Middleby Marshall installation manual Heat Transfer and How It Works, Series PS200-R68 Air Flow

SECTION 1

DESCRIPTION

II. PRINCIPLE OF AIR FLOW

Air is heated and then pulled through the fan which pushes the air into the oven plenum and delivers heated air into the air fingers. The fingers contain an inner plate and outer plate which columnate the air and evenly distribute heated air across the conveyor belt on which the product rides. Air is then pulled back into the blower and the process continues.

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 which are conduction, 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 the Middleby Series PS200-R68 Oven is light in color to reflect more heat back to the product.

Convection: This path has to do with moving amounts of air. It explains why hot air will rise and cooler air replaces hot air. An industrial application of this principle is to incorporate a fan to force the hot air movement which in turn will increase the heat transfer to the product.

The Middleby Series PS200-R68 Oven has a large fan to move the hot air through the air fingers and onto the product so the most efficient bake is achieved.

2.Temperature is the intensity of heat at the point which 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.

Side View

Figure 1-2

Series PS200-R68 Air Flow

4