6
PA W
.
PA
01
W2
Air temperature af
ter heater [°C
]
Air flow through the heater [m
3
/h]
Air speed inside the water heating coils [m/s]
Wa
ter flow through the water heating coils [l/s]
Water pressure drop [kP
a]
External air temperature [°C
]
Coil heating capacity [kW
]
Water heater parameters calculation example Air Speed.
Starting from 950
m
3
/h on the air flow scale draw a vertical line (1) till the air speed axis which makes 3.35 m/s.
Supply air temper
atur
e.
Pr
olong the line (1) of air flow up to the point where it crosses the outside air temperature (blue cur
ve),
e.
g.
-15°C;
then draw a horizontal line (2) from this point to the lef
t till crossing water in/out temperature cur
ve (90/70).
Fr
om this
point draw a
ver
tical line (3) to the supply air temperature axis on top of the graphic (+23 °C
).
Heating coil capacit
y.
Pr
olong the line (1) up to the point where it crosses the outside air temperature -15°C (red cur
ve) and draw a
horizontal line (4) from this point to the right until it crosses water in/out temperature cur
ve (90/70), from here draw a ve
rt
ical line (5) up to
the scale representing the heating coil capacity (13.5 kW
).
Wa
ter flo
w.
Pr
olong the line (5) down to water flow axis at the bottom of the graphic (6) (0.14 l/s).
Wa
ter pressure drop
. Draw the line (7) from the point where line (6) crosses the black cur
ve to the pressure drop axis. (1.5 kP
a).
Fig. 2 Calculation of water heater parameters
The basic thermal dynamic characteristics of the water heater for the units PA 01 W2 are stated
in fig. 2.
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