Traditionally, the downtime needed to defrost freezers has been an obstacle preventing food and beverage processors from getting maximum efficiency out of their production lines. But recent advances in freezing technology can keep production lines running longer, resulting in greater throughput – and greater profitability.
Reducing Frost through Better Design
When a freezer runs, snow builds up on the coldest part of the freezer – the evaporator. For a given freezer capacity, a greater total surface area on the evaporator creates a more efficient freezer that can run longer without defrosting. By significantly increasing the face area on the evaporator coil and on the cooling surface of the evaporator’s fins, the latest generation of JBT FoodTech freezers gives frost more places to build up. This keeps the frost from concentrating in one location, thus extending the time the freezer can run without defrosting.
The air leaving the evaporator is very dry, since moisture is left on the evaporator fins. In the past, JBT FoodTech freezers featured fans that were positioned in front of the evaporator, facing the air flow direction. As a result, the fans had problems with snow buildup. On new JBT FoodTech M-series freezers, the fans are located past the evaporator, eliminating this issue and its potential to reduce run times.
Techniques to Extend Run Times
One technology developed nearly a quarter-century ago that remains an efficient option by JBT FoodTech is air defroster, or ADF, technology. This technology, which sends a quick shockwave of pressurized air to blow off the inlet face of the coil and remove frost, can alone double or triple run times. This option is applied on all freezing equipment product lines from JBT FoodTech.
Another technique that can be used instead of ADF is mid-shift defrost. During the night shift when the line isn’t running, the freezer is stopped and the ammonia refrigeration system is reversed to send hot gas instead of refrigerant to the evaporator. This quickly defrosts the evaporator while still maintaining the rest of the freezer below freezing point. Then water is flushed over the evaporator to rinse it and the freezer is restarted.
Producers who need even greater run times than provided by ADF or mid-shift defrost have another option – a freezer with sequential defrosters. A typical freezer uses one chamber to which all the evaporator pieces connect. Freezers with a sequential defroster, such as JBT FoodTech’s GYRoCOMPACT self-stacking spiral and FLoFREEZE IQF freezers, feature separate chambers that each have their own dedicated fan and evaporator. This enables the freezer to have spare capacity available at all times so that one evaporator and fan can be shut down to defrost while the other chambers continue to operate.
Due to higher purchase and utility costs, freezers with sequential defrost are not for everyone. The constant cycling up and down of temperatures to defrost the chambers and the increased use of waste water to clean the chambers results in relatively high utility costs. However, this technology does provide a critical advantage to producers of products such as pizza and potatoes who want to be able to run 20 hours a day for as many as six days without stopping the line for cleaning or a producer of fully cooked products with high dehydration and high throughput who wants to run up to 20 hours a day before cleaning.
In addition to extending run times, reducing the effects of frost on the evaporator also enables producers to run their freezers at a lower temperature than they could previously without suffering excess frost build-up. Since quicker freezing of the product reduces how much the product is dehydrated by the freezing process, the end result is a juicier, better-tasting final product.
Refrigeration Advances
Beyond the anti-frost measures JBT FoodTech has developed, the company offers another exclusive advantage to help processors lower freezer temperatures without incurring higher utility costs. A conventional pump refrigeration system sends a mixture of liquid and gas back to the engine room, resulting in a pressure drop that can create a temperature increase of 3 to 4 degrees Fahrenheit. On the other hand, JBT FoodTech’s patented low-volume refrigeration system (LVS), featured with GYRoCOMPACT and ADVANTEC impingement freezers, returns pure gas back to the engine room, creating a pressure drop that is close to zero – and a lower freezer temperature for the same utility cost as a traditional system.
Fact box:
The GYRoCOMPACT spiral steamer is part of an integrated family of food processing equipment from JBT FoodTech, designed to enhance the saleable value of processed food products while capturing their quality, nutrition and taste. It efficiently steams products ranging from diced vegetables and pasta to bone-in whole poultry – plain, marinated, glazed, battered or breaded – as well as performing all types of in-pack pasteurization. Uniform heat transfer throughout the product zone ensures a high and even food product quality. In addition the steamer’s unique Top Hat drying zone helps deliver exactly the right appearance and surface texture on your product, and a dry finish on sealed packaging that facilitates error-free in-line labeling, before onward in-line chilling or freezing.
The FLoFREEZE A freezer provides true fluidization. All key interior metal parts are stainless steel. The optional Extended Track Rinser quickly and efficiently cleans the first belt without raising freezer temperature, meeting the industry’s toughest requirements for hygiene, energy usage, operating economy and user-friendliness.
Frigoscandia ADVANTEC impingement airflow technology uses a straight belt that moves food product through the freezing zone without wrinkling or deformation. It is designed to quickly freeze flat products up to 25 mm thick, and to chill and crust freeze products up to 200 mm thick with dehydration less or equal to cryogenic freezing. It has optimized air velocity through the evaporator, maximizing heat transfer, frost pick-up and performance.