An additively manufactured metallic manifold-microchannel heat exchanger for high temperature applications

Abstract

This work presents an additively manufactured manifold-microchannel heat exchanger made of Inconel 718 and experimentally tested for high temperature aerospace applications. The heat exchanger core with a size of 66 mm × 74 mm × 27 mm was fabricated as a single piece through the direct metal laser sintering process. A minimum fin thickness of 180 μm was achieved. Successful welding of additively manufactured headers with the heat exchanger core and conventionally manufactured flanges was demonstrated through the fabrication of the unit. The heat exchanger was tested using nitrogen (N2) on the hot-side and air on the cold-side as the working fluids. The experimental tests were conducted at 600 °C on the hot-side and 38 °C on the cold-side. A maximum heat duty of 2.78 kW and a maximum overall heat transfer coefficient of 1000 W/m2K were achieved during the experiments. The decent agreement between the experimental and the numerical results demonstrates the validity of the numerical analysis model used for heat transfer and pressure drop prediction of the additively manufactured manifold-microchannel heat exchanger. Compared to conventional plate fin heat exchangers, nearly 25% improvement in heat transfer density— the ratio between heat duty and mass (Q/m)—was noted at a coefficient of performance (COP) of 62.