Refrigeration | My Business | Mississippi Power | A Southern Company

Refrigeration

The growth of the food service industry has led to the development of highly specialized refrigeration equipment for varied needs ranging from food storage to presentation. This equipment is generally easy to operate and highly reliable, but careless operation and lack of maintenance can be quite costly since this equipment typically must run all the time.

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Refrigerators and freezers operate more hours than any other kitchen equipment. Their energy use depends on their location in the kitchen, food loading and removal practices, and level of periodic maintenance.

It is usually wise to purchase the most energy-efficient unit available, but there are other important factors to consider, such as convenience and accessibility. Problems in these areas may cost more in the long run than inefficient energy use. In addition, some refrigeration equipment offers heat recovery options that can reduce site water heating requirements. Therefore, when trying to select an appropriate unit, you may want to work with someone having specialized expertise in refrigeration evaluation, such as a technical representative from your energy company.

Ice machines

Commercial ice machines are actually small manufacturing plants that use water and electricity to produce cubed or flaked ice. Cube ice is clear and most often used where appearance is important, such as cocktail ice, carbonated beverages, and ice water for table service. Flake ice is used mostly for packing around food containers in self-serve cold food displays and salad bars. However, it is also used for beverages in smaller food service establishments, despite its reduced visual appeal.

Water purity to the ice machine is important and a water filter should be installed regardless of water conditions. Sizing the ice-making capacity of the machine depends on the type of restaurant and the number of patrons served. It is generally wise to size the storage small enough to force the ice machine to turn off during "off-peak" times by filling the bin.

Refrigerator types

There are a wide range of refrigerator types. The most common types are described below.

Walk-in units

When a large amount of refrigeration space is needed, a walk-in unit is often the best choice. Walk-in units easily accommodate the bulk storage of refrigerated and frozen foods. They are manufactured in virtually any size or custom design, ranging from as small as 4 by 6 feet to units so large they approximate cold storage warehouses.

Walk-ins are available for both indoor and outdoor installation. Most are prefabricated, permitting flexible design and allowing manufacturers to meet nearly any special need.

Most restaurants use walk-ins predominately for bulk cold storage. However, restaurants may also use a portion of this space for pantry items. To accommodate this need, a popular option for a walk-in unit is one or more glass reach-in doors for easy access, with incidental access to the walk-in refrigerator. This option is considerably more efficient than using a separate small reach-in cooler.

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The primary access doors for walk-ins come in a wide variety of designs. Traditional hinged doors with safety latches can be replaced with insulated double-swing doors. Some larger walk-in coolers also have sliding or overhead doors to provide clearance for forklifts.

Larger facilities often use multiple refrigeration units or zones. For example, one unit may be used to store fresh produce at 32° to 36°F, while meats are stored in a separate unit at 34° to 38°F. Dairy products and seafood are often kept in their own separate refrigeration units. However, it is obviously not feasible to have a separate walk-in for every type of product.

Smaller food service facilities with only one cooler generally operate them at 38°F with a typical freezer temperature kept between 0° and 5° Fahrenheit, or slightly colder if ice cream is stored.

Reach-in

Reach-in refrigerators and freezers are used in supplement bulk cold storage equipment. Some restaurants install these in preparation areas next to primary cook stations, in pantries, and in waitress stations. Some very small kitchens may actually use reach-ins for their bulk storage.

Reach-in units are available with one-, two-, or three-doors, plus half-door models. Doors may open on one side only or from both sides (called pass-through refrigerators). Sliding and glass door designs often have controlled compartments with variable temperature regulation devices. Typical reach-in refrigerators are available in 10 to 75 cubic feet of capacity, and average about 50 cubic feet.

Reach-in refrigerators and freezers may be mounted on castors for added flexibility or designed to receive roll-in carts or racks. Refrigeration systems for reach-in refrigerators can be self-contained or remote.

Convenience

There are three basic types of convenience refrigeration: display cases, base units, and preparation tables.

Display cases are normally located in the customer traffic areas. They are often equipped with sliding-glass doors and mirrored walls for high product visibility. Display cases are available in numerous shapes and sizes and can be ordered with either sliding or hinged doors. Some have doors at the front and back for easier access. Display cases may be mounted on a wall, a counter, or on the floor with legs or a solid base. Most are constructed of stainless steel and have foamed-in-place insulation.

Refrigerator and freezer base units offer the convenience of bulk storage at the point of use. Most are floor-mounted and can be installed almost anywhere. These units usually come in one-, two-, and three-door models with optional hinged doors or roll-out drawers. Base units alternately function as workbench surfaces, and can be fitted with special tops to function as preparation-table bases.

Preparation tables are specially designed to be mounted on top of refrigerated base units. These prep tables include deep removable stainless steel pans that can be used for such items as sandwich or salad fixings and pizza toppings. Most of these pans have hinged lids. The units are mounted to the back of the base unit, providing a work surface for food preparation.

Energy and money saving tips

Here are a few common-sense operating tips that save money with a refrigerator.

  • Carefully review and compare manufacturer's stated energy efficiency and estimated operating costs before purchasing equipment. However, note that frost-free versions, although generally less energy efficient, may be cheaper overall to use given the added labor and operational nuisance of manual defrost units.
  • Locate refrigeration equipment away from kitchen heat sources.
  • Open doors as infrequently as possible and close doors promptly after each use.
  • Don't store food at temperatures colder than necessary.
  • Whenever possible, allow cooked food to cool to near room temperature before putting it in a refrigerator.
  • Keep the space near the condenser clear to allow open air flow. Also , periodically check and clean condenser coils to remove dirt and grease buildup.

Refrigerator components

The principle components of a refrigeration device are the evaporator, compressor, condenser, expansion device, door and hatch gaskets, and an insulated enclosure. The refrigeration cycle uses the evaporator to produce the cooling or freezing effect. The evaporator coil may have a fan blowing air over it or may simply cool the walls of the refrigerated area. Frost-free devices periodically heat these evaporator coils to melt off the ice and frost that naturally forms on freezing surfaces.

The evaporator boils a fluid (called a refrigerant) at a relatively low temperature to remove heat from the refrigerated area. The resulting refrigerant vapors are fed into a compressor that raises the pressure enough to condense (that is, re-liquefy) the vapors in the component called the condenser, which also removes heat. On some systems, the heat removed by the condenser is trapped and used for site water heating or defrosting. However, in most systems this removed heat is either released into the kitchen (in small cooling equipment) or to outdoor condenser coils. Most condensers are cooled with fans, just like a home air conditioner or heat pump, but in some locations condensers can also be cooled with cooling towers or ground water.

The expansion device controls the flow of refrigerant by maintaining the proper pressure difference (called head) between the condenser and the evaporator. Older, inefficient refrigeration units had relatively simple expansion devices. Many newer "floating head" refrigeration designs use microprocessor- based controls to increase energy efficiency.

Optimal storage temperatures by food type

A food service facility's menu determines the types of foods that must be stored, which largely establishes the cooling requirements for a kitchen's refrigeration units. The table below lists approximate storage temperatures for several main food categories:

Frozen foods -20° to 0°F
Ice cream -15° to +15°F
Fish and shellfish 23° to 30°F
Meat and poultry 30° to 38°F
Dairy products 38° to 46°F
Fruits and vegetables 44° to 50°F