A field survey of ammonia-water absorption heat pump performance.

A school building located on the mountains in the North-East of Italy is equipped with ammonia water absorption heat pumps both for room heating and for heating the ventilation air. Whereas the formerresort to vertical ground boreholes and solar collectors as cold source, the heat pumps of the ventilation section use the ground or as well the heat recovery from the exhausted air. The plant was carefully monitored and the following energy flows were logged hourly, via thermal energy meters, together with inlet and outlet temperatures: - condenser/absorber and evaporator of each heat pump; -ground circuits, separately for ventilation and space heating. The long term survey during a period of more than 4 years allows to experimentally evaluate in real operation the absorption heat pumps performance for different temperatures of the cold source, as the inlet temperature extended from few degrees when the source is the ground to even more than 20 °C when the source is from the solar collectors. Moreover it is possible to estimate the eventual equipment decay of performance during the considered period.