Heat transfer improvement by an Al2O3-water nanofluid coolant in printed-circuit heat exchangers of supercritical CO2 Brayton cycle

2020 ◽  
Vol 20 ◽  
pp. 100694 ◽  
Author(s):  
Apostolos A. Gkountas ◽  
Lefteris Th. Benos ◽  
Konstantinos-Stefanos Nikas ◽  
Ioannis E. Sarris
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Supercritical Co2 ◽  
Brayton Cycle ◽  
Printed Circuit ◽  
Heat Transfer Improvement

Numerical Investigation on Maldistribution of Supercritical CO2 Flow Inside Printed Circuit Heat Exchanger

2018 ◽  
Author(s):  
Xiao Qi ◽  
Ke Hanbing ◽  
Zhao Zhenxing ◽  
Li Yongquan ◽  
Liao Mengran
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Supercritical Co2 ◽  
Brayton Cycle ◽  
Printed Circuit ◽  
Co2 Flow ◽  
Thermal Physical Properties ◽  
Flow Nonuniformity

Supercritical CO2 (S-CO2) Brayton cycle has been identified as a promising power conversion method for the next generation of nuclear reactors due to its high efficiency and compactness. The heat exchanger is one of the most important components for S-CO2 Brayton cycle, and the printed circuit heat exchanger (PCHE) is supposed to be one of the promising candidates for the heat exchangers in S-CO2 Brayton cycle. It should be noted that the fluid maldistribution would induce heat transfer deterioration, especially for heat exchangers with micro- or mini-scale channels like PCHE. The thermal-physical properties of S-CO2 change violently during the heat transfer process, which makes the flow inside PCHE more complex. In this paper, the distribution of S-CO2 flow inside PCHE would be studied by 2-D CFD simulations. For the working fluids with constant properties, the flow nonuniformity increases with the mass flow rate. For the working fluid with S-CO2, the thermal-physical properties change significantly with temperature, and there exist a minimum value in the flow nonuniformity-mass flow rate curves (1.64 × 105 ≤ Rein ≤ 1.31 × 106). Insertion of baffles at manifolds could significantly improve the flow distribution uniformity and reduce the pressure drop. And it has been found that insertion of baffles at the collecting manifold has better performance compared with that at the distributing manifold or both.

Investigation of Supercritical CO2 Thermal Hydraulic Characteristics in a Printed Circuit Heat Exchanger

2018 ◽  
Author(s):  
Wen Fu ◽  
Xizhen Ma ◽  
Peiyue Li ◽  
Minghui Zhang ◽  
Sheng Li
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Supercritical Co2 ◽  
Three Dimensional ◽  
Working Fluid ◽  
Printed Circuit ◽  
Carbon Dioxide Co2

Printed circuit heat exchangers are considered for use as the intermediate heat exchangers (IHXs) in high temperature gas-cooled reactors (HTGRs), molten salts reactors (MSRs) and other advanced reactors. A printed circuit heat exchanger (PCHE) is a highly integrated plate-type compact heat exchanger with high-temperature, high-pressure applications and high compactness. A PCHE is built based on the technology of chemical etching and diffusion bonding. A PCHE with supercritical carbon dioxide (CO2) as the working fluid was designed in this study based on the theory correlations. Three-dimensional numerical analysis was then conducted to investigate the heat transfer and pressure drop characteristics of supercritical CO2 in the designed printed circuit heat exchanger using commercial CFD code, FLUENT. The distributions of temperature and velocity through the channel were modeled. The influences of Reynolds number on heat transfer and pressure drop were analyzed. The numerical results agree well with the theory calculations.

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