24 June 2014

ABSORPTION/COMPRESSION CYCLE FOR HIGH TEMPERATURE HEAT PUMPS – SIMULATION MODEL, PROTOTYPE DESIGN AND INITIAL EXPERIMENTAL RESULTS


The objective of this work is to develop a small capacity absorption/compression
heat pump system for decentralized industrial heat recovery. By means of the solution cycle, it is intended to reach hot water outlet temperatures above 100°C at moderate pressure
levels. Aiming to build up a prototype, different system configurations are investigated, using e.g. variation of the working pair and design boundaries, and solutions for system design
problems are researched.

It is shown that heat transfer and pressure drop characteristics, crystallization issues, compressor outlet temperatures and oil-management have to be particularly considered. The
results of the simulation model are used as basis for the choice of a working-pair and the system design. Due to limited pressure levels of standard components and limited
compressor outlet temperatures a suitable control strategy has to be worked out.

Within this work a prototype was designed and constructed with NH3-LiNO3 as working pair. With the prototype first measurements were realized and the Coefficient of Performance (COP) is determined for different temperature lifts. In this context, tests at different pressure
levels and inlet temperatures were carried out.