Question

Moist air enters a cooling coil at 27°C DBT and 60 percent relative humidity at a flow rate of 1.15 kg/s and leaves at 16°C DBT and 90 percent relative humidity. Calculate the latente load on the coil, the sensible heat ratio and the bypass factor.

Answer 1

. coel Inlet condition of moist air at cooling T, = 27°C dry bulb temperature 8, = 60% = Relative humidity Outlet condition To=16°c of moest air at cooling coil dry bulb temperature Relative humidity 90 % Mass flow rate of air = sa = 1.15 kg/sec 1) Latent load on cooling cool 7. (5 - 6) from phychrometric chart, at T = 27°C & P, = 60% Q - h, = 61.5 kJ/kg hi= 53 kJ/kg R = 1.15 (61.5 - 53) å = 9.775 K W 2) Sensible load cooling coel cooling coel : Senseble load es given as 1

ria Chi-ha) ås from psychrometric chart, T₂ = 16°c (DBT & Ra=90% RH at h₂ = 42 kJ/kg Qs = 1.15 (53 - 42) ås = 12.65 12.65 kW 3) By pass Factor of cooling coal (BPF) BPF is given as, Tz - Tade BPE = T - Tade Where Tadp = app aratus dew point temperat- iure we when extend process (1-2) further up to Saturation line, the point of intersection saturation point gives Apparatus due point temperature From psychometric chart,

Tade = 13°c 16-13 BP = = 0.214 27 - 13 BPF 0.214 (4-14) ow=" I specific Humidi (110 Lap 88/8) 1 Qs malni - ha) T2 Ti Tadp Dry Bulb Temp °c Refer above figure & attached chart for better understanding

100 105 110 115 120 kJ/kg/d.a) 30 29 29 ..0- - 0.8 -10.0 28 10.00 20 -5.0 8.0 -0.7 7.0 6.0 +0.6 SENSIBLE HEAT TOTAL HEAT -4.01 1.0 -2.0- +0.0 95 90 85 80 75 70 5.0 +0,5 18 -0.4 03 -1.0- 4.0 27 26 25 24 23 22 21 20 20 - 65 ENTHALPY dH HUMIDITY RATIO dw 60 55 50 45 40 %06 %08 %04 . 19 18 17 16 15 Humidity Ratio, g/kg(d.a) 60% 060 35 50% 14 13 12 30 - 11 25 20 10 9 15 30% 10 8 7 6 5 20% 10% 4 3 -5 2 -10 1 0 50 -10 -5 0 5 40 45 10 15 20 25 30 35 Dry Bulb Temperature, °C. Pressure = 101325 Pa

100 105 110 115 120 kJ/kg/d.a) 30 95 29 -1.0- .- 00 8:9 10.007 -0.8 -10.0 1.5 +5.0 2.0 27 1.6 6.0 - 1.0 SENSIBLE HEAT TOTAL HEAT -4.07 1.0 -1.0- 0.0 5.00 lo -0.4 10.3 4.0- -0.5 0.0 -02 +0, 26 25 24 23 22 21 m 2.5 90 85 80 75 70 65 60 55 50 45 40 35 ENTHALPY dH HUMIDITY RATIO dw 20 %06 80% 70% 11 Humidity Ratio, g/kg(d.a) 60% 19 18 17 16 15 14 13 12 11 10 060 k pop 30 25 40% 29 9 15 50% 8 10 7 6 5 20% 5 4 20% 3 -5 2 1 - -10 -10 -5 0 Сл 40 0 50 4! 10 15 20 25 30 35 Dry Bulb Temperature, °C. Pressure = 101325 Pa