The change in enthalpy of ammonia between state 1 at a quality of 0.6 and state 2 at 48ºC while the pressure remains constant at 120 kPa is nearest:
A) 718 kJ/kg
B) 716 kJ/kg
C) 714 kJ/kg
D) 712 kJ/kg
B) 716 kJ/kg
The enthalpy at state 1 is h1 = h f + x1hgf = 44.7 + 0.6× 1360 = 861 kJ/kg . Consider state 2: at 50ºC and 120 kPa the enthalpy is observed to be 1581.4 and at 40ºC and 120 kPa it is observed to be 1559.6. Interpolation (use 0.8 times the difference between 40ºC and 50ºC) then gives the enthalpy at state 2 to be h2 = 1577 kJ/kg. Finally, the enthalpy difference between states 2 and 1 is
h = h2 ? h1 = 1577 ? 861 = 716 kJ/kg
The IRC Calculator would give a slightly different answer [it would be (A)] but either one would be acceptable for engineering calculations.
You might also like to view...
Which of the following is the ECM output used to manage rail pressure at any given moment of operation in a diesel CR fuel system?
A. rail pressure sensor B. rail flow limiter valve C. EHI actuators D. rail pressure control valve
To properly ____________________ a wire, correct tension must be maintained while rotating the wire between the fingers and thumb
Fill in the blank(s) with correct word
12 ft?lb @ 1500 RPM
What will be an ideal response?
Fiber-optic cable transmits light instead of _______________
A. electronic signals B. high speed C. telephone transmissions D. computer transmissions