ACS 08 — A First Generation Product

At the beginning of 2008, SorTech AG defined a first product named ACS 08, which is being manufactured and sold in a small series production since March 2008.

Подпись: Fi g 4. ACS 08.

The machine has the following technical data:

Technical data ACS 08

Cooling Capacity

7.5 kW

Thermal COP

0.56

Electrical Power

9 W

Consumption

Chilled Water Circuit

18/15°C at 2.0 m3/h

Heat Rejection Circuit

27/32°C at 3.7 m3/h

Heat Supply Circuit

72/67°C at 1.6

The machine may also be used under other temperature conditions (see as an example the variation of cooling capacity and COP as a function of heat rejection temperature in fig. 5). SorTech AG provides a programme based on Excel for the calculation of cooling capacity and COP under all temperature conditions.

The control of the adsorption chiller is managed in a way, that it is easy to operate the machine under partial load. The inner adsorption-desorption cycle of the system is automatically adjusted to the cooling demand. Therefore under certain temperature conditions there is not a single value but a range of COP and cooling powers under which the machine may be driven.

COP over Chilled water capacity of ACS-08

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Chilled water capacity [kW]

Fig. 5. Cooling capacity and COP depending on the heat rejection temperature. Hot water and chilled water circuits are fixed on 72/67°C and 18/15°C. The inlet temperature of the heat rejection circle with respect to the chiller is varied from 25°C to 35°C at fixed volume flow of 3.7 m3/h. Similar graphs may be generated by variation of the other cycle temperatures. SorTech provides a calculation programme based on Excel, which generates chilled water capacity and COP under all temperature conditions.

4. PILOTE TESTING

A series of pilot tests of prototypes were carried during the cooling season of 2007. The applications range from solar air conditioning of small offices and homes, solar assisted heating and cooling of the canteen kitchen at Fraunhofer Institute for Solar Energy Systems to small-scale trigeneration and installation in a district heating network.

The locations of the field tests were in Germany and Austria. Field tests in hotter climatic regions like Spain and Italy are being conducted in 2008. For chilled water distribution different system, like fan coils, wall heating systems and ducted air handling units were used. All systems were prepared for sole cooling with the exception of Fraunhofer ISE, where the combination of cooling in summer and heating assistance during winter, operating the ACS as a thermal driven heat pump, was tested. The system at Fraunhofer ISE is using ground coupled vertical bore holes for heat rejection during summer and as a heat source in winter. The system looks attractive for private homes in heating dominated regions such as Germany with a rather short cooling season.

After the first cooling season of 2007 some preliminary results may be summarized as follows:

Up to now all machines worked well — no breakdown or serious problem occurred.

The installation procedure proved to be rather difficult, consequently SorTech is working on a simplified installation procedure and is carrying out training courses for installers of the product in 2008.

Basic problem is the overall electricity consumption of the system. Although ACS 08 has a consumption of only 9 W, pumps and fans consume much more electricity especially on the heat rejection circle. As a consequence SorTech improved hydraulic design in order to reduce pressure losses on all three circuits.

The most important component for solar air conditioning after the chiller is the heat rejection unit. In order to combine the advantages of dry (no legionella problems) and wet re-cooling (better performance at high air temperatures) SorTech designed and tested a hybrid re-cooler (RCS 08), equipped with energy saving EC fans, which are controlled by ACS 08. After a first cooling season of continual operation we think that packaging chiller and re-cooler makes an attractive product for solar air-conditioning.