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OIL AIR COOLER - Selection Procedure
 
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The indispensable datas to for cooler selection are:
Qex ------ Heat to be exchanged;
Toil in --- Oil in Temperature;
moil in -- Oil flow ;
Tair ------ Ambient temperature;
Therefore: Dt= Toil in- Tair
When Dt is calcutated, you should enter
in the graph to intersect the right flow line (moil in ).
From this point, you can read on Y axis, the heat exchanged..
With the same principle, entering with the flow on the dedicated graph,
you can find the pressure drop for 32 cst oil.
The correction factor (to be moltiplicate) allow you to obtain oil
pressure drop for different density.
Example: Oil 50 cst; Flow (moil in)90 lt/min; Oil in temperature (Toil
in ) 80°C; Air temperture (Tair) 35°C.
Solution: Dt= Toil in- Tair = 80-34=45°C
From graphs it is obtained:
Exchanged heat: 17.400 Kcal/h.
Pressure drop: 0,48 bar x 1,4 (correction factor. for 50 cst oil)
= 0,672 bar
Other useful formulas:
Kw=Kcal/h : 860
Heat given from an hot fluid --- Q=m cp (tin-tout)
In which: Q = Heat [Kcal/h]
m = flow [Kg/h]
cp = Specific heat capacity [Kcal/(Kg °C)]
(tin-tout) = Temp. diffrential [°C]
Heat exchanged through a surface --- Q=K S (t1-t2)
In which:
Q = heat [Kcal/h]
K = Global exchanging capacity [KCal/(h m2 °C)]
S = exchanging area [m2]
(t1-t2) = Temp. diffrential [°C]
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