Experimental Study of Shell-Side Fogging Condensation of a Mixture

2017 ◽  
Author(s):  
Hongfang Gu ◽  
Haiyang Guo ◽  
Haijun Wang ◽  
Yuqiang Gu
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Vapor Pressure ◽  
Gas Phase ◽  
High Speed ◽  
Saturated Vapor ◽  
Saturation Temperature ◽  
Bulk Temperature ◽  
Transfer Performance ◽  
Shell Side

Fog formation occurs if the vapor pressure in the gas-phase is higher than the saturated vapor pressure and the bulk temperature is lower than its saturation temperature (supersaturated) for condensation in the presence of non-condensable gases. Generally, fogging is formation of entrained small droplets mixing in the vapor-gas stream, and the vapor condenses at the mist-flow and share-controlled flow regime. The phenomenon and mechanism of fogging need to be considered for determining condensation rate and separation of the condensate from vapor-gas phase for the down-stream process. The experimental study of shell-side condensation using steam mixing with non-condensable air was conducted in a shell-side horizontal baffled tube bundle. Experimental data has been obtained including visualization findings using high-speed photograph. The characteristics of fog formation related to the heat and mas transfer performance are analyzed based on experimental data and observation. The general equation for determining fog formation (degree of supersaturation) is evaluated with experimental data. Results confirm that the transition band of fogging formation is in the range of S = 1.0 to 1.75. This paper presents experimental data and visualization findings on fogging characteristics and heat transfer performance for condensation in the presence of non-condensable gas.

Phenomenon of Fog Formation and Flow Characteristics of Droplet-Vapor-Gas Mixture in a Cooler-Condenser

2019 ◽  
Author(s):  
Hongfang Gu ◽  
Qiwei Guo ◽  
Changsong Li ◽  
Qing Zhou
Keyword(s):  
Experimental Data ◽  
Numerical Analysis ◽  
High Speed ◽  
Flow Characteristics ◽  
Saturation Temperature ◽  
Bulk Temperature ◽  
Dropwise Condensation ◽  
Operation Conditions ◽  
Droplet Transport ◽  
Wide Range

Abstract Fog formation occurs in the process of condensation in the presence of non-condensable gas if the bulk temperature is lower than its saturation temperature (supersaturated). The phenomena of fogging is the formation of small condensate particles mixing with the vapor/gas stream, which creates potential problems of the vapor/gas/condensate separation and environmental pollution. Therefore, understanding of fogging mechanism and prevention of fog droplet entrainment are one of technical concerns for design and operation of cooler-condensers in the process industry. This paper presents the experimental study and numerical simulation of shell-side condensation with fog formation using a mixture of steam/non-condensable gas. The experimental data were collected on the two tube bundles (modified plastic tubes and stainless steel tubes). Using a high-speed photograph technique, the phenomenon of fog formation and flow characteristics of vapor/droplet transport were recorded over a wide range of test conditions. The numerical analysis of film and dropwise condensation, fog formation and droplet particle transport were simulated using different tube geometry and material, and flow velocity of air/droplet mixture. Based on simulation results, a new droplet trapping parameter is proposed to assess the optimal parameters of heat exchanger structural and operation conditions. Comparisons show that the numerical analysis results have a good agreement with experimental data and observations. These findings provide fundamental approach to account for the effect of fog formation, film and dropwise condensation, and droplet transport crossflow in cooler-condensers.

Influence of Nano-Refrigeration-Oil on Saturated Vapor Pressure of R22

2011 ◽  
Vol 694 ◽  
pp. 309-314 ◽  
Author(s):  
Jiang Feng Lou ◽  
Rui Xiang Wang ◽  
Min Zhang
Keyword(s):  
Experimental Data ◽  
Vapor Pressure ◽  
Mass Fraction ◽  
Saturated Vapor Pressure ◽  
Saturated Vapor ◽  
Experimental Results ◽  
Vapor Pressures ◽  
Temperature Range ◽  
Mass Fractions

The saturated vapor pressures of R22 uniformly mixed with refrigeration oil and nano- refrigeration-oil were measured experimentally at a temperature range from 263 to 333K and mass fractions from 1 to 5%. The experimental results showed that the saturated vapor pressure of R22/KT56 mixture was lower than that of pure R22; the pressure deviation between them increased with a raising mass fraction of refrigeration oil and temperature. After adding nano-NiFe2O4 and nano-fullerene into KT56, the pressure deviation increased at the same mass fraction and temperature. A saturated vapor pressure correlation for R22 and refrigeration oil/nano-refrigeration-oil mixture was proposed, and the calculated values agreed with the experimental data within the deviation of ± 0.77%.

Enhanced Condensation Heat-Transfer on Mini or Low Fin Tubes

2006 ◽  
Author(s):  
Adrian Briggs
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Thermophysical Properties ◽  
Heat Transfer Performance ◽  
Three Dimensional ◽  
Transfer Performance ◽  
Transfer Enhancement ◽  
Shell Side ◽  
Wide Range ◽  
Fin Tubes

This paper presents an overview of the use of low or mini-fin tubes for improving heat-transfer performance in shell-side condensers. The paper concentrates on, but is not limited to, the experimental and theoretical program in progress at Queen Mary, University of London. This work has so far resulted in an extensive data base of experimental data for condensation on single tubes, covering a wide range of tube geometries and fluid thermophysical properties and in the development of a simple to use model which predicts the majority of this data to within 20%. Work is progressing on the effects of vapor shear and on three-dimensional fin profiles; the later having shown the potential for even higher heat-transfer enhancement.

The Constitution of Rubber According to Its Swelling in Liquids

1930 ◽  
Vol 3 (4) ◽  
pp. 576-585
Author(s):  
Paul Bary
Keyword(s):  
Experimental Study ◽  
Vapor Pressure ◽  
Saturated Vapor ◽  
Point Of View ◽  
Single Sample ◽  
Saturation Point ◽  
Liquid Solutions ◽  
Before And After ◽  
The Stability

Abstract In various publications we have previously shown that in many cases it is advantageous to consider jellies as formed of a polymerized colloidal substance, the length of the molecular chains being easily changed according to the conditions of the system and unlike one another at all times in a single sample. These chains retain free affinities at their extremities to which can be linked so-called solvating groups arising from the solvent or from soluble substances contained in the jelly. The present work refutes the interpretation given to recent experiments on the vapor pressure of jellies and confirms in certain new ways this constitution. (1) The experiments of Stamberger on the vapor pressure of rubber jellies and their consistency before and after a prolonged mastication do not support the Harries hypothesis on the stability of the rubber molecule, but merely show that the theory of true liquid solutions is not applicable to jellies. (2) Based on the idea that polymerization changes with solvation, it is easily shown that the relative swelling in a solvent and in its saturated vapor are not contradictory with the principles of thermodynamics, as it would seem, but on the contrary proceed normally and could have been predicted. (3) In the study by Scott on the slow but unlimited swelling of rubber beyond the saturation point, this author has come to assume that swelling is a double phenomenon, which confirms our point of view. (4) The experimental study of the contraction of rubber during swelling shows that this effect does not change its sign at any moment and that consequently the change of sign of the heat evolved in this same process has a cause distinct from that of the initial swelling; perhaps it is to be attributed to the chemical phenomenon of solvation.

Numerical and experimental study of heat transfer in gas-solid flow: Particle cooling

2012 ◽  
Vol 3 (1) ◽  
pp. 21-29
Author(s):  
S. M. El-Behery ◽  
W. A. El-Askary ◽  
M. H. Hamed ◽  
K. A. Ibrahim
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Experimental Study ◽  
High Speed ◽  
Solid Phase ◽  
Ideal Gas ◽  
Particle Rotation ◽  
Two Phase ◽  
Solid Flow ◽  
Speed Flow

Abstract Heat transfer in gas-solid two-phase flow is investigated numerically and experimentally. The numerical computations are carried out using four-way coupling Eulerian-Lagrangian approach. The effects of particle rotation and lift forces are included in the model. The gas-phase turbulence is modeled via low Reynolds number k-ε turbulence models. The SIMPLE algorithm is extended to take the effect of compressibility into account. The experimental study is performed using crushed limestone to simulate the solid phase. The effects of Reynolds numbers, particles size and temperature on the pressure drop and the temperature of the phases are investigated. The model predictions are found to be in a good agreement with available experimental data for high speed gas-solid flow and present experimental data for low speed flow. The present results indicate that heat transfer in gas solid flow can be modeled using ideal gas incompressible flow model at low conveying speed, while for high speed flow, a full compressible model should be used.

scholarly journals Modification of the Redlich-Kwong-Aungier Equation of State to Determine the Degree of Dryness in the CO2 Two-phase Region

2021 ◽  
Vol 24 (4) ◽  
pp. 17-27
Author(s):  
Hanna S. Vorobieva ◽  
Keyword(s):  
Experimental Data ◽  
Equation Of State ◽  
Gas Phase ◽  
Saturated Vapor ◽  
Phase Region ◽  
Working Fluid ◽  
Two Phase ◽  
Real Gas ◽  
Liquid Phases ◽  
Good Agreement

The degree of dryness is the most important parameter that determines the state of a real gas and the thermodynamic properties of the working fluid in a two-phase region. This article presents a modified Redlich-Kwong-Aungier equation of state to determine the degree of dryness in the two-phase region of a real gas. Selected as the working fluid under study was CO2. The results were validated using the Span-Wanger equation presented in the mini-REFPROP program, the equation being closest to the experimental data in the CO2 two-phase region. For the proposed method, the initial data are temperature and density, critical properties of the working fluid, its eccentricity coefficient, and molar mass. In the process of its solution, determined are the pressure, which for a two-phase region becomes the pressure of saturated vapor, the volumes of the gas and liquid phases of a two-phase region, the densities of the gas and liquid phases, and the degree of dryness. The saturated vapor pressure was found using the Lee-Kesler and Pitzer method, the results being in good agreement with the experimental data. The volume of the gas phase of a two-phase region is determined by the modified Redlich-Kwong-Aungier equation of state. The paper proposes a correlation equation for the scale correction used in the Redlich-Kwongda-Aungier equation of state for the gas phase of a two-phase region. The volume of the liquid phase was found by the Yamada-Gann method. The volumes of both phases were validated against the basic data, and are in good agreement. The results obtained for the degree of dryness also showed good agreement with the basic values, which ensures the applicability of the proposed method in the entire two-phase region, limited by the temperature range from 220 to 300 K. The results also open up the possibility to develop the method in the triple point region (216.59K-220 K) and in the near-critical region (300 K-304.13 K), as well as to determine, with greater accuracy, the basic CO2 thermodynamic parameters in the two-phase region, such as enthalpy, entropy, viscosity, compressibility coefficient, specific heat capacity and thermal conductivity coefficient for the gas and liquid phases. Due to the simplicity of the form of the equation of state and a small number of empirical coefficients, the obtained technique can be used for practical problems of computational fluid dynamics without spending a lot of computation time.

Experimental study of ZrF62– stability in hydrothermal solutions at 90–255 ᵒC

2019 ◽  
pp. 107-111
Author(s):  
M. E. Tarnopolskaya ◽  
A. Yu. Bychkov
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Water Vapor ◽  
Vapor Pressure ◽  
Dissociation Constants ◽  
Water Vapor Pressure ◽  
Hydrothermal Solutions ◽  
Free Energies ◽  
Saturated Water Vapor ◽  
Saturated Water

The solubility of fluorite in HCl and HF solutions with a variable concentration of Zr at 90, 155, 205 and 255 ᵒC and the pressure of saturated water vapor were investigated. The results showed that the solubility of fluorite increases with increasing concentration of zirconium. Using the OptimA program, the free energies of the ZrF62– complex were determined from the experimental data, from which the dissociation constants of the reaction ZrF62– =Zr4+ + 6F- were calculated. The pK values were 29,86±0,13; 34,03±0,062; 38,28±0,033; 40,94± 0,079 at 90, 155, 205 and 255 ᵒС (saturated water vapor pressure).

Unified approach for conjugate heat-transfer analysis of high speed air flow through a water-cooled nozzle

2016 ◽  
Vol 120 (1224) ◽  
pp. 355-373
Author(s):  
F. I. Barbosa ◽  
E. L. Zaparoli ◽  
C. R. Andrade
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
High Speed ◽  
Conjugate Heat Transfer ◽  
Cold Water ◽  
Transfer Problem ◽  
Air Flow ◽  
Heat Transfer Analysis ◽  
Bulk Temperature ◽  
Unified Approach

ABSTRACTThis article presents a unified approach to solve steady-state conjugate heat-transfer problem including simultaneously gas, liquid and solid regions in just one 3D domain, distinguished by their particular properties. This approach reduces approximation errors and the time to solve the problem, which characterise iterative methods based on separated domains. The formulation employs RANS equations, realisablek-ε turbulence model and near-wall treatment model. A commercial CFD code solves the pressure-based segregated algorithm combined with spatial discretisation of second order upwind. The problem consists of a convergent-divergent metallic nozzle that contains cooling channels divided in two segments along the wall. The nozzle wall insulates the high-speed hot air flow, dealt as perfect gas, from the two low-speed cold water flows, dealt as compressed liquid, both influenced by transport properties dependent of the local temperature. The verification process uses three meshes with increasing resolutions to demonstrate the independence of the results. The validation process compares the simulation results with experimental data obtained in high-enthalpy wind tunnel, demonstrating good compliance between them. Results for the bulk temperature rise of the water in the second cooling segment of the nozzle showed good agreement with available experimental data. Numerical simulations also provided wall temperature and heat flux for the gas and liquid sides. Besides, distribution of temperature, pressure, density and Mach number were plotted along the nozzle centerline showing a little disturbance downstream the throat. This phenomenon has been better visualised by means of 2D maps of those variables. The analysis of results indicates that the unified approach herein presented can make easier the task of simulating the conjugate convection-conduction heat-transfer in a class of problems related to regeneratively cooled thrust chambers.

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