As any grocery store owner knows, the costs of proper storage of both cold and frozen food is substantial, typically accounting for 40–50% of electricity consumption storewide. That’s why refrigeration system design is so critical. Whether you need to install cases in a new store or it’s time to upgrade an existing store, UNFI Professional Services’ Store Design & Equipment department is here to help you find the value-based refrigeration system that best fits your store’s needs and goals.
When we work on a refrigeration design project, one of the first steps we start with is the base specifications — the minimum required to meet the refrigeration load at the design conditions. Items beyond base specification are evaluated based on ROI or payback calculations.
In this blog, we’ll cover two important areas — mechanical subcooling and electronically driven expansion valves. Mechanical subcooling has been utilized for some time in the grocery industry and many stores already use it. Electronic expansion is relatively new and is not yet widely used in supermarkets. Both have their place and are worth considering for any refrigeration project.
Mechanical Subcooling. This can be an effective method of increasing system capacity and improving refrigeration efficiency. With this method, a refrigerant is used to overcool the liquid feeding refrigerated fixtures. To maximize subcooling, a higher efficiency refrigeration system performs the cooling of the liquid. Subcooling shifts load from a lower efficiency freezer compressor to a higher efficiency compressor without a loss of capacity. Average savings when installed on a low temp rack is 12-15% of compressor energy. Subcooling adds 8-12% of rack costs. For most stores this works out to a less than three-year payback.
Electronic Expansion Valve: It’s like adding fuel injection to an automobile engine. By utilizing electronic control in place of a mechanically actuated expansion valve, the injection of refrigerant will be optimized, reducing the amount of refrigerant circulating, the compressor run time (mass flow) and adjusting to changing load conditions. The largest energy savings is due to the reduction of the required compressor discharge pressure for valve operation, allowing the discharge pressure to fall further in colder weather versus a mechanical valve. Compressor energy savings are most advantageous in northern climates (A savings of 19.7% in Minneapolis for example) vs. southern locations (Oklahoma City 11.4% savings). The electric expansion valve will increase case costs approximately 17% to 25%, however reductions in electrical and controls install costs are expected due to less field wiring.
Questions? We have answers. There also are many more features to evaluate based on your store and location. Contact UNFI Store Design & Equipment to let us optimize your refrigeration systems. E-mail us at [email protected].
