A review of boiling heat transfer and heat pipes behaviour with self-rewetting fluids

Hu, Yi; Huang, Kaixin; Huang, Jin

doi:10.1016/j.ijheatmasstransfer.2017.12.158

Cited by 47 publications

(8 citation statements)

References 47 publications

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“…The use of binary mixtures to improve the wettability of used fluids which affect the adhesion and surface tension forces that reduce the entrainment effect during the transit of the two-phases streams inside the THP [11,12]. ii.…”

Section: Introductionmentioning

confidence: 99%

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Study of Heat Pipe Thermal Performance with Internal Modified Geometry

Temimy¹,

Abdulrasool

Hamad

2021

Fluids

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The aim of this study was to investigate the effect of inserting a new internal tube packing (TP) on the thermal performance of a thermosyphon heat pipe (THP). The THP pipe was made from copper with an inner diameter of 17.4 mm and length of 600 mm. The new internal tube packing (TP) had a central copper disc with two copper tubes soldered onto both sides to transport vapor and condensate. The upper tube or riser had an inner diameter of 8.3 mm and was 300 mm long; it was connected to a hole in the disc from the upper side to transport the steam to the condenser section. The lower tube or downcomer had an inner diameter of 5 mm, was 225 mm long and was connected to the lower side of the disc to collect the condensate and transport it to the evaporator. The TP was inserted inside the THP to complete the design of the improved heat pipe (TPTHP). Experimental results showed that the TPTHP reduces the transit time from 16 to 11 min and the thermal resistance by 17–62% based on the input power and depending on the conditions of the THP. The results also showed that the inclination angle and filling ratio have no effect on the thermal resistance of the TPTHP.

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Section: Introductionmentioning

confidence: 99%

“…The condenser performance was also modified using extensive fins on the heat transfer/cooling walls. Several studies have shown that both techniques enhance the THP [11,12,[17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Study of Heat Pipe Thermal Performance with Internal Modified Geometry

Temimy¹,

Abdulrasool

Hamad

2021

Fluids

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“…The surface tension plays an essential role in determining the heat and fluid flow characteristics (Ho et al, 2018;Dijksman et al, 2019;Wang et al, 2019). The effect of surface HFF 31,4 tension gradient vitally affects the capillarity and dry-out limit of a microscale phase-change heat transfer device (Fumoto and Kawaji, 2011;Hu et al, 2014a;Fumoto et al, 2015;Sitar and Golobic, 2015;Hu et al, 2018). While most of the working fluids possess a negative surface tension gradient, the thermal performance of a working fluid is overrated when the thermocapillary effect is neglected (Lim and Hung, 2015).…”

Section: Introductionmentioning

confidence: 99%

“…Heptanol is considered immiscible in water, hence the thermo-physical properties of water are not affected by the addition of a small quantity of heptanol, except that the surface tension gradient is altered. Although the thermal enhancement induced by the self-rewetting fluid in a two-phase flow microscale system is evident (Fumoto and Kawaji, 2011;Hu et al, 2014a;Fumoto et al, 2015;Sitar and Golobic, 2015;Hu et al, 2018), the fundamental characteristics of evaporation and the heat transfer enhancement have not been fully understood. To elucidate the underlying physical transport phenomena associated with the inverse thermocapillary effect in an evaporating thin film of self-rewetting liquid, we numerically model and study the hydrodynamic and thermal characteristics of such liquid.…”

Section: Introductionmentioning

confidence: 99%

Inverse-thermocapillary evaporation in a thin liquid film of self-rewetting fluid

Lim

Kueh²,

Hung³

2020

HFF

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Purpose The present study aims to investigate the inverse-thermocapillary effect in an evaporating thin liquid film of self-rewetting fluid, which is a dilute aqueous solution (DAS) of long-chain alcohol. Design/methodology/approach A long-wave evolution model modified for self-rewetting fluids is used to study the inverse thermocapillary characteristics of an evaporating thin liquid film. The flow attributed to the inverse thermocapillary action is manifested through the streamline plots and the evaporative heat transfer characteristics are quantified and analyzed. Findings The thermocapillary flow induced by the negative surface tension gradient drives the liquid from a low-surface-tension (high temperature) region to a high-surface-tension (low temperature) region, retarding the liquid circulation and the evaporation strength. The positive surface tension gradients of self-rewetting fluids induce inverse-thermocapillary flow. The results of different working fluids, namely, water, heptanol and DAS of heptanol, are examined and compared. The thermocapillary characteristic of a working fluid is significantly affected by the sign of the surface tension gradient and the inverse effect is profound at a high excess temperature. The inverse thermocapillary effect significantly enhances evaporation rates. Originality/value The current investigation on the inverse thermocapillary effect in a self-rewetting evaporating thin film liquid has not been attempted previously. This study provides insights on the hydrodynamic and thermal characteristics of thermocapillary evaporation of self-rewetting liquid, which give rise to significant thermal enhancement of the microscale phase-change heat transfer devices.

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“…Note also, that some alcohol solutions have revealed an increase in surface tension with temperature (selfrewetting) which can prevent surface dry-out in boiling, as per Refs. [24][25][26]. Hence, selfrewetting liquids are mixtures with unique properties due to which both thermal and concentration Maran-goni flows are directed to the hot regions resulting in rewetting of the heater surface.…”

Section: Introductionmentioning

confidence: 99%

Pool boiling in deep and shallow vessels and the effect of surface nano-texture and self-rewetting

Sankaran

Zhang

Yarin

2018

International Journal of Heat and Mass Transfer

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Pool boiling of ethanol and self-rewetting fluids on bare copper surface and copper surface with polymer nanofibers were studied experimentally. No significant effect of the depths of ethanol layer on the heat removal rate was found. That indicates that only the heat transfer in the liquid microlayer near the heater surface is a dominant factor. As a result, one can expect that selfrewetting fluids can significantly affect boiling performance. Accordingly, several alcohol solutions including the self-rewetting ones were investigated as working fluids in the boiling chamber. It was found that at the 0.1% (v/v) concentration, only the high carbon-alcohol, nheptanol in aqueous solution, improved boiling heat transfer considerably. Furthermore, the experimental study of the effect of surface nano-texture on boiling characteristics was undertaken. For that aim, polyacrylonitrile (PAN) nanofibers were deposited onto the copper heater surface. Measurements of the boiling curve revealed a detrimental effect of such nano-texture in the case of such working fluids as ethanol and self-rewetting n-heptanol solutions. On the other hand, when polystyrene (PS) nanofibers were deposited onto the copper heater surface instead of PAN nanofibers, a significant improvement in boiling heat transfer was observed. The more hydrophobic nature of PS compared to copper is responsible for this effect, i.e. is the reason of the heat transfer enhancement on such a nano-textured surface compared to the pure copper one. In addition, the critical heat flux in the case of n-heptanol solution was found to be reduced considerably on the PS nano-textured surface compared to the pure copper one. This stems from the increased propensity of the heater surface to be covered by vapor, while the rewetting is insufficiently effective at high heat fluxes in presence of PS nanofibers.

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A review of boiling heat transfer and heat pipes behaviour with self-rewetting fluids

Cited by 47 publications

References 47 publications

Study of Heat Pipe Thermal Performance with Internal Modified Geometry

Study of Heat Pipe Thermal Performance with Internal Modified Geometry

Inverse-thermocapillary evaporation in a thin liquid film of self-rewetting fluid

Pool boiling in deep and shallow vessels and the effect of surface nano-texture and self-rewetting

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