23. The Second Law of Thermodynamics

The cycle in the figure shows four processes. Process a is an isobaric expansion at $330\mathrm{kPa}$. Process b is a constant volume reduction in pressure to $100\mathrm{kPa}$. Process c returns the gas to its original state where the volume is $100{\mathrm{cm}}^3$. If the gas does $15\mathrm{J}$ of work each cycle, what is the maximum volume of the gas?

The figure shows the cycle of a heat engine that uses a diatomic gas. The temperature at point 1 is $350\mathrm{K}$. What is the thermal efficiency of the engine?

A heat engine does 200 J of work per cycle while exhausting 400 J of waste heat. What is the engine's thermal efficiency?

A Boeing 777 jet engine, the world's largest, has a power output of 82 MW. It burns jet fuel with an energy density of 43 MJ /kg. What is the engine's fuel consumption rate, in kg/s, if its efficiency is 30%?

The power output of a car engine running at 2400 rpm is 500 kW. How much (a) work is done and (b) heat is exhausted per cycle if the engine's thermal efficiency is 20%? Give your answers in kJ.

What are Wₒᵤₜ and QH and (b) the thermal efficiency for the heat engine shown in FIGURE EX21.14?

What are (a) the thermal efficiency and (b) the heat extracted from the hot reservoir for the heat engine shown in FIGURE EX21.16?

A 15 kW electric generator burns 1.2 gal of diesel fuel per hour. The energy density of diesel fuel is 140 MJ/gal. What is the generator's thermal efficiency?

A nuclear power plant generates 3000 MW of heat energy from nuclear reactions in the reactor's core. This energy is used to boil water and produce high-pressure steam at 300℃. The steam spins a turbine, which produces 1000 MW of electric power, then the steam is condensed and the water is cooled to 25℃ before starting the cycle again.b. What is the plant's actual efficiency?

FIGURE P21.57 shows the cycle for a heat engine that uses a gas having r = 1.25. The initial temperature is T₁ = 300 K, and this engine operates at 20 cycles per second.a. What is the power output of the engine?

The heat engine shown in FIGURE P21.62 uses 2.0 mol of a monatomic gas as the working substance.b. Make a table that shows ∆Eₜₕ, Wₛ, and Q for each of the three processes.

The heat engine shown in FIGURE P21.62 uses 2.0 mol of a monatomic gas as the working substance.c. What is the engine's thermal efficiency?

A heat engine with 0.20 mol of a monatomic ideal gas initially fills a 2000 cm³ cylinder at 600 K. The gas goes through the following closed cycle:Isothermal expansion to 4000 cm³.Isochoric cooling to 300 K.Isothermal compression to 2000 cm³.Isochoric heating to 600 K.How much work does this engine do per cycle and what is its thermal efficiency?