Boiling enhancement by laser powder bed fusion surface roughness

Open Access
Author:
Bichnevicius, Michael Joseph
Area of Honors:
Mechanical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Stephen P Lynch, Thesis Supervisor
  • Hosam Kadry Fathy, Honors Advisor
Keywords:
  • boiling
  • laser powder bed fusion
  • heat exchanger
  • two-phase heat transfer
Abstract:
Recent studies have shown that the surface roughness of horizontal boiling surfaces produced by laser powder bed fusion (LPBF) can increase average heat transfer coefficient, ¯h, in the nucleate boiling regime and critical heat flux, q00 crit, but the strong dependence of LPBF surface roughness characteristics on build angle has not yet been considered. Prior work by the author presented in this thesis on heat transfer augmentation by surface roughness in LPBF single-phase heat exchangers also serves as motivation to study LPBF two-phase heat exchangers. The present work shows the design of an experiment to investigate the boiling heat transfer performance of AlSi10Mg boiling surfaces produced by LPBF at several build angles. Sample boiling surfaces were fabricated by LPBF at build angles of 0, 45, 90, and 135 using two common AlSi10Mg LPBF machine parameter configurations, and the sample boiling surfaces were machined to be tested in a pool boiling test apparatus recently developed in Penn State’s Heat Transfer and Multiphase Flow Laboratory (HTML). Surface roughness was characterized by scanning electron microscopy and white light interferometry. Boiling surfaces built at greater build angles had rougher surfaces as expected, and it is anticipated that these rougher surfaces will correspond to higher ¯h and q00 crit.