Assessment of the Feasibility of Using Additive Manufacturing from Metal Powder to Produce Compact Heat Exchangers

Area of Science:

• Materials Science
• Mechanical Engineering
• Manufacturing Technology

Background:

• Miniaturization of heat exchangers demands advanced manufacturing beyond conventional methods like milling or casting.
• Microscale geometries in compact heat exchangers present significant fabrication challenges.

Purpose of the Study:

• To investigate the feasibility of selective laser melting (SLM) for fabricating compact heat exchangers with minichannels using 316L stainless steel.
• To assess the material properties, dimensional accuracy, and surface quality of SLM-produced heat exchangers.

Main Methods:

• Design of a compact heat exchanger with minichannels using Autodesk Inventor 2023.3.
• Fabrication using selective laser melting (SLM) with optimized process parameters for 316L stainless steel powder.
• Characterization via hydrostatic weighing, microhardness testing, computed tomography, optical microscopy, and contact profilometry.

Main Results:

• Achieved a relative material density of 99.5% with optimized SLM parameters.
• The fabricated heat exchanger exhibited high geometric fidelity and channel permeability.
• Average microhardness was 255 HV, with minor chemical composition deviations from the feedstock. Average surface roughness (Ra) was 11.11 ± 1.63 µm.

Conclusions:

• Selective laser melting (SLM) is a viable technology for producing functionally capable micro-heat exchangers with complex geometries.
• Limitations include challenges with dimensional accuracy, powder removal, and surface roughness.
• Further research is essential for performance testing under operational conditions, particularly for two-phase flow applications.