Convection

General:
The Atom
Kinetic &
Potential Energy

Introduction

Applications:
Conduction
Convection
Radiation

Bibliography:
Books
Other Sites


Convection Ovens


What is a convection oven?

cookies!!!
For years, restaurants, commercial bakeries and professional chefs have used convection ovens for their speed and efficiency to produce the bounty of their trade. This ranges from the basic pizzas, cakes, cookies and hamburgers to the lavish meals of beef Wellington and Duck Orange; every chef relies on the superior results of convection ovens.


What is different about the convection oven that makes it the chef's choice? Operating on standard household current, the convection oven uses electricity to heat the air in the oven. A fan circulates warm air continuously so wasted heat cannot collect at the top of the oven. Since circulating air heats faster than does still air of the same temperature, food is heated more efficiently than with still air, resulting in cooking times 1/3 faster than regular ovens. The amount of time saved varies with the type of food cooked. With some foods, the convection oven cooks at a lower temperature than a regular oven, for about the same time. This results in electricity savings when compared with a regular oven.


Also the oven cavity of the convection oven will cook more food per cubic inch than a regular oven. Since this heat-circulating fan is not inside the oven cavity, the oven can be filled from top to bottom as long as an inch of space is left for the air to circulate between the food and the oven walls. Frequently smaller in size, the convection oven has less air in the oven to heat, making convection an efficient choice of ovens.


This is an image of a convection oven.
Click to enlarge.


In a regular oven, air is warmest close to the heat source. Placement of food is critical for best results since food cools the air immediately around it and the area near the elements may be too hot. When the air is still, heat rises from the source at the bottom and collects at the top of the oven. In the regular electric oven, food must be place in the centre of the oven for even baking and roasting results. The convection oven moves cool air away from the food. As hot air flows around the food, the cool air is recirculated past the source of heat.

Convection ovens provide more uniform heat than regular ovens by moving the oven air away from both the heat source and the top of the oven cavity. Circulating hot air seals in natural juices from the start of cooking. With a convection oven, food cooks faster or at a lower temperature than it does in a regular oven.


What factors effect convection cooking?


This image shows air circulation in a convection oven.
To use a convection oven most efficiently, the oven door must be kept closed as much as possible. Airflow must be maintained.


The air in the oven must circulate freely. Shape of food affects convection cooking. A long thin meat cooks faster than a bulky one of the same weight because more surface is exposed to moving hot air. Size of pan also must be considered. The same quantity of food cooks faster in two small pans than it does in one large pan since air can circulate more freely.

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2000 Yummy Physics!
Langstaff Secondary School ISU

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