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Metal foams are a relatively recent category of materials used in different applications, such as: compact heat sinks, geothermal operations, heat exchanger and solar thermal plants. The use of metal foams in heat exchangers gives it efficiency, compact and light for the open porosity, a high thermal conductivity and a large accessible surface area per unit volume.
A numerical study has been conducted to evaluate the thermal and fluid dynamic behaviors of a tubular aluminum foam heat exchanger. The thermal non-equilibrium energy condition is considered to execute two-dimensional simulations on metal foam heat exchanger. The examined foams are characterized by distinct porosity, from 0.90 to about 0.97, for different values of pores per inch, equal to 5, 10, 20 and 40. Different air flow rates and an assigned surface tube temperature are imposed. The results are given in terms of heat transfer coefficient and local Nusselt number evaluated on the external surface of the tube. Typical global parameters in a compact heat exchanger, such as effectiveness and NTU, are showed. Moreover, local air temperature and velocity profiles are presented in the cross section, between two consecutive tubes. Finally, the Energy Performance Ratio (EPR) is showed in order to demonstrate the effectiveness of the metal foams.
aluminum foam, heat exchanger, heat transfer enhancement
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A |
cross section, m2 |
|
CF |
drag factor coefficient |
|
cp |
specific heat, J kg-1 K-1 |
|
d |
tube diameter, m |
|
df dp |
fiber diameter, m pore diameter, m |
|
f |
friction factor |
|
h |
heat transfer coefficient, W m-2 K-1 |
|
hsf |
interfacial heat transfer coefficient, W m-2 K-1 |
|
H |
half pitch, m |
|
Htot |
heat exchanger height, m |
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j |
Colburn factor |
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k |
thermal conductivity, W m-1 K-1 |
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K |
porous permeability, m2 |
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L |
thickness of porous media, m |
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˙m
|
mass flow rate, kg s-1 |
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Nu |
Nusselt number |
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NTU |
number transfer of units |
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p |
static pressure, Pa |
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Pr |
Prandtl number |
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Q |
heat transfer rate, W |
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r |
radius tube, m |
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Re |
Reynolds number |
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s |
curvilinear abscissa, m |
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T |
Temperature, K |
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u |
x-velocity, m s-1 |
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u0 |
inlet air velocity, m s-1 |
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v |
y-velocity, m s-1 |
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x |
Cartesian axis direction, m |
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y |
Cartesian axis direction, m |
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Greek symbols
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|
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asf |
specific surface area density, m-1 |
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Δ |
difference |
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ɛ |
effectiveness |
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µ |
dynamic viscosity, kg m-1 s-1 |
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ρ |
density, kg m-3 |
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f |
porosity |
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w |
number of pores per inch, m-1 |
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Subscripts |
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0 |
inlet condition |
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clean |
system without foam |
|
d |
tube diameter |
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df |
fiber diameter |
|
eff |
effective |
|
f |
fluid phase of metal foam |
|
mf |
metal foam |
|
s |
solid phase of metal foam |
Abouei Mehrizi A., Farhadi M., Sedighi K., Aghajani Delavar M. (2013). Effect of fin position and porosity on heat transfer improvement in a plate porous media heat exchanger. Journal of the Taiwan Institute of Chemical Engineers, Vol. 44, pp. 420-431. http://doi.org/10.1016/j.jtice.2012.12.018
Bello F., Viggiano A., Fanelli E., Magi V. (2014). A CFD analysis of the air flow through the matrix regenerator of Stirling engines. Proceedings of 16th International Stirling Engine Conference, pp. 58–71.
Bhattacharya A., Calmidi V. V., Mahajan R. L. (2001). Thermophysical properties of high porosity metal foams. Int. J. Heat Mass Transfer, Vol. 45, pp. 1017-1031. https://doi.org/10.1016/s0017-9310(01)00220-4
Buonomo B., di Pasqua A., Ercole D., Manca O., Nardini S. (2018). Numerical investigation on aluminum foam application in a tubular heat exchanger. Heat and Mass Transfer, Vol. 54, No. 3, pp. 1-9. https://doi.org/10.1007/s00231-018-2305-7
Calmidi V. V. (1998). Transport phenomena in high porosity metal foams. Ph.D. Thesis, University of Colorado, Boulder, CO.
Calmidi V. V., Mahajan R. L. (2000). Forced convection in high porosity metal foams. ASME J. Heat Transfer, Vol. 122, pp. 557-565. https://doi.org/10.1115/1.1287793
Chumpia A., Hooman K. (2015). Performance evaluation of tubular aluminum foam heat exchangers in single row arrays. Appl. Therm. Eng, Vol. 83, pp. 121-130. https://doi.org/10.1016/j.appl thermaleng.2015.03.015
Dukhan N. (2013). Metal foam: Fundamentals and Applications.
Erkinaci T., Baytas F. (2017). CFD investigation of a sensible packed bed thermal energy storage system with different porous materials. Int. J. Heat and Technology, Vol. 35, Special Issue 1, pp. S281-S287. https://doi.org/10.18280/ijht.35Sp0138
Feng S. S., Kuang J. J., Wen T., Lu T. J., Ichimiya K. (2014). An experimental and numerical study of finned metal foam heat sinks under impinging air jet cooling. Int. J. Heat Mass Transfer, Vol. 77, pp. 1063-1074. https://doi.org10.1016/j.ijheatmasstransfer.2014.05.053
Huisseune H. D., Schampheleire S., Ameel B., De Paepe M. (2015). Comparison of metal foam heat exchangers to a finned heat exchanger for low Reynolds number applications. Int. J. Heat Mass Transfer, Vol. 89, pp. 1-9. https://doi.org/10.1016/j.ijheatmasstransfer.2015.05.013
Huisseune H., De Schampheleire S., Ameel B., De Paepe M. (2014). Evaluation of the thermal hydraulic performance of round tube metal foam heat exchangers for HVAC applications. Proceedings of the 15th Int. Heat Transfer Conf. https://doi.org/10.1615/IHTC15.pmd.008831J
Jha B. K., Yusuf T. S. (2018). Transient pressure driven flow in an annulus partially filled with porous material: Azimuthal pressure gradient. Mathematical Modelling of Engineering Problems, Vol. 5, No. 3, pp. 260-267. https://doi.org/10.18280/mmep.050320
Kim S. Y., Paek J. W., Kang B. H. (2000). Flow and heat transfer correlations for porous fin in a plate-fin heat exchanger. ASME J. Heat Transfer. Vol. 122, pp. 572-578. https://doi.org/10.1115/ 1.1287170
Lin W., Sunden B., Yuan J. (2013). A performance analysis of porous graphite foam heat exchangers in vehicles. Appl. Therm. Eng, Vol. 50, pp. 1201-1210. https://doi.org/10.1016/j. applthermaleng.2012.08.047
Mahjoob S., Vafai K. (2008). A synthesis of fluid and thermal transport models for metal foam heat exchangers. Int. J. Heat Mass Transfer, Vol. 51, pp. 3701–3711. https://doi.org/10.1016/j. ijheatmasstransfer.2007.12.012
Mao S., Love N., Leanos A., Rodriguez-Melo G. (2014). Correlation studies of hydrodynamics and heat transfer in metal foam heat exchangers. Appl. Therm. Eng, Vol. 71, pp. 104-118. https://doi.org 10.1016/j.applthermaleng.2014.06.035
Nield D. A., Bejan A. (2013). Convection in Porous Media.
Odabaee M., Hooman K. (2012). Metal foam heat exchangers for heat transfer augmentation from a tube bank. Appl. Therm. Eng, Vol. 36, pp. 456-463. https://doi.org/10.1016/j.applthermaleng.2011.10.063
Odabaee M., Hooman K., Gurgenci H. (2011). Metal foam heat exchangers for heat transfer augmentation from a cylinder in cross-flow. Trans. Porous Media, Vol. 86, pp. 911-923. https://doi.org/10.1007/s11242-010-9664-y
Sheikha M., Al-Weheibi Rahman M. M. (2018). Convective heat transmission inside a porous trapezoidal enclosure occupied by nanofluids: Local thermal nonequilibrium conditions for a porous medium. Italian J. Eng. Sc., Vol. 61+1, No. 2, pp. 102-114. https://doi.org/10.18280/ijes.620208
Whitaker S. (1998). The Method of Volume Averaging.
Wong K. C., Saeid N. H. (2008). Numerical study of mixed convection on jet impingement cooling in a horizontal porous layer under local thermal non-equilibrium conditions. International Journal of Thermal Sciences, Vol 48, pp. 860-870. https://doi.org/10.1016/j.ijthermalsci.2008.06.004
Xu H. J., Gong L., Zhao C. Y., Yang Y. H., Xu Z. G. (2015). Analytical considerations of local thermal non-equilibrium conditions for thermal transport in metal foams. Int. J. Therm. Sc. Vol. 95, pp. 73-87. https://doi.org/10.1016/j.ijthermalsci.2015. 04.007
Yuan W., Tang Y., Yang X., Wan Z. (2012). Porous metal materials for polymer electrolyte membrane fuel cells – A review. Appl. En, Vol. 94, pp. 309–329. https://doi.org/10.1016/j.apenergy.2012.01.073
Zafari M., Panjepour M., Emami M. D., Meratian M. (2015). Microtomography-based numerical simulation of fluid flow and heat transfer in open cell metal foams. App. Therm. Eng, Vol. 80, pp. 347-354. https://doi.org/10.1016/j.applthermaleng. 2015.01.045
Zhao W., France D. M., Yu W., Kim T., Singh D. (2014). Phase change material with graphite foam for application in high-temperature latent heat storage systems of concentrated solar power plants. Renew Energy, Vol. 69, pp. 134-146. https://doi.org/10.1016/j.renene.2014.03
