The project deals with the optimization of refrigeration and thermal systems in order to minimize the total yearly cost represented by the sum between the operating cost and the investment cost. Therefore, an exergoeconomic analysis of thermal systems has been performed. Exergoeconomics represent the union between thermodynamic analysis of irreversible processes and economics. Exergy concept is the only measure that accounts for both quantity and quality of a specific form of energy. Unlike of energy, exergy is consumed in a productive process and that is the reason why it can be a part of an economic balance.
The choice of the optimal temperature difference in the heat exchangers of a refrigeration system has been found for the optimization. Afterwards it has been applied in the organic Rankine cycle. To point out only the net effect of the temperature differences in the evaporator and condenser, an efficiency has been introduced as the ratio between a Carnot cycle operating between the temperatures of condensation and evaporation and another one operating between the temperatures of the environment and the cold chamber. The exergy destructions in the compressor and the throttling valve have been neglected in this phase, so they have been given by the exergetic efficiency of the specific zone.
Thus, the exergetic efficiency of the global system is calculated as the product between the efficiency of the cycle with only the heat transfer exergy destruction and the efficiency accounting only the destructions of the compressor and the throttling valve. Both terms represent the objective function that minimize the operating and investment cost.
