Chapter 7, Problem 7.8E

When T > T0, the exergy and heat transfer are in the same direction.

Thermodynamics I

Select the Kelvin-Plank statement of the second law of Thermodynamics___________   A. It is impossible to construct a device that operates in a cycle and produces no effect other than the transfer of heat from a lower-temperature body to a higher-temperature body.     B. It is impossible for any device that operates on a cycle to receive heat form a single reservoir and produce a net amount of work.

If the specific exergy of a gas in a cylinder of an internal combustion engine modeled as air behaving like an ideal gas is 368.91 kJ / kg and the cylinder contains 2450 cm2 of gaseous combustion products. Åt what elevation in meters 3-kg mass does it have to be lifted from zero elevation with respect to the reference environment so that its exergy equals the exergy of the cylinder? Assume gravity as g = 9.81 m /s^2 NOTE: The density of dry air at a pressure of 7 bar and a temperature of 867 ° C is 2.1388 kg / m^3.

2. A heat engine operates between two temperature limits of 1000 K and 300 K (environment temperature). It receives 1MJ of heat while producing 500 kJ of useful work. Determine: The exergy of the heat engine. b. The energy that is not available for work production. c. The irreversibility of the process. а.

A power cycle operating between two reservoirs receives energy Qu by heat transfer from a hot reservoir at TH = 2000 K and rejects energy Qc by heat transfer to a cold reservoir at Tc = 400 K. For the cases below you will be asked to determine the cycle n and whether the cycle operates Reversibly, Irreversibility, or is Impossible. Сycle Сycle Сycle Assume: п — пСarnot n пСarnot 1. The maximum thermal efficiency nCarnot for the cycle is equal to а. 0.2 b. 0.8 с. 1.0 d. none of the above. 2. If QH = 1100 kJ and the Weycle = 900 kJ then the cycle is Reversible b. Irreversible c. Impossible а. d. none of the above. 3. If QH = 1000 kJ and Qc = 200 kJ then the cycle is a. Reversible b. Irreversible c. Impossible d. none of the above. 4. If Wq a. Reversible b. Irreversible c. Impossible d. none of the above. суcle 1400 kJ and Qc= 600 kJ then the cycle is 5. If n = 50% then the cycle is a. Reversible b. Irreversible c. Impossible d. none of the above.

Is energy added to the gas by heating or removed by cooling in each cycle? Support your claim in a coherent paragraph-length response that qualitatively compares the amounts of energy added to the gas by heating or removed by cooling in the two cycles and refers to the work done on the gas and the change in internal energy of the gas.

Define the exergy destruction, which is the wasted work potential during a process as a result of irreversibilities.

A power cycle operating between two reservoirs receives energy by heat transfer from a hot reservoir, Qh = 1600 kJ at Th = 1575 K and rejects energy by heat transfer Qc= 800kJ to a cold reservoir at Tc = 495 K. Determine whether the cycle operates reversibly, irreversibly, or does not verify the second law of thermodynamics. O a. irreversibly O b. reversibly does not verify the second law of thermodynamics TOSHIBA