3-D thermal-hydraulic analysis for louver fin heat exchangers with variable louver angle

In the present study, successively increased or decreased louver angle patterns are proposed and 3-D numerical analysis on heat and fluid flow are carried out. Five different cases of successively increased or decreased louver angles (+2 degrees, +4 degrees, -2 degrees, -4 degrees, and uniform angle 20 degrees) are investigated: case A (20 degrees, 22 degrees, 24 degrees,26 degrees, 24 degrees, 22 degrees, 20 degrees), case B (20 degrees, 24 degrees, 28 degrees, 32 degrees, 28 degrees, 24 degrees, 20 degrees), case C (26 degrees, 24 degrees, 22 degrees, 20 degrees, 22 degrees, 24 degrees, 26 degrees), case D (32 degrees, 28 degrees, 24 degrees, 20 degrees, 24 degrees, 28 degrees, 32 degrees), case E (uniform angle 20 degrees). For case A (+2 degrees), case B (+4 degrees), case C (-2 degrees) and D (-4 degrees), the maximum heat transfer improvement interpreted by j/j(0) are 115%, 118%, 109% and 107%, and the corresponding friction factor ratio f/f(0) are 116%, 119% 110% and 108%, respectively, where j/j(0) and f/f(0) are the Colburn factor ratio and friction factor ratio between successively variable louver angles and uniform angle, respectively. It is also shown that the maximum area reduction for case B can reach up to 25.5% compared to a plain fin surface. The present results indicated the successively variable louver angle patterns applied in heat exchangers could effectively enhance the heat transfer performance. (c) 2005 Elsevier Ltd. All rights reserved.