Film Condensation of Refrigerant-113 and Ethanediol on a Horizontal Tube—Effect of Vapor Velocity

1984 ◽  
Vol 106 (3) ◽  
pp. 524-530 ◽  
Author(s):  
W. C. Lee ◽  
S. Rahbar ◽  
J. W. Rose
Keyword(s):  
Heat Transfer ◽  
Ethylene Glycol ◽  
Horizontal Tube ◽  
Low Pressure ◽  
Film Condensation ◽  
Vapor Velocity

Heat transfer measurements are reported for condensation of refrigerant-113 and ethanediol (ethylene glycol) on a single horizontal tube with vertical downflow. For refrigerant-113, vapor velocities up to around 6 m/s were obtained, while for ethanediol, velocities in excess of 100 m/s were obtained at low pressure. The results are compared with those of earlier investigators and with theory.

An Analytical Study of Laminar Film Condensation: Part 2—Single and Multiple Horizontal Tubes

1961 ◽  
Vol 83 (1) ◽  
pp. 55-60 ◽  
Author(s):  
Michael Ming Chen
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Horizontal Tube ◽  
Vertical Tube ◽  
Film Condensation ◽  
Transfer Coefficients ◽  
Inertia Effects ◽  
Horizontal Tubes ◽  
Laminar Film ◽  
Laminar Film Condensation

The boundary-layer equations for laminar film condensation are solved for (a) a single horizontal tube, and (b) a vertical bank of horizontal tubes. For the single-tube case, the inertia effects are included and the vapor is assumed to be stationary outside the vapor boundary layer. Velocity and temperature profiles are obtained for the case μvρv/μρ ≪ 1 and similarity is found to exist exactly near the top stagnation point, and approximately for the most part of the tube. Heat-transfer results computed with these similar profiles are presented and discussed. For the multiple-tube case, the analysis includes the effect of condensation between tubes, which is shown to be partly responsible for the high observed heat-transfer rate for vertical tube banks. The inertia effects are neglected due to the insufficiency of boundary-layer theory in this case. Heat-transfer coefficients are presented and compared with experiments. The theoretical results for both cases are also presented in approximate formulas for ease of application.

Experimental Study of Film Condensation From Steam-Air Mixtures Flowing Downward Over a Horizontal Tube

1974 ◽  
Vol 96 (1) ◽  
pp. 83-88 ◽  
Author(s):  
J. W. Rauscher ◽  
A. F. Mills ◽  
V. E. Denny
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Theoretical Analysis ◽  
Mass Fraction ◽  
Horizontal Tube ◽  
Forced Flow ◽  
Film Condensation ◽  
Air Mass ◽  
Average Value ◽  
Pure Steam

Experiments have been performed to study the effects of air on filmwise condensation from steam-air mixtures undergoing forced flow over a 3/4 in. OD horizontal tube. Local condensation rates at the stagnation point are reported for saturation temperatures of 100–150 deg F, bulk to wall temperature differences of 3–30 deg F, bulk air mass fraction 0–7 percent and oncoming vapor velocity 1–6 ft/sec. For pure steam the average value of q/qNu, where qNu is the Nusselt result, was 0.98 ± 0.10, which compares favorably with the value of 1.04 predicted by a theory which accounts for vapor drag. For steam-air mixtures the reduction in heat transfer was found to be in excellent agreement with the theoretical analysis of Denny and South; the average discrepancy in q/qNu was −2.7 percent, while the maximum was 7.1 percent.

Stratified Flow Condensation of CO2 in a Tube at Low Temperatures

2015 ◽  
Vol 789-790 ◽  
pp. 184-192
Author(s):  
Pei Hua Li ◽  
Joe Deans ◽  
Stuart Norris
Keyword(s):  
Heat Transfer ◽  
Temperature Difference ◽  
Saturation Temperature ◽  
Horizontal Tube ◽  
Stratified Flow ◽  
Heat Transfer Process ◽  
Film Condensation ◽  
Significant Feature ◽  
Transfer Coefficients ◽  
Flow Condensation

This study presents an experimental investigation of CO2flowing condensation at the saturation temperature of-10°C, mass flux in the range from 40 to 60kgm-2s-1and vapour quality ranging from 0.2 to 0.8, in a 6.52mm inside diameter horizontal tube. Previous research on refrigerant condensation has shown that under these conditions, CO2two phases are expected to develop as a stratified flow. The significant feature of the stratified flow heat transfer is vapour film condensation in the upper region which dominates the overall heat transfer process. Test series in this study confirm that the saturation-to-tube wall temperature difference has a significant influence on the condensing heat transfer coefficient when the temperature difference is within 3K. Comparisons between the experimental results and the predictions by the Dobson, Cavallini and Thome models show that CO2stratified flow condensation heat transfer coefficients are over-predicted by these models with mean deviations of 104%, 81% and 127%, respectively.

Numerical Investigation of Laminar Filmwise Condensation of Water Vapor in Horizontal Tube With VOF Method in the Presence of Air

2014 ◽  
Author(s):  
Zhan Yin ◽  
Jianjun Wen ◽  
Min Zeng ◽  
Qiuwang Wang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Volume Fraction ◽  
Horizontal Tube ◽  
Vof Method ◽  
Film Condensation ◽  
Interface Temperature ◽  
Condensation Process ◽  
Laminar Film Condensation

A steady three-dimensional numerical simulation of laminar film condensation of vapor in the presence of air inside a 1 mm horizontal tube is presented. The volume of fluid (VOF) method is used to capture the liquid-vapor interface with a phase change model. According to a generally accepted flow regime map, annular flow pattern is to be expected. Uniform wall temperature and interface temperature are assumed to be boundary condition. The influence of gravity is obvious while the effect of surface tension is neglected. At inlet, the liquid film is thin and evenly distributed around tube wall. Moving downstream the tube, film at the bottom half becomes thicker under the influence of gravity, while film on upper half remains almost constant. Correspondingly, local heat transfer coefficient on bottom half declines gradually and global average heat transfer coefficient shows little difference along axial direction. Existence of air makes heat transfer coefficient decrease sharply compared with that of pure vapor condensation, caused by an existed air layer which increases the thermal resistance during condensation process. As inlet volume fraction of air increases from 0.5% to 3%, the decline trend of heat transfer coefficient slows down.

Effect of Vapour Velocity on Condensation of Ethylene Glycol on Horizontal Integral Fin Tubes: Heat Transfer and Retention Angle Measurements

2010 ◽  
Author(s):  
Claire L. Fitzgerald ◽  
Adrian Briggs ◽  
Huasheng Wang ◽  
John W. Rose
Keyword(s):  
Heat Transfer ◽  
Ethylene Glycol ◽  
Root Diameter ◽  
Transfer Coefficients ◽  
Vapor Velocity ◽  
Finned Tubes ◽  
Tube Wall Temperature ◽  
Transfer And Retention ◽  
Plain Tube ◽  
Fin Tubes

Heat-transfer data are reported for forced-convection filmwise condensation of ethylene glycol flowing vertically downward over two single, horizontal instrumented integral-fin tubes and one plain tube. Vapor-side, heat-transfer coefficients were obtained by direct measurement of the tube wall temperature using two specially manufactured, instrumented tubes with thermocouples embedded in the tube walls. Both tubes have fin height of 1.6 mm and fin root diameter and 12.7 mm, with fin thickness and spacings of 0.3 mm and 0.6 mm, respectively for one of the tubes and 0.5 mm and 1 mm, respectively for the other. Tests were performed at low pressures; 5.59kPa, 8.15kPa and 11.23kPa, at nominal vapour velocities from 13m/s to 82 m/s. All the data show that both of the finned tubes provided an increase in heat flux at the same vapour-side temperature difference with increasing vapour velocity. Visual observations were made and photographs obtained of the fluid retention angle φf at each combination of vapor velocity and pressure tested. It was observed that the curvature of the meniscus was distorted by the increase in vapor velocity and in many cases, the extent of condensate flooding decreased compared to its value in the quiescent vapor case.

Laminar Film Condensation on a Porous Horizontal Tube With Uniform Suction Velocity

1965 ◽  
Vol 87 (1) ◽  
pp. 95-102 ◽  
Author(s):  
N. A. Frankel ◽  
S. G. Bankoff
Keyword(s):  
Heat Transfer ◽  
Perturbation Technique ◽  
Porous Plate ◽  
Horizontal Tube ◽  
Film Condensation ◽  
Suction Velocity ◽  
Uniform Suction ◽  
Laminar Film Condensation ◽  
Wide Range ◽  
Perturbation Parameters

The analysis of Bankoff and Jain [10] of film condensation on a vertical porous plate with uniform suction velocity is extended to the case of a horizontal porous tube. Integral momentum and energy balances are written for the system, including the effects of interface drag and condensate heat capacity, and the dimensionless equations are solved using a perturbation technique. All dependent variables are expressed in a double power series in the two perturbation parameters, ξ = kΔt/μλ (acceleration parameter) and α (dimensionless suction velocity), and the resulting equations are solved up to the second order perturbation. An asymptotic solution valid for high values of α is derived, and this solution together with the perturbation solution describes the system for a wide range of α. The case of heat transfer in a zero gravity field is treated, and the Nusselt number is found to be directly proportional to the suction velocity. Based on the results it is concluded that significant increases in heat transfer are possible with the use of suction.

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