An Experimental Study of Boiling Heat Transfer on Mesh-Covered Fins

2009 ◽  
Author(s):  
Liang-Han Chien ◽  
H.-L. Huang
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Mesh Size ◽  
Wire Mesh ◽  
Finned Tubes ◽  
Enhanced Tubes ◽  
Boiling Heat Transfer Coefficient ◽  
Fin Tube ◽  
Enhanced Boiling ◽  
Fin Tubes

This study investigates a new enhanced boiling surface, which is made by wrapping wire mesh on finned tubes. Pool boiling performance of the new enhanced tubes has been tested in Refrigerant-134a at 5, 10, 20, and 26.67°C saturation temperatures. Brass or copper mesh of 80, 100, or 120 meshes per inch was wrapped on finned tubes of 42 or 60 FPI (fins per inch). The fin heights were either 0.2 mm or 0.4 mm. The test results show that the mesh covered fin tubes significantly enhanced the boiling performance by forming many pores of proper sizes on the surface and sustaining vapor in the tunnels formed by the mesh and fins. The preferred mesh size decreases with decreasing heat flux. The mesh covered on 60FPI fin tube having 0.4 mm fin height and 100 mesh per inch yields the best boiling performance. It enhances the boiling heat transfer coefficient by 7∼8 folds at 5°C as compared with the smooth tube.

Donald Q. Kern Lecture Award Paper: Odyssey of the Enhanced Boiling Surface

2004 ◽  
Vol 126 (6) ◽  
pp. 1051-1059 ◽  
Author(s):  
Ralph L. Webb
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Pore Diameter ◽  
Surface Geometry ◽  
Exchange System ◽  
Heat Exchange System ◽  
Fundamental Understanding ◽  
Boiling Heat Transfer Coefficient ◽  
Coated Surface ◽  
Enhanced Boiling

This paper traces the evolution of enhanced boiling surfaces. Early work was highly empirical and done in industrial research. The 1968 Milton patent [“Heat Exchange System,” U.S. Patent 3,696,861] described the first porous coated surface, and the 1972 Webb patent [“Heat Transfer Surface Having a High Boiling Heat Transfer Coefficient,” U.S. Patent 3,521,708] described a “structured” tube surface geometry. The first fundamental understanding of the “pore-and-tunnel” geometry was published by Nakayama in 1980 [Nakayama, W., Daikoku, T., Kuwahara, H., and Nakajima, T. 1980, “Dynamic Model of Enhanced Boiling Heat Transfer on Porous Surfaces Part I: Experimental Investigation,” J. Heat Transfer, 102, pp. 445–450]. Webb and Chien’s flow visualization allowed observation of the evaporation in the subsurface tunnels [Chien, L.-H., and Webb, R. L., 1998, “Visualization of Pool Boiling on Enhanced Surfaces,” Exp. Fluid Thermal Sci., 16b, pp. 332–341]. They also performed an experimental parametric study that defines the effect of pore diameter and pitch on the boiling performance. The progression of work on analytical boiling models is also reviewed.

Influencing Factors on Heat Transfer Performance for Flow Boiling of R410A in Horizontal Micro-Fin Tubes

2012 ◽  
Vol 472-475 ◽  
pp. 1676-1680
Author(s):  
Hong Ping He ◽  
Hu Gen Ma ◽  
Jian Mei Bai
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Forced Flow ◽  
Transfer Coefficients ◽  
Flow Boiling Heat Transfer ◽  
Boiling Heat Transfer Coefficient ◽  
Fin Tubes

Flow boiling heat transfer performances of refrigerant R410A in the horizontal micro-fin tubes with different geometric parameters were investigated. The dependencies of forced flow boiling heat transfer coefficient of R410A on mass flow rate, heat flux and were studied and the mechanism of flow boiling heat transfer under different working conditions were discussed. For a comparison, the influences of fin number and fin height of micro-fin tubes on heat transfer were also studied. The differences of heat transfer coefficient between R22 and R410A were analyzed. It is found that the heat transfer coefficients were nearly same for R22 and R410A and, in fact, the heat transfer coefficient of R22 was just a little higher than that of R410A by 4-7%.

Film Condensation of R-113 on In-Line Bundles of Horizontal Finned Tubes

1991 ◽  
Vol 113 (2) ◽  
pp. 479-486 ◽  
Author(s):  
H. Honda ◽  
B. Uchima ◽  
S. Nozu ◽  
H. Nakata ◽  
E. Torigoe
Keyword(s):  
Heat Transfer ◽  
Tube Bundle ◽  
Three Dimensional ◽  
Finned Tube ◽  
Film Condensation ◽  
Line Bundles ◽  
Finned Tubes ◽  
Fin Tube ◽  
Fin Tubes ◽  
Annular Fins

Film condensation of R-113 on in-line bundles of horizontal finned tubes with vertical vapor downflow was experimentally investigated. Two tubes with flat-sided annular fins and four tubes with three-dimensional fins were tested. The test sections were 3×15 tube bundles with and without two rows of inundation tubes at the top. Heat transfer measurements were carried out on a row-by-row basis. The heat transfer enhancement due to vapor shear was much less for a finned tube bundle than for a smooth tube bundle. The decrease in heat transfer due to condensate inundation was more marked for a three-dimensional fin tube than for a flat-sided fin tube. The predictions of the previous theoretical model for a bundle of flat-sided fin tubes agreed well with the measured data for low vapor velocity and a small to medium condensate inundation rate. Among the six tubes tested, the highest heat transfer performance was provided by the flat-sided fin tube with fin dimensions close to the theoretically determined optimum values.

An Experimental Study of R-113 Film Condensation on Horizontal Integral-Fin Tubes

1990 ◽  
Vol 112 (3) ◽  
pp. 758-767 ◽  
Author(s):  
P. J. Marto ◽  
D. Zebrowski ◽  
A. S. Wanniarachchi ◽  
J. W. Rose
Keyword(s):  
Heat Transfer ◽  
Surface Area ◽  
Theoretical Models ◽  
Smooth Tube ◽  
Film Condensation ◽  
Transfer Coefficients ◽  
Finned Tubes ◽  
Drainage Patterns ◽  
Fin Tube ◽  
Fin Tubes

Heat transfer measurements were made at near-atmospheric pressure on a smooth tube, on 24 integral-fin tubes having machined, rectangular-shaped fins, and on a commercial integral-fin tube. All tubes were made of copper. The vapor flowed vertically downward with a nominal velocity of 0.4 m/s. Vapor-side heat transfer coefficients were determined with a typical uncertainty of ± 7 percent using a “modified Wilson plot” technique. The vapor-side heat transfer coefficient of the integral-fin tubes (based upon the outside surface area of the smooth tube) was enhanced considerably more than the surface area enhancement provided by the fins. Heat transfer enhancements (for the same vapor-to-wall temperature difference) up to around 7 were measured for a corresponding area enhancement of only 3.9. The optimum fin spacing was found to lie between 0.2 and 0.5 mm, depending upon fin thickness and height. The data were compared with those of other investigations and with several existing theoretical models. Visual observations of condensate drainage patterns from the finned tubes were also made.

scholarly journals Flow Boiling Heat Transfer Characteristics in Horizontal, Three-Dimensional Enhanced Tubes

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 927 ◽  
Author(s):  
Zhi-Chuan Sun ◽  
Xiang Ma ◽  
Lian-Xiang Ma ◽  
Wei Li ◽  
David Kukulka
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Tube Length ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow Boiling Heat Transfer ◽  
Developed Surface ◽  
Enhanced Tubes ◽  
Surface Patterns

An experimental investigation was conducted to explore the flow boiling heat transfer characteristics of refrigerants R134A and R410A inside a smooth tube, as well as inside two newly developed surface-enhanced tubes. The internal surface structures of the two enhanced tubes are comprised of protrusions/dimples and petal-shaped bumps/cavities. The equivalent inner diameter of all tested tubes is 11.5 mm, and the tube length is 2 m. The experimental test conditions included saturation temperatures of 6 °C and 10 °C; mass velocities ranging from 70 to 200 kg/(m2s); and heat fluxes ranging from 10 to 35 kW/m2, with inlet and outlet vapor quality of 0.2 and 0.8. It was observed that the enhanced tubes exhibit excellent flow boiling heat transfer performance. This can be attributed to the complex surface patterns of dimples and petal arrays that increase the active heat transfer area; in addition, more nucleation sites are produced, and there is also an increased interfacial turbulence. Results showed that the boiling heat transfer coefficient of the enhanced surface tubes was 1.15–1.66 times that of the smooth tubing. Also, effects of the flow pattern and saturated temperature are discussed. Finally, a comparison of several existing flow boiling heat transfer models using the data from the current study is presented.

Numerical and Experimental Investigation Into the Effects of Nanoparticle Mass Fraction and Bubble Size on Boiling Heat Transfer of TiO2–Water Nanofluid

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Cong Qi ◽  
Yongliang Wan ◽  
Lin Liang ◽  
Zhonghao Rao ◽  
Yimin Li
Keyword(s):  
Heat Transfer ◽  
Bubble Size ◽  
Boiling Heat Transfer ◽  
Mass Fraction ◽  
Experimental Methods ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Mass Fractions ◽  
Boiling Heat Transfer Coefficient ◽  
Bubble Sizes

Considering mass transfer and energy transfer between liquid phase and vapor phase, a mixture model for boiling heat transfer of nanofluid is established. In addition, an experimental installation of boiling heat transfer is built. The boiling heat transfer of TiO2–water nanofluid is investigated by numerical and experimental methods, respectively. Thermal conductivity, viscosity, and boiling bubble size of TiO2–water nanofluid are experimentally investigated, and the effects of different nanoparticle mass fractions, bubble sizes and superheat on boiling heat transfer are also discussed. It is found that the boiling bubble size in TiO2–water nanofluid is only one-third of that in de-ionized water. It is also found that there is a critical nanoparticle mass fraction (wt.% = 2%) between enhancement and degradation for TiO2–water nanofluid. Compared with water, nanofluid enhances the boiling heat transfer coefficient by 77.7% when the nanoparticle mass fraction is lower than 2%, while it reduces the boiling heat transfer by 30.3% when the nanoparticle mass fraction is higher than 2%. The boiling heat transfer coefficients increase with the superheat for water and nanofluid. A mathematic correlation between heat flux and superheat is obtained in this paper.

Sign in / Sign up

Export Citation Format

Share Document