Analytical Modeling for Vapor Condensation in the Presence of Noncondensable Gas and Experimental Validation

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Wei Zhang ◽  
Suilin Wang ◽  
Mu Lianbo
Keyword(s):  
Heat Transfer ◽  
Film Thickness ◽  
Latent Heat ◽  
Flue Gas ◽  
Vertical Surface ◽  
Vapor Condensation ◽  
Condensation Heat Transfer ◽  
Wall Area ◽  
Cooling Surface ◽  
Applicable Range

Abstract The sensible and latent heat transfer are two essential considerations in investigating vapor condensation in the presence of noncondensable gases. In this paper, a new model for filmwise condensation heat transfer was developed using similarity-based solution. The expression of gas–liquid interfacial temperature, film thickness, and heat transfer coefficient were derived and calculated, respectively. The analytical results showed that the temperature difference between gas–liquid interfacial and cooling surface is decreased as there is an increase in cooling surface temperature. In addition, the forced-convective condensation heat transfer and film thickness on the vertical surface were experimentally carried out. The proportion of latent heat is 62–67% and relatively larger than sensible heat in the range of wall temperature (17–32.5 °C). The experimental film thickness is less than analytical film thickness by 2–10%. It is because that the liquid film may evaporate back to water vapor in the neighboring wall area due to high temperature of flue gas. Further, a new nondimensional correlation of condensation heat transfer of flue gas is fitted with Nu = 0.62Re0.5Ja0.67 and applicable range is Re = 1000–2500, Ja = 1.7–4.4. The fitting shows a good agreement between experimental and correlated values except some points in the low Nu number. The model proposed is applicable to predict the temperature and velocity distribution for condensation heat and mass transfer of multicomponent gases.

Calculation and Analysis on Condensation Heat Transfer for Pressurized Oxy-Coal Combustion Flue Gas

2013 ◽  
Vol 325-326 ◽  
pp. 346-352
Author(s):  
Jing Lan Dong ◽  
Wei Ping Yan ◽  
Xue Hong He
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Water Vapor ◽  
Film Thickness ◽  
Flue Gas ◽  
Coal Combustion ◽  
Vertical Tube ◽  
Condensation Heat Transfer ◽  
Condensation Rate ◽  
Set Up

For the convective condensation heat transfer of flue gas with a few water vapors produced by pressurized oxy-coal combustion in vertical tube, investigation and calculation were carried out by theoretical analyzing method. Heat transfer mathematical model was set up by modified film model and Nusselt's condensation theory. Calculations were performed for condensation heat transfer at different wall temperatures, Reynolds numbers and water vapor fractions. Results show that with the increase of wall temperature, the condensation rate of flue gas, heat flux and condensation film thickness decrease. And with the increase of Reynolds number of the mixture gas, the condensation rate of flue gas and heat flux increase too, while the condensation film thickness decrease. With the decrease of water vapor fraction, the condensation rate of flue gas and heat flux decrease too, while the decrease of condensation film thickness is not obvious.

scholarly journals An Experimental Investigation of Water Vapor Condensation from Biofuel Flue Gas in a Model of Condenser, (1) Base Case: Local Heat Transfer without Water Injection

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 844
Author(s):  
Robertas Poškas ◽  
Arūnas Sirvydas ◽  
Vladislavas Kulkovas ◽  
Povilas Poškas
Keyword(s):  
Heat Transfer ◽  
Water Vapor ◽  
Flue Gas ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Water Injection ◽  
Vapor Condensation ◽  
Base Case ◽  
Water Vapor Condensation ◽  
Condensing Heat Exchanger

Waste heat recovery from flue gas based on water vapor condensation is an important issue as the waste heat recovery significantly increases the efficiency of the thermal power units. General principles for designing of this type of heat exchangers are known rather well; however, investigations of the local characteristics necessary for the optimization of those heat exchangers are very limited. Investigations of water vapor condensation from biofuel flue gas in the model of a vertical condensing heat exchanger were performed without and with water injection into a calorimetric tube. During the base-case investigations, no water was injected into the calorimetric tube. The results showed that the humidity and the temperature of inlet flue gas have a significant effect on the local and average heat transfer. For some regimes, the initial part of the condensing heat exchanger was not effective in terms of heat transfer because there the flue gas was cooled by convection until its temperature reached the dew point temperature. The results also showed that, at higher Reynolds numbers, there was an increase in the length of the convection prevailing region. After that region, a sudden increase was observed in heat transfer due to water vapor condensation.

Condensation heat transfer on tubes in actual flue gas (Parametric study for condensation behavior)

2003 ◽  
Vol 32 (2) ◽  
pp. 153-166 ◽  
Author(s):  
Masahiro Osakabe ◽  
Kiyoyuki Yagi ◽  
Tsugue Itoh ◽  
Kunimitsu Ohmasa
Keyword(s):  
Heat Transfer ◽  
Flue Gas ◽  
Parametric Study ◽  
Condensation Heat Transfer ◽  
Actual Flue Gas

Effect of Open Micro-Channels on External Condensation Heat Transfer

2016 ◽  
Author(s):  
Brandon Hulet ◽  
Andres Martinez ◽  
Melanie Derby ◽  
Amy Rachel Betz
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Film Thickness ◽  
Transfer Coefficient ◽  
Heat Fluxes ◽  
Condensation Heat Transfer ◽  
Dropwise Condensation ◽  
Micro Channels ◽  
Lower Heat ◽  
The Heat Transfer Coefficient

This research experimentally investigates the heat transfer performance of open-micro channels under filmwise condensation conditions. Filmwise condensation is an important factor in the design of steam condensers used in thermoelectric power generation, desalination, and other industrial applications. Filmwise condensation averages five times lower heat transfer coefficients than those present in dropwise condensation, and filmwise condensation is the dominant condensation regime in the steam condensers due to a lack of a durable dropwise condensation surface. Film thickness is also of concern because it is directly proportional to the condenser’s overall thermal resistance. This research focuses on optimizing the channel size to inhibit the creation of a water film and/or to reduce its overall thickness in order to maximize the heat transfer coefficient of the surface. Condensation heat transfer was measured in three square channels and a plane surface as a control. The sizes of the square fins were 0.25 mm; 0.5 mm; and 1 mm, and tests were done at a constant pressure of 6.2 kPa. At lower heat fluxes, the 0.25mm fins perform better, whereas at larger heat fluxes a smooth surface offers better performance. At lower heat fluxes, droplets are swept away by gravity before the channels are flooded. Whereas, at higher heat fluxes, the channels are flooded increasing the total film thickness, thereby reducing the heat transfer coefficient.

Vapor Condensation and Absorption of SO2 in Wet Flue Gas

2003 ◽  
Author(s):  
Li Jia ◽  
Xiaofeng Peng
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Flue Gas ◽  
Phase Interface ◽  
Vapor Condensation ◽  
High Mass ◽  
Condensation Process ◽  
Gas Mixture ◽  
Vapor Fraction ◽  
So2 Absorption

The convection-condensation heat transfer mechanism of the gas mixture and its influence on SO2 absorption were theoretically analyzed with vapor fraction of 8% to 28%. A modified film model of mass transfer in mixture gas and Nusselt theory were used to describe the characteristics of mass, momentum and energy transfer at the phase interface. The effects of the velocities induced by mass transfer (vapor condensation and SO2 absorption) were included in conducting governing equations. Vapor condensation improves the SO2 absorption in the wet flue gas. Vapor fraction in the gas mixture would alter the mechanism of heat transfer modes, single-phase convection or condensation. But for high mass fraction of vapor the SO2 absorption will be an important phenomenon in the condensation process. Another important factor influencing the SO2 absorption is the Re number of bulk flow of wet flue gas.

scholarly journals Condensation Heat Transfer on Tubes in Actual Flue Gas. Experiment using Flue Gas at Different Air Ratios.

1998 ◽  
Vol 64 (626) ◽  
pp. 3378-3383 ◽  
Author(s):  
Masahiro OSAKABE ◽  
Kazuhiko ISHIDA ◽  
Kiyoyuki YAGI ◽  
Tugue ITOH ◽  
Kunimitu OHMASA
Keyword(s):  
Heat Transfer ◽  
Flue Gas ◽  
Condensation Heat Transfer ◽  
Actual Flue Gas

Condensation heat transfer on tubes in actual flue gas

2001 ◽  
Vol 30 (2) ◽  
pp. 139-151 ◽  
Author(s):  
Masahiro Osakabe ◽  
Kazuhiko Ishida ◽  
Kiyoyuki Yagi ◽  
Tugue Itoh ◽  
Kunimitu Ohmasa
Keyword(s):  
Heat Transfer ◽  
Flue Gas ◽  
Condensation Heat Transfer ◽  
Actual Flue Gas
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