Abstract
We conducted experimental research using high-porosity sintered fiber attached on the surface, as a passive method to increase the heat flux for subcooled flow boiling. Two different porous thicknesses (1 and 0.5 mm) and one bare surface (0 mm) were compared under three different inlet subcooling temperatures (30, 50 and 70 K) and low mass flux (150–600 kg·m−2·s−1) using deionized water as the working fluid under atmospheric pressure. The test section was a rectangular channel, and the hydraulic diameter was 10 mm. The results showed that the heat flux on porous surfaces with a thickness of 1 and 0.5 mm increased by 60% and 40%, respectively, compared to bare surfaces at ΔTsat = 40 K at a subcooled temperature of 50 K and mass flux of 300 kg·m−2·s−1. An abrupt increase in the wall superheat was avoided, and critical heat flux (CHF) was not reached on the porous surfaces. The flow pattern and bubble were recorded with a high-speed camera, and the bubble dynamics are discussed.
Highlights
The heat transfer process has been investigated due to the high heat flux dissipation demand of modern cooling systems
The temperature of copper block A was controlled by a proportional integral derivate (PID) controller; the test section was set to the desired heat flux and wall superheat
K, where the bubble formation transfer was dominant; around ∆Tsat = 20 K, where the bubble formation became became and intense and nucleate heat transfer became dominant, heat flux theporous intense nucleate boilingboiling heat transfer became dominant, thethe heat flux ofofthe porous surface was improved in comparison to the bare surface at the same wall surface was improved in comparison to the bare surface at the same wall superheat degree
Summary
The heat transfer process has been investigated due to the high heat flux dissipation demand of modern cooling systems. Proposed a honeycomb porous media on pool boiling and their results showed an enhancement in the critical heat flux (CHF) of approximately 2.5 times in comparison with the plain surface. They attributed the CHF performance to the capillary suction, permeability, pore radius, wall thickness, height of the porous media, and vapor scape channels. Leong et al [27] reviewed the literature and compared the works related to flow boiling and pool boiling, concluding that the nucleation site density was higher for the porous media than for the plain surfaces These nucleation sites promote bubble formation and fast heat dissipation. The bubble formation was recorded and analyzed with a high-speed camera
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