Effect of Operating Conditions on the Mixed Convection in a Channel with Discrete Heat Sources and Partially Filled with Porous Media. | ||||
| MEJ- Mansoura Engineering Journal | ||||
| Article 13, Volume 24, Issue 4, December 1999, Page 47-61 PDF (653.43 K) | ||||
| Document Type: Research Studies | ||||
| DOI: 10.21608/bfemu.2002.148891 | ||||
 View on SCiNiTO | ||||
| Author | ||||
M. S. El-Kady 
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| Mechanical Power Engineering Department., Faculty of Engineering., El-Mansoura University., Mansoura., Egypt. | ||||
| Abstract | ||||
| An experimental study of laminar mixed convection in a partially filled porous channel with two discrete heat sources on the bottom wall was performed The main object is to show the effect of Reynolds number, the heat flux, and Grashof number on the heat transfer characteristics. A channel of 120x120mm cross section and length of 200mm is fitted in a low turbulence wind channel. The passages above the heat sources are filled with patous layers and the channel is non-porous the heat sources are elsewhere. The air flow velocity was varied up to 3 m/s which gives a variation of Reynolds number up to 6000. heat flux and Grashof number were varied up to 7017 W/m2 and 58x106 respectively. Aluminum porous filtration screen sheets of 3mm) thickness, poroşity of 0.95, 122.85 kg/m3 density, 1.28 x10-8 m2 permeability and Darcy number = 8x10-6were used as porous layers. The results show that with the increase of Reynolds number, the surface and maximum temperature of the heat sources decrease. and both the local and average Nusselt number increase. For Re=3404 the decrease in maximum temperature and the increase of average Nusselt number are relatively small. Therefore, if the maximum temperatures of the heat sources at Re=3404 are within the safe range of operation, there is no need to increase the Reynolds number over Re =3404, which coresponds to air flow velocity of about 1.7 m/s, which cause a decrease in the required cooling power cost. With increasing the heat flux or Grashof number, the temperatures of the heat sources increase, the heat transfer coefficient increases, the maximum temperature increases linearly and the average Nusselt number increases exponentially. Correlations were obtained for the maximun temperatures and average Nusslet number for both heat sources with Reynolds and Grashof numbers. | ||||
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