Chapter 7, Problem 7.5E

a) Using the second law of thermodynamics, describe exergy d law of thermodynamics, describe exergy. Explain the different types of exergy b) What do you understand by the term reference environme c) Determine the specific exergy of saturated water vapour we having a velocity of 30m/s and an elevation of 6m, each relative to an exergy reference environment where T = 298K. P. = 1 atm and g = 9.8m/s.  d) Steam enters a turbine with a pressure of 30 bar, a temperature of 400°C, a velocity of 160 m/s and exits as saturated vapor at 100°C with a velocity of 100 m/s. At steady state, the turbine develops work at a rate of 540 kJ per kg of steam flowing through the turbine. The heat transfer rate (cv/m = -22.6 – Heat transfer between the turbine and its surroundings occurs at an average outer surface temperature of 350 K. Neglect the change in potential energy between the inlet and exit of the turbine, and assume that To = 25°C. Po =1 atm. Using a neat sketch, determine: i net exergy carried…

7.36 At steady state, hot gaseous products of combustion from a gas turbine cool from 3000°F to 250°F as they flow through a pipe. Owing to negligible fluid friction, the flow occurs at nearly constant pressure. Applying the ideal gas model with ₂ = 0.3 Btu/lb/ºR, determine the exergy transfer accompanying heat transfer from the gas, in Btu per lb of gas flowing. Let T. = 80°F and ignore the effects of motion and gravity. -568.43

Thermodynamics. 1) For a closed system, as the exergy reference environment temperature ___________, the exergy destruction rate decreases 2) Which of the following statements does not describe the exergy reference environment? It is large in extent. It has a uniform temperature. It is incompressible. It has a uniform pressure.   3) Air within a piston–cylinder assembly undergoes an expansion process from an initial volume of 0.5 m3 to 1 m3. The dead state pressure is 100 kPa. If the work associated with the process is 60 kJ, determine the exergy transfer accompanying work, in kJ.

7. What kind of resources does nuclear energy require? Is it worth the effort and the investment to acquire nuclearenergy?8. Exactly how important is nuclear power and nuclear waste?

7.5 Equal molar amounts of carbon monoxide and neon are maintained at the same temperature and pressure. Which has the greater value for exergy relative to the same reference environment? Assume the ideal gas model with constant c, for each gas. There are no significant effects of motion and gravity.

EXERGY TRANSFER BY HEAT, WORK, AND MASS

A domestic water heater holds 189 L of water at 60°C, 1 atm. Determine the exergy of the hot water, in kJ. To what elevation, in m, would a 1000-kg mass have to be raised from zero elevation for its exergy to equal that of the hot water? Let T0 = 298 K, p0 = 1 atm, g = 9.81 m/s2 .

A boiler uses coal for fueling a power plant. The heating value of coal is 74500 kJ per kg of fuel with 90% excess air. Determine:a. Mass of air if the boiler consumes 25lb/s of coal.b. Heat transfer in BTU if air enters at 16 deg. C and leaves at 70 deg. Cc. Heat transfer in kilowatts if air enters at 16 deg. C and leaves at 70 deg. C Please answer ASAP.

Determine the exergy in kJ at 1 kg, 0.7 bar and 90 °C. a) In case of Water (H2O) as fluid type, b) Refrigerant R-134a, c) With air condition as ideal gas for constant cp value For T0=20 °C, P0=1 bar, evaluate with reference to the exergy reference medium, in any case, assuming the mass at rest.