What is convection. Free convection
The word "convection" in translation from Latin means movement. What is convection and how does it occur? This is a peculiar process of heat transfer, in which particles of substances are mixed together. This action can be observed in liquids and gases.
How does the process of convection
The movement of particles occurs due to differences in temperature and density in certain places of the medium when heated. In this case, the lower layers of the substance, when heated, become lighter and rise upwards. The upper particles, cooling down, become heavier and fall down. This process is repeated several times. When creating certain conditions, the process becomes the structure of vortex flows, forming a grid of convection cells.Many atmospheric processes are manifestations of natural convection, for example, the movement of tectonic rocks, the occurrence of clouds, and the formation of formations in the sun due to the movement of plasma. When forced convection process occurs under the action of external forces.
Types of convection
There are two types of convection - it is free convection, or natural, and forced. Natural convection currents are observed as a result of changes in density during heat exchange in a gravitational field. These are circulation in the lower layers of the earth’s atmosphere, currents in oceans and water bodies, the occurrence of stable winds (monsoons, trade winds), hurricanes or cyclones. The movement of warm air in a heated room, the heat emitted from a light bulb. Freon gas cools the air in the refrigerator. Cold air goes down.While cooling products, it gradually heats up and rises again. Moving air layers in the fridge is nothing more than free convection. Therefore, for better air circulation, it is not recommended to lay out products too tightly on the shelves of the refrigerator. To perform some technical tasks, it is required, on the contrary, to suppress natural convection to reduce heat loss.
Forced convection occurs with the help of instruments or extraneous forces. This may be stirring a liquid with a spoon, pump or fan operation.
What is convection with regards to room heating? The basis of any system involves the principle of heat transfer from the energy source to the room air. These can be central heating batteries or individual heating devices. Convector heaters have become very popular. With the help of a heating element, the air entering from below heats up and begins to move. Next, the process of mixing the cooled and heated air.Convector heaters can be water, gas and electric. The phenomenon of heat transfer when moving air by force is often used in various sectors of the economy. With the latest technology, convection function is widely used in household appliances. One of the most common kitchen appliances of this kind are microwaves and ovens. The effect of convection greatly expands the possibilities of cooking. In this case, forced convection contributes to the circulation of hot air masses, forming a vortex flow. This allows you to evenly warm the product from all sides.
Microwave ovens have long become a familiar attribute of home appliances. The microwave oven is mainly used to heat the finished products, defrost fish and meat, cooking simple dishes. Bake a pie or fry a chicken with a ruddy crust electromagnetic waves of high frequency will not. But the microwave oven with convection can easily cope with this task. With the help of a built-in fan, hot air circulates through the chamber. Heat evenly affects the cooking dish on all sides.It is recommended to preheat the oven for 15 minutes. To bake well the product, it is better that it consisted of several small portions. Dishes in a microwave oven should be placed on the grid so that the air evenly circulates. Dishes should be made of special heat-resistant glass. To cook, you need to pick up your recipe and a certain temperature for your microwave.
To speed up the cooking and at the same time not spend a lot of energy, you can use a combined mode - microwave convection and grill. These two options will make the meat soft and tender inside, and the crust crisp and appetizing.The presence of convection will help to prepare the dish without oil and salt, which is useful for people leading a healthy lifestyle. Additional heating element has a grill. Convection contributes to the formation of a crust on the meat. The heater, available in the oven-grill, can be ten or quartz. Shadow grill, moving and turning, heats the product evenly. Quartz heating elementnot visible and located at the top of the furnace. Benefits of Quartz Grillin that it consumes less energy, but the process of roasting with it is slower.Although the power of the shadow spiral is higher than the quartz grill. What is convection in combination with a grill? The combination of grill and convector simulates roasting on a spit or grill.
Oven and convection
A good oven - the dream of every hostess. But sometimes the cakes in it are burned, and the meat is poorly cooked. The baking tray with the dish has to be turned over and then rearranged higher, then lowered down. What is convection in the oven and how does it work? Hot air inside the cabinet is moved using the built-in fan. The temperature becomes the same at all points of the oven.In this oven, you can immediately cook several dishes at different levels, using several trays. In the closed space of the oven, forced convection is created using a fan on the back wall. With this effect, the products are uniformly heated from all sides. The mode allows you to cook large cuts of meat, bake large pies and small delicate cakes. You can make crackers or homemade potato chips, as well as dry the herbs. The oven with convection, both gas and electric, will allow you to cook with joy and pleasure.