Chapter 6, Problem 6.60P

Steam enters a turbine operating at steady state at 800°F and 450 lbf/in? and leaves as a saturated vapor at 1.4 lbf/in?. The turbine develops 12,000 hp, and heat transfer from the turbine to the surroundings occurs at a rate of 2 x 106 Btu/h. Neglect kinetic and potential energy changes from inlet to exit. Determine the exit temperature, in °F, and the volumetric flow rate of the steam at the inlet, in ft /s.

A divider separates 1 lb mass of carbon monoxide (CO) from a thermal reservoir at 150o F. the carbon monoxide, initially at 60o F  and 150 lbf/in2, expands isothermally to a final pressure of 10 lbf/in2 while receiving heat transfer through the divider from the reservoir. The carbon monoxide can be modeled as an ideal gas. (a) For the carbon monoxide as the system, evaluate the work and heat transfer, each in Btu and the amount of entropy produced, in Btu/oR. (b) Evaluate the entropy production, in Btu/oR, for an enlarged system that includesthe carbon monoxide and the divider, assuming the state of the divider remains unchanged. Compare with the entropy production of part (a) and comment on the difference.

Refrigerant 134a enters an insulated diffuser as a saturated vapor at 80oF with a velocity of 1200 ft/s. The inlet area is 1.4 in2.  At the exit, the pressure is 400 lbf/in2 and the velocity is negligible. The diffuser operates at steady state and potential energy effects can be neglected. Determine the mass flow rate, in lb/s, and the exit temperature, in oF.