HW3Prob5 - A PWR has dimensions and operating conditions...

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Single Phase 22 1 A PWR has dimensions and operating conditions given below. Core Height 144 inches Core Mass Flux 2.62 x 10 6 lbm/hr-ft 2 Number of Fuel Rods 56,876 Rod Diameter 0.374 inches Rod Pitch 0.496 inches Core Inlet Loss Coefficient 1.5 Core Exit Loss Coefficient 1.5 Grid Loss Coefficient 0.5 Number of Grids 8 Pressure 2250 psia Core Inlet Temperature 560 F Maximum Channel Heat Flux 265,700 Btu/hr-ft 2 Extrapolation Distance 0.866 ft You may assume an axial heat flux profile of the form ′′ = + qz q z H e () s in 0 πλ Determine the acceleration, friction, forms, elevation and total pressure loss. Compare to that which would be obtained from a simple Bernoulli’s Equation approach where the density is approximated by the average channel density 2 / ) ( inlet exit ρ + and the density is evaluated at the average coolant temperature. Assume the same treatment holds for viscosity also. Solution Integrate the conservative form of the steady-state Momentum Equation over the channel length 11 gA z vvA P z P A g g cx x ww xc τ ρθ =− sin (1) or 1 22 2 gz GP z f D G g Kz z G g g g ce c jj c j c ∂ρ δ ⎟=− + s i n (2) where we have assumed a uniform flow area and a vertical flow channel. For convenience the momentum equation has been written in terms of the mass flux. 1 2 1 2 1 2 2 1 2 2 1 2 1 2 G dz P z dz f D G g dz K z z G g dz g g dz c c j c ⎟= + ∫∫ (3) 1 2 2 2 1 2 1 2 2 2 2 1 1 H H g g g G K g G D L f P P g G c c j j j j i c i i e i i c i = (4) Rearranging gives for the core pressure drop
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Single Phase 22 2 core c c j j j c e core c core H g g g G K g G D H f g G P ρ + + + = Δ 2 2 1 1 2 2 1 2 2 (5) where location 1 is the core inlet, location 2 is the core exit and and are appropriate average fluid densities in the core. The core pressure drop then consists of four components: 1) The
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This note was uploaded on 12/08/2010 for the course NE 402 taught by Professor Doster during the Fall '08 term at N.C. State.

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HW3Prob5 - A PWR has dimensions and operating conditions...

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