Energy savings and economic benefits of using electronic expansion valves in supermarket display cabinets

This paper reports on the energetic and economic comparison between electronic and thermostatic expansion valves in a centralized refrigeration plant of a supermarket. Adopting electronic expansion valves enables an appreciable energy saving, due to the fact that electronic valves allow a lower condensation pressure in systems equipped with air cooled condensers, which is adjusted to variations in outside air temperature. Furthermore, superheating at the evaporator is lower and more stable, increasing cooling capacity and decreasing refrigerant temperature at the compressor discharge (the latter ensures better effi ciency and lower wear and tear for the compressor). This study is supported by experimental work where the cabinets of a supermarket, located in the northern Italy, have been equipped with both thermostatic and electronic expansion valves, alternatively activated by solenoid valves on a daily basis, in order to compare the two systems in the same environment and at similar load conditions. This allowed the building of a simulation model of the application to evaluate the performance, energy and economic savings in different climates (the energetic analysis considers total electricity consumptions – compressors, fans and electrical switchboards).