Analysis of entropy generation during natural convection in porous right-angled triangular cavities with various thermal boundary conditions

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• 作者：Tanmay Basak ; ^{tanmay@iitm.ac.in} ; Praveen Gunda ^{praveeng850@gmail.com} ; R. Anandalakshmi ^{anandalakshmir@gmail.com}
• 关键词：Entropy generation ; Natural convection ; Porous media ; Triangular cavities ; Isothermal heating ; Linear heating ; Bejan number
• 刊名：International Journal of Heat and Mass Transfer
• 出版年：2012
• 出版时间：August, 2012
• 年：2012
• 卷：55
• 期：17-18
• 页码：4521-4535
• 全文大小：1108 K

文摘

Entropy generation due to natural convection in right-angled triangular enclosures filled with porous media with top angles 15¡ã and 45¡ã for various thermal boundary conditions (cases 1-4) has been studied numerically using Galerkin finite element method. Simulations are carried out for Pr = 0.025 and 1000 in the range of Darcy numbers 10^?-10^?. Note that, S_¦È,max is observed at vertex of the cavity for cases 1 and 3, near corner between left wall and bottom wall for case 2 and near lower portion of the right wall for case 4. It is found that, S_¦×,max is observed near middle portions of the side walls for all cases and the location of S_¦×,max mainly depends on the presence of high velocity gradients. The total entropy generation, S_total, is found to be an increasing function of Da. It is observed that decrease in Be_av with Da for both ¦Õs is due to increase in fluid friction irreversibility. Analysis of the variation of Be_av with Da for various fluids indicates that, higher Be_av values are observed for Pr = 0.025 due to low frictional irreversibility. It is observed that ¦¨_cup decreases with Da for all Pr due to decrease in thermal mixing. It is found that, the maximum heat transfer rate ( or ) occurs for ¦Õ = 15¡ã cavities compared to ¦Õ = 45¡ã cavities at Da = 10^? in both isothermal and linear heating cases for all Pr due to larger thermal gradients at ¦Õ = 15¡ã. Overall, triangular cavities with ¦Õ = 15¡ã may be the optimal top angle for right angled triangular enclosure for thermal processing of all types of fluids (Pr = 0.025 and 1000) due to its high heat transfer rate or ), high thermal mixing (high ¦¨_cup) and less total entropy generation (S_total) for all heating strategies (cases 1-4) especially at Da = 10^?.