A new approach to the analysis of heat and mass transfer characteristics for laminar air flow inside vertical plate channels with falling water film evaporation

This paper describes the results of experimental tests carried out to study falling film evaporation on a heated flat plate with countercurrent air flowing in a rectangular channel. Experimental tests have been run with different channel depths with respect to a previous facility configuration in order to evaluate the effect of this parameter on the measured heat and mass transfer rates. The present work is then focused on the analysis of the effect that developing flow conditions may have on the evaporation of the falling water film. Three different values of the length over the hydraulic diameter ratio of the channel have been considered: L/D = 11.83, 20.86 and 33.88. Series of dry tests with 45° inclined channel were investigated with inlet nominal velocities of 1, 2.5, 5, 7.5, 9 m/s and with nominal heated plate temperature of 70 °C and 90 °C. Corresponding wet tests were investigated with nominal film flow rate at 60 and 100 g/s, with the same nominal inlet velocities but with a temperature of the heated plate of 70 °C. The obtained results point out interesting parametric trends that provide greater insight into the considered phenomena and support the use of the heat and mass transfer analogy for predicting evaporation rates in the considered range of parameters.

Download Full-text

Study on heat and mass transfer characteristics of humid air-flow in a fin bundle

International Journal of Refrigeration ◽

10.1016/j.ijrefrig.2010.05.013 ◽

2010 ◽

Vol 33 (7) ◽

pp. 1434-1443 ◽

Cited By ~ 2

Author(s):

Dong-Hwi Kim ◽

Shigeru Koyama ◽

Ken Kuwahara ◽

Jeong-Tae Kwon ◽

Byung-Duck Park

Keyword(s):

Mass Transfer ◽

Heat And Mass Transfer ◽

Air Flow ◽

Humid Air ◽

Transfer Characteristics

Download Full-text

Modeling heat and mass transfer processes during evaporation of a water film in a horizontal channel with a cocurrent flow of moist air

Journal of Physics Conference Series ◽

10.1088/1742-6596/2119/1/012150 ◽

2021 ◽

Vol 2119 (1) ◽

pp. 012150

Author(s):

M V Gorbachev ◽

V I Terekhov

Keyword(s):

Mass Transfer ◽

Heat And Mass Transfer ◽

Air Flow ◽

Water Film ◽

Horizontal Channel ◽

Cocurrent Flow ◽

Moist Air ◽

Transfer Processes ◽

Mass Transfer Processes ◽

Wide Range

Abstract Modeling of heat and mass transfer processes in a horizontal channel during evaporative cooling of a moist air flow with regard to the finite thickness of the liquid film is considered. The mathematical model consists of a system of differential equations in the boundary layer approximation. The simulation results have been obtained in a wide range of initial parameters: temperature T 0 = 10÷50°C, humidity φ0=0÷100%, Reynolds number Re=100÷2000. Calculations were carried out at atmospheric pressure. Quantitative analysis of influence of initial parameters of flows on values of parameters of wet air flow at the outlet of the channel with and without taking into account the final thickness of the water film was carried out.

Download Full-text

Heat and Mass Transfer Characteristics of Evaporating Falling Films

Process Analysis, Design, and Intensification in Microfluidics and Chemical Engineering - Advances in Chemical and Materials Engineering ◽

10.4018/978-1-5225-7138-4.ch009 ◽

2019 ◽

pp. 251-276

Author(s):

Monssif Najim ◽

M'barek Feddaoui ◽

Abderrahman Nait Alla ◽

Adil Charef

Keyword(s):

Mass Transfer ◽

Liquid Film ◽

Heat And Mass Transfer ◽

Gas Flow ◽

Thermal Protection ◽

Liquid Films ◽

Two Phase ◽

Film Evaporation ◽

Transfer Characteristics ◽

Two Phases

This chapter presents a numerical investigation of heat and mass transfer characteristics during the evaporation of liquid films in vertical geometries. A two-phase model is developed to simulate laminar film evaporation into laminar gas flow. The liquid film evaporation is evaluated under adiabatic and heated wall conditions for both pure and binary liquid film. The model is based on a finite difference method to solve the governing equations of the two phases. The obtained results concerns two industrial processes. The first part of the chapter is devoted to the analysis of the thermal protection of vertical channel wall, while the second part is devoted to the desalination process by falling liquid film. The simulations results allowed the determination of the optimal operating conditions for both processes.

Download Full-text