Answer:
(a). 575 kJ/kg.
(b). 290kw.
Explanation:
We have the following set of information or parameters from the question above;
Pressure(1) = 100kPa, Pressure (2) = 1MPa, temperature(1) = b1= 12°C = 285K = 285kJ/kg, efficiency = 80% and the mass flow rate of the air = 1kg/s.
At a temperature of 12°C, we have the value from steam table; gx= 1.2, thus gx22 = 1.2 × (1000/100) = 12.
We have that the value for b12 = 517.
Therefore, the value for h2a can be calculated as;
80/100 = (517 - 285)/ (tp at exist) - 285.
0.8 = 232/ (tp at exist) - 285.
232 = 0.8 × (tp at exist) - 285).
232 = 0.8 (tp at exist) - 228 .
(tp at exist) = 575.
Therefore, the temperature 575 kJ/kg.
Thus, the required power input of the compressor = 1kg/s × ( 575 - 285) = 290kw.
