ISSN Online: 2377-424X
ISBN Print: 978-1-56700-474-8
ISBN Online: 978-1-56700-473-1
International Heat Transfer Conference 16
CHARACTERISITICS OF POOL BOILING HEAT TRANSFER ON A HETEROGENEOUS WETTING MICROCHANNEL SURFACE
Abstrakt
Manipulation of wettability, such as the usage of hydrophobic/hydrophilic combined surfaces, has been proved to
enhance boiling heat transfer dramatically. However, most of the existing investigations about wettability
manipulation were performed on a two-dimensional planar surface, which neglected the influence of
microstructures. In order to find out the effect of non-uniform wettability on a 3D boiling surface, three types of
heterogenous wetting microchannel surface (TS#1, TS#2, TS#3) were fabricated by using surface modification
technology and Electrical Discharge Machining (EDM). Each microchannel has the same rectangular cross section
with a depth of 800 µm and width of 600 µm. These microchannel surfaces have the same contact angle of 113.2° for the sidewall and bottom surface, but for the top surface of the fin, the contact angles are 8.6°(TS#1), 88.1°(TS#2) and 156.1°(TS#3), respectively. With deionized water as the working fluid, the statured pool boiling heat transfer characteristics on these microchannel surfaces were investigated experimentally. Compared with the bare copper
surface (BS, θ=88.6°), the critical heat fluxes for TS#1 and TS#3 were increased by 61% and 35%, while the maximum heat transfer coefficients were increased by 2.3 and 6 times. By visualization investigation, it was found
that the bubble column coalescence was postponed due to the non-uniform wettability effect, thus the gaps among bubble columns can provide more effective routes for the liquid supplementary to the heated surface.