Numerical study of turbulent heat transfer of nanofluids containing eco-friendly treated carbon nanotubes through a concentric annular heat exchanger

2018 ◽  
Vol 127 ◽  
pp. 403-412 ◽  
Author(s):  
Maryam Hosseini ◽  
Ali H. Abdelrazek ◽  
Rad Sadri ◽  
A.R. Mallah ◽  
S.N. Kazi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Carbon Nanotubes ◽  
Heat Exchanger ◽  
Numerical Study ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Treated Carbon

Supercritical Carbon Dioxide Heat Transfer in Horizontal Semicircular Channels

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Alan Kruizenga ◽  
Hongzhi Li ◽  
Mark Anderson ◽  
Michael Corradini
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Heat Exchanger ◽  
Supercritical Carbon Dioxide ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Brayton Cycle ◽  
Heat Exchanger Design ◽  
Transfer Behavior ◽  
Supercritical Carbon

Competitive cycles must have a minimal initial cost and be inherently efficient. Currently, the supercritical carbon dioxide (S-CO2) Brayton cycle is under consideration for these very reasons. This paper examines one major challenge of the S-CO2 Brayton cycle: the complexity of heat exchanger design due to the vast change in thermophysical properties near a fluid’s critical point. Turbulent heat transfer experiments using carbon dioxide, with Reynolds numbers up to 100 K, were performed at pressures of 7.5–10.1 MPa, at temperatures spanning the pseudocritical temperature. The geometry employed nine semicircular, parallel channels to aide in the understanding of current printed circuit heat exchanger designs. Computational fluid dynamics was performed using FLUENT and compared to the experimental results. Existing correlations were compared, and predicted the data within 20% for pressures of 8.1 MPa and 10.2 MPa. However, near the critical pressure and temperature, heat transfer correlations tended to over predict the heat transfer behavior. It was found that FLUENT gave the best prediction of heat transfer results, provided meshing was at a y+ ∼ 1.

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