Conclusions
This study has been focused on the dynamic simulation of an air conditioning system which employs thermal solar flat plate collectors as heat source in a water-lithium bromide vapor absorption chiller, showing an increment of the heating energy gained by using nanofluids( colloidal dispersion of 3.0 volume % of Al2O3 nanoparticles in bi-distilled water) as working fluid in the solar thermal field, compared with conventional water based one. It follows that the hot fluid stream headed to the chiller’ s generator needs a lower external auxiliary heating, to reach the hot inlet temperature of about 85 ° C required by the absorption chiller, which means energy and cost savings.
In June the simulation presents an energy rate deriving from the solar collectors with nanofluids and stored in the tank, increased by about 6.76 %, with a saving of 29.06 % on the auxiliary heating; in July 6.42 % more stored energy is recorded, with a saving of about 22.10 % on the heater’ s energy consumption; in August 7.26 % more stored energy is calculated, with a saving of 17.21 % on the auxiliary heating and in September energy rate increased by 7.79 % with a saving of 14.80 % on the heater’ s energy consumption.
In conclusion, according to the need to increase the efficiency of renewable energy systems and the general necessity to increase energy savings for a country like Italy which depends in large part by third parties with regard to energy supplies, these results suggest the possibility to use nanofluids in several systems characterized by closed loop working fluids, in order to improve their energy efficiency.
Acknowledgements
This work has been possible thanks to the financial support of the“ Innovasol” project( Pon02 _ 00323 _ 3588246), funded by the Italian Government.
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