RZ eta-engl Kopie - HOWATHERM

Energy-Optimized Drive Technology
Technical information about our energy-optimized fan
design in central air handling units and
ETA SYSTEM volume flow measuring technology

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Energy-
optimized
HOWATHERM Klimatechnik has been specializing
for nearly 30 years in the development
and production of efficient
systems for air handling applications to
create and maintain comfortable indoor
atmospheres for people.
In the evaluation of contracts, operating
costs have long been a key parameter. An
environmentally responsible and economical
use of resources, in both the manufacture
and the use of AHU equipment, are
important decision-making factors to specifiers
and equipment users. Electrical
power savings are a particularly important
criterion.
This is why HOWATHERM's engineers, in
their ongoing design improvement, have
made the reduction of electrical power
consumption an overriding objective.
Investment and operating cost
estimates
An evaluation of our ETA SYSTEM versus
conventional designs may appear to show
initially higher investment costs.
If the equipment side is included in these
calculations - and about 60% of all systems
require converter control - the frequency
converter cannot generally be taken into
account in the pre-investment analysis.
Without the frequency converter, however,
the investment cost of an ETA SYSTEM
looks even more favorable when compared
against conventional equipment, given
the reduced mechanical complexity. And
even if the frequency converter is included
in the analysis, the ETA SYSTEM offers payback
periods of 1 - 2 years on average.
With the fundamental option of an ondemand
flow control system, this payback
period will be cut by another 50%.
Evidently, the elimination of the belt drive
can often make a second filter stage dispensable.
Let us assume that you intend to replace a
conventional AHU with one from our
energy-optimized ETA SYSTEM range, all
other design characteristics being equal.

In this case you will find the investment
cost of the ETA system to be significantly
lower, despite the frequency converter.
Add to this estimate the facilitated startup
process, convenient maintenance and
cleaning behavior, fast and innovative diagnostics,
continuous availability, etc., and
you will discover a whole range of further
key cost benefits.
For more information on the various systems,
simply give us a call on (++49)(6782)
99990 or send an e-mail to the staff member
in charge of your enquiry. You will
find the addresses of our agencies and
branch offices at www.howatherm.de.
Our in-house and field staff will be glad to
provide advice and support anytime, relying
on advanced communication media.
The reduced electrical power
consumption of our systems is a result of
the following factors:
Optimized drive components with
optional on-demand air flow control
Optimized fan concept based on the
plug-fan principle, reducing the
influence of dynamic pressure effects
Optimized mounting position with
inlet and/or outlet guide vanes
Optimized drive components (high
efficiency motors, EFF1 / EFF2)
Frequency converter based speed
control
Low electrical
power input
ETA System inlet
device reduces air
flow losses and
improves the overall
system efficiency.
Patent protected in
Germany.
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Optimized design
The ETA fan system is one of the most
technologically advanced members of our
central AHU range with energy-optimized
drive systems.
A comparison of the characteristic curves
between the energy-optimized ETA SYSTEM
and the conventional (standard) fan KZG
SYSTEM reveals the difference: depending
on the installation situation, the savings
potential varies between approx. 15% at a
static pressure increase of 1000 Pa and
about 40% at 400 Pa.
In conventional systems with spiral housing
fans, a factor of 2 to 3 times the
dynamic pressure can be viewed as pressure
loss for the fan section.
The ETA SYSTEM relies on the use of single-intake
fans without spiral casing (plug
fan type). The key benefits of this design
are that dynamic pressure levels will
account for a lower portion of the total
pressure and that inflow and outflow pressure
losses are reduced.
Since the belt drive has thus been made
redundant, the fan and motor are combined
into a single compact unit. The nonencased
impeller is mounted overhung on
the motor shaft. This design eliminates losses
due to, e.g., the belt pulley and bearing
support struts in the fan intake, belt
guards, wall influences, that means flow
losses plus belt-related losses are minimized
if not eliminated.
We recommend the use of the ETA
SYSTEM, regardless of volume flow, at
total pressure levels up to 2000 Pa. The
dynamic portion of the total pressure increase
is relatively large at low pressures,
so energy savings will be smaller.
With the direct drive system mechanical
losses are reduced, caused by the belt
drive. Also speed control is achieved via a
frequency converter integrated into the
AHU. By using an asynchronous motor of
increased efficiency, an additional 3 - 10%
power consumption can be saved depending
on system type (class EFF1 / EFF2).

On-demand air flow control
The air flow control based on the frequency
converter permits a speed adjustment in
line with specific operating situations, e.g.,
to allow or compensate for filter resistance,
bypass operation, mixed flow mode, partload
conditions, etc.
In AHU equipment, a reliable measurement
and control of the air flow rate contributes
greatly to electrical power savings,
true output performance, and operating
reliability. For this reason we are offering
an air flow rate measurement system (VSM)
for ETA SYSTEM central AHUs. This system
provides a direct reading of the air volume
flow with a tolerance of ± 5% of the
nominal air flow rate.
In duct work measurements - a notoriously
time-consuming and costly as well as inaccurate
measuring principle - the measurement
error is often more than 10 - 15%.
Compared to constant-flow systems, it is
possible to save a further 20 to 80% of the
remaining electrical power consumption,
depending on the requirement profile.
The key to these advantages is the basic
control capability provided by our ETA
SYSTEM frequency converters.
Design description
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Optimum outflow
Direct drive
Controlability
F7 F7
Maintenance benefits and operating
reliability
In addition to our efforts to minimize the
electrical power consumption of this range,
maintenance behaviour and operating reliability
were priority optimization objectives
for our development engineers.
In this respect, too, the elimination of the
belt drive provides major advantages. The
F7
time-consuming and costly replacement of
the belt, re-tensioning and belt monitoring
are no longer an issue. Since no belt
abrasion takes place, the pressure-side filter
becomes redundant as well. And a
non-existent fan bearing needs no maintenance
and, of course, cannot fail.
The load on the motor bearing exerted by
the fan wheel is actually smaller than that
imposed by belt tension. As a result, availability
rates will be increased.
Single intake fans with backward curved
blade wheels, direct driven, turned 90° to
the operating plane. Optimum inflow in
the air direction without flow deflection
losses.
The arrangement of the motor right in the
airflow results in optimum cooling. The
use of high-efficiency motors additionally
reduces the amount of energy converted
into heat. Direct coupling to the fan eliminates
wheel drive and belt losses; motor
speed is varied by the frequency control
action of a frequency converter.
The basic control capability of the fan permits
an on-demand flow control, e.g., to
account for filter resistance in normal service,
different resistances in mixed-flow
mode, or varying resistance levels across
the cooler during dry or demoisturizing
operation.

Free intake, no bearings, no belt pulleys
obstructing the cross-section, no interference
from the casing walls.
Optimum air outflow into the downstream
component chamber with partial recovery
of dynamic pressure. Low outlet losses,
optimum air outflow into downstream
component chambers. Outlet-side improvement
of the local mixing efficiency by
600%, meaning barely any temperature or
velocity differences downstream of the fan
- for optimum mixing.
Air control and shutoff dampers based
on the HOWATHERM SYSTEM: air-tight
dampers are standard on our AHU´s, not
just on units meeting hygiene requirements.
HOWATHERM SYSTEM heat exchanger:
Depending on the requirement situation,
we recommend this component to be
arranged on the pressure side for improved
mixing conditions in the fan after a
mixing section and superior handling of
waste heat from the motor, particularly in
cooling mode.
Key design benefits
of the ETA SYSTEM
No need for a fan baseframe
No belt guard, baffle plate, inspection
sleeve or condensate drain
No belt drive
No fan bearings
No motor adjustment carriage for
belt tensioning
Reduced installation length
Improved inlet and outlet conditions,
with better inflow into downstream
components
Freely definable air outlet connections
Free intake
Optimum hygiene
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Other improvements
Filterefficiency
Filter
Where two-stage filtration is inevitable
we recommend the combination of an F7
pre-filter with an F7 second filter stage.
We have found this combination to achieve
the same particle recovery rates as an F5 /
F9 combination at greatly reduced filter
change costs and lower average filter
pressure-drop, which may average around
200 Pa lower than F5 / F9 combination.
In addition, the use of a single filter
medium size will simplify maintenance.
99,9%
of the
particles
are smaller
than 1µm

Filter
With the use of a class F7 air filter, no prefilter
is required. Quite the opposite is true
- an upstream coarse particle filter will at
best result in a 30% service life improvement,
less than the cost of more frequent
filter changes. A high-efficiency filter stage
at the inlet into the unit ensures an optimum
protection of downstream components
while enhancing the cost-effectiveness
of your filter media.
Although a higher-class inlet filter needs
to be replaced more frequently than the
same filter stage combined with a pre-filter,
the cost of changing filters (including
the pre-filter) are higher in relative terms
by a factor of about 1.5 than for a configuration
without pre-filter. In addition
according to VDI 6022 standart the first filter
stage is to be changed at the latest
once a year. Moreover, the volume of
"special waste" accumulating in the form
of filter media is minimized.
For the ETA SYSTEM, this means that
only a single filter stage will be used for
fresh and supply air (except for hygienic
AHU´s per DIN 1946 Part 4). Since no belt
abrasion particles have to be dealt with,
one single inlet-side air filter is enough -
its outlet-side counterpart becomes redundant.
Another key argument in favor of the ETA
SYSTEM is hygiene.
The elimination of the spiral casing makes
for better hygiene conditions in the drive
system, since non-hygienic matter will no
longer accumulate on the interior housing
surfaces.
In addition, the system is easier to clean,
since many areas in which impurities tended
to collect are no longer part of the
design (baseframe structure, motor carriage,
belt guard, baffle plate, etc.). The
impeller is accessible for maintenance from
the operating side at any point - a major
factor in central AHU equipment in hygienic
service.
For details on our HYGIENE system refer to
www.howatherm.de.
Function:
Differential pressure
to flow rate
V = √∆ p (∆ p = differential pressure at the fan nozzle)
or
V = k* √∆ p [k = constant (depends on fan)]
Fan design
ETA SYSTEM - optimized
fan concept
based on the plugfan
principle with
volume flow measuring
technology and
frequency converter
based speed control
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Benefits of “smart”
frequency
converters
Volume flow measu-
ring technology
ETA SYSTEM designs are generously sized,
with flow velocities of around 2 m/s.
This means that the droplet eleminator on
the cooler can be void, resulting in a further
decrease in internal pressure losses. In
fact, the lower velocity reduces both the
pressure loss (by a square correlation) and
the electrical power consumption (by a
third correlation). Moreover, the power
consumption of the new drive concept is
lower in relative terms at reduced pressures
(approx. 15% savings at 1000 Pa, about
40% at 400 Pa), implying still higher relative
electrical power savings - with the result
of further economic benefits.
The power consumption of these units was
measured on HOWATHERM test rigs and in
RWTÜV trials and is EUROVENT-certified.
An additional improvement feature is the
execution of the fan casing in the thermally
insulated ETA 40 T sectional structure.
This design minimizes thermal bridges, and
the casing is air-tight to DIN EN 1886 tightness
class B.

Principle of operation
We use the fan inlet nozzle as a flow
nozzle for our measurement. Since the differential
pressure changes subject to a
square law with the volume flow or air
velocity, this parameter is well suited as a
standard of volumetric throughput. The
ETA fan system ensures an undisturbed air
flow in the inlet nozzle. No bearing support,
belt pulley, belt or inlet guard components,
etc., obstruct its cross-section. The
air flows quite simply in a direction vertical
to the nozzle plane. This explains the high
degree of measuring accuracy obtained.
The influence of the downstream fan
impeller on the measuring accuracy is
negligible. In extensive trials conducted on
HOWATHERM test rigs, the inaccuracy caused
by varying impeller speed was found
not to exceed ± 0,5 %.
The VSM system is based on the physical
principle of differential pressure loss across
a nozzle. It is the same principle that is
commonly employed in test-rig measurements
of the volumetric flow rate according
to DIN 1952, DIN 24163, VDI 2041 or
AMCA 210-67.
The reference signal fed to the frequency
converter may be in a 0-10 V voltage,
4-20 mA or 0-20 mA current, or digital format.
The advanced frequency converters employed
by HOWATHERM also provide the
possibility to create control loops without
a separate control system. An integrated
PID controller can maintain the volume
flow or duct pressure constant to a specified
setpoint value. The pressure or velocity
ratio will thus remain unchanged regardless
of the fan speed.
The characteristic curves of our inlet
nozzles were calibrated according to
DIN 24 163 by RWTÜV on a voluntary
basis.
ETA System inlet device reduces air flow losses
and improves the overall system efficiency.
Patent protected in Germany.
Control system
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Practical advantages

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Energie savings and
true output
reporting
Opimized operating
convinience
Air flow measuring
system
Control system: practical advantages
Fan efficiency remains essentially unchanged
throughout the operating
speed range.
A stable fan operating regime is achieved
through the full fan speed range.
Stepless speed changes can be effected
via input signal control.
Minimum and maximum speed levels can
be preset.
Motors may be of standard design.
The need for soft starters is eliminated,
given that the start-up current is limited
to a defined value by the frequency converter.
The additional electrical losses associated
with the frequency converter are low
(approx. 4% at full load).
Control and monitoring systems can be
easily interfaced with the frequency converter
Control parameters facilitate optimum
system adjustment.
A constant volume flow regulation is
provided.
Simple control loops can be implemented
even without higher-order controller
or control system.
System adjustments can be made at the
touch of a button.
Control options
The differential pressure transducers provides
a linearized output signal (0/4-20 mA)
corresponding to the volumetric flow rate.
This output signal is wired at our factory
to the integrated frequency converter. It
will thus serve as a reference signal for the
frequency converter's built-in PID controller
but may also be fed to an external higher-order
control system. The 24 V d.c.
power supply is likewise generated by the
integrated frequency converter.
Following parametrization of the frequency
converter in our factory, the flow rate
can be directly read off the frequency converter's
display in m3 /h. In addition, the air
flow can be kept constant to an externally
defined setpoint via the built-in PID controller.
Via an output signal, the volumetric
flow rate may be transmitted to a higher-order
control system, e.g., for efficiency
optimization. For more detailed information
refer to our HP-WRG system description.
Varying due to changes in filter pressure
drops, dry or wet cooler conditions, mixing
flow mode, etc., will thus be compensated
for by the control system.
HOWATHERM is a member of the German
Federation of Manufacturers of Air
Handling Units (Herstellerverband
Raumlufttechnische
Geräte e.V.)
Practical advantages
The volumetric flow rate measurement
embodied in our ETA SYSTEM helps to reduce
the electrical power consumption
and provides a true output picture, given
that the actual volume flow will correspond
exactly to the target value and no
additional volume loss for conventional
flow rate measurement (e.g., orifice plates,
nozzles) is en-countered. The system is
easier to adjust, requiring just the touch of
a button on the frequency converter. The
specific volume flow is digitally displayed
throughout the adjustment process.

Reduced capital outlay is another benefit,
since no extra measuring loops or instruments
are needed. Time-consuming and
inaccurate measuring routines have thus
become a thing of the past. With the volume
flow measuring system embodied into
our ETA SYSTEM we have made a further
contribution to enhancing the safety, energy
efficiency and true-to-specification performance
of your plant.
Optimized operating convenience
To facilitate diagnostics, a keypad and
display for data and menus (IP 65 protection
class) have been integrated into the
front panel of the fan chamber. From this
keypad, all control parameters can be entered
using a menu-based microprocessor
program. Operating variables such as r.p.m.,
current, power, volumetric flow, kWh, etc.
are displayed for effective maintenance
support and transparency, ensuring that
you will always know exactly how your system
is performing. Parameters can be
changed directly on the unit at any time;
in the same way, parameter changes can
be disabled where appropriate.
Frequency converter installation
site
As a general rule, the system benefits outlined
above (diagnostics, adjustment, etc.)
are available only with the frequency con
Specifications
verter fitted inside the casing. Short cabling
connections between the motor and
frequency converters minimize power losses,
and the integral installation of the frequency
converter will ensure that it receives
optimum cooling.
Another aspect worth mentioning in this
context is radio interference suppression. If
an external installation site is used, it is
possible to route so-called "antennas"
through the building. We use mains filters
to ensure electromagnetic compatibility.
The radio interference suppression behaviour
of our systems meet VDE 0875 Curve B
specifications. HOWATHERM engineers will
ensure a skilful and professional installation.
Volumetric flow rate measurement based on pressure transducer.
Differential pressure sensor with 0/4-20 mA signal output.
Linearity ± 1,0 %
Medium non-aggressive gases
Output signal to frequency converter input 0/4-20 mA (RL> 1 kOhm )
Power supply (via frequency converter) 24 V d.c. (± 0.20%)
Protection class (casing) IP 54
Protection class (keypad) IP 65
Frequency converter
installation site
Spezifications
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For further information contact our inhouse
or agencies, or visit us on the
Internet.
HOWATHERM Klimatechnik GmbH
Innovative Ventilation and Air Handling
Technology
Degussagelände 11-15
55767 Brücken / Germany
Postal address:
Postfach 1461
55762 Birkenfeld / Germany
Phone: (+49) (0)6782-99 99- 0
Telefax: (+49) (0)6782-99 99-10
0700HOWATHERM
E-mail: info@howatherm.de
www.howatherm.de
We enjoy working with you.
SchillerKrenz-Gestaltung
©HOWATHERM KLIMATECHNIK GMBH
P004-07/03