Question

Moist air at 20° c, 1 atm, and 43% relative humidity and a volumetric flow rate of 900 m/hrs. enters a control volume at steady state and flow along a surface maintained at 65 C, through which heat transfer occurs. Liquid water at 20" C is injected at a rate of 5 kg/hr and evaporates into flowing stream. For the control volume, Wa=0, and kinetic and potential energy effects are negligible. Moist air exits at 32c, 1 atm, (a) draw the system schematic with given data, (b) determine the rate of heat transfer in kW and (c) calculate the relative humidity at exit in % (d) use the attached psychrometric chart to compare your answers in (b) and (c) by drawing the process on the chart.

Answer 1

ç ns3 = 5 kg ht 12=20°c 2 2 Pic 20°C Ø - 43% P2= lam T, = 32°C. U= gou malhr Piel atom - for point hiz 36 ICT kg Pi=1,2 lcgim3. IWBT = 13°C Eu U=0.839 alis 0.0062 109 leg 400 =1072-7 kg hr ma 0.839 balane curez mass m, tom3 = m2 f Wz اقدا W2= 5 Icy leg W25 0.0062+1072.4 W2= 0.0108611 lag Tag.

For DBT= 32°c and W2 = 0.01 08611 lcg Tey this de = 37010 For pont -a h = 60.33 lej ܦEGEܐ WBT = 21°C lag P2 = 1.15 m3 U₂ = o.fg malike Tepeutit humidity © W2-0.011 lg reg A = 0.0062 lees OB? 2004 3200 pg1 c 2 © Rate of heat transfer ma Chr-hi) -0.2938660-33-36) 그 7915 KW @ 2 = 37% leguist relattive humidity)