Experimental Study of Effects of Interfacial Properties on Nucleate Pool Boiling in Water

2011 ◽  
Author(s):  
U. Verma ◽  
R. M. Manglik ◽  
M. A. Jog
Keyword(s):  
Heat Transfer ◽  
Interfacial Tension ◽  
Aqueous Solutions ◽  
Pool Boiling ◽  
Interfacial Properties ◽  
Dynamic Surface Tension ◽  
Chain Molecule ◽  
Nucleate Pool Boiling ◽  
Dynamic Surface ◽  
Fluorinated Carbon

Saturated, nucleate pool boiling on a horizontal, cylindrical heater in aqueous solutions of a fluorosurfactant (FS-50) is experimentally investigated. FS-50 is a long chain molecule of fluorinated carbon atoms, and it produces very low dynamic surface tension (varying from 72.5 mN/m to 17.4 mN/m with surface age and concentration) in aqueous solutions. Boiling curves (given by the variation of heat flux with wall superheat) and photographic records of the ebullient behavior are presented, along with a detailed characterization of the interfacial tension of the solutions. It is seen that nucleate pool boiling behavior of water is significantly altered by the addition of FS-50, and the heat transfer is increased. The enhancement in boiling is seen to stem from the substantial changes in the interfacial properties. A rather complex interplay of dynamic interfacial tension and surface wetting due to varying surfactant concentrations is seen to affect the phase change ebullient dynamics and associated heat transfer.

Pseudoplasticity and Dynamic Interfacial Tension Relaxation Effects on Nucleate Pool Boiling in Aqueous Polymeric Liquids

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
R. M. Manglik ◽  
A. D. Athavale
Keyword(s):  
Heat Transfer ◽  
Interfacial Tension ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Shear Thinning ◽  
Heat Fluxes ◽  
Nucleate Pool Boiling ◽  
Dynamic Surface ◽  
Boiling Regime ◽  
Polymeric Solutions

Nucleate pool boiling heat transfer and its ebullient dynamics in polymeric solutions at atmospheric pressure saturated conditions are experimentally investigated. Three grades of hydroxyethyl cellulose (HEC) are used, which have intrinsic viscosity in the range 5.29 ≤ [η] ≤ 10.31 [dl/g]. Their aqueous solutions in different concentrations, with zero-shear viscosity in the range 0.0021 ≤ η0 ≤ 0.0118 [N⋅s/m2], exhibit shear-thinning rheology in varying degrees, as well as gas–liquid interfacial tension relaxation and wetting. Boiling heat transfer in solutions with constant molar concentrations of each additive, which are greater than their respective critical polymer concentration C*, is seen to have anomalous characteristics. There is degradation in the heat transfer at low heat fluxes, relative to that in the solvent, where the postnucleation bubble dynamics in the partial boiling regime is dominated by viscous resistance of the polymeric solutions. At higher heat fluxes, however, there is enhancement of boiling heat transfer due to a complex interplay of pseudoplasticity and dynamic surface tension effects. The higher frequency vapor bubbling train with high interfacial shear rates in this fully developed boiling regime tends to be influenced by increasing shear-thinning and time-dependent differential interfacial tension relaxation at the dynamic gas–liquid interfaces.

Additive Adsorption and Interfacial Characteristics of Nucleate Pool Boiling in Aqueous Surfactant Solutions

2005 ◽  
Vol 127 (7) ◽  
pp. 684-691 ◽  
Author(s):  
Juntao Zhang ◽  
Raj M. Manglik
Keyword(s):  
Contact Angle ◽  
Pure Water ◽  
Pool Boiling ◽  
Dynamic Surface Tension ◽  
Nucleate Pool Boiling ◽  
Dynamic Surface ◽  
Wetting Contact Angle ◽  
Optimum Heat ◽  
Adsorption Desorption ◽  
And Control

Interfacial phenomena and ebullient dynamics in saturated nucleate pool boiling of aqueous solutions of three surfactants that have different molecular weight and ionic nature are experimentally investigated. The additive molecular mobility at interfaces manifests in a dynamic surface tension behavior (surfactant adsorption–desorption at the liquid–vapor interface), and varying surface wetting (contact angle) with concentration (surfactant physisorption at the solid–liquid interface). This tends to change, enhance, and control the boiling behavior significantly, and an optimum heat transfer enhancement is obtained in solutions at or near the critical micelle concentration (CMC) of the surfactant. Furthermore, wettability (contact angle) is observed to be a function of the molecular makeup of the reagent, and shows distinct regions of change along the adsorption isotherm that are associated with the aggregation mode of adsorbed ions at the solid–water interface. This distinguishably alters the ebullience from not only that in pure water, but also between pre- and post-CMC solutions. Increased wetting tends to suppress nucleation and bubble growth, thereby weakening the boiling process.

Nucleate Pool Boiling Heat Transfer in Microgravity

1998 ◽  
Vol 29 (1-3) ◽  
pp. 196-207
Author(s):  
Haruhiko Ohta ◽  
Koichi Inoue ◽  
Suguru Yoshida ◽  
Tomoji S. Morita
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Nucleate Pool Boiling ◽  
Pool Boiling Heat Transfer
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