Sphw4b - HOMEWORK SET 4b 6.9 In a boiler you vaporize some...

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6.9 In a boiler you vaporize some liquid water at 100 kPa flowing at 1 m/s. What is the velocity of the saturated vapor at 100 kPa if the pipe size is the same? Can the flow then be constant P? The continuity equation with average values is written m . i = m . e = m . = ρ A V = A V /v = A V i /v i = A V e /v e From Table B.1.2 at 100 kPa we get v f = 0.001043 m 3 /kg; v g = 1.694 m 3 /kg V e = V i v e /v i = 1 1.694 0.001043 = 1624 m/s To accelerate the flow up to that speed you need a large force ( Δ PA ) so a large pressure drop is needed. P i cb P e < P i 6.17 A nozzle receives 0.1 kg/s steam at 1 MPa, 400 o C with negligible kinetic energy. The exit is at 500 kPa, 350 o C and the flow is adiabatic. Find the nozzle exit velocity and the exit area. Solution: Energy Eq.6.13: h 1 + 1 2 V 2 1 + gZ 1 = h 2 + 1 2 V 2 2 + gZ 2 Process: Z 1 = Z 2 State 1: V 1 = 0 , Table B.1.3 h 1 = 3263.88 kJ/kg State 2: Table B.1.3 h 2 = 3167.65 kJ/kg Then from the energy equation 1 2 V 2
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This homework help was uploaded on 04/10/2008 for the course ME 235 taught by Professor Borgnakke during the Spring '07 term at University of Michigan.

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Sphw4b - HOMEWORK SET 4b 6.9 In a boiler you vaporize some...

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