streamwise direction of the air inlet manifolds. Despite the interior design modifications between the three heat exchangers, results suggested comparable thermal and hydrodynamic performances. For a water inlet temperature of 60 °C, a normalized rate of heat transfer as high as around 4.76 W/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> was achieved for an air-side Reynolds number of around 4000. The air-side convection heat transfer coefficient was obtained as high as around 800 W/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> K. The range of air-side pressure drop was between around 2000 and 4000 Pa, depending on the airflow rate. Heat exchanger A demonstrated the lowest pressure drop and heat exchangers B and C, which incorporated pin fins on their air manifold, caused higher air-side pressure drops.