Rational form of the correlation of the heat transfer coefficients of organic liquids boiling at atmospheric pressure in vertical tubular apparatus with natural circulation

1972 ◽  
Vol 8 (6) ◽  
pp. 510-515
Author(s):  
N. I. Gel'perin ◽  
K. N. Solopenkov ◽  
A. Kh. Uzunov ◽  
V. V. Lyapin
Keyword(s):  
Heat Transfer ◽  
Atmospheric Pressure ◽  
Natural Circulation ◽  
Organic Liquids ◽  
Transfer Coefficients ◽  
Rational Form ◽  
Heat Transfer Coefficients

Method and tools for determining heat transfer coefficients in organic liquids and solutions

2020 ◽  
pp. 45-55
Author(s):  
Aleksandr S. MYAKOCHIN ◽  
Petr V. NIKITIN ◽  
Sergey Yu. POBEREZHSKIY ◽  
Anna A. SHKURATENKO
Keyword(s):  
Heat Transfer ◽  
Experimental Studies ◽  
Pulse Method ◽  
Organic Liquids ◽  
Transfer Coefficients ◽  
Resistance Thermometer ◽  
Film Sensor ◽  
Heat Transfer Coefficients ◽  
Aerospace Technology ◽  
New Generation

The paper presents a method, tools and a newly developed algorithm for experimentally determining heat transfer coefficients in organic liquids and solutions. This work is made relevant by the problem of development of a new generation of aerospace technology. In this connection, improvements have been made to the pulse method of determining heat transfer coefficients that is based on the use of a micron-thick film sensor. The measurement setup was modified. A math model was constructed for the measuring sensor. Algorithms were developed for conducting the experiment and processing measurement results to determine heat transfer coefficients. Experimental uncertainties were analyzed. The paper provides results of experimental studies on certain organic liquids. The authors believe that the material presented in the paper will find application in research conducted at research institutions, engineering offices and universities, among researches, postgraduates and students. Key words: thermal and physical characteristics, organic liquids and their solutions, film-type electrical resistor, thin-film temperature sensor, voltage pulse, resistance thermometer, irregular heat transfer regime.

The Use of Organic Coatings to Promote Dropwise Condensation of Steam

1987 ◽  
Vol 109 (3) ◽  
pp. 768-774 ◽  
Author(s):  
K. M. Holden ◽  
A. S. Wanniarachchi ◽  
P. J. Marto ◽  
D. H. Boone ◽  
J. W. Rose
Keyword(s):  
Heat Transfer ◽  
Atmospheric Pressure ◽  
Polymer Coatings ◽  
Organic Coatings ◽  
Major Constituent ◽  
Dropwise Condensation ◽  
Test Results ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Sustained Performance

Fourteen polymer coatings were evaluated for their ability to promote and sustain dropwise condensation of steam. Nine of the coatings employed a fluoropolymer as a major constituent; four employed hydrocarbons and one a silicone. Each coating was applied to 25-mm-square by approximately 1-mm-thick metal substrates of brass, copper, copper–nickel, and titanium. While exposed to steam at atmospheric pressure, each coating was visually evaluated for its ability to promote dropwise condensation. Observations were also conducted over a period of 22,000 hr. Hardness and adhesion tests were performed on selected specimens. On the basis of sustained performance, six coatings were selected for application to the outside of 19-mm-dia copper tubes in order to perform a heat transfer evaluation. These tubes were mounted horizontally in a separate apparatus through which steam flowed vertically downward. Steam-side heat transfer coefficients were inferred from overall measurements. Test results indicate that the steam-side heat transfer coefficient can be increased by a factor of five to eight through the use of polymer coatings to promote dropwise condensation.

An Experiment of Natural Circulation Flow and Heat Transfer With Supercritical Water in Parallel Channels

2016 ◽  
Vol 2 (3) ◽  
Author(s):  
Yuzhou Chen ◽  
Chunsheng Yang ◽  
Minfu Zhao ◽  
Keming Bi ◽  
Kaiwen Du
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flow Rate ◽  
Supercritical Water ◽  
Dynamic Instability ◽  
Flow Instability ◽  
Natural Circulation ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Parallel Channels

An experiment of natural circulation of supercritical water in parallel channels was performed in bare tubes of inner diameter 7.98 mm and heated length 1.3 m, covering the ranges of pressure of 24.7–25.5 MPa, mass flux of 400–1000  kg/m2 s, and heat flux of up to 1.83  MW/m2. When the heat flux reached 1.12  MW/m2, the outlet water temperature jumped from 325°C to 360°C, associated with a decrease in the flow rate and an initiation of dynamic instability. When the heat flux exceeded 1.39  MW/m2, the flow instability was stronger, and the flow rate increased in one channel and decreased in another one. Until the heat flux reached 1.61  MW/m2, the outlet water temperatures of two channels reached the pseudocritical point, and the flow rates of two channels tended to close each other. The experiment with a single heated channel was also performed for comparison. The measurements on the heat-transfer coefficients (HTCs) were compared to the calculations by the Bishop et al., Jackson’s, and Mokry et al. correlations, showing different agreements within various conditions.

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.

Some Effects of Geometry, Orientation, and Acceleration on Pool Film Boiling of Organic Fluids

1966 ◽  
Vol 88 (1) ◽  
pp. 17-23 ◽  
Author(s):  
C. A. Heath ◽  
C. P. Costello
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Atmospheric Pressure ◽  
Boiling Heat Transfer ◽  
Film Boiling ◽  
Transfer Coefficients ◽  
Actual System ◽  
Heat Transfer Coefficients ◽  
Organic Fluids ◽  
The Heat Transfer Coefficient

Ethanol, pentane, and Freon-113 were tested for atmospheric pressure, saturated film-boiling characteristics. Turbulent waves arise close to the bottom of vertical platinum plates and the data become identical to those obtained with horizontal plates, verifying an earlier contention by Y. P. Chang. The equation of Berenson fits the data for both horizontal and vertical heaters fairly well if modified for geometry, and the equation also correctly predicts the effect of acceleration on film-boiling heat-transfer coefficients. At high temperature differences, Berenson’s equation for the heat-transfer coefficient is slightly conservative, which is qualitatively predictable by analyzing the departures of the actual system from the idealized model of Berenson.

Heat Transfer to Sulfur Hexafluoride Near the Thermodynamic Critical Region in a Natural-Circulation Loop

1968 ◽  
Vol 90 (1) ◽  
pp. 37-42 ◽  
Author(s):  
G. E. Tanger ◽  
J. H. Lytle ◽  
R. I. Vachon
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Critical Region ◽  
Test Section ◽  
Specific Volume ◽  
Sulfur Hexafluoride ◽  
Natural Circulation ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Vertical Distance

Heat transfer near the thermodynamic critical region to sulfur hexafluoride was investigated in two closed natural circulation loops. The vertical distance between the test section and the heat exchanger was the primary difference between two loop configurations. Local and average heat transfer coefficients along the test section were calculated from the experimental data. Test results were correlated by the equation. (Nu)(Grf)(Pr)=0.00982(Re)11/4 The range of variables included: System pressure, 535–896 psia, mean fluid bulk temperature, 111–193 deg F; specific volume, 0.016–0.043 cu ft/lbm; heat flux, 1900–9040 Btu/hr sq ft. The highest heat transfer coefficients were obtained at system pressures and mean fluid bulk temperatures slightly greater than the critical values with mean specific volumes in the loop slightly less than the critical specific volume of the system fluid. The heat transfer coefficients were increased by expanding the vertical distance between the test section and heat exchanger.

scholarly journals Boiling of a refrigerant of low GWP on the surface with copper microchannels

2018 ◽  
Vol 70 ◽  
pp. 02007
Author(s):  
Robert Kaniowski ◽  
Robert Pastuszko
Keyword(s):  
Heat Transfer ◽  
Cross Section ◽  
Atmospheric Pressure ◽  
Rectangular Cross Section ◽  
Heating Surface ◽  
Heat Transfer Process ◽  
Geometrical Parameters ◽  
Variable Depth ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

The boiling curves and heat transfer coefficients between the heating surface and fluid were investigated in the paper. Copper samples with horizontal microchannels of rectangular cross-section, variable depth and width were the objects of the study. The following geometrical parameters have been used: microchannel width 0.2; 0.3 and 0.4 mm, depth between 0.2 and 0.5 mm (change every 0.1 mm). Boiling refrigerant was Novec-649 (GWP = 1), and the experiment was performed at atmospheric pressure. Geometrical parameters impact, within a given range of heat flux 3 – 130 kW/m2, on the heat transfer process was determined.

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.

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