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.