Experimental optimization of energy consumption for direct current refrigerator by PID controller tuning and comparison with ON/OFF refrigerator

In this research the optimization of energy consumption for DC refrigerator used in commercial cold store was conducted. To achieve this object a test facility was installed into the introduction room of a national refrigeration company. Due to the imperfect data given by the producer, the proportional-integral-derivative controller of DC refrigerator had to be tuned by setting the correct proportional, integral and derivative parameter values to achieve optimal energetic operation. During the research the energy consumption of this system was compared with a very commonly used traditional refrigerator system on the home market operated by reciprocating compressor, mechanical expansion valve and on/off controller technic in the similar cooling capacity range. The combined effects of electronic expansion valve, scroll compressor operation and the correct experimental settings of proportional-integral-derivative controller in DC refrigerator results around 62.4% energy saving opposed to the traditional on/off controlled appliance under the same operational conditions in the same cold store.