Question

1. Air at 15°C and 60% RH is first heated to 20°C in a heating section and then humidified by introducing water vapor. The air leaves the humidifying section at 25°C and 65% RH. Determine: 1. The amount of steam added to air. 2. The amount of heat transfer to air in the heating section.

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Answer 1

Statel 15°C, 60%. RH From psychromemc choos, ho = 31 kJ/kg of day ari W1=0.0063 kg /kg of doy ani State2 20°C, W, =W2 = 0.0063 kg kg of dry ais hz = 37 kJ/kg of day can State3 25°C, 65% RH bz = 58 kJ (kg of day ani W3 = 0.013 kg/kg of day an (a) The amount of steam added to aro, ms= W3 - W2 = (0.013 -0.0063) kalkg of an [ms = 0.0067 kg/kg of day and (b) The amount of heat added is healing section. Q4 = Che-hu) = 87-31) KIIkg of day aw [QH = 6 kJ/kg of day and <3 657 3 ------- -- - + -------- 0,W2 Goy DDT 150 200 250