An aqua ammonia absorption plant operates between pressures at 206.8 and 1378 kPaa. The strong solution enters the generator saturated at 82.2°C and the weak solution leaves the generator saturated at 93.3°C. Saturated vapor leaves the generator with a concentration of 0.993 kg NH3 /kg mixture. Assuming that the strong solution leaving the absorber is saturated, neglecting pump work and heat losses, calculate per kg/min flow of refrigerant through the evaporator: a. the mass flow of strong solution entering the generator in kg/min b. the mass flow of weak solution leaving the generator in kg/min c. the enthalpy of the weak solution entering the absorber in kJ/kg weak solution and the heat rejected in the absorber in kW Saturated liquid at 1378 kPaa and 82.2°C has a concentration of 0.46 kg NH3 /kg mixture and an enthalpy of 209.2 kJ/kg of mixture, saturated liquid at 1378 kPaa and 93.3°C has a concentration of 0.41 kg NH3 /kg mixture and an enthalpy of 255.68 kJ/kg of mixture, saturated liquid at 206.8 kPaa with a concentration of 0.46 kg NH3 per kg of mixture has an enthalpy of -93.0 kJ/kg mixture; saturated vapor at 206.8 kPaa with a concentration of 0.993 NH3 per kg mixture has an enthalpy of 1464.37 kJ/kg mixture. Note: From Chart of properties of aqua-ammonia at 1378 kPaa and 0.993 kg NH3 /kg mixture, h2 = 1390 kJ/kg and at 1378 kPaa and x4 = 0.993 kg NH 3 /kg mixture, h4 = 162.7 kJ/kg
An aqua ammonia absorption plant operates between pressures at 206.8 and 1378 kPaa. The strong
solution enters the generator saturated at 82.2°C and the weak solution leaves the generator saturated at
93.3°C. Saturated vapor leaves the generator with a concentration of 0.993 kg NH3 /kg mixture. Assuming that
the strong solution leaving the absorber is saturated, neglecting pump work and heat losses, calculate per
kg/min flow of refrigerant through the evaporator:
a. the mass flow of strong solution entering the generator in kg/min
b. the mass flow of weak solution leaving the generator in kg/min
c. the enthalpy of the weak solution entering the absorber in kJ/kg weak solution and the heat rejected in the absorber in kW
Saturated liquid at 1378 kPaa and 82.2°C has a concentration of 0.46 kg NH3 /kg mixture and an enthalpy of
209.2 kJ/kg of mixture, saturated liquid at 1378 kPaa and 93.3°C has a concentration of 0.41 kg NH3 /kg mixture
and an enthalpy of 255.68 kJ/kg of mixture, saturated liquid at 206.8 kPaa with a concentration of 0.46 kg NH3
per kg of mixture has an enthalpy of -93.0 kJ/kg mixture; saturated vapor at 206.8 kPaa with a concentration
of 0.993 NH3 per kg mixture has an enthalpy of 1464.37 kJ/kg mixture.
Note: From Chart of properties of aqua-ammonia at 1378 kPaa and 0.993 kg NH3 /kg mixture, h2 = 1390
kJ/kg and at 1378 kPaa and x4 = 0.993 kg NH 3 /kg mixture, h4 = 162.7 kJ/kg
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