Refrigeration

General

Commercial RefrigerationThe size and growth of the food service industry led to the development of highly specialized refrigeration equipment, ranging from food storage to presentation. While this equipment is generally simple to operate and highly reliable, careless operation and lack of maintenance can be quite costly to a food service establishment because this equipment typically runs all the time.

For example, refrigerators and freezers operate more hours than any other type of kitchen equipment. Their energy use depends upon their location in the kitchen, food loading and unloading practices, as well as periodic maintenance.

While it is generally wise to purchase the most energy-efficient equipment available, there are other parameters that are important to consider, like convenience and accessibility. Deficiencies in these areas often cost more in the long run than inefficient energy use. This is one area where many energy customers appreciate help during the process of selecting an appropriate unit and turn to their utility representative.

In addition, there are heat recovery options in some of these refrigeration equipment choices that can also reduce site water heating requirements. The economic evaluation of this option is often beyond the food service owner's area of expertise.

Ice Machines

Commercial ice machines are actually small manufacturing plants using water and electricity to produce cubed or flaked ice. Cube ice is clear and most often used where appearance is important: cocktail ice, carbonated beverages, and ice water for table service. Flake ice is primarily used for packing around food containers in self-serve, cold-food displays, and salad bars. It is also used for beverages in small food service establishments, despite its lower aesthetic 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.

Storage Temperatures

The menu largely determines a kitchen's refrigeration requirements. Here is a list of approximate storage temperatures for several main food categories:

Ideal Storage Temperatures for Several Main Food Categories
Refrigerated FoodTemperature
Frozen Foods-20° to 0°F
Ice Cream-15° to +15°F
Fish and Shellfish23° to 30°F
Meat and Poultry30° to 38°F
Dairy Products38° to 46°F
Fruits and Vegetables44° to 50°F

Types

Walk-in

When a large amount of refrigeration space is needed, a walk-in unit is often the best choice. These units are designed to accommodate the bulk storage of refrigerated and frozen foods. Walk-in units are manufactured today in virtually any size or custom design, ranging from as small as 4 by 6 feet to units so large they virtually amount to cold storage warehouses. Most walk-ins are prefabricated, making design parameters flexible and allowing manufacturers to meet just about any special need. Walk-ins are available for both indoor and outdoor installation.

Most restaurants use this form of cold-storage space predominately for bulk storage. However, restaurants often use a portion of this space for pantry items. One popular feature for a walk-in unit that accommodates this is one or more glass reach-in doors for easy access, providing incidental access to the walk-in refrigerator. This modification is considerably more efficient than using a small reach-in cooler.

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 large walk-in coolers 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. Obviously, it would not be 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 degrees Fahrenheit, or slightly colder if ice cream is stored.

Reach-in

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

Reach-in units are available with one, two, or three-doors as well as half-door models. Doors may open on one side only or from both sides (called pass-through refrigerators). The sliding and glass door designs often have controlled compartments for variable temperature regulation devices. The common reach-in refrigerator is available in 10 to 75 cubic feet of capacity, with the industry average being 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 frequently equipped with sliding-glass doors and mirrored walls to allow for high product visibility. Display cases are available in a variety of shapes and sizes and can be ordered with either sliding or hinged doors. Certain types 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 either legs or a solid-base. Most of these units are constructed of stainless steel and have foamed-in-place insulation.

Display Case

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 generally come in one, two, and three-door models with optional hinged doors or roll-out drawers. Base units alternately function as workbench surfaces. They can be fitted with special tops to function as preparation-table bases.

Base Units

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.

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 coils to melt off the ice and frost that forms naturally on freezing surfaces.

The evaporator boils a fluid (called a refrigerant) at a relatively low temperature to remove heat from the refrigerated area. The vapors are fed into a compressor that raises the pressure high enough so that the vapors can be condensed in the condenser. The heat removed in this condenser can be used for site water heating or for defrosting but is most often rejected 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. Condensers can be cooled with cooling towers or with ground water in some locations.

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

Efficiency

The best way to save money in refrigeration is to use common sense. Take a close look at the manufacturer's stated energy efficiency and estimate operating costs before purchasing the equipment. Frost-free versions are generally less energy efficient but may be very worthwhile given the added labor and operational nuisance of manual defrost units.

Links to Related Topics

Fryers
Griddles
Braising Pans
Broilers
Ovens
Steamers
Dishwashing
Vent Systems
Cook/Chill Systems