Chapter 6, Problem 6.55CU

Thermodynamics, please help and show all work please.

Water within a piston-cylinder assembly, initially at 10 lbf/in.2, 750°F, undergoes an internally reversible process to 80 lbf/in.², 800°F, during which the temperature varies linearly with specific entropy. For the water, determine the work and heat transfer, each in Btu/lb. Neglect kinetic and potential energy effects. W12 m Q12 m = tel tel Btu/lb Btu/lb

As in mechanical systems, friction in the workplace is bound to generate entropy and reduce performance.

2. An ideal gas undergoes a process from state 1 ( T1= 300 K, P1= 100 kPa) to state 2 ( T2= 600 K, P2 500 kPa). The specific heats of the ideal gas are : c, = 1 kJ/kg-K and c, = 0.7 kJ/kg-K. The change in specific entropy of the ideal gas from state 1 to state 2 (in kJ/kg-K) is (correct to two decimal places).

Saturated water vapor at 300°F enters a compressor operating at steady state with a mass flow rate of 5 lb/s and is compressed adiabatically to 600 lbf/in.² If the power input is 2150 hp, determine for the compressor: (a) the percent isentropic compressor efficiency and (b) the rate of entropy production, in hp/°R. Ignore kinetic and potential energy effects.

answer 96,97,98

A pure crystalline substance at absolute zero temperature is in perfect order, and its entropy is zero (the third law of thermodynamics).

If the entropy change of an adiabatic, closed system process is positive, the process is which of the following? Impossible, irreversible, externally reversible, internally reversible?

Water at p1 = 20 bar, T1 = 400oC enters a turbine operating at steady state and exits at p2 = 1.5 bar, T2 = 180oC.  The water mass flow rate is 4000 kg/hour. Stray heat transfer and kinetic and potential energy effects are negligible. Determine the power produced by the turbine, in kW, and the rate of entropy production in the turbine, in kW/K.