Question

Moist air at 300C and 50% RH enters a dehumidifier operating at steady state with a volumetric flowrate of 280 m3/min. the moist air passes over the refrigerating coil and water condenses. The condensate leaves at 100C. Saturated moist air leaves in a separate stream at the same temperature. There is no significant loss of energy by heat transfer to the surroundings and the pressure remains constant at 1.013 bar. What is the rate of condensation of water in kg/min? ans: 1.87

Answer 1

* 2 0 Dehumidifiere 10°C 100%RH 30°C 50% RH 280 m/min 1.013 bar watere wondencate min 00 Pressure = 1.013 bar = 101.3 k Pa., T=30°C = (30+273) K= 303 K Applying ideal gos law at inlet condition, PV = nRT na PV 101.3 kPa x 280 m3 RT 8.314 KJ x 303K Neembaca Molar Kmol-k flow rate of Air = 11:25.94 kmol. min Molecular weight of Air = 29 kg Kmol. .: Mass flow rate of Air = 11.25 g4 kmol min x 29 kg kmol = 326.522 6 Kg Now from psychometric chart: Act 30°c and 50% RH Humidity Ratio, My = 13.31 &g wadere Okg dsy all And at 10°c and secturated air (100% RH) Humidity Ratio, H₂ = 7.6 g watere min alr. Kg dry ais. Assuming amount of. watere initially is less with compared to Amount of Alr. Mass flow of day Air = Mass flow of humed atsa

of kg dry ais Amount watere condensed = (13-31 - 7.6) g watere x 326.5226 Kg min = 1864.44 Kg water min 1864.44 kg water min 10864 Kg watere min so, the rate of condensation of watere 1.864 kg watere min AUS 1000