Numerical Investigation of Air-Side Heat Transfer and Pressure Drop Characteristics of a New Triangular Finned Microchannel Evaporator with Water Drainage Slits
Abstract
:1. Introduction
2. Method
2.1. Geometry of the Microchannel Evaporator
2.2. CFD Simulation Points
2.3. CFD Modeling Setup
2.3.1. Modeling
2.3.2. Mesh Analysis
2.3.3. Velocity, Temperature, and Pressure Profiles
2.4. Data Reduction
3. Results
3.1. Heat Transfer and Pressure Drop Regression
- Linear regression of based on the first five consecutive points longitudinally (the choice of five points was based on visual interpretation of the results),
- Linear regression of ,
- Nonlinear regression of ,
- A repeated nonlinear regression of the coefficients and in order to alleviate errors related to the visual interpretation in step 1.
3.2. Analysis of Entrance Region
3.3. Volume Goodness Factor
4. Discussion
5. Conclusions
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
Nomenclature
Minimum free flow area, m2 | |
Fin Area, m2 | |
Frontal area, m2 | |
Total heat transfer area, m2 | |
Regression coefficients, (-) | |
Heat capacity at constant pressure, J kg−1K−1 | |
Lowest heat capacity rate, W K−1 | |
Hydraulic diameter, m | |
Friction power per unit surface area W m−2 | |
f | Friction factor, (-) |
Fin pitch, m | |
Fin thickness, m | |
Maximum mass velocity, kg s−1m−2 | |
h | Heat transfer coefficient, W m−2K−1 |
j | Colburn factor, (-) |
Thermal conductivity of fin, W m−1K−1 | |
Expansion and Contraction coefficient, (-) | |
Tube rows, (-) | |
Longitudinal length, m | |
Transverse length, m | |
Pressure, Pa | |
Fin perimeter, m | |
Prandtl number, (-) | |
Heat transfer to the fin, W | |
Heat transfer to an ideal fin, W | |
R2 | Coefficient of determination, (-) |
Re | Reynolds number, (-) |
Tube height, m | |
Tube width, m | |
T | Temperature, K |
Fluid ambient temperature, K | |
Fin base temperature, K | |
Fin average temperature, K | |
Maximum air velocity, m s−1 | |
Frontal air velocity, m s−1 | |
Flow velocity in x-direction, m s−1 | |
Longitudinal tube pitch, m | |
Transverse tube pitch, m | |
Dimensionless distance to the wall, (-) | |
Greek Symbols | |
Compactness, m−1 | |
Fin efficiency, (-) | |
Overall surface efficiency, (-) | |
Viscosity, Pa s−1 | |
Fluid density, kg m−3 | |
Contraction ratio, (-) | |
Fin angle, deg | |
Pressure drop, Pa | |
Abbreviation | |
CFD | Computational Fluid Dynamics |
FEM | Finite Element Method |
LES | Large Eddy Simulation |
LMTD | Logarithmic Mean Temperature Difference |
MAD | Mean Absolute Deviation |
MRD | Mean Relative Deviation |
NTU | Number of Transfer Units |
SST | Shear Stress Transport |
Subscripts | |
ent | Entrance |
fd | Fully developed |
i | Inlet |
m | Mean |
o | Outlet |
v | Vapor |
w | Wall |
Appendix A
Appendix A.1. Fin Efficiency
Appendix A.2. Longitudinal Extrapolation Analysis
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Parameters | Variation |
---|---|
Transverse tube pitch, (mm) | 9.00, 13.00, 17.00, 21.00 |
Fin pitch, (mm) | 2.50, 5.00, 7.50, 10.00 |
Longitudinal tube pitch, (mm) | 4.50 |
Tube rows, (-) | 35 |
Tube height, (mm) | 2.00 |
Tube width, (mm) | 2.00 |
Fin thickness, (mm) | 0.1625 |
Frontal air velocity, (m·s−1) | 1.47, 2.93, 4.40 |
Coefficient | j-Factor | f-Factor |
---|---|---|
0.8539 | 0.8665 | |
−0.5433 | −0.2804 | |
−0.4234 | −0.8512 | |
0.0424 | 0.1777 | |
−0.0966 | 0.9961 | |
0.0303 | 1.4393 | |
−0.2697 | −0.5795 | |
0.1015 | −0.1196 | |
0.1095 | −0.2454 | |
3.1784 | 1.2611 |
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Rogie, B.; Brix Markussen, W.; Honore Walther, J.; Ryhl Kærn, M. Numerical Investigation of Air-Side Heat Transfer and Pressure Drop Characteristics of a New Triangular Finned Microchannel Evaporator with Water Drainage Slits. Fluids 2019, 4, 205. https://doi.org/10.3390/fluids4040205
Rogie B, Brix Markussen W, Honore Walther J, Ryhl Kærn M. Numerical Investigation of Air-Side Heat Transfer and Pressure Drop Characteristics of a New Triangular Finned Microchannel Evaporator with Water Drainage Slits. Fluids. 2019; 4(4):205. https://doi.org/10.3390/fluids4040205
Chicago/Turabian StyleRogie, Brice, Wiebke Brix Markussen, Jens Honore Walther, and Martin Ryhl Kærn. 2019. "Numerical Investigation of Air-Side Heat Transfer and Pressure Drop Characteristics of a New Triangular Finned Microchannel Evaporator with Water Drainage Slits" Fluids 4, no. 4: 205. https://doi.org/10.3390/fluids4040205