Chapter 5, Problem 5.6CU

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.

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.

A cogeneration power plant operating in a thermodynamic cycle at steady state. The plant provides electricity to a community at a rate of 80 MW. The energy discharged from the power plant by heat transfer is denoted on the figure by Q Of this, 70 MW is provided to the community for water heating and the remainder is discarded to the environment without use. The electricity is valued at $0.08 per kWh. If the cycle thermal efficiency is 40 %, determine the i. rate energy is added by heat transfer, Q in MW rate energy is discarded to the environment, in MW value of the electricity generated, in $ per year ii. ii.

If a closed system undergoes a process for which S2=S1, the process must be internally reversible. - True or False One of the Carnot principles states that all power cycles operating between the same two thermal reservoirs have the same thermal efficiency. - True or False One statement of the second law of thermodynamics recognizes that the extensive property entropy is produced within systems whenever internal irreversibilities are present. - True or False

Find the cycle entropy production and answer if it operates irreversibly, reverisbly, or impossibly. A system executes a power cycle while receiving 1000 kJ by heat transfer at a temperature of 500 K and discharging energy by heat transfer at 300 K. Determine the cycle entropy production if the cycle thermal efficiency is 25% in kJ / K. Enter the answer without units, but with a minus sign if applicable. This cycle operates     irreversibly     reversibly     impossibly.

A reversible heat pump cycle operates at steady state between hot and cold reservoirs at TH = 30°C and Tc 10°C, respectively. The rate of heat transfer at the high temperature is 10 kW. a. Determine the net power input, in kW. b. Determine the heat transfer rate from the cold reservoir at Tc, in kW. c. Determine the coefficient of performance of the cycle.

The gasoline internal combustion engine operates in a cycle consisting of six parts. Four of these parts involve, among other things, friction, heat exchange through finite temperature differences, and accelerations of the piston; it is irreversible. Nevertheless, it is represented by the ideal reversible Otto cycle with a pV-diagram as illustrated below. The working substance of the cycle is assumed to be air. PA Q1 D B Q2 Ро V V8 = Vc VA = VD

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.

Two reversible power cycles are arranged in series. The first cycle receives energy by heat transfer from a reservoir at temperature TH and rejects energy to a reservoir at an intermediate temperature T. The second cycle receives the energy rejected by the first cycle from the reservoir at temperature T and rejects energy to a reservoir at temperature TC lower than T. Derive an expression for the intermediate temperature T in terms of TH and TC when,a. The net works of the two power cycles are equalb. The thermal efficiencies of the two power cycles are equal