Special Problems for ME 200 – Spring 2010 Special Problems 30 & 31 Due Friday, April 9, 2010 SP30:In a steam power plant, some steam from the turbine is bled off (stream 1) and used in a mixing chamber to heat sub-cooled water (stream 2) before it enters the boiler. Stream 1 is at a pressure of 100 lbf/in2and a quality of 98% (state 1) while stream 2 is at a pressure of 100 lbf/in2and a temperature of 80F. The mixed stream leaves the mixing chamber at a pressure of 95 lbf/in2and at a temperature of 290F (state 3) with a mass flow rate of 25,000 lbm/hr. The flow through the mixing chamber is at steady state, the mixing chamber can be assumed to be adiabatic, and the changes in kinetic and potential energy can be neglected. (a) Complete the following table for water. StatePressure Temperature Specific Enthalpy Specific EntropyPhaseQuality (%)(psia)(°F)(Btu/lbm)(Btu/lbm-R)(If Applicable)110098210080395290(b) Calculate the mass flow rate (lbm/hr) for stream 1 and stream 2.
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