Boiling and Evaporation From Heat Pipe Wicks With Water and Acetone

1974 ◽  
Vol 96 (3) ◽  
pp. 331-337 ◽  
Author(s):  
A. Abhat ◽  
R. A. Seban
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Atmospheric Pressure ◽  
Saturated Vapor ◽  
Pool Boiling ◽  
Tube Surface ◽  
Evaporation Surface ◽  
Nucleation Sites ◽  
Boiling And Evaporation ◽  
Vertical Tubes

Heat transfer for pool boiling with flaxes in the range of 5 × 102 5 × 104 Btu/(ft2 hr) and the associated excess of wall over saturation temperatures are presented, primarily for atmospheric pressure, for vertical tubes in water, ethanol, and acetone, bare or wrapped with screen or felt metal. For the wrapped tubes, this performance is given also for evaporation into surrounding saturated vapor with the liquid being supplied by the wick: this is the significant mode in respect to heat pipe applications. For this mode maximum evaporation rates are also indicated and it is shown that this maximum can be rationalized either in terms of a partially full wick with conduction transfer to the evaporation surface or in terms of a full wick with vapor holes originating at nucleation sites on the tube surface.

scholarly journals Pool boiling of ethanol and FC-72 on open microchannel surfaces

2018 ◽  
Vol 180 ◽  
pp. 02042 ◽  
Author(s):  
Robert Kaniowski ◽  
Robert Pastuszko
Keyword(s):  
Heat Transfer ◽  
Atmospheric Pressure ◽  
Pool Boiling ◽  
Experimental Investigations ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Nucleation Sites ◽  
Open Microchannel ◽  
Acquisition Speed ◽  
Parallel Microchannels

The paper presents experimental investigations into pool boiling heat transfer for open microchannel surfaces. Parallel microchannels fabricated by machining were about 0.3 mm wide, and 0.2 to 0.5 mm deep and spaced every 0.1 mm. The experiments were carried out for ethanol, and FC-72 at atmospheric pressure. The image acquisition speed was 493 fps (at resolution 400 × 300 pixels with Photonfocus PHOT MV-D1024-160-CL camera). Visualization investigations aimed to identify nucleation sites and flow patterns and to determine the bubble departure diameter and frequency at various superheats. The primary factor in the increase of heat transfer coefficient at increasing heat flux was a growing number of active pores and increased departure frequency. Heat transfer coefficients obtained in this study were noticeably higher than those from a smooth surface.

Effects of a Flow Disturbing Plate on Pool Boiling Heat Transfer on a Vertical Tube

2003 ◽  
Author(s):  
Myeong-Gie Kang
Keyword(s):  
Heat Transfer ◽  
Atmospheric Pressure ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Vertical Tube ◽  
Tube Surface ◽  
Transfer Coefficients ◽  
Pool Boiling Heat Transfer ◽  
Heat Transfer Coefficients ◽  
Plate Width

Effects of the width and location of a flow disturbing circular plate, installed at a vertical tube surface, on nucleate pool boiling heat transfer of water at atmospheric pressure have been investigated experimentally. Through the tests, changes in the degree of intensity of liquid agitation have been analyzed. The plate changes the fluid flow around the tube as well as heat transfer coefficients on the tube surface. It is identified that the plate width changes the rate of the circulating flow whereas its location changes the growth of the active agitating flow. Moreover, the flow chugging was observed at the downside of the plate.

Pool Boiling on Polished and Chemically Etched Stainless-Steel Surfaces

1968 ◽  
Vol 90 (2) ◽  
pp. 231-238 ◽  
Author(s):  
R. I. Vachon ◽  
G. E. Tanger ◽  
D. L. Davis ◽  
G. H. Nix
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Stainless Steel ◽  
Atmospheric Pressure ◽  
Pool Boiling ◽  
304 Stainless Steel ◽  
Distilled Water ◽  
Preparation Technique ◽  
Nucleation Sites ◽  
Steel Surfaces

This paper presents pool boiling data at atmospheric pressure for mechanically polished and chemically etched 304 stainless-steel surfaces in contact with distilled water. The surfaces were prepared by these techniques to produce variation in nucleation sites. Surface roughness was varied from 2–61 rms. The results show the changes in heat transfer with varying rms surface roughness and preparation technique. The Rohsenow pool boiling correlation was used to discuss the data.

scholarly journals Effect of Uniformly and Nonuniformly Coated Al2O3 Nanoparticles over Glass Tube Heater on Pool Boiling

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Nitin Doifode ◽  
Sameer Gajghate ◽  
Abdul Najim ◽  
Anil Acharya ◽  
Ashok Pise
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
High Speed ◽  
Pool Boiling ◽  
Glass Tube ◽  
Al2o3 Nanoparticles ◽  
High Speed Camera ◽  
Coated Nanoparticles ◽  
Nucleation Sites ◽  
Coated Surface

Effect of uniformly and nonuniformly coated Al2O3 nanoparticles over plain glass tube heater on pool boiling heat transfer was studied experimentally. A borosilicate glass tube coated with Al2O3 nanoparticle was used as test heater. The boiling behaviour was studied by using high speed camera. Result obtained for pool boiling shows enhancement in heat transfer for nanoparticle coated surface heater and compared with plain glass tube heater. Also heat transfer coefficient for nonuniformly coated nanoparticles was studied and compared with uniformly coated and plain glass tube. Coating effect of nanoparticles over glass tube increases its surface roughness and thereby creates more nucleation sites.

Simple Model of Boiling Heat Transfer on Tubes in Large Pools

1997 ◽  
Vol 119 (2) ◽  
pp. 376-379 ◽  
Author(s):  
Y. Parlatan ◽  
U. S. Rohatgi
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Flux ◽  
Heat Exchanger ◽  
Atmospheric Pressure ◽  
Boiling Heat Transfer ◽  
Saturation Temperature ◽  
Flow Dynamics ◽  
Simple Method ◽  
Vertical Tubes

A simple method has been developed to model boiling heat transfer from a heat exchanger to pools using the experimental data available in the literature without modeling the flow dynamics of the pool. In this approach the heat flux outside vertical tubes is expressed as a function of outside wall temperature of the tubes and saturation temperature of the pool at or near atmospheric pressure.

On the Influence of the Thickness and Thermal Properties of Heating Walls on the Heat Transfer Coefficients in Nucleate Pool Boiling

1975 ◽  
Vol 97 (2) ◽  
pp. 173-178 ◽  
Author(s):  
U. Magrini ◽  
E. Nannei
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Atmospheric Pressure ◽  
Metal Layer ◽  
Pool Boiling ◽  
Transfer Coefficients ◽  
Heating Wall ◽  
Heat Transfer Coefficients ◽  
The Heat Transfer Coefficient ◽  
Zinc Nickel

An experimental investigation was conducted under conditions of saturated pool boiling of water at atmospheric pressure on thin, horizontal, cylindrical walls of different metals and thicknesses, electrically heated. The heating walls, ranging in thickness from 5 to 250 μm, were obtained by plating copper, silver, zinc, nickel, and tin on nonmetallic rods. Experiments showed that the heat transfer coefficient can be affected, in particular conditions, by the heating wall thickness. In particular, it resulted that the smaller the thermal conductivity of the metal layer, the higher the influence of the thickness. A semiempirical correlation of the form ΔT = (q/A)nf(κd, √κρc) suitable to correlate the experimental data within ±15 percent in the whole range of variables here investigated is proposed.

Effect of Nano-Particles on Pool Boiling Heat Transfer of Refrigerant 141b

2007 ◽  
Author(s):  
Da-Wei Liu ◽  
Chien-Yuh Yang
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Heat Transfer Performance ◽  
Pool Boiling ◽  
Nano Particles ◽  
Test Results ◽  
Tube Surface ◽  
Transfer Coefficients ◽  
Pool Boiling Heat Transfer ◽  
Heat Transfer Coefficients

Fluids with nano-sized particles have been proved that may effectively enhance the single-phase convective heat transfer performance. For pool boiling heat transfer, the published test results seems conflicted to each other. Some measured heat transfer coefficient decreased with increasing particle concentration but some showed no appreciable difference. This study provides an experimental investigation on pool boiling heat transfer performance of refrigerants R-141b with and without nano-sized Au particles on horizontal plain tubes. The test results show that the boiling heat transfer coefficients increase with increasing nano-particles concentration. At particles concentration of 1.0%, the heat transfer coefficient is more than twice higher than those without nano-particles. However, the heat transfer coefficients decreased for each test after every 5 days and finally close to those of R-141b without nano-particles. The SPM investigation shows that the test tube surface roughness decreased from 0.317 μm before boiling test to 0.162 μm after test. Further investigation by TEM and Dynamic Light Scattering particle analyzer shows that the nano-particles aggregated from 3 μm before test to 110 μm after test. This results show that the nano-sized Au particles are able to significantly increase pool boiling heat transfer of refrigerant R-141b on plain tube surface. The tube surface roughness and particle size changed after boiling test. Both of these effects degrade the boiling heat transfer coefficients.

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