Xylem Fire diesel pump D Series GEN D Series - Manual (Page 48)

48
Cp determination NORMOGRAM
Intersection of central scale with the straight line that joins temperature and pressure
If an extractor fan is installed, the applicable formula is the following:
Where
Q= Total heat input into the room expressed in [kcal/h]
Cp = Specific heat of air at constant pressure expressed in [kcal/m3 °C] , the value is obtained
from the normogram shown below.
Vt = Vr+Ve = total air capacity of engine radiator fan (Vr) and extractor fan (Ve) expressed
in [m3/h]
Δ
tmax = Tmax -Ta= difference between the maximum temperature of the air affecting the
radiator (Tmax) and the temperature of the outdoor air supplied to the room (Ta) expressed
in [°C]
From the reverse formula we obtain the Vt value and consequently, by subtraction, Ve.
Δ Tmax =
Q
Vt • Cp