RUN-AROUNd-cOIL-SySTEM ENERGy REcOvERy - AL-KO

AIR-HANdLING-UNITS
HIGH PERfORMANcE-
RUN-AROUNd-cOIL-SySTEM
ENERGy REcOvERy

Benefits of energy recovery
The heat capacity transferred to the out-
side air is not generated afresh but re-
covered through heat recovery from the
extract air. The use of heat recovery units
in air-conditioning-systems results in a
higher capital investment but results in
much lower operation costs. A feasibility
study determines whether the installation
of a heat recovery unit is economic.
Reasons for using a heat
recovery system:
I Capacity reduction for heat generation
I Reduction of annual heating energy
consumption
I Capacity reduction for cooling. This
means a scaling down and saving of
investment in heating coils, pipelines,
pumps, cooling systems, refrigeration
plant, cooling towers and cooling coils.
I Reduction of the annual cooling energy
consumption, thus lower operating
costs
I Reduction in environmental pollution
Supporting frame for Hydraulic components Heat recovery system according to VDI 2071
The most important heat
recovery systems
Recuperators
The hot and cold air-flows are directed
along common interfaces through which
the heat is transferred.
Regenerators
Heat and possibly humidity exchange via
contact surfaces. Hot and cold air flows
physically separated through the heating
wheel. This absorbs the heat in the ex-
tract air and passes it to the supply air.
Run-around-coil-systems
The heat recovery unit is made up of se-
veral heat exchangers. The energy is
transferred indirectly using heat transfer
medium via the interface between the
hot air and the heat transfer medium
and the interfaces between the energy
heat transfer medium and the cold air.

Run-around-coil-systems
In the run-around-coil-system the heat
exchange elements for cooling are in-
tegrated into the extract air-flow and for
heating in the outside air-flow. A pipe
system connects the two coils and serves
as a energy transport medium. The circu-
lating water-glycol fluid removes the heat
energy from the hot extract air and trans-
fers it to the cold outside air.
Heat exchangers with special
water conduit circuit
AL-KO HEHR (High Efficieny Heat Recovery)
The AL-KO run-around-coil-system
achieves the highest possible heat re-
covery values considering construc-
tional criteria, like hydraulic circuit,
AL-KO standard system design
Air-flow ratio outside / exhaust
Air velocity on corrugated exchanger surface
Temperature efficiency outside air
Inlet, fresh air
Outlet, fresh air
Inlet, exhaust air
Outlet, exhaust air
Glycol content, Antifrogen N
r.h. = relative humidity
geometry and heat flow capacity. The
capacity of the system can be adjusted
to high demands for optimal achievement
of economic criteria.
1 : 1
2 m/s
70 %
-12 °C / 85 % r. h.
11.8 °C / 13,2 % r. h.
22 °C / 10 % r. h.
-1.8 °C / 50 % r. h.
25 %

System description
Operation of the AL-KO
run-around-coil-system
I Use of high performance heat exchangers
in a multiple countercurrent circuit. This
achieves high annual utilisation ratios
of 80 %.
I Each heat exchanger has only one mode
of air-flowing through (fresh or extract
air) so that germs and contamination
cannot be transferred.
I The system is used during the winter
period to pre-heat the fresh air and in
the summer to pre-cool the fresh air
through adiabatic cooling of the ex-
tract air.
I Because of humidification of the ex-
tract air during summer period the air
is cooled and the cooling transferred
to the supply air. Humidity cannot be
transferred between the air-flows Be-
cause the exhaust air temperature is
raised in the exhaust air heat exchanger,
it leaves the building without moisture.
I Depending on the type of humidifier
(evaporation humidifier, high pressure
nebuliser, air washer) the humidification
is able to use service water, demin-
eralized or adul terate water.
I The AL-KO outside air heater can be
divided in accordance with VDI 6022.
The defroster with wide fin spacing, in-
stalled before the filter, raises the out-
side air temperature sufficiently to avoid
frost formation on the filter medium
and thus ensures compliance with the
relative humidity required by VDI 6022.
ETA
SUP
performance
control
pump-hotwater
50/30
I For dehumidifying an additional heat
recovery system exchanger is installed
after the dehumidifying cooler. During
dehumidifying operation the energy me-
dium will first be directed over the heat
recovery reheater to raise the supply air
temperature. The thereby reduced water
temperature considerably reduces the
outlet temperature at the heat recovery
coil. This system circuit saves approximately
20 % cooling capacity.
Hybrid humidifier
ZL
M
MID
PTH
DVE
M VE
SN
M
Hydraulic
Modul
pump-hotwater
50/30
5 2 4 3 2
EHA
ODA

HEHR run-around-coil-system design
I The division in to separate self-sufficient
systems ensures a very high operational
safety and optimal energy transfer.
The heat transfer medium impinges
directly on the heater and cooler. This
design removes the need for an inter-
mediate medium and additional medium
pumps.
I All hydraulic components needed for
the operation are contained on a supporting
frame.
I Cooler and heater are tubed and connected
in accordance with proven
layouts.
I This energy transfer concept is installed
at the factory and piped together
on site by customer installers. There is
no requirement for factory specialists
for this system. The same applies for
servicing and maintenance. All heat exchangers
can be high-pressure cleaned
up to the core.
I The excellent performance values of the
AL-KO-systems result in a short amortisation
period.
Heat exchangers:
The standardised AL-KO heat exchangers
consist as standard of copper tubes with
expanded aluminium fins and stainless
steel frame. For increased requirements
the multifarious material combinations
are further enhanced by high quality coat-
ings from two component epoxy resin
or polyamide. The heat exchangers are
designed around the principle of multiple
countercurrents. The heat exchangers
can be completely drained and vented

AL-KO Air-Technology – extract of references
Project SUP total
m 3 /h
AL-KO THERM GmbH
Hauptstraße 248 - 250
89343 Jettingen-Scheppach
Phone (+49) 82 25 / 39 - 269
Fax (+49) 82 25 / 39 - 271
E-Mail madelene.laeth@al-ko.de
www.al-ko.com
ETA total
m 3 /h
Number
of units
Heat
recovery
Energy
recovery
Re-heating
during
summ time
via energy
recovery
Run-
around-
coil-
system
Adiabatic
humidifying
of ETA
Aircabin Laupheim 382 000 382 000 6 + 6 X X
Bio Centrum Köln 264 000 220 800 6 + 9 X X
Böhringer Ingelheim 27 500 27 500 1 + 1 X
Creavis Marl I. BA 58 300 51 450 5 + 4 X X X
Creavis Marl II. BA 59 500 45 500 6 + 5 X X
Diakonie Bremen 38 000 38 000 1 + 3 X X X
Ehrmann Moskau 50 000 50 000 1 + 1 X
FHG IZI Labore Leipzig 9 000 9 000 2 + 2 X X
Franziskus Stift Lohne 35 000 35 000 1 + 1 X
Fraunhofer Erlangen II. BA 52 650 52 650 6 + 6 X
Fraunhofer ITEM Hannover 83 000 71 700 1 + 2 X X X
Main Station Dresden 43 150 44 120 3 + 3 X
Heiligenhafen 21 080 21 080 2 + 2 X
IFOK Rostock 64 000 64 000 4 + 4 X
Jogu Mainz lecture rooms 26 315 19 425 1 + 1 X
Clinic Siloah 10 600 10 850 1 + 1 X
Maritim Hotel Berlin 10 600 10 600 1 + 1 X
Coiseum Heilgenhafen 10 000 10 000 X
PTB Braunschweig 30 000 30 000 1 + 1 X X
Rehab Kirchberg Luxembourg 129 200 129 200 9 + 9 X
Residenztheatre München 9 000 8 500 1 + 2 X X
Rietberg museum Schweiz 20 000 1 X
Schülke & Mayr 35 000 38 000 1 + 1 X X
Technic centre Warnemünde 29 275 29 590 1 + 1 X
TIH Hannover 23 000 23 000 1 + 1 X X
Köln university facilities 254 000 250 000 2 + 7 X X
ERG: Energy recovery (heating, cooling)
Run-around-coil-system: Several air-handling-units connected
Hybrid
humidifying
of ETA