Heat Transfer in a Reciprocating Thermosyphon Fitted with Staggered Transverse Ribs

Chang, Shyy Woei; Morris, William Z.; Liou, Tong‐Miin; Chiou, Shyr Fuu

doi:10.2514/1.28131

Cited by 6 publications

(14 citation statements)

References 22 publications

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“…For a blind duct, the HTE impacts of these passive devices are considerably suppressed from the Poiseuille-flow counterparts. Only marginal HTE impacts are generated in an antigravity blind duct which is enhanced by twisted tape insert [8], surface ribs [9] or channel inclination [10]. The limited HTE performances attributed from these HTE devices in a blind duct are mainly caused by the weak flow momentum in the duct-wise direction.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Turbulent Flow and Heat Transfer in an Anti- Gravity Blind Duct with Tangential Entry Jet

Chang¹

2011

TOTHERJ

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This numerical study investigates the flow and heat transfer characteristics in a vertical square blind duct with the coolant fed by a tangential entry jet. The detailed Nusselt number (Nu) distributions over the five constituent walls of the blind duct are calculated at duct (jet) Reynolds numbers Re(Re j ) of 5000(20000), 7000(28000) and 10000(40000) using the commercial CFD Star CD code. As an attempt to explore the buoyancy effect on heat transfer performances, three different heat fluxes, which vary the gravitational Grashof numbers (Gr g ) at the fixed Re, are imposed on each duct wall to vary the buoyancy levels. The jet-induced flow phenomena in the blind duct exhibit various heat transfer impacts on the five duct walls over which the different near-wall flow structures are generated. This is demonstrated by cross-examining the detailed Nu distributions and the area-averaged Nusselt number ( Nu ) over the five duct walls at the tested Re and Gr g . The cross-plane swirls induced by the tangential entry jet together with the impinging jet flows considerably elevate the Heat Transfer Enhancement (HTE) performances in the blind duct. Within the parametric conditions simulated, the ratios of Nu to the Dittus-Boelter levels (Nu ) over the jet wall, back wall, impingement wall, side wall and end wall are respectively raised to 3-5.7, 2.8-5.6, 3-5.8, 2.7-4.8 and 3.1-6.1; while the HTE ratios ( Nu /Nu ) over these duct walls consistently decrease as Re increases.

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Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Turbulent Flow and Heat Transfer in an Anti- Gravity Blind Duct with Tangential Entry Jet

Chang¹

2011

TOTHERJ

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“…Nusselt [1,2,4], this research group starts probing into the thermophysics in a titled reciprocating open thermosyphon since the most of blind bores featured in Fig. 1a are tilted.…”

Section: Introductionmentioning

confidence: 99%

“…In this respect, increases of vibration frequency generally improve heat transfer but can also decrease heat transfer in the so-called intermediate vibrational convection regime [15,16]. Although the periodic forces acting on fluids in cavities can be introduced by the pulsating heat fluxes [13] or the additional vibrational forces [14][15][16], subtle differences in thermophysics still exist between the cavities examined in [14][15][16] and the reciprocating thermosyphons studied by [1,2,4,17]. In the case of reciprocating anti-gravity open thermosyphon, the channel is reciprocated that affect the buoyancy interaction and the flow condition developed over the open-end of the thermosyphon [1,2,4,17].…”

Section: Introductionmentioning

confidence: 99%

“…Although the periodic forces acting on fluids in cavities can be introduced by the pulsating heat fluxes [13] or the additional vibrational forces [14][15][16], subtle differences in thermophysics still exist between the cavities examined in [14][15][16] and the reciprocating thermosyphons studied by [1,2,4,17]. In the case of reciprocating anti-gravity open thermosyphon, the channel is reciprocated that affect the buoyancy interaction and the flow condition developed over the open-end of the thermosyphon [1,2,4,17]. With weak reciprocating forces, heat transfer coefficients are initially impaired from the static levels but recovered after further increases of reciprocating forces in the vertical anti-gravity open thermosyphon with smooth or ribbed surfaces [1,4].…”

Section: Introductionmentioning

confidence: 99%

“…In the case of reciprocating anti-gravity open thermosyphon, the channel is reciprocated that affect the buoyancy interaction and the flow condition developed over the open-end of the thermosyphon [1,2,4,17]. With weak reciprocating forces, heat transfer coefficients are initially impaired from the static levels but recovered after further increases of reciprocating forces in the vertical anti-gravity open thermosyphon with smooth or ribbed surfaces [1,4]. In the likewise reciprocating thermosyphon with twisted tape insert, the isolated reciprocating force effect consistently improves heat transfer at both sub-cooled and superheated conditions [17].…”

Section: Introductionmentioning

confidence: 99%

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