0603RHC4-JLGBEN
16
/
21
1
1
1
2
+
⎟
⎠
⎞
⎜
⎝
⎛
−
×
=
VR
V
x
x
V
V
tot
tot
HS
)
/
³
7413
(
/
³
.
2
1
1
.
1
.
3
.
426
250
.
3
06
58
61
50
61
h
m
s
m
V
HS
=
+
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
−
×
=
Example 3 : RHC 4075 09 RJL
with :
-
total air flow = 1.94m³/s = 7000 m³/h
-
by-pass besides heat exchanger
-
calculation for heat output H1
Result :
- dimension B
= 670.
50
mm
- dimension X
= 800mm (see fig. 13)
- R1
= 206.
50
- R2
= -319.
20
- dimension C
= 206.
50
x 1.
94
– 319.
20
4
C = 81.
40
mm
Note
In this case 1.58m³/s (= 5700m³/h) flows through
the heat exchanger enclosure. The remaining
0.36m³/s (=1300m³/h) flows through the by-pass
duct
(1.94m³/s – 1.58m³/s = 0.36m³/s)
Example 4 : RHC 4075 09 RJL
with :
-
total air flow = 1.94m³/s = 7000 m³/h
-
by-pass besides heat exchanger
-
calculation for heat output H2
This is impossible because the total airflow (=
7000m³/h) is less than the minimum required
airflow V2 for heat output H2
.
Pressure loss :
In this case the total pressure loss over the RHC
module with by-pass can be extracted from
figures 12a/b/c. The airflow through the heat
exchanger enclosure must be applied to
determine the total pressure drop.
Example 1 :
- Airflow through the heat exchanger
enclosure = 2.58 m
³
/s (5700 m
³/
h
)
- Total pressure drop = 40 Pa (approx.)
Example 2 :
- Airflow through the heat exchanger
enclosure = 2.44 m
³
/s (8800 m
³/
h
)
- Total pressure drop = 90 Pa (approx.)
11.3
Calculation of alternative by-pass dimension
Due to space restrictions it may not be possible
to use the above mentioned maximum dimension
by-pass.
In this case a smaller by-pass can be applied.
Obviously, this smaller by-pass will result in
higher portion of the total air flow through the
heat exchanger enclosure and
consequently in a higher total pressure
drop
To calculate this air flow through the heat
exchanger enclosure, following interpolation
rule should be applied :
With :
- VR =
Recommended air flow
(Table 7) (m³/s)
- Vtot =
Total air flow (m³/s)
- x1 =
Recommended by-pass (dim
A or C) (as calculated in
section
11.1).
- x2 =
Applied by-pass dim. (mm)
Then VHS (air flow through heat
exchanger enclosure) can be calculated
as :
As explained, the air flow VHS through the
heat exchanger enclosure must be used in
figure 12 to extract the correct total pressure
drop over the RHC module with by-pass.
The air flow VHS may not exceed the
maximum airflow allowed according to
section 4.1.2 to avoid supercooling ot the flue
gases.
E
XAMPLE
.
RHC 4075 09 RJL
with :
- Total air flow : 3.61m³/s (13000m³/h)
- Expected min. inlet temperature : -5°C
- Recommended max. dim C = 426.50mm
(see example 1)
- Dimension X = 800mm
- Applied by-pass dim. C = 250mm
Then :
- x1 = 426.50mm
- x2 = 250mm
- Vtot = 3.61m³/s
- VR = 1.58m³/s (5700m³/h)
Result
:
