Date:

2025-10-16

Title of Paper:

Experimental study on flow boiling of fluorocarbon fluid in the pin-ribbed micro-channel with rigid tails

Journal:

Int. J. Thermal Science

Summary:

In this work, a novel type of pin-ribbed micro-channel with rigid tails is designed based on the conventional pinribbed
 micro-channel. A comparative experimental study is carried out using ffuorocarbon ffuid Novec649. The
ffow boiling heat transfer and pressure drop characteristics are investigated under horizontal/vertical placement
at inlet subcooling temperature of 25 ◦C. The ranges of inlet mass ffux and heat ffux are 519–1818 kg⋅m− 2
⋅s
− 1
and 50–500 kW⋅m− 2
, respectively. The results show that at a given mass ffux, and heat ffux of 300–500 kW⋅m− 2
,
the vertical pin-ribbed micro-channel with rigid tails has the lowest average wall temperature, the largest
average heat transfer coefffcient, and the smallest total pressure drop, therefore it has the largest j-factor, more
than 60% higher than that of the horizontal/vertical channel without rigid-tails. With the aid of a high-speed
camera, the localized bubble movement phenomena in horizontal/vertical micro-channel with rigid tails was
photographed at a mass ffux of 519 kg⋅m− 2
⋅s
− 1 and a heat ffux of 100 kW⋅m− 2
. Three types of bubble detachment
modes in the wake region at the boiling stable state are observed: natural shedding, one-sided shear and twosided
 shear. The bubble detachment diameter under the one-sided shear is more than 23% smaller than that
of two-sided shear, and that of the horizontal channel is more than 44% higher than that in the vertical channel,
whereas its bubble detachment frequency is only 50% of that in the vertical channel. Therefore, the vertical
placement is more helpful for the rigid tails playing a role in the breakup and detachment of bubbles. The
experimental results conffrm the advantages of adding rigid tails behind the square-rib to enhance the
comprehensive heat transfer performance of ffow boiling, which can provide a guidance for the structural design
of two-phase miniature heat sinks.

Co-author:

Shuang Wang, Lei Xie, Mei Lin, Qiuwang Wang

Volume:

209

Page Number:

109541

Translation or Not:

No

Date of Publication:

2025-03-01