16 September 2011
Thermally driven absorption heat pumps are attracting increasing research
interests because primary energy can be saved and they can use waste heat or renewable sources such as solar or geothermal energy. These systems can replace the vapor compression systems, phasing out the ozone layer depletion effect of the refrigerants. This
paper presents a mathematical model for ammonia-water absorption heat pumps developed for performance prediction. The system is analyzed based on the driven energy and the
coefficient of performance. The thermal powers are calculated for each component of the heat pump based on heat and mass balance equations. The model uses non-linear equations for estimating the thermodynamic properties of ammonia-water mixture. The described model is implemented in a software application which is used to investigate the influence of the important operating parameters on the heat pump performance. The results
reveal that the COP of the system increases slightly when increasing the evaporator water inlet temperature and decreases when increasing the condenser inlet water temperature and
the inlet driving temperature.