Experimental Investigation on thermal-hydraulic performance of microchannel heat sink with airfoil pin fin array and supercritical carbon dioxide

Mostafa Asadzadeh
Department of Mechanical and Aerospace Engineering, University of Central Florida P.O. Box 162450 Orlando, FL, USA, 32186-2450

Yoav Peles
Rensselaer Polytechnic Institute, 110, 8th Street, Troy NY, 12180-3590; University of Central Florida Department of Mechanical and Aerospace Engineering Pegasus Blvd., P.O. Box 162450, Orlando, FL 32816-245012760, USA

DOI: 10.1615/TFEC2020.hte.031880
pages 401-408

Abstract

Supercritical carbon dioxide (SCO₂) has shown an excellent capability in cooling applications in recent decade for its stunningly high thermal efficiency along pseudocritical line. Airfoil shaped staggered micro pin fin array were modeled and designed inside the microchannel according to NACA 0030 standard profile with chord span of 160 µm, height of 100 µm, and dimensionless longitudinal an traversal pitch ratio of ζ_s = 2L_s/L_h, ζ_h = 2L_h/L_c, ζ_v = 2L_v/L_t. Then microfluidic device was fabricated at cleanroom. In this study, preliminary results for heat transfer performance of SCO₂ including local and average surface temperature, heat transfer coefficient, Nusselt number as a function of Reynolds number and Prandtl number, and the effect of applied heat flux on pressure drop are presented. In all experiments a pick value for heat transfer coefficient is observed at reduced temperature (T_bulk/T_PC) and pressure (P_bulk/P_PC) near unity. High values of heat transfer coefficient and Nusselt number up to 105000 w/m²k and 110 are obtained. Up to 70% deviation in Nusselt number is observed between experimental data and conventional correlation used in text books for internal turbulent flow, which illustrates the need for developing new correlations for SCO₂ with airfoil pin fin heat sink in micro scale. Also, small values of pressure drops up to 0.4 MPa is observed while using airfoil fin array, which is due to very small amount of friction coefficients for airfoil geometries