A Film-Theory-Based Model for a Multicomponent Droplet Evaporation at Both Low- and High-Pressure Environments

2005 ◽  
Vol 128 (3) ◽  
pp. 290-294 ◽  
Author(s):  
Guangfa Yao
Keyword(s):  
Mass Transfer ◽  
High Pressure ◽  
Heat And Mass Transfer ◽  
Film Theory ◽  
Droplet Evaporation ◽  
Published Data ◽  
Real Gas ◽  
New Model ◽  
The Real ◽  
Transfer Equations

Modeling of a multicomponent droplet evaporation is investigated based on the film theory in both low- and high-pressure environments. Unlike the classical film theory, effects of blowing due to evaporation on gas-side heat and mass transfer are included through the film thicknesses. The corresponding gas-side heat and mass transfer equations are derived in terms of film thicknesses. In a high-pressure situation, the real gas behavior is considered. Based on the derived equations, a new model for multicomponent droplet evaporation is formulated and validated against the published data.

Evaluation and Development of Simple Evaporation Models Used in Spray Simulations

2005 ◽  
Author(s):  
G. F. Yao
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Droplet Evaporation ◽  
Droplet Surface ◽  
Published Data ◽  
Single Droplet ◽  
New Model ◽  
Transfer Equations ◽  
Evaporation Models

Given the droplet surface temperature distribution versus time derived from the recent numerical modeling and experimental measurements of a single droplet evaporation, the gas side heat and mass transfer equations used in simple evaporation models for spray simulation in CFD codes are first evaluated. A new model for droplet evaporation is formulated. Instead of using the infinite or conduction limited models for liquid side heat transfer, in the new model, the liquid side heat transfer is simulated based on the Nusselt number. The model is validated against the published data and was found to be accurate in representing the gas and liquid side heat and mass transfer of a single droplet evaporation.

Simultaneous Modeling of Heat and Mass Transfer of Steam-Air Mixture on a Shell and Tube Condenser Based on Film Theory

2003 ◽  
Author(s):  
Yousef Haseli ◽  
Javad M. R. Roudaki
Keyword(s):  
Experimental Data ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Control Volume ◽  
Film Theory ◽  
Outlet Temperature ◽  
Transfer Equations ◽  
Shell And Tube ◽  
Cooling Media ◽  
Tube Condenser

The idea of this work is to analyze condensation of steam-air mixture in a baffled shell and tube condenser with one path tube. Film Theory was used to consider the effects of heat and mass transfer on each other. Accordingly heat and mass transfer equations through proposed algorithm were solved simultaneously for each of baffle spacing considered as a control volume in this work. The predicted outlet temperature of both gas (air-water vapor mixture) and cooling media and total condensation rate is compared with the available experimental data taken from a typical semi-industrial condenser. A very good consistency of the analytical approach with the experimental data is achieved and presented.

The Experimental Investigation of Steam Condensation With Non-Condensable Gas Under Natural Convection

2018 ◽  
Author(s):  
Xizhen Ma ◽  
Wen Fu ◽  
Haijun Jia ◽  
Peiyue Li ◽  
Jun Li
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
High Pressure ◽  
Natural Convection ◽  
Heat And Mass Transfer ◽  
Vertical Wall ◽  
Experimental System ◽  
Steam Condensation ◽  
Transfer Coefficients ◽  
Calculation Results

The non-condensable gas is used to keep the pressure stable in the steam-gas pressurizer. The processes of heat and mass transfer during steam condensation in the presence of non-condensable gas play an important role and the thermal hydraulic characteristics in the pressurizer is particularly complicated due to the non-condensable gas. The effects of non-condensable gas on the process of heat and mass transfer during steam condensation were experimental investigated. A steam condensation experimental system under high pressure and natural convection was built and nitrogen was chosen in the experiments. The steam and nitrogen were considered in thermal equilibrium and shared the same temperature in the vessel under natural convection. In the experiments, the factors, for instance, pressure, mass fraction of nitrogen, subcooling of wall and the distribution of nitrogen in the steam, had been taken into account. The rate of heat transfer of steam condensation on the vertical wall with nitrogen was obtained and the heat transfer coefficients were also calculated. The characteristics curve of heat and mass transfer during steam condensation with non-condensable gas under high pressure were obtained and an empirical correlation was introduced to calculated to heat transfer coefficient of steam condensation with nitrogen which the calculation results showed great agreement with the experimental data.

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