23 September 2011

A 10 kW INDIRECTLY FIRED ABSORPTION HEAT PUMP: CONCEPTS FOR A REVERSIBLE OPERATION


In the last decade several small and medium sized solar or waste heat driven
chillers have been developed and brought to market. Nevertheless, in Central Europe where
many of these chillers are installed, the required cooling period of buildings is rather short. By
using them as a heat pump during winter time their operating period can be extended in
order to shorten the payback period and increase the cost effectiveness, and at the same
time, the benefit to the environment is increased.
From a thermodynamical point of view it is possible to run a chiller also as a heat pump, but
in practice there are restrictions in application due to the dependency of the driving
temperature and the temperatures of heat source and heat sink. Using the example of a
10 kW H2O/LiBr absorption chiller, constraints of and demands on different possible
peripheral systems (heat sources and heat sinks) for the reversible operation have been
investigated. In the paper we present combinations which are favorable, and others which
should be avoided from a primary energy point of view.