22 May 2008

THERMODYNAMIC ANALYSIS OF A SMALL-CAPACITY AMMONIA / WATER ABSORPTION HEAT PUMP FOR HEATING AND COOLING


At the Institute of Thermal Engineering a small-capacity ammonia/water
absorption heat pumping unit has been developed which is able to operate at cold water
temperatures from -10°C to 20°C and cooling water temperatures from 30°C to 50°C. For the
generator a standard plate heat exchanger has been used where the rich solution is partly
evaporated and the vapour and liquid phase flows in co-current flow through the component.
This leads to a thermodynamic disadvantage compared to a counter-current flow component.
In this work two designs of an NH3/H2O absorption heat pump, one with co-current flow
generator and one with a counter-current flow generator are investigated using both first and
second law analysis. Finally the results are compared to each other in order to identify the
thermodynamic penalty of the co-current design and to find potential for improvements at
different operating conditions.