Middleby Marshall PS540 installation manual Section Description, Ii. Principle Of Air Flow

SECTION 1

DESCRIPTION

II. PRINCIPLE OF AIR FLOW

The fan-style blower draws air into the oven plenum where it is heated. The blower then pushes the hot air through the air fingers into the baking chamber. Each air finger contains an inner plate and outer plate that form the hot air into jets, distributing it across a conveyor belt on which the food product rides. Air is then pulled back into the blower and the process continues. The curving, black arrows of Figure 1-4 show this air flow.

A. Heat Transfer and How It Works

1.Heat constantly moves from a warm object to a cold object. Heat moves using three different paths: Conduc- tion; Radiation; and Convection.

Conduction: This path utilizes surface-to-surface con- tact. The pizza dough in contact with the pan is a good example of conduction.

Radiation: This path has to do with objects radiating heat. Dark objects absorb heat whereas light or shiny objects reflect more heat. This is the reason that the inside of a

PS540-Series Oven is light in color: To reflect more heat back onto the food product.

Convection: This path has to do with moving a volume of air. It explains why hot air rises and cooler air replaces hot air. An industrial application of this principle is to incorpo- rate a fan to force the hot air movement, which in turn increases the heat transfer to the food product.

Each PS540-Series Oven has a large fan-style blower to move the hot air through the air fingers and onto the product to cook/bake the food product most efficiently.

2.Temperature is the intensity of heat at the point where it is sensed. As discussed above, heat flows by conduc- tion, radiation and convection. The speed at which the heat flows is determined by the temperature difference between the oven and the food product. The larger the difference, the faster the heat flows to the item that is being baked.

Upper Air Fingers Conveyor Belt(s)

Window

Lower Air Fingers

Figure 1-4. PS540-Series Oven Air Flow

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