Determine the second-law efficiency of an ideal regenerator in the Brayton cycle.

A Brayton cycle has inlet at 290 K, 90 kPa, and the combustion adds 1000 kJ/kg. How high can the compression ratio be so that the highest temperature is below 1700 K? Use cold air properties to determine this.

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An air-standard Diesel cycle has u compression ratio of 16 and a cutoff ratio of 2. At the beginning of the compression process, air is at 95 kPa and $27^{\circ} \mathrm{C}.$ Determine the total exergy destruction associated with the cycle, assuming a source temperature of 2000 K and a sink temperature of 300 K. Also, determine the exergy at the end of the isentropic compression process. Account for the variation of specific heats with temperature.

An air-standard Diesel cycle has a compression ratio of 16 and a cutoff ratio of 2. At the beginning of the compression process, air is at 95 kPa and $27^{\circ} \mathrm{C}$. Accounting for the variation of specific heats with temperature, determine (a) the temperature after the heat-addition process, (b) the thermal efficiency, and (c) the mean effective pressure.

In a car’s defrost/defog system atmospheric air, 21$^{\circ} \mathrm{C}$, relative humidity 80%, is taken in and cooled such that liquid water drips out. The nowdryer air is heated to 41$^{\circ} \mathrm{C}$ and then blown onto the windshield, where it should have a maximum of 10% relative humidity to remove water from thewindshield. Find the dew point of the atmospheric air, specific humidity of air onto the windshield, the lowest temperature, and the specific heat transferin the cooler.

Air in a tank is at 300 kPa, 400 K with a volume of 2 m3. A valve on the tank is opened to let some air escape to the ambient to a final pressure inside of 200 kPa. Find the final temperature and mass, assuming a reversible adiabatic process for the air remaining inside the tank.

A fraction of some power to a motor (1), 2 kW, is turned into heat transfer at 500 K (2) and then it dissipates in the ambient at 300 K (3). Give the rates of exergy along the process 1–2–3.

A “pseudo-Brayton cycle” consists of two isothermal processes in place of the two adiabatic processes in a Brayton cycle. Find the efficiency of a pseudo-Brayton heat engine.

A car air-conditioning unit has a 0.5-kg aluminum storage cylinder that is sealed with a valve. It contains 2 L of refrigerant R134a at 500 kPa, and both are at room temperature, 20$^{\circ} \mathrm{C}$. It is now installed in a car sitting outside, where the whole system cools down to ambient temperature at −10$^{\circ} \mathrm{C}$. What is the irreversibility of this process?

A cylinder having an initial volume of 100 ft3 contains 0.2 lbm of water at 100 F. The water is then compressed in an isothermal quasi-equilibrium process until it has a quality of 50%. Calculate the work done in the process, assuming that water vapor is an ideal gas.

R134a is flowed into an insulated 0.2-m3 initially empty container from a line at 500 kPa, saturated vapor until the flow stops by itself. Find the final mass and temperature in the container and the total irreversibility in the process.

Steam at 500 kPa, 300$^{\circ} \mathrm{C}$ is used to heat cold water at 15$^{\circ} \mathrm{C}$ to 75$^{\circ} \mathrm{C}$ for a domestic hot water supply. How much steam per kilogram of liquid water is needed if the steam should not condense?

A flow of 4 kg/s ammonia goes through a device in a polytropic process with an inlet state of 150 kPa, −20$^{\circ} \mathrm{C}$ and an exit state of 400 kPa, 60$^{\circ} \mathrm{C}$. Find the polytropic exponent n, the specific work, and the heat transfer.