HVAC SYSTEMS - HFT Stuttgart

ABSTRACT
III
ABSTRACT
During the last 10 years solar cooling systems attracted more and more interest
not only in the research area but also on a private and commercial level.
Several demonstration plants have been installed in different European
countries and first companies started to commercialise also small scale
absorption cooling machines. However, not all of the installed systems operate
efficiently and some are, from the primary energy point of view, even worse
than conventional systems with a compression chiller. The main reason for this
is a poor system design combined with suboptimal control. Often several non
optimised components, each separately controlled, are put together to form a
‘cooling system’. To overcome these drawbacks several attempts are made
within IEA task 38 (International Energy Agency Solar Heating and Cooling
Programme) to improve the system design through optimised design guidelines
which are supported by simulation based design tools. Furthermore, guidelines
for an optimised control of different systems are developed. In parallel several
companies like the SolarNext AG in Rimsting, Germany started the
development of solar cooling kits with optimised components and optimised
system controllers. To support this process the following contributions are made
within the present work:
- For the design and dimensioning of solar driven absorption cooling systems
a detailed and structured simulation based analysis highlights the main
influencing factors on the required solar system size to reach a defined solar
fraction on the overall heating energy demand of the chiller. These results
offer useful guidelines for an energy and cost efficient system design.
- Detailed system simulations of an installed solar cooling system focus on the
influence of the system configuration, control strategy and system
component control on the overall primary energy efficiency. From the results
found a detailed set of clear recommendations for highly energy efficient
system configurations and control of solar driven absorption cooling systems
is provided.