Closed feed water heater

2. Closed feed water heater • Ideal Rankine cycle. Steam enters the turbine at 8MPa & 480oC. The condenser operates at 8kPa. Steam extracted for close heater at 0.7MPa. Condensate drains from the closed heater and is trapped to the condenser. Feed water leaves the heater at 8MPa and at the saturated temperature for 0.7MPa.

3. Closed feed water heater • Net power output is 100MW. • Find • Thermal efficiency • Cooling water flow when the entering temperature is 15oC & the exit flow is 35oC.

4. Reverse cycle • Refrigeration – A/C • Heat pump • Performance

7. History • Dr. Gorrie - 1830 • Carrier – 1902 • Frigidaire – 1913 • Heat pump patented – 1924 • 1928 – home A/C • 1939 – auto A/C • 1940 – refrigerated truck

9. History • 1950’s – window A/C • 1950’s – growth southeast & southwest due to A/C

10. Working fluid • NH3, CH3Cl, SO2 • Toxic • 1928 – 1930 Freon – DuPont • Nontoxic • Nonflammable • Inexpensive • High latent heat • Low pressure requirement

11. Freon • Chlorofluorocarbon • Refrigeration & A/C • Aerosol • Foaming agent • Ozone layer 1974 • Banned R12 in 1980’s • R11 → R134a → what’s next?

14. COP • Refrigeration/air conditioning • Heat pump

16. VCC • 1→2 isobaric heat addition; saturated vapor at 2. • 2→3 isentropic compression of vapor • 3→4 isobaric heat rejection; saturated liquid at 4. • 4→1 isentropic expansion

18. Expansion • Expansion valve • Throttling process

19. Cycle analysis • Isentropic compression • Heat out • Throttling • Heat in

20. Equipment • Compressor • Expansion valve

29. Performance • SEER • HSPF • Tons of cooling

34. Example • An ideal vapor compression cycle operates with R134a at steady state. Superheated vapor enters the compressor at 10psi & 0oF; saturated liquid leaves the condenser at 180psi. The refrigeration capacity is 8 tons. • Find the compressor power (hp), condenser heat transfer rate (Btu/min), and COP

35. Heat pump • Air source • Ground coupled • Central conditioning

39. Assignment • M&S Ch. 10 • C&B Ch. 11