COBEM99

SR27 Transferência de Calor e Massa

Title:

THERMALLY DEVELOPING LAMINAR FLOW INSIDE RECTANGULAR DUCTS SUBMITTED TO BOUNDARY CONDITIONS OF THIRD KIND

Summary :

THERMALLY DEVELOPING, HYDRODYNAMICALLY DEVELOPED, LAMINAR FORCED CONVECTION INSIDE RECTANGULAR DUCTS, SUBJECT TO BOUNDARY CONDITIONS OF THIRD KIND, IS ANALYTICALLY STUDIED BY USING THE GENERALIZED INTEGRAL TRANSFORM TECHNIQUE, ALLOWING FOR THE SOLUTION OF A CONVECTION-DIFFUSION PROBLEM WITH NON-SEPARABLE EIGENVALUE PROBLEM. CONSTANT FLUID PROPERTIES, HIGH PECLET NUMBER AND NEGLIGIBLE VISCOUS DISSIPATION ASSUMPTIONS ARE UTILIZED. TRANSFORMING THE ENERGY EQUATION FOR THE UNKNOWN TEMPERATURE PROFILE BY THE USE OF THE INTEGRAL TRANSFORM TECHNIQUE RESULTS A COUPLED SYSTEM OF FIRST ORDER ORDINARY DIFFERENTIAL EQUATIONS FOR THE UNKNOWN TRANSFORMED-TEMPERATURE DISTRIBUTION. THAT SYSTEM IS THEN SOLVED AND THE TEMPERATURE PROFILE CAN BE OBTAINED BY USING THE INVERSION FORMULA. REFERENCE RESULTS WERE ESTABLISHED FOR QUANTITIES OF PRACTICAL INTEREST WITHIN THERMAL ENTRY REGION, FOR A WIDE RANGE OF AXIAL VARIABLE, VARIOUS ASPECT RATIOS AND BIOT NUMBERS. AMONG THAT, THERMAL QUANTITIES ARE BULK FLUID TEMPERATURE, AVERAGE WALL TEMPERATURE, AVERAGE AND LOCAL NUSSELT NUMBERS AND THERMAL ENTRY LENGTH. THE ACCURACY OF PREVIOUSLY REPORTED RESULTS WAS THEN CRITICALLY EXAMINED, FOR BOTH THE DEVELOPING AND FULLY DEVELOPED REGIONS.

Author :

Aparecido, Aparecido Batista
Dias-Júnior, Tito 0

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