Multi-criteria (thermo-economic) optimization and environmental analysis of a food refrigeration system working with low environmental impact refrigerants

In order to cope with the performance requirements of the Eco-design and to the limitations of European regulations, manufacturers of refrigeration devices must find an optimum between performance and costs. In this paper, we propose a thermo-economic analysis based on calibrated models and real constraints to explore possible design options for a 2.5 kW commercial refrigeration unit including the effects of the refrigerant type (R404A as baseline, R454C, R449A, R452A, R455A and R290 as low environmental impact fluids). The results are proposed in two dimensions: the first one related to the manufacturer point of view with a Pareto front of costs and performance, and the second one related to the customer point of view with the environmental impact evaluation for each configuration that belongs to a Pareto front. The calibration of models is based on real and actual data for compressors, heat exchangers and costs. Different scenarios are proposed depending on the location and the related specific energy costs and emission factors (Italy, France, Germany). The results show that R449A performs better as mid-term scenario refrigerant in European market. Instead, R454C can be suitable as long-term replacement. Finally, the environmental analysis shows that the optimal configuration in terms of performance has not the lowest environmental impact. The latter aspect requires more attention by the regulatory panels.