Challenges on Converting an Upright Ice-Cream Freezer from R404a to R290 Complying with 150g Refrigerant Charge Restriction

Glass door vertical refrigeration systems for commercial applications located in places with an elevated flux of people throughout the day have a high door opening rate, turning the maintenance of the inner temperatures below -18°C a huge challenge. Usually evaporators with wide surface area are used in order to improve the heat exchange, demanding greater refrigerant charge. Other factors, namely the evaporator’s heat exchange efficiency loss caused by the ice formation between fins and the power supply oscillations, contribute to the system’s capacity losses, affecting the fresh food flavor and preservation time as well as the end customer’s expectation.  The present work shows the results obtained through the optimization and conversion of vertical ice-cream freezer from R404a to R290 with limit of 150 g. The use of variable cooling capacity compressor and system component’s optimization were fundamental to reach the operation requirements and maintain the internal temperature even in critical operating conditions as door opening tests, with extra benefit of energy consumption reduction