Combined heat and mass transfer analysis for LiCl dehumidification process in a plate type heat exchanger

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.

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Heat and Mass Transfer Behavior Prediction and Thermal Performance Analysis of Earth-to-Air Heat Exchanger by Finite Volume Method

Energies ◽

10.3390/en11061542 ◽

2018 ◽

Vol 11 (6) ◽

pp. 1542 ◽

Cited By ~ 5

Author(s):

Qinggong Liu ◽

Zhenyu Du ◽

Yi Fan

Keyword(s):

Mass Transfer ◽

Heat Exchanger ◽

Performance Analysis ◽

Finite Volume Method ◽

Heat And Mass Transfer ◽

Finite Volume ◽

Thermal Performance ◽

Behavior Prediction ◽

Transfer Behavior ◽

Volume Method

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Influence of Frost Growth and Migration in Cryogenic Heat Exchanger on Air Refrigerator

Applied Sciences ◽

10.3390/app9040753 ◽

2019 ◽

Vol 9 (4) ◽

pp. 753 ◽

Cited By ~ 1

Author(s):

Shanju Yang ◽

Zhan Liu ◽

Bao Fu ◽

Yu Chen

Keyword(s):

Mass Transfer ◽

Heat Exchanger ◽

Numerical Model ◽

Heat And Mass Transfer ◽

Frost Formation ◽

Transient Model ◽

Transfer Rates ◽

Low Humidity ◽

And Migration ◽

Frost Layer

Frost formation degrades the performance of heat exchangers greatly, thus influencing the cryogenic refrigerator. Different from frost formation on the evaporator surface, the growth and migration of frost layer inside the heat exchanger is of low temperature and humidity. In addition to the constantly changing boundary conditions, the effective prediction is difficult. In the present study, a numerical model was proposed to analyze the frost formation in the cryogenic heat exchanger of a reverse Brayton air refrigerator. Under small amounts of moisture, the growing of frost layer was simulated through the numerical heat and mass transfer by adopting semiempirical correlations. The frost formation model was inserted into the transient model of refrigerator, and numerical calculations were performed on heat and mass transfer rates, and growth and migration of frost layers in forced convection conditions. Experiments were conducted under different air humidity to investigate the frost formation and verify the numerical model. Through the model, the influences of frosting on the refrigerator were evaluated under different moisture contents and running time. It can be used to predict the performance of air refrigerators with low humidity and provide a basis for improving the system operation and efficiency.

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A Fully Wet and Fully Dry Tiny Circular Fin Method for Heat and Mass Transfer Characteristics for Plain Fin-and-Tube Heat Exchangers Under Dehumidifying Conditions

Journal of Heat Transfer ◽

10.1115/1.2739589 ◽

2006 ◽

Vol 129 (9) ◽

pp. 1256-1267 ◽

Cited By ~ 11

Author(s):

Worachest Pirompugd ◽

Chi-Chuan Wang ◽

Somchai Wongwises

Keyword(s):

Heat Transfer ◽

Mass Transfer ◽

Heat Exchanger ◽

Heat And Mass Transfer ◽

Heat Exchangers ◽

Heat Transfer Characteristic ◽

Transfer Characteristic ◽

Tube Heat Exchanger ◽

Mass Transfer Characteristic ◽

Transfer Characteristics

This study proposes a new method, namely the “fully wet and fully dry tiny circular fin method,” for analyzing the heat and mass transfer characteristics of plain fin-and-tube heat exchangers under dehumidifying conditions. The present method is developed from the tube-by-tube method proposed in the previous study by the same authors. The analysis of the fin-and-tube heat exchangers is carried out by dividing the heat exchanger into many tiny segments. A tiny segment will be assumed with fully wet or fully dry conditions. This method is capable of handling the plain fin-and-tube heat exchanger under fully wet and partially wet conditions. The heat and mass transfer characteristics are presented in dimensionless terms. The ratio of the heat transfer characteristic to mass transfer characteristic is also studied. Based on the reduced results, it is found that the heat transfer and mass transfer characteristics are insensitive to changes in fin spacing. The influence of the inlet relative humidity on the heat transfer characteristic is rather small. For one and two row configurations, a considerable increase of the mass transfer characteristic is encountered when partially wet conditions take place. The heat transfer characteristic is about the same in fully wet and partially wet conditions provided that the number of tube rows is equal to or greater than four. Correlations are proposed to describe the heat and mass characteristics for the present plain fin configuration.

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