TITLE.PM5

458 ENGINEERING THERMODYNAMICS dharm \M-therm\Th10-1.pm5 If wet bulb and dry bulb temperatures are known, the dew point can be ...

PSYCHROMETRICS 459 dharm \M-therm\Th10-1.pm5 W 1 W tdb 2 D B T WW 32 W– W 13 tdb 3 tdb 1 W 2 W 3 1 2 3 h 2 h 1 h 3 h–h 32 h–h ...

460 ENGINEERING THERMODYNAMICS dharm \M-therm\Th10-1.pm5 The by-pass factor is expressed as follows : BF tt tt db db db db = − − ...

PSYCHROMETRICS 461 dharm \M-therm\Th10-1.pm5 Air in Air out 1 2 3 Cooling coil 3 2 1 h 1 h 2 h 3 tdb 3 tdb 2 tdb 1 DBT W Fig. 10 ...

462 ENGINEERING THERMODYNAMICS dharm \M-therm\Th10-1.pm5 from a continuous mixing of air which is connecting a particular part o ...

PSYCHROMETRICS 463 dharm \M-therm\Th10-1.pm5 1 W 2 3 h 1 D B T tdb 3 tdb 2 tdb 1 Fig. 10.13. Cooling and humidification. ratio o ...

464 ENGINEERING THERMODYNAMICS dharm \M-therm\Th10-1.pm5 (^1) W 2 ′ 3 4 4 ′′ 3 ′ 4 ′ 2 tdb 1 D B T 1 2 W h 1 h 2 D B T tdb 1 tdb ...

PSYCHROMETRICS 465 dharm \M-therm\Th10-1.pm5 0.009625 – 0.0095 pv = 0.622 pv pv = 0.01524 bar. (Ans.) (ii)Relative humidity φ : ...

466 ENGINEERING THERMODYNAMICS dharm \M-therm\Th10-1.pm5 Solution. Corresponding to 30ºC, from steam tables, pvs = 0.0425 bar ∴ ...

PSYCHROMETRICS 467 dharm \M-therm\Th10-1.pm5 (i)Specific humidity, W = 0 622 0 622 0 0252 1 0312 0 0252 ... (.. ) p pp v tv− = × ...

468 ENGINEERING THERMODYNAMICS dharm \M-therm\Th10-1.pm5 Enthalpy, h = cptdb + Whvapour = 1.005 tdb + W [hg + 1.88 (tdb – tdp)] ...

PSYCHROMETRICS 469 dharm \M-therm\Th10-1.pm5 (ii)Heat added to air per minute : Enthalpy, h 2 = cptdb + Whvapour = 1.005 × 30 + ...

470 ENGINEERING THERMODYNAMICS dharm \M-therm\Th10-1.pm5 Example 10.8. Cooling and dehumidification : 120 m^3 of air per minute ...

PSYCHROMETRICS 471 dharm \M-therm\Th10-1.pm5 Example 10.9. Adiabatic humidification : 150 m^3 of air per minute is passed throug ...

472 ENGINEERING THERMODYNAMICS dharm \M-therm\Th10-1.pm5 The specific humidity at the inlet (equation 10.18) W 1 = ct t W h h hh ...

PSYCHROMETRICS 473 dharm \M-therm\Th10-2.pm5 (a) 18 Cº 38 Cº 1 2 W 1 W 2 W D B T 85% 75% h 2 h 1 (b) Fig. 10.16 Heat transfer ra ...

474 ENGINEERING THERMODYNAMICS dharm \M-therm\Th10-2.pm5 At 18ºC : hg 2 = 2534.4 kJ/kg, pvs = 0.0206 bar ∴ W 1 = 0 622 0 01657 1 ...

PSYCHROMETRICS 475 dharm \M-therm\Th10-2.pm5 D B T 2 1 3 55% 100% R. H. 3Cº W (b) Fig. 10.17 (i)Mass of spray water required At ...

476 ENGINEERING THERMODYNAMICS dharm \M-therm\Th10-2.pm5 [ctpdb 2 + W 2 hvapour (2)] + (W 3 – W 2 )h 2 = ctpdb 3 + W 3 hvapour ( ...

PSYCHROMETRICS 477 dharm \M-therm\Th10-2.pm5 Then, & . (. ) ( ) ma= ×× ××+ 10 1 00064 9 0 287 10 18 273 5 3 = 10.78 kg/s and ...