ACA Series selection
Examples:
( Note: All air flow rates must be converted to SCFM)
Application 1 Air Rotary Screw Compressor
Determine the heat load "Q" =Btu/hr T 1 = Inlet gas temperature: 200 o f T 2 = Outlet gas temperature: Ambient + 10 T a = Ambient temperature: 85 o f Airflow rate: 350 SCFM PSIG = Operating Pressure 100 psig CF = Correction factor: 1.13 S = Specific gravity with air being 1.0 C = Specific heat (Btu/Lb o f): .25 Model Selection - ACA-4362
Q = [SCFM x CF x (T 1 -T 2 )] or [350 x 1.13 x 105
o ] = 41,528 Btu/hr
Refer to graph example on page 215
Determine the Fs = Btu/hr or 41,528 = 4,153 Fs
o f= (95 o f)
T
2 - T a
10
CF = (.0753 x S x C x60) or (.0753 x 1.0 x .25 x 60) = 1.13
x 144 = 1.46" or (1.5" minimum nozzle) (350 x 4.512) (270,000 x .50) .7854
Application 2 Methane Gas
Determine the heat load "Q" = Btu/hr T 1 = Inlet gas temperature: 300 o f T 2 = Outlet gas temperature: 90 o f T a = Ambient temperature: 60 o f Gas flow rate: 500 SCFM PSIG = Operating pressure: 150 psig CF = Correction factor: 1.428 S = Specific gravity with air being 1.0: .55 C = Specific heat (Btu/Lb o f) Model Selection - ACA-6421
Q = [SCFM x CF x (T 1 -T 2 )] or [500 x 1.428 x 210
o ] = 149,940 Btu/hr
Refer to graph example on page 215
Determine the Fs = Btu/hr or 149,940 = 4,998 Fs
T
2 - T a
30
CF = (.0753 x S x C x 60) or (.0753 x .55 x .575 x 60) = 1.428
x 144 = 1.44" or (1.5" minimum nozzle) (500 x 4.512) (270,000 x .74) .7854
Application 3 Low Pressure Blower
Determine the heat load "Q" = Btu/hr T 1 = Inlet gas temperature: 250 o f T 2 = Outlet gas temperature: 100 o f T a = Ambient temperature: 90 o f CF = Correction Factor: 1.13 PSIG = Operating pressure: 2 psig
Q = [SCFM x CF x (T 1 -T 2 )] or [76 x 1.13 x 150
o ] = 12,882 Btu/hr
Refer to graph example on page 215
Determine the Fs = Btu/hr or 12,882 = 1,288 Fs
T
2 - T a
10
To Convert
Airflow rate: 90 ACFM
ACFM to SCFM = ACFM x (PSIG + 14.7) x 528 = 90 x 16.7 x 528 = 76 SCFM
S = Specific gravity with air being 1.0
(T 1 + 460) x 14.7
710 x 14.7
C = Specific heat (Btu/lb o f): .25 P = 5" water column or less (example pg. 220) Model Selection - ACA-3302
(76 x 4.512) (270,000 x .075) .7854
x 144 = 1.76" or (2.0" minimum nozzle)
Pressure Drop (see page 220 for graphs)
Since gas is compressible the density of the gas changes from one temperature or pressure to the next. While the mass flow rate may not change, the pressure differential across the heat exchanger will change dramatically from high (70-125 psig) to low (1-5 psig) pressure. A low pressure condition requires larger carrying lines to move flow than does the same gas rate un- der a higher pressure. At lower pressures the differential pressure across the heat exchanger can be quite high compared to the same flow rate at a higher pressure. For that reason it is suggested that the pressure differential graphs on page 220 be consulted prior to making your final selection. The ACA series heat exchanger is designed to be easily modified to accept larger port sizes in the event your system pressure requires larger nozzles. Consult our engineering department for more exacting information regarding pressure differ- ential issues.
note: AIHTI reserves the right to make reasonable design changes without notice.
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