Assessment of mixture boiling heat transfer correlations for ammonia/water mixture

This paper addresses a multidimensional numerical simulation of the saturated flow boiling heat transfer in bubble pumps of absorption–diffusion refrigeration cycles. The bubble pump with a shape of vertical tube is subjected to a uniform heat flux from the tube outer wall surface along the entire pump length. As the bubble pump wall is heated, a nonazeotropic mixture of saturated strong ammonia/water entering into the bubble pump transforms to ammonia vapor and diluted ammonia/water mixture. The weaker ammonia/water mixture is lifted by the buoyant force created by the ammonia vapor. The present multidimensional numerical simulation was performed using the two-fluid model with the equilibrium phase change model and the standard k-ε turbulence model. The numerical model designed for the present simulation was validated through a comparative study referring to available experimental data. The present numerical model was compared with the one-dimensional model to assess its applicability for numerical simulation of the saturated flow boiling heat transfer in bubble pumps. As a result, it is seen that the present numerical model predicts the performance of ammonia/water bubble pumps more realistically than the one-dimensional model. In addition, the effects of the bubble pump's geometrical dimension and heat input on the pump performance were investigated using the present numerical approach.

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Effect of salt on boiling heat transfer of ammonia-water mixture

Heat and Mass Transfer ◽

10.1007/s00231-011-0898-1 ◽

2011 ◽

Vol 48 (3) ◽

pp. 497-503 ◽

Cited By ~ 3

Author(s):

A. Sathyabhama

Keyword(s):

Heat Transfer ◽

Boiling Heat Transfer ◽

Water Mixture ◽

Ammonia Water

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Assessment of boiling heat transfer and pressure drop correlations of ammonia/water mixture in a plate heat exchanger

International Journal of Refrigeration ◽

10.1016/j.ijrefrig.2011.10.003 ◽

2012 ◽

Vol 35 (3) ◽

pp. 633-644 ◽

Cited By ~ 32

Author(s):

Francisco Táboas ◽

Manel Vallès ◽

Mahmoud Bourouis ◽

Alberto Coronas

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Pressure Drop ◽

Boiling Heat Transfer ◽

Plate Heat Exchanger ◽

Water Mixture ◽

Ammonia Water ◽

Plate Heat

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Nucleate Pool Boiling Heat Transfer Measurement and Flow Visualization for Ammonia-Water Mixture

Journal of Heat Transfer ◽

10.1115/1.4004258 ◽

2011 ◽

Vol 133 (10) ◽

Author(s):

A. Sathyabhama ◽

T. P. Ashok Babu

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Transfer Coefficient ◽

Boiling Heat Transfer ◽

Mass Fraction ◽

Pool Boiling ◽

Bubble Nucleation ◽

Water Mixture ◽

Nucleate Pool Boiling ◽

Ammonia Water

Visualization of bubble nucleation during nucleate pool boiling outside a vertical cylindrical heated surface was done for ammonia-water binary mixture in order to obtain a descriptive behavior of the boiling, which was directly compared with the measured heat transfer coefficient data at low pressure of 4–8 bar and at low mass fraction of 0 < x < 0.3 and at different heat flux. Still images taken with high speed camera are used to demonstrate the decrease in boiling heat transfer coefficient with increase in ammonia mass fraction. Jensen and Memmel model has better agreement with experimental bubble diameter. Further work is required to obtain quantitative information about bubble nucleation parameters. It is found that both Calus and Rice and Stephan–Koorner correlation can predict the experimental heat transfer coefficient values with a maximum deviation of ± 20%.

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Heat Transfer Correlations for Air-Water Two-Phase Flow of Different Flow Patterns in a Horizontal Pipe

10.1115/imece2000-1534 ◽

2000 ◽

Author(s):

Dongwoo Kim ◽

Jae-yong Kim ◽

Afshin J. Ghajar ◽

Ronald L. Dougherty

Keyword(s):

Heat Transfer ◽

Flow Patterns ◽

Mean Deviation ◽

Water Mixture ◽

Two Phase ◽

Horizontal Pipe ◽

Flux Boundary Condition ◽

Uniform Wall ◽

Heat Transfer Correlations ◽

Two Phase Heat Transfer

Abstract New heat transfer correlations were developed for two-phase heat transfer in a horizontal pipe for different flow patterns. Flow patterns were observed in a transparent circular pipe (2.54 cm I.D. and L/D = 96) using an air/water mixture. Visual identification of the flow patterns was supplemented with photographic data, and the results were plotted on the flow regime map proposed by Taitel and Dukler and agreed quite well with each other. A two-phase heat transfer experimental setup was built for this study and a total of 150 two-phase heat transfer data with different flow patterns were obtained under a uniform wall heat flux boundary condition. For these data, the superficial Reynolds number ranged from 640 to 35,500 for the liquid and from 540 to 21,200 for the gas. Our previously developed robust two-phase heat transfer correlation for a vertical with modified constants predicted the horizontal pipe air-water heat transfer experimental data with good accuracy. Overall the proposed correlations predicted the data with a mean deviation of 1.0% and an rms deviation of 12%.

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