Experimental investigation of flow boiling in a novel semi-open micro-pin-finned heat sink with regionally decreasing heights under low mass flux
Applied Thermal Engineering, cilt.303, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 303
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.applthermaleng.2026.132478
- Dergi Adı: Applied Thermal Engineering
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Compendex, INSPEC, DIALNET, Business Source Ultimate (EBSCO)
- Anahtar Kelimeler: Flow boiling, Low mass flux, Scaling analysis, Semi-open micro-pin-finned heat sink, Stage-wise decreasing pin-fin heights
- Recep Tayyip Erdoğan Üniversitesi Adresli: Evet
Özet
This study introduces and experimentally investigates a novel semi-open micro square pin-finned heat sink (DPFH) featuring stage-wise decreasing pin-fin heights to address an identified gap in flow boiling literature. Testing was conducted under a low mass flux of 76 kg m−2 s−1, covering a heating power range from 140 W to 300 W (equivalent to an effective heat flux of 211.8 to 461.4 kW m−2). High-speed flow visualization and thermal metrics were evaluated against a uniform baseline (UPFH). For the DPFH, CHF was not observed even at the maximum heat flux tested, and across the tested operational conditions, the two-phase heat transfer coefficient was enhanced by up to approximately 513% compared with the UPFH. This superior performance stems from the stage-wise expanding passages, which mitigate the adverse hydrodynamic effects of the evaporation momentum force and introduce a supportive unbalanced surface tension force, promoting rapid vapor discharge and rewetting. Flow images uniquely revealed partial bubble breakup in the 100 μm clearance, which is consistent with stronger viscous/shear interactions. Regional variations in Bo, Re, We, Ca, and Co, together with area-normalized force-scale terms, further support the reduced vapor confinement, enhanced vapor discharge, and clearance-dependent bubble deformation observed in the DPFH. Despite a manageable pressure drop penalty of 10.5% to 60.3%, the DPFH achieved a maximum performance evaluation criterion (PEC) of 5.82 and reduced inlet pressure fluctuations by about 46.7%, significantly mitigating flow boiling instabilities.