system undergoes a power cycle while receiving 1450 kJ by heat transfer from a thermal reservoir at a the temperature of 780 K and discharging 560 kJ by heat transfer to a thermal reservoir at (a) 250 K, (b) 380 K, (c) 460 K.  For each case, determine whether the cycle operates irreversibly, operates

A system executes a power cycle while receiving 1000 Btu by heat transfer at a temperature of 900oR and discharging 600 Btu by heat transfer at a temperature of 540oR. There are no other heat transfers.Determine the cycle thermal efficiency.  Use the Clausius Inequality to determine σcycle, in Btu/oR. Determine if this cycle is internally reversible, irreversible, or impossible.

Water stored in a large, well-insulated storage tank at 21oC, and atmospheric pressure is being pumped at steady state from this tank by a pump at the rate of 40m3/h. The motor driving the pump supplies energy at the rate of 8.5 k.W. The water is used as a cooling medium and passes through a heat exchanger where 255 k.W of heat is added to the water. The heated water then flows to a second large, vented tank, which is 25 m above the first tank. Determine the final temperature of the water delivered to the second tank.

A steady-state system for producing power consist of a pump, heat exchanger and a turbine. Water at 1.0 bar and 20°C (state 1) enters the adiabatic pump and leaves at 10 bar (state 2). The pump draws 110 kW of power, and the mass flow rate of water is 45 kg/s. The water leaving the pump enters a heat exchanger and heated at constant pressure to 400°C (state 3) using exhaust gases (Cp of gases = 1.1 kJ/kgK) that enters at 500°C and exits at 182°C. The steam is adiabatically expanded in a turbine having an isentropic efficiency of 0.71. The turbine exhausts (state 4) to the surroundings at 1.0 bar. What is thermal efficiency of this power production process? If the pump and turbine are reversible, would the efficiency of this system equal the maximum possible efficiency? (Answer Yes or NO and provide a short explanation.)