An alkali metal, potassium, is the working fluid in a nuclear power system that was proposed in

Question:

An alkali metal, potassium, is the working fluid in a nuclear power system that was proposed in the 1960s for space application, either on board of a spacecraft or in power stations on the Moon or Mars. Given recent developments, it might be considered again. It employs similar hardware to that in Exercise 4.15, except that a nuclear reactor replaces the Sun as the energy source. The potassium enters the pump as a saturated liquid at 1000 K, is compressed, is then evaporated at 2 bar and superheated to 1350 K in the reactor-boiler. The turbine discharge is at 1000 K with 97% quality. Neglect the pressure drop through the reactor and condenser for this simplified thermodynamic analysis. The power required to operate the pump is 2% of the turbine-shaft power. Determinea. The energy conversion efficiency of this system, i.e., the net shaft power divided by the energy transfer rate as heat to the working fluid from the reactor,b. The potassium mass flow rate,c. The reactor power required for 500 kWe of net power, assuming that a 97% efficient electric generator is employed.?

Use Appendix A.11 for data.

Data From 4.15

A small solar engine is used for water pumping in a desert area. Water is the working fluid.

Water enters the pump as saturated liquid at 50?C and is pumped up to 2 bar by a small centrifugal pump. The boiler evaporates the water at 2 bar, and saturated vapor at this pressure enters a small expander. The steam leaves the expander at 50?C and with a liquid fraction of 6%, and is subsequently condensed. The mass flow rate is 140 kg/hr and the pump is driven by a 0.4 kW motor. Determine the power output of this solar engine, the energy conversion efficiency taken as the net shaft work output divided by the energy transfer as heat to the fluid in the boiler, and estimate the area of the solar collectors, assuming the collectors can absorb 800 W/m².?

Data From A.3