Exergy analysis and optimisation of a ground or water source heat pump system for maximum environmental exergy potential utilisation

The non-flow exergy potential of the near ground air with respect to the soil conditions at Évora region has been calculated from monthly averaged hourly data of temperature and specific humidity. The results show that the exergy potential is higher when either heating (wintertime) or cooling (summertime) is most required. The use of this potential for reducing the power consumption of indoor air conditioning systems through ground or water source heat pumps systems is investigated. In order to obtain an optimal operation an exergy analysis was carried out offering the opportunity of defining a new objective function for the optimisation of the use of use of exergy sources: 'In any system powered by an external exergy source optimisation is achieved when the exergy flux to the environment is minimum under the existing constraints'