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.

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.

scholarly journals Heat transfer under conditions of operation of a gas infrared emitter and an air exchange system

2021 ◽  
Vol 2057 (1) ◽  
pp. 012125
Author(s):  
B V Borisov ◽  
G V Kuznetsov ◽  
V I Maksimov ◽  
T A Nagornova ◽  
A V Vyatkin
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Two Dimensional ◽  
Exchange System ◽  
Convective Flows ◽  
Exhaust Ventilation ◽  
Transfer Equations ◽  
Infrared Emitter ◽  
Transfer Parameters

Abstract In this work, the processes of heat transfer in a premise heated by a gas infrared emitter (GIE) are studied on the basis of numerical solution of the heat and mass transfer equations in a two-dimensional formulation. Calculations are carried out taking into account the presence of supply and exhaust ventilation in the considered area. Ventilation is required during the operation of high-intensity type GIE. The analysis of the main heat and mass transfer parameters by radiant and convective flows is carried out.

Modelling of Combined Heat and Mass Transfer of Water Droplets in Thermal Technology Equipment

2011 ◽  
Author(s):  
Gintautas Miliauskas ◽  
Stasys Sinkunas ◽  
Kristina Norvaisiene ◽  
Kestutis Sinkunas
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Gas Flow ◽  
Thermal State ◽  
Droplet Evaporation ◽  
Heat Transfer Process ◽  
Droplet Surface ◽  
Convective Heating ◽  
Two Phase ◽  
Balancing Energy

Water droplet evaporation process is numerically modelled under various heat and mass transfer conditions. Regularities of heat transfer process interaction are examined. Modelling in this work was performed using the combined analytical–numerical method to investigate heat and mass transfer in the two-phase droplets-gas flow system. The influence of forced liquid circulation on the thermal state of droplets is taken into account by the effective coefficient of thermal conductivity. Calculating the rate of droplet evaporation and the intensity of convective heating, the influence of the Stefan’s hydrodynamic flow is taken into account. Balancing energy fluxes in the droplet to within one hundredth of a percent and using the fastest sinking the droplet surface temperature is determined.

Method for Determining Overall Performances of Solar Kilns

1987 ◽  
Vol 109 (1) ◽  
pp. 26-29 ◽  
Author(s):  
J. A. Guzman ◽  
A. Lauterbach ◽  
R. Jordan
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Theoretical Model ◽  
Heat And Mass Transfer ◽  
Drying Process ◽  
Solar Kiln ◽  
Model Based ◽  
Transfer Equations

A theoretical model based on heat and mass transfer equations was developed for determining a reliable comparison between different solar kiln designs. It involves dividing the drying process into two sequential steps, one in which only heat transfer occurs and a second one in which the actual drying process takes place. The model gives an equation for determining the evaporated water in function of the normal drying variables, together with a specially defined parameter which gives account for the air recirculation inside the kiln. The model was validated experimentally for a box-type collector solar kiln operating under constant and falling rate drying periods. It was found that although the model could be applied satisfactorily, the tested design proved to be a very inefficient one, giving low values for the recirculating parameter.

scholarly journals Impact of Binary Chemical Reaction and Activation Energy on Heat and Mass Transfer of Marangoni Driven Boundary Layer Flow of a Non-Newtonian Nanofluid

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 702
Author(s):  
Ramanahalli Jayadevamurthy Punith Gowda ◽  
Rangaswamy Naveen Kumar ◽  
Anigere Marikempaiah Jyothi ◽  
Ballajja Chandrappa Prasannakumara ◽  
Ioannis E. Sarris
Keyword(s):  
Heat Transfer ◽  
Activation Energy ◽  
Boundary Layer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Velocity Gradient ◽  
Boundary Layer Flow ◽  
Biological Fluids ◽  
Porosity Parameter ◽  
Layer Flow

The flow and heat transfer of non-Newtonian nanofluids has an extensive range of applications in oceanography, the cooling of metallic plates, melt-spinning, the movement of biological fluids, heat exchangers technology, coating and suspensions. In view of these applications, we studied the steady Marangoni driven boundary layer flow, heat and mass transfer characteristics of a nanofluid. A non-Newtonian second-grade liquid model is used to deliberate the effect of activation energy on the chemically reactive non-Newtonian nanofluid. By applying suitable similarity transformations, the system of governing equations is transformed into a set of ordinary differential equations. These reduced equations are tackled numerically using the Runge–Kutta–Fehlberg fourth-fifth order (RKF-45) method. The velocity, concentration, thermal fields and rate of heat transfer are explored for the embedded non-dimensional parameters graphically. Our results revealed that the escalating values of the Marangoni number improve the velocity gradient and reduce the heat transfer. As the values of the porosity parameter increase, the velocity gradient is reduced and the heat transfer is improved. Finally, the Nusselt number is found to decline as the porosity parameter increases.

CFD-based structure optimization of plate bundle in plate-fin heat exchanger considering flow and heat transfer performance

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yao Li ◽  
Haiqing Si ◽  
Jingxuan Qiu ◽  
Yingying Shen ◽  
Peihong Zhang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat Exchanger ◽  
Heat And Mass Transfer ◽  
Field Performance ◽  
High Specific Surface Area ◽  
Calculation Model ◽  
Air Separation ◽  
Transfer Efficiency ◽  
Heat Transfer Efficiency

Abstract The plate-fin heat exchanger has been widely applied in the field of air separation and aerospace due to its high specific surface area of heat transfer. However, the low heat transfer efficiency of its plate bundles has also attracted more attention. It is of great significance to optimize the structure of plate-fin heat exchanger to improve its heat transfer efficiency. The plate bundle was studied by combining numerical simulation with experiment. Firstly, according to the heat and mass transfer theory, the plate bundle calculation model of plate-fin heat exchanger was established, and the accuracy of the UDF (User-Defined Functions) for describing the mass and heat transfer was verified. Then, the influences of fin structure parameters on the heat and mass transfer characteristics of channel were discussed, including the height, spacing, thickness and length of fins. Finally the influence of various factors on the flow field performance under different flow states was integrated to complete the optimal design of the plate bundle.

An Overview: Analysis of Heat and Mass Transfer in Fractal Media by Fractal Geometry and Technique

2010 ◽  
Author(s):  
Boming Yu
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Porous Media ◽  
Heat And Mass Transfer ◽  
Oil Recovery ◽  
Fractal Geometry ◽  
Boiling Heat Transfer ◽  
Nucleate Boiling ◽  
Fractal Media ◽  
Nucleate Boiling Heat Transfer

In the past three decades, fractal geometry and technique have received considerable attention due to its wide applications in sciences and technologies such as in physics, mathematics, geophysics, oil recovery, material science and engineering, flow and heat and mass transfer in porous media etc. The fractal geometry and technique may become particularly powerful when they are applied to deal with random and disordered media such as porous media, nanofluids, nucleate boiling heat transfer. In this paper, a summary of recent advances is presented in the areas of heat and mass transfer in fractal media by fractal geometry technique. The present overview includes a brief summary of the fractal geometry technique applied in the areas of heat and mass transfer; thermal conductivities of porous media and nanofluids; nucleate boiling heat transfer. A few comments are made with respect to the theoretical studies that should be made in the future.

Sign in / Sign up

Export Citation Format

Share Document