An　Experimental　and　Numerical　Study　of　Natural　Convection　Heat　Transfer　in　Horizontal　Annuli　between　Eccentric　Cylinders

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Natural convection heat transfer in eccentric annuli made of two isothermal horizontal circular cylinders is numerically investigated. Bipolar coordinates are used for the eccentric annuli. The governingequations are transformed into finite difference equations (FDE) by the central difference approach.Heat transfer and flow convection pattern results are simulated for 5.0≤RaL≤1.0×105, withPr = 0.3 - 100, Do/Di = 1.25 - 5.0, andε= 0.01-0.95. The axis of the inner cylinder lies onan inclined plane with θp= 0°- 180°.A Mach-Zehnder interferometer is used for the experimentalstudy. The range is for RaL = 5.3×102-2.41×104, with Do/Di = 2.0, 2.5 and 3.125,ε= 0.0-0.85,and θp= 0°-180°.Air is used as the medium. Comparison of the numerical results with the experimental data shows good agreement.