Question

Problem 3 You move to Tempe Arizona on co-op and have the enviable job of analyzing an evaporative cooler for outdoor shops. Air flows enter evaporative cooler at 17 m3/min, 40°C, and 10% relative humidity. Liquid water also at 40°C is sprayed into the airstream at 0.15 kg/min. Assume all the water evaporates. Determine: (a) the mass flow rate of dry air in kg/min (b) the humidity ratio of the moist air exiting (c) the enthalpy of the moist air exiting in kJ/kg dry air (d) the temperature and relative humidity of the moist air exiting water 40°C t 0.15 kg/min Tz Ti= 40°C $ = 10% ý = 17 has a IT IN $2

Answer 1

T To a noc "Tuzuvc an ma 20.15 0,= 107. = 17 m3 min webilsiglaulu rate of dry aly kg/min The Mall flow ma РЧ 2014 kg ma 1.2 x 17 m3 min Ratio of moist air existing Humidity mall conservation & m final mat mwe 20.14 & 0.15 = 20.55 Pemering more of weapour conservation - mora & myw= matinal W. Ma, & W, (MW) = w Anal M final for aor ab Peo 1 atm Te 407273 Te 313 Qeluy. 7 Py saturation standard Taudc from 1 Plug = 7+372 kPq Pr p/ Piece Pue 0.7372kog &= Pu 2 py 7-372 Orto Prs 2-372

0.6 22 Pt-Pr w 4.62x10-3 = 0.622xo.7372 100-0.7372) 2 for water U +62 810-3 x 20.4 & 1x 0.15= Wfinal X (20.55) whinala 601188

eyoue tylne = mfinal ha a, no ery hi 211005 t tweC 2500 41.88 +) 2110055X40 + (4.62x10-3) (2500 +1.88X40) Z 52-09 kolleg for water ha Cp Tw 2 4.2 % 3132 Bolls on gonist 1314.6

michat Maha amzhz (20.4)~ ( 52.9) + 0.15*(1814,6)= 20.55 hz ha = 62.10 lesling han 1.005tt WAI (2500 f1.88t) G 2.10 - 1.005 tt0.01188 (2500 f1.88+) 62.10 2 1.005 t t 29.7 t o.0223t 6 2.10 zl.o 27 t +29,7 tz 31-54°c form standard table, I= 31.54°c Plug = 4.626 kra Espeon 0,622 Pt-Pya 0-011882 0.622 Pu (مم ) 0.01902 pu Copy 0.0190 -0.0190 pvz py Pu= 0.019 01874 h atm 140.019 Pez 1.874 kpq Pu 21.874 20:40 → pus 4.624 40% (Rebeline Themetipy)