Air with a mass flow rate of $5\ \mathrm{lb} / \mathrm{s}$ enters a horizontal nozzle operating at steady state at $800^{\circ} \mathrm{R}, 50\ \mathrm{lbf} / \mathrm{in}^2$ and a velocity of $10\ \mathrm{ft} / \mathrm{s}$. At the exit, the temperature is $570^{\circ} \mathrm{R}$ and the velocity is $1510\ \mathrm{ft} / \mathrm{s}$. Using the ideal gas model for air, determine

(a) the area at the inlet, in $\mathrm{ft}^2$, and

(b) the heat transfer between the nozzle and its surroundings, in Btu per lb of air flowing.

Residential integrated systems capable of generating electricity and providing space heating and water heating will reduce reliance on electricity supplied from central power plants. For a $2500-ft^2$ dwelling in your locale, evaluate two alternative technologies for combined power and heating: a solar energy-based system and a natural gas fuel cell system. For each alternative, specify equipment and evaluate costs, including the initial system cost, installation cost, and operating cost. Compare total cost with that for conventional means for powering and heating the dwelling. Write a report summarizing your analysis and recommending either or both of the options if they are preferable to conventional means.

Steam enters a well-insulated nozzle at $300\ \mathrm{lbf} / \mathrm{in}{ }^2$, $600^{\circ} \mathrm{F}$, with a velocity of $100\ \mathrm{ft} / \mathrm{s}$ and exits at $40\ \mathrm{lbf} / \mathrm{in}^2$. with a velocity of $1800\ \mathrm{ft} / \mathrm{s}$. For steady-state operation, and neglecting potential energy effects, determine the exit temperature, in $\mathrm{F}$.

Refrigerant 134a enters a well-insulated nozzle at $200 \: lbf/in.^2$, $220^{\circ}$F, with a velocity of 120 ft/s and exits at $20 \: lbf/in.^2$ with a velocity of 1500 ft/s. For steady-state operation, and neglecting potential energy effects, determine the exit temperature, in $^{\circ}$F.

Steam enters a nozzle operating at steady state at $30\ \text{bar}$ , $320^{\circ} \mathrm{C}$. with a velocity of $100 \mathrm{~m} / \mathrm{s}$. The exit pressure and temperature are 10 bar and $200^{\circ} \mathrm{C}$, respectively. The mass flow rate is $2 \mathrm{~kg} / \mathrm{s}$. Neglecting heat transfer and potential energy, determine

(a) the exit velocity, in $\mathrm{m} / \mathrm{s}$.

(b) the inlet and exit flow areas, in $\mathrm{cm}^2$.

Steam enters a nozzle operating at steady state at 20 bar, $280^{\circ}$C, with a velocity of 80 m/s. The exit pressure and temperature are 7 bar and $180^{\circ}$C, respectively. The mass flow rate is 1.5 kg/s. Neglecting heat transfer and potential energy, determine (a) the exit velocity, in m/s. (b) the inlet and exit flow areas, in $cm^2$ .

For air flowing through a converging-diverging channel, sketch the variation of the air pressure as air accelerates in the converging section and decelerates in the diverging section.

Steam enters a well-insulated, horizontal nozzle operating at steady state with a velocity of $10 \mathrm{~m} / \mathrm{s}$. If the specific enthalpy decreases by $45 \mathrm{~kJ} / \mathrm{kg}$ from inlet to exit, determine the velocity at the exit, in $\mathrm{m} / \mathrm{s}$.

Water vapor enters an insulated nozzle operating at steady state at $500^{\circ} \mathrm{C}, 40$ bar, with a velocity of $100 \mathrm{~m} / \mathrm{s}$, and exits at $300^{\circ} \mathrm{C}, 10$ bar. The velocity at the exit, in $\mathrm{m} / \mathrm{s}$, is approximately (a) 104 (c) 888 , (b) 636 , (d) 894 .

A $0.5-\mathrm{m}^3$ tank contains ammonia, initially at $-40^{\circ} \mathrm{C}, 8$ bar. A leak develops, and refrigerant flows out of the tank at a constant mass flow rate of $0.04 \mathrm{~kg} / \mathrm{s}$. The process occurs slowly enough that heat transfer from the surroundings maintains a constant temperature in the tank. Determine the time, in s, at which half of the mass has leaked out, and the pressure in the $\operatorname{tank}$ at that time, in bar.

Conduct a term-length project centered on using a low- wind turbine to meet the electricity needs of a small business, farm, or neighborhood selected by, or assigned to, your project group. Take several days to research the project and then prepare a brief written plan having a statement of purpose, a list of objectives, and several references. As part of your plan, schedule on-site wind-speed measurements for at least three different days to achieve a good match between the requirements of candidate low-wind turbines and local conditions. Your plan also should recognize the need for compliance with applicable zoning codes. During the project, observe good practices.Provide a well-documented report, including an assessment of the economic viability of the selected turbine for the application considered.

A 380-L tank contains steam, initially at $400^{\circ}$C, 3 bar. A valve is opened, and steam flows out of the tank at a constant mass flow rate of 0.005 kg/s. During steam removal, a heater maintains the temperature within the tank constant. Determine the time, in s, at which 75% of the initial mass remains in the tank; also determine the specific volume, in $m^3/kg$, and pressure, in bar, in the tank at that time.

Refrigerant 134 a flows at steady state through a horizontal pipe having an inside diameter of $4 \mathrm{~cm}$, entering as saturated vapor at $-8^{\circ} \mathrm{C}$ with a mass flow rate of $17 \mathrm{~kg} / \mathrm{min}$. Refrigerant vapor exits at a pressure of 2 bar. If the heat transfer rate to the refrigerant is $3.41 \mathrm{~kW}$, determine the exit temperature, in ${ }^\circ \mathrm{C}$, and the velocities at the inlet and exit, each in $\mathrm{m} / \mathrm{s}$.

At steady state, air at $200\ \mathrm{kPa}, 52^{\circ} \mathrm{C}$ and a mass flow rate of $0.5 \mathrm{~kg} / \mathrm{s}$ enters an insulated duct having differing inlet and exit cross-sectional areas At the duct exit, the pressure of the air is $100\ \mathrm{kPa}$, the velocity is $255 \mathrm{~m} / \mathrm{s}$, and the cross-sectional area is $2 \times 10^{-3} \mathrm{~m}^2$. Assuming the ideal gas model. determine

(a) the temperature of the air at the exit, in ${ }^{\circ} \mathrm{C}$.

(b) the velocity of the air at the inlet, in $\mathrm{m} / \mathrm{s}$.

(c) the inlet cross-sectional area, in $\mathrm{m}^2$.