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Problem 4.205

Problem 4.205 - = Since m rate ρ Q ⋅ = and V 1 V 2...

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Problem 4.205 [Difficulty: 3] Given: Data on centrifugal water pump Find: Pump efficiency Solution: Basic equations: (4.56) pS G Hg ρ g h = η W s P in = Available data: D 1 0.1 m = D 2 0.1 m = Q 0.02 m 3 s = P in 6.75 kW = ρ 1000 kg m 3 = SG Hg 13.6 = h 1 0.2 m = p 2 240 kPa = Assumptions: 1) Adiabatic 2) Only shaft work 3) Steady 4) Neglect u 5) z = 0 6) Incompressible 7) Uniform flow Then W s p 1 v 1 V 1 2 2 + m rate () p 2 v 2 V 2 2 2 + m rate ()
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Unformatted text preview: + = Since m rate ρ Q ⋅ = and V 1 V 2 = (from continuity) W s − ρ Q ⋅ p 2 v 2 ⋅ p 1 v 1 ⋅ − ( ) ⋅ = Q p 2 p 1 − ( ) ⋅ = p 1 ρ Hg g ⋅ h ⋅ = or p 1 SG Hg ρ ⋅ g ⋅ h 1 ⋅ = p 1 26.7 − kPa ⋅ = W s Q p 1 p 2 − ( ) ⋅ = W s 5.33 − kW ⋅ = The negative sign indicates work in η W s P in = η 79.0 % ⋅ =...
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