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Water (CP = 4 kJ/kg K) is fed to a boiler at 30°C, the enthalpy of vaporization at atmospheric pressure in the boiler is 2400 kJ/kg; the steam coming from the boiler is 0.9 dry. What is the net heat supplied in the boiler?

Water (CP = 4 kJ/kg K) is fed to a boiler at 30°C, the enthalpy of vaporization at atmospheric pressure in the boiler is 2400 kJ/kg; the steam coming from the boiler is 0.9 dry. What is the net heat supplied in the boiler? Correct Answer 2440 kJ/kg

Concept:

The total heat supplied will be comprised of heat supplied up to saturated water state and then latent heat.

Total heat will be Q = CP ΔT + x hfg

Calculation:

Given CP = 4 kJ/kg K; ΔT = 100 - 30 = 70°C, x = 0.9, hfg = 2400 kJ/kg

Q = 4 × 70 + 0.9 × 2400 = 2440 kJ/kg

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