Chapter 8, Problem 8.50CU

4. In part of a Carnot cycle, water undergoes two internally reversible processes shown in the image. Determine the heat transfer (in kJ/kg) for each process. pi =1 MPa, T2 = 400 °C, p2 = 2 MPa. %3D %3D 3.

As shown in the figure below, two reversible cycles arranged in series each produce the same net work, Weycle. The first cycle receives energy QH by heat transfer from a hot reservoir at TH = 1500°R and rejects energy Q by heat transfer to a reservoir at an intermediate temperature, T. The second cycle receives energy Q by heat transfer from the reservoir at temperature T and rejects energy Qc by heat transfer to a reservoir at Tc = 500°R. All energy transfers are positive in the directions of the arrows. Hot reservoir at T RI W. cycle Reservoir at T R2 Wcycle Cold reservoir at Te Determine: (a) the intermediate temperature T, in °R, and the thermal efficiency for each of the two power cycles. (b) the thermal efficiency of a single reversible power cycle operating between hot and cold reservoirs at 1500°R and 500°R, respectively. Also, determine the ratio of the net work developed by the single cycle to the net work developed by each of the two cycles, Woycle-

Shown below is P-V diagram for a reversible cycle enclosed by 4 reversible process curves.  The curve 1-2 and the curve 3-4 are  reversible isothermal processes, and the curve 2-3 and the curve 1-4 are reversible adiabatic processes. If the cycle direction is counter clockwise, answer the question below. Does the cycle have net work input or output?____     A. Input   B. output

Give solution to the thermodynamics problem.

As shown in the figure below, two reversible cycles arranged in series each produce the same net work, Wcycle. The first cycle receives energy QH by heat transfer from a hot reservoir at TH = 1500°R and rejects energy Q by heat transfer to a reservoir at an intermediate temperature, T. The second cycle receives energy Q by heat transfer from the reservoir at temperature T and rejects energy QC by heat transfer to a reservoir at TC = 450°R. All energy transfers are positive in the directions of the arrows.   Determine:(a) the intermediate temperature T, in °R, and the thermal efficiency for each of the two power cycles.(b) the thermal efficiency of a single reversible power cycle operating between hot and cold reservoirs at 1500°R and 450°R, respectively. Also, determine the ratio of the net work developed by the single cycle to the net work developed by each of the two cycles, Wcycle.

7.66 Referring to the discussion of Sec. Z.6.2 as required, evaluate the exergetic efficiency for each of the following cases, assuming steady-state operation with negligible effects of heat transfer with the surroundings: a. Turbine: Wer 1200 hp, e 250 Btu//lb, eg = 15 Btu/lb, m 240 lb/min. b. Compressor: Wev/m=-105 kJ /kg, e = 5 kJ/kg, eg = 90 kJ/kg, m 2 kg /s. c. Counterflow heat exchanger: mh = 3 kg/s, me 10 kg /s, ef = 2100 kJ/kg, e = 300 kJ/kg, É = 3.4 MW 10 lb /s, m3 15 b /s, en = 1000 Btu/Ib, eg = 50 Btu/Ib, eg = 400 Btu/lb d. Direct contact heat exchanger: m1

As shown in the figure below, two reversible cycles arranged in series each produce the same net work, Wcycle. The first cycle receives energy QH by heat transfer from a hot reservoir at TH = 1000°R and rejects energy Q by heat transfer to a reservoir at an intermediate temperature, T. The second cycle receives energy Q by heat transfer from the reservoir at temperature T and rejects energy Qc by heat transfer to a reservoir at Tc = 500°R. All energy transfers are positive in the directions of the arrows. Determine: Hot reservoir at TH QH Reservoir at T R1 lo ali R2 Qc Cold reservoir at Te W. cycle W cycle (a) the intermediate temperature T, in °R, and the thermal efficiency for each of the two power cycles. (b) the thermal efficiency of a single reversible power cycle operating between hot and cold reservoirs at 1000°R and 500°R. respectively. Also, determine the ratio of the net work developed by the single cycle to the net work developed by each of the two cycles, Wcycle.

A closed system undergoes a cycle consisting of three process 1-2, 2-3 and 3-1.  Given that Q12 = 30kJ, Q23 = 10 kJ, 1w2 = 5 kJ, 3w2 = 5 kJ and DE31 = 15 kJ, Evaluate Q31, w23, DE12 and DE23.

The adjacent figure provides steady-state operating data for a vapor power plant using water as the working fluid. The mass flow rate of water is 12 kg/s. The turbine and pump operate adiabatically but not reversibly. Determine a) the thermal efficiency. b) the rates of heat transfer QQ and QQ000000, each in kW. State 1 2 3 4 5 6 P 6 MPa 10 kPa 10 kPa 7.5 MPa 7 MPa 6 MPa T(°C) 500 Sat. 40 550 h (kJ/kg) 3422.2 1633.3 191.83 199.4 167.57 3545.3