Environmental Engineering Reference
0.7. A 570m 2 floor area is cooled by the solar-powered systemwhich also consists of a
small hot water buffer tank (less than 0.1m 3 ) and a cold water storage tank (Henning,
Further projects are a 35 kW SE ACM with 70m 2 of VTCs in Perpignan, France,
and an SE ACM with a 35 kW cooling capacity and 60m 2 of collectors at the CSTB
in Valbonne, France.
Low-Power SE ACM Projects
After the experiences in the 1970s with the low-power systems from Arkla, some
projects were recently carried out once again with small-scale ACMs. Since 1999
there has been a 7 kW H 2 O/LiBr ACM Yazaki WFC-600 installed for laboratory and
office cooling at ZAE Bayern in Garching, Germany. The driving heat is produced
by 19.6m 2 of VTCs and stored in two 0.6m 3 hot water storage tanks. The operating
characteristics of the ACM are T h 88 ◦ C and T o 16/14 ◦ C with a COP of 0.6.
A newly developed SE H 2 O/LiBr ACM from the German company Sonnen Klima
with a 10 kWcooling capacity was installed for its first field test at an office building in
Berlin Treptow, Germany, in August 2003, providing 152 m 2 of cooled office space.
The ACM is driven alternately with 42m 2 of FPCs or 25m 2 VTCs and a 0.75m 3
hot water buffer tank is also installed. The nominal operating temperatures are T h
72/62 ◦ C, T c 27/35 ◦ C and T o 18/15 ◦ C and the COP ranges between 0.76 and 0.82
(Storkenmaier et al ., 2003; Kohlenbach et al ., 2004).
Further field tests, each based on a 15 kW H 2 O/LiBr ACM (Wegracal SE 15 from
the EAW company, Germany), have been carried out since 2003. The first is at a sales
store in Neumarkt, Italy, where 55m 2 of FPCs and a 0.75m 3 hot water storage tank
are used as heat sources for the ACM. The second field test is being performed at
the technology centre TZ Kothen, Germany, for office cooling with 77m 2 of VTCs.
The determined operating parameters are T h 90/80 ◦ C, T c 32/38 ◦ C, T o 21/15 ◦ C and
an average COP of 0.5. Within the system, there is also a paraffin latent heat storage
with a melting temperature of 90 ◦ C, a 0.5m 3 conventional hot water storage tank
and a 0.2m 3 cold water buffer tank (Safarik and Weidner, 2004). A further EAW
H 2 O/LiBr ACM has been used since 2003 for a laboratory test stand at the Technical
University of Ilmenau, Germany. This test cooling machine, however, has a reduced
cooling capacity of 10 kW. The ACM is driven by 10m 2 of FPCs and a 2m 3 hot water
buffer tank. The nominal operating temperatures are T h 85/75 ◦ C, T c 30/35 ◦ C and T o
14/8 ◦ C. The reach COPs about 0.4 (Ajib et al ., 2004).
There are only a few laboratory prototypes of air-cooled, SE H 2 O/LiBr ACMs.
A prototype of an air-cooled H 2 O/LiBr absorption chiller can be found at the Poly-
technic University of Catalunya in Terrassa, Spain. The unit has measured cooling
capacities between 1.2 and 1.8 kW and COPs from 0.3 to 0.5 for an input temperature
T h of 75-95 ◦ C, input cooling air T c of 32 ◦ C and input chilled water T o of 20 ◦ C