Innovations in freezing mean reduced frost-related downtime

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.

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 thru put 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.

Beyond the anti-frost measures JBT FoodTech has developed, the company offers another 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 three to four degrees Fahrenheit.

On the other hand, JBT FoodTech's 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.

The GYRoCOMPACT spiral steamer 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. The FLoFREEZE A freezer provides true fluidisation.

- For more information, visit www.jbtfoodtech.com

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