Efficiency and Energy Savings Evaluation for Dry-Cooler Equipped Plants

The problem of the high energy requirements for the building climatization is well known. Some significant energy savings may be achieved by means of indirect free cooling. The aim of this work is to analyze the possibility to exploit this systems to cool down water of fan coil plants, in some kind of buildings taking into account different climate conditions and internal gains. The water supplying the plant terminals is cooled in the Dry-Cooler or in the chiller: an external air-water heat exchanger. The external climate conditions can guarantee a free cooling effect in order to reduce the load absorbed by the chiller. First of all, the thermal loads of two kind of buildings (a shopping centre and an office block) have been evaluated through the simulation of their behaviour during a whole year, with a hourly time-step, for different climate conditions, using the software Energy Plus. Realistic working conditions, suggested by Dry Coolers manufacturers, have been imposed. For each hour during the simulation period, it has been determined the external maximum temperature that lets the Dry Cooler balance the cooling load while the chiller is off. Then it has been possible to verify the sharing out of the thermal load between Dry Cooler and Chiller.