Spray Humidifier Design PED II Final-

7/30/2019 Spray Humidifier Design PED II Final-

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Process Design

Calculation of Cross Section area of the spray chamber

Lets assume that the velocity of air inside the chamber be 300 m/min i.e 5 m/s.

Therefore the cross section area of the chamber will be

=.

. =

=3.333 m2

Calculation of diameter of the spray chamber

The diameter of the chamber is given by

=

= .

=2.06065 m


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Calculation of length and Volume of the spray chamber

Volume of spray chamber can be calculated by

=

h= 90 Btu/.hr.ft3

LMTD=

,;, ;(,;,)

ln(,,,,

)

, = 35 = 95 , , = 25 = 77 , , = 20 = 68

Now as per our assumption temperature of water remains unchanged

Temperature of the outlet water, ,= 20 = 68 LMTD=16.3843Taking =32 =, =,

= 0.24 + 0.45 =

, = = 0.8875

=67607

= 149047.9117 Btu/hr


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=, =, = 0.24 + 0.45

= 35, = 22 = 0.0108

= 0.015

=2299400 Btu/hr

=1640000 Btu/hr

Now using the previous energy equation

Volume, V=455.6492 ft3 =12.9025 m3

Length of chamber =

= 3.87

Standard available length = 4 m


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Calculation of kg. of water sprayed in the spray chamber

We assume that the rate of water sprayed by the nozzles is 5600

Therefore the water sprayed in the chamber is = 5600cross section area=5600 3.4307 kg/hr =19212 kg/hr

Calculation of rate of the make up water needed to be supplied to the spray

chamber

We have make up water M= E+B+W

Where E=evaporated water, B=blow Down, W=windage lost

= ( ) =283.9494 Kg of water/hr

Assuming 0.2% windage lost

W= 0.2% of total water sprayed=0.00219212 kg/hr=38.424 Kg of water/hr

Write this part


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Calculation of rate of the Re circulated water

Rate of re-circulated water =

Total water sprayed in the spray chamber make up water needed to be supplied

Rate of re-circulated water = (19212423.654) kg of water/hr

= 18788.346 kg of water/hr

Calculation of number of nozzles required

Let us assume that the nozzle spacing to be 20 inch i.e. 50.8 cm, nozzle spray angle

65 and spray overlap to be 30%.

Assumption is based on reference SPRAYER NOZZLES: selection and calibration

Prepared by Monte P. Johnson, Entomology, and Larry D. Swetnam, Agricultural

Engineering published from U N I V E R S I T Y OF K E N T U C K Y C O L L E G E O FA G R I C U L T U R E

We also assume that the nozzle arrangement is circular.

no of total nozzles in such configuration = 30;


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Let the spraying sate of each nozzle 45 l/min Spraying area for each nozzle with 65 angle and 30% overflow for 4m length =14.29

Total spraying rate = 30

. =5668


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Volume contribution of each nozzle =

= 0.444

Calculation of number of power required to operate the nozzle

Power = 1.5 From Antoine equation

= exp 11.93 .

:;.= 5487.8

= 1 = 101325 Power = 776.4484 watt= 1.04 HP

Taking standard power =1.5 HP

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Spray Humidifier Design PED II Final-