Hoval A 60 - 7 System Design; Hoval CASER Design Program; Design Data; Local Conditions, Installation Position

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7 System design
7.1 Hoval CASER design program
The Hoval CASER design program is available for fast
and accurate design of Hoval rotary heat exchangers
(= Computer Aided Selection of Energy Recovery). It runs
under Microsoft
®
Windows and offers the following applica-
tions:
■ Secure planning with Eurovent and TÜV-certied data
■ Accurate calculation of a specic Hoval rotary heat
exchanger
■ Calculation of all applicable rotary heat exchangers for a
specic project
■ Calculation of the efciency class in accordance with
EN 13053
■ Calculation of leakage in accordance with Eurovent
■ Price calculation for the selected rotary heat exchangers
Notice
You can download the Hoval CASER design program
free of charge from our home page (hrs.hoval.com).
The program is also available as a Windows DLL le and can
therefore be integrated into other spreadsheet programs (on
request).
Hoval CASER
7.2 Design data
As with all design, achieving the setpoint values depends
on the correct starting data. This often causes problems,
particularly in ventilation applications. The reason is the
dependence of the temperature of the specic density and
the specic heat. Water vapour in the air is also very impor-
tant for the design. This is why the data available on entry to
the exchanger are essential for accurate calculation of a heat
exchanger.
Exhaust air
stream
Extract air owrate V
11
[m
3
/s]
Extract air temperature t
11
[°C]
Extract air rel. humidity RH
11
[%]
Supply air
stream
Fresh air owrate V
21
[m
3
/s]
Fresh air temperature t
21
[°C]
Fresh air rel. humidity RH
21
[%]
Table 9: Design data
The following errors must be avoided with data recording:
■ Volume ow is not equal to mass ow. The mass ows
of supply air and exhaust air must be known for correct
design.
■ The humidity in the extract air is generally estimated too
high, particularly for winter operation. (Where does the
humidity come from?)
■ Are the temperatures (fresh air, extract air) really as stated
in practice (or are they wishful thinking)?
7.3 Local conditions, installation position
■ Where should the heat recovery unit be installed?
■ Which is the optimum air path?
■ What dimensions are approved?
Notice
Please note that the wheel must be accessible for
maintenance and cleaning. Hoval therefore recom-
mends to provide 600 mm free space in front of and
behind the wheel (= width of an inspection door).
7.4 Wheel type
The wheel type must be selected depending on the applica-
tion. The following are recommended:
■ The condensation or enthalpy wheel is suitable for venti-
lation systems without mechanical cooling and without
humidity control.
■ Sorption wheels are recommended for ventilation systems
with mechanical cooling. The high humidity efciency,
even under summer conditions, dries the fresh air. This
requires less cooling capacity and reduces energy costs
for cooling up to 50%.
System design