Project ForgeThermodynamics
First Law of Thermodynamics
GATE 2008
Hard
Atmospheric air at 3 kg/s (dry basis) enters a cooling/dehumidifying coil with enthalpy 85 kJ/kg dry air and humidity ratio 19 g/kg dry air, and leaves with enthalpy 43 kJ/kg dry air and humidity ratio 8 g/kg dry air. The condensate leaves with enthalpy 67 kJ/kg. The required cooling capacity of the coil in kW is
- A75.0
- 123.8
- C128.2
- D159.0
Explanation
Condensate flow=3(0.019-0.008)=0.033 kg/s. Q_removed=ṁda(h1-h2)-ṁcond·hcond=3(85-43)-0.033(67)=126-2.21≈123.8 kW.
Source: GATE ME 2008 (2008)
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