skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Nucleate boiling in drag-reducing polymer solutions

Abstract

Two types of experiment have been done to study the effects of polymer additives in nucleate boiling for plates and wires. Here, boiling on a flat surface is simulated by placing a flat unheated surface immediately underneath an electrically heated platinum wire. Saturated nucleate pool boiling curves were measured for water and solutions of six different polymers at various concentrations. For a bare wire and a simulated flat surface, the nucleate boiling curves are qualitatively similar. For equal heat fluxes, the temperature difference increases as the relative viscosity increases, although the temperature difference for the simulated flat surface is less than that for the bare wire. The observed changes in the nucleate boiling curves for polymer solutions are in qualitative agreement with those predicted using the Rohsenow correlation to account for change in the solution viscosity. These results show that for both wires and simulated flat surfaces, drag-reducing additives will reduce the heat transfer rate in nucleate boiling. Bubble dynamics on the heated wire and simulated flat surface were also measured using a high speed movie camera for water and Separan AP-30 at a relative viscosity of 1.16. The data were used to determine the relative contribution to the boilingmore » heat flux of latent heat transport by bubbles, natural convection heat transfer, and enhanced convection heat transfer.« less

Authors:
Publication Date:
Research Org.:
Stanford Univ., CA (USA)
OSTI Identifier:
5136565
Alternate Identifier(s):
OSTI ID: 5136565
Resource Type:
Thesis/Dissertation
Resource Relation:
Other Information: Thesis (Ph. D.)
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; NUCLEATE BOILING; HEAT TRANSFER; PLATES; WIRES; ADDITIVES; AQUEOUS SOLUTIONS; POLYMERS; SURFACES; BOILING; DISPERSIONS; ENERGY TRANSFER; MIXTURES; PHASE TRANSFORMATIONS; SOLUTIONS 420400* -- Engineering-- Heat Transfer & Fluid Flow

Citation Formats

Jeun, G. Nucleate boiling in drag-reducing polymer solutions. United States: N. p., 1986. Web.
Jeun, G. Nucleate boiling in drag-reducing polymer solutions. United States.
Jeun, G. Wed . "Nucleate boiling in drag-reducing polymer solutions". United States. doi:.
@article{osti_5136565,
title = {Nucleate boiling in drag-reducing polymer solutions},
author = {Jeun, G.},
abstractNote = {Two types of experiment have been done to study the effects of polymer additives in nucleate boiling for plates and wires. Here, boiling on a flat surface is simulated by placing a flat unheated surface immediately underneath an electrically heated platinum wire. Saturated nucleate pool boiling curves were measured for water and solutions of six different polymers at various concentrations. For a bare wire and a simulated flat surface, the nucleate boiling curves are qualitatively similar. For equal heat fluxes, the temperature difference increases as the relative viscosity increases, although the temperature difference for the simulated flat surface is less than that for the bare wire. The observed changes in the nucleate boiling curves for polymer solutions are in qualitative agreement with those predicted using the Rohsenow correlation to account for change in the solution viscosity. These results show that for both wires and simulated flat surfaces, drag-reducing additives will reduce the heat transfer rate in nucleate boiling. Bubble dynamics on the heated wire and simulated flat surface were also measured using a high speed movie camera for water and Separan AP-30 at a relative viscosity of 1.16. The data were used to determine the relative contribution to the boiling heat flux of latent heat transport by bubbles, natural convection heat transfer, and enhanced convection heat transfer.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jan 01 00:00:00 EST 1986},
month = {Wed Jan 01 00:00:00 EST 1986}
}

Thesis/Dissertation:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this thesis or dissertation.

Save / Share:
  • Nucleate boiling curves and bubble dynamics have been experimentally measured in both pure water and aqueous solutions of drag-reducing polymers. The boiling curves have been measured using an electrically heated platinum wire submerged in a saturated pool of liquid at atmospheric pressure. Polymer concentrations corresponding to relative viscosities of 1.01, 1.04, 1.08, 1.16, and 1.32 have been tested. The observed changes in the nucleate boiling curves for polymer solutions are in qualitative agreement with those predicted based only on how the polymers change the solution viscosity. Drag reduction effects appear to be unimportant. The bubble dynamics have been measured usingmore » a high speed movie camera. For pure water, the average number density of active nucleation sites has been found to increase linearly with the boiling heat flux. In addition, the frequency distribution of bubble departure diameters has been found to be well represented by an asymptotic expansion of the normal frequency function. These data have been used to determine the relative contributions to the boiling heat flux of latent heat transport by vapor bubbles, natural convection heat transfer, and enhanced convection heat transfer. For drag-reducing polymer solutions, the bubble dynamics are significantly different from those observed with pure water. Each specific type of polymer changes the nucleation characteristics of the heated surface, and therefore, generalizations cannot be made as to how drag-reducing polymers as a group affect the bubble dynamics.« less
  • The enhancement of nucleate boiling by small amounts of added polymer has been demonstrated. The mechanism for this enhancement is unknown, although a number of possibilities have been proposed. A likely candidate which emerged from literature research is a mechanism which assumes that the added polymer increases the thermal boundary layer thickness, delta, at the heated surface and decreases mixing with the bulk fluid. More heat is thus available at the surface thereby increasing latent heat transfer. The assumptions of this mechanism were tested theoretically and experimentally. A model for single bubble growth explicitly including delta was constructed. Temperature profilesmore » above a boiling surface were measured with a thermocouple probe in both water and four organic solvents containing hydroxyethylcellulose and polysiobutylene, respectively. Results were compared with those obtained in the pure solvents for both a 600 grit polished and a 0.05 micron polished copper surface. The bubble growth model was found to compare well with available growth data both with pure fluids and polymer solutions when the increased viscosity was taken into account.« less
  • Nucleate boiling curves for aqueous solutions of drag-reducing polymers have been measured experimentally. The polymers examined are a galactomannan polysaccharide (Galactasol 211), a polyacrylamide (Separan MGL), two polymers consisting of both acrylamide and acrylic acid monomers (Separan NP-10P and Separan AP-30), two polyethylene oxides (Aldrich No. 18202-8 and No. 18946-4), and three hydroxyethyl celluloses (Natrosol 250MR, 250HR, and 250HHR). The boiling curves have been measured using an electrically heated platinum wire submerged in a saturated pool of liquid at atmospheric pressure. Polymer concentrations corresponding to relative viscosities of 1.01, 1.04, 1.08, 1.16, and 1.32 have been tested. The observed changesmore » in the nucleate boiling curves for polymer solutions are in qualitative agreement with those predicted by the Rohsenow pool boiling correlation. In particular, the temperature shifts in the boiling curves are predicted adequately based only on how the polymers change the solution surface tension and, more importantly, the solution viscosity. Drag reduction effects appear to be unimportant; hence, polymer type, molecular weight, and concentration are important only insofar as they affect solution properties. These results differ from those reported by earlier investigators for pool boiling of dilute polymer solutions on heated flat plates.« less
  • The nucleate boiling heat-transfer coefficient and the maximum heat flux were studied experimentally as functions of velocity, quality and heater diameter for single-phase flow, and two-phase flow of Freon-113 (trichlorotrifluorethane). Results show: (1) peak heat flux: over 300 measured peak heat flux data from two 0.875-in. and four 0.625-in.-diameter heaters indicated that: (a) for pool boiling, single-phase and two-phase forced convection boiling the only parameter (among hysteresis, rate of power increase, aging, presence and proximity of unheated rods) that has a statistically significant effect on the peak heat flux is the velocity. (b) In the velocity range (0 < U/submore » infinity/ < 0.68 ft/sec) covered in this study the peak heat flux appears to exhibit a shallow minimum in the vicinity of U/sub infinity/ - 0.4 ft/sec. (c) The two-phase flow peak heat flux is 8 to 15% higher than the single-phase flow peak heat flux and the increase is independent of the quality of the flowing mixture. (d) For simultaneously heated elements at identical power inputs the excursion into film boiling always occurs at the most upstream heater regardless of the flow conditions. (2) Boiling pattern: single-phase forced convection drastically reduces the thickness of the two-phase zone surrounding the heater. (3) Local surface temperature: the coldest and the hottest spots of the heater are identified as the bottom (0/sup 0/ position or the point of impact of the incident fluid) and the top (180/sup 0/ position) of the test element, respectively.« less