Frying, as most exponents of the art would be quick to agree, is rather more than simply immersing foods in hot oil. For fryer manufacturers, a host of other factors come into the equation, such as the quantity of oil required and the flow of oil in the fryer. In short, the issues associated with making the most effective and economic use of the frying medium are of paramount concern to those in the equipment manufacturing and food production businesses.

Gem Equipment in Oregon has been addressing these issues for several years using FIDAP. Gem engineers use the powerful predictive fluid-flow capabilities that CFD offers to optimize and improve their commercial fryer designs so that more uniform product quality can be achieved using reduced oil volume.

Unwanted vortex generated by improper geometry over fryer pan return

To obtain consistent product quality for items such as French fries and Tater Tots®(a type of fried potato product, popular in the U.S.), it is important that all potato pieces are exposed to the same conditions when in the fryer. Fryers are equipped with a number of devices that are used to control these conditions. For example, because the oil temperature has a direct effect on the color and textural characteristics of the finished product, temperature controls are used. By maintaining different oil temperatures in separate zones of the fryer, products with different characteristics can be produced simultaneously.

Fryers are also equipped with filters for the removal of fines and small pieces from the oil. If these pieces are not removed, they burn and damage the oil by altering both its color and flavor. In addition to the harmful effects fines have on the product quality, they can be responsible for reducing the shelf life of the food as well.

The use of FIDAP has been a major factor in enhancing Gem's advanced fryer technology. Smooth (i.e., laminar) oil f low in the fryer kettle is critical for uniform heat distribution and "first in, first out" potato products without clumps - the ideal scenario. CFD flow modeling has allowed Gem to determine fryer oil levels for each cooking requirement rather than make use of conventional flow rates recommended for general-purpose processing, which are usually higher than they need to be. Their analysis, to be presented at the U.S. FIDAP Users' Group Meeting in June 2001, has shown that the installation of a simple perforated plate in the fryer can bring about performance improvements. The net effect of these results is substantial oil savings for the customer, especially in large fryers.

Vortex removed using FIDAP to analyze new 3D geometry

During the past few years, there has been an increased demand on the part of the consumer for differentiated potato products. To satisfy this demand, all major American fast food chains are offering special promotional products such as "coated" fries or fried wedges cooked in seasoned batter. Thus, while the quest for the perfect fryer goes on, CFD is helping to meet the exacting and ever-changing demands of the French-fry-eating public around the world!

Larger than the average kitchen pan, an industrial fryer has many controls that are used to ensure food products of consistently high quality.
Courtesy of Gem Equipment

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