Question

The weather report indicates that the temperature outside is 15°C with a relative humidity of 75%. Using this information, provide the following: a) Wet bulb temperature b) Dew point temperature c) Moisture content of the outside air d) Specific volume of the outside air e) Enthalpy of the outside air f) How much moisture would you need to add to the air in order to saturate it? (Give this answer in kg moisture/kg dry air). g) The air temperature in a room is increased by 20°C using a space heater. Does the relative humidity in the room increase, decrease, or remain the same? Explain.

Answer 1

9, = 15 RH = =15% Pat at 15c = Purs = 0.017 bar 2. Pu= 0.01215 bar RH = P = 0.45 Pric . temperature corresponds to Pra Tsat (P) = 10.5c 6) Dew point temperature = 10.50 (C) Moisture content W = 0.622 P - Pe- Pr = 7.9265 x 10 Kg/ We 0.622 x 0,012515 1.01325 -0.01275 Ra T T Ra I c) Specifre volume = Repeat lume - R the Ru Pa R-RU 28+(273+15) (1.01325 - 0.01275] x105 = 0.826 milte @) Enthalpy , h = 1.005 tab + hi (2500+ lige tilby h = 1.005x (5] + 31.9265x16* [2500 + 1.58 x 15] Pus 35.115 bolly f) At Saturahon, Py = Pvs, ks = 0.622 We = 0.0106 Kling og ans moisture need to add = kals - W = 2.687x10 Pr_pus kg legg air

75% 0 7560 وا Locate 6 (Intersection of 15°c & 75 % RH). Dalhile hearing , per temperature increases, so that point ® shift towards right in Psychrometric chart. Gence to Relative hus medity decreases dening hearing (a) from Chost, bleh bulb temperature 13€.