scholarly journals Evaporation/Condensation Heat Transfer and Pressure Drop of R1336mzz (E) and Its Mixture Working Fluid for High-temperature inside Horizontal Microfin Tubes

2021 ◽  
Vol 56 (3) ◽  
pp. 355-366
Author(s):  
Norihiro Inoue ◽  
Yufei Liu ◽  
Kazuhide Watanabe ◽  
Daisuke Jige
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Pressure Drop ◽  
Condensation Heat Transfer ◽  
Working Fluid ◽  
Microfin Tubes

Condensation Heat Transfer and Pressure Drop of R-134a Flowing in Annular Helical Pipes at Different Orientations

2003 ◽  
Author(s):  
B. Yu ◽  
C. X. Lin ◽  
M. A. Ebadian ◽  
R. C. Prattipati
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Cooling Water ◽  
Saturation Temperature ◽  
Condensation Heat Transfer ◽  
Working Fluid ◽  
Transfer Coefficients ◽  
Cooling Water Temperature ◽  
Helical Pipe ◽  
R 134A

This paper presents an experimental investigation of condensation heat transfer and pressure drop characteristics of refrigerant R-134a flowing through an annular helicoidal passage with the hydraulic diameter of 8.5 mm. The angles of helix axis are oriented at 0, 45, 90 degrees to gravity. The overall and refrigerant-side heat transfer coefficients and pressure drops are experimentally determined at saturation temperature 35°C, refrigerant mass flux 35–180 kg/s·m2, and cooling water temperature 27°C. The results show that orientation has significant influence on the thermal and hydraulic behaviors of the helical pipe. The results can be employed for reference in the effective design of annular helicoidal heat exchangers with R-134a as the working fluid.

Numerical Simulation of Heat Transfer and Pressure Drop Characteristics of Internal Microfin Tubes

2016 ◽  
Author(s):  
Jingzhi Zhang ◽  
Jinpin Lin ◽  
Wei Li
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Radial Direction ◽  
Apex Angle ◽  
Hot Water ◽  
Heated Wall ◽  
Working Fluid ◽  
Wall Region ◽  
Smooth Tubes ◽  
Microfin Tubes

Heat transfer and pressure drop characteristics of mini smooth and microfin tubes were studied numerically using water as working fluid at Reynolds number ranging from 7500 to 17500. Seven microfin tubes were used with the same inner diameters of 4.6 mm and 18° helix angle and with number of fins ranging from 30 to 50, fin apex angle ranging from 10° to 40°, and fin height ranging from 0.1 to 0.15 mm. The numerical results fit well with the empirical correlations for heat transfer coefficients and pressure drops. The results indicate that the j-factor of the microfin tubes is approximately 1.2∼1.4 times of that in smooth tubes at the same Re. The j-factor increases with increasing number of microfin and the microfin height and with decreasing fin apex angle. The f-factor of the microfin tubes is approximately 1.05∼1.25 times of that in the smooth tube at the same Re, and the difference between the factors increases with the Re rising. The performance evaluation criterions (PEC) of the seven microfin tubes ranges from 1.15 to 1.35, indicating that microfin tubes exhibit better comprehensive performance compared with smooth tubes. The fluid at the center has a strong tendency to move towards the heated wall along the radial direction due to the directing effect of the microfins. The distinctive flow pattern in the radial direction can sufficiently enhance the turbulent flow near the wall and strengthen the mixing between the cold fluid at the center and hot water at the wall, leading to the enhancement of heat transfer in the near-wall region.

An Experimental Investigation of Condensation Heat Transfer Coefficients and Pressure Drops of Refrigerants Inside Multiport Mini-channel Tubes

2017 ◽  
Vol 25 (02) ◽  
pp. 1750013 ◽  
Author(s):  
Pham-Quang Vu ◽  
Kwang-Il Choi ◽  
Jong-Taek Oh ◽  
Honggi Cho
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Drop ◽  
Mass Flux ◽  
Condensation Heat Transfer ◽  
Working Fluid ◽  
Vapor Quality ◽  
Transfer Coefficients ◽  
Pressure Drops ◽  
Heat Transfer Coefficients

The condensation heat transfer coefficients and pressure drops of R410A and R22 flowing inside a horizontal aluminum multiport mini-channel tube having 18 channels are investigated. Experimental data are presented for the range of vapor quality from 0.1 to 0.9, mass flux from 50 to 500[Formula: see text]kg/m2s, heat flux from 3 to 15[Formula: see text]kW/m2 and the saturation temperature at 48[Formula: see text]C. The pressure drop across the test section was directly measured by a differential pressure transducer. At a small scale, the noncircular cross-sections can enhance the effect of the surface tension. The average heat transfer coefficient increased with the increase of vapor quality, mass flux and heat flux. Under the same test conditions, the heat transfer coefficients of R22 are higher than those for R410A, the pressure drops for R410A are 7–19% lower than those of R22. The lower pressure drop of R410A has an important advantage as an alternative working fluid for R22 in air-conditioning and heat pump systems.

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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