The right dosage makes the difference. This also goes for the circulated air quantity in convection baking ovens. Perfect results are only possible if the quantity of circulated air is adapted adequately to the bakery product, also saving energy costs on the side.
When it comes to rack ovens, every baker knows that it's primarily convection, i.e. conducting heat by air circulation, that ensures the transfer of heat onto the baked goods.
Here, two parameters play an important role: the temperature difference between the recirculated air and the baked goods and the quantity (or speed) of recirculated air. Both parameters determine each other mutually. To transfer the same energy, it is possible (within certain physical and technologically determined limits) to reduce the air quantity with the temperature increased or to increase it with a lower temperature.
However, the result will not be the same, neither in terms of energy (lower temperatures require less energy) nor technologically (the increased air circulation also leads to more intensive drying on the surface of the product). In practice, for every pastry in every baking phase, there is an optimal combination of temperature and air quantity.
Fine adjustment of air circulation
In order to use this leeway offered by the parameters and optimise the baking quality accordingly, a technical device is required that allows the air recirculation to be regulated as easily yet as sensitively as possible. And which can also reliably withstand the continuous thermal load surrounding the heating coil and even in case of failure does not lead to the baking oven being brought to a complete standstill.
Robust mechanics for continuous use
Frequency converters do not satisfy these requirements.
This is why the MIWE developers already devised a solution years ago. A solution that has a higher performance level than frequency-controlled ventilators and is also superior to them in terms of robustness and maintenance convenience: the patented MIWE aircontrol. Here, the air quantity is regulated via the variable opening profile of a slider that is fitted between the baking chamber and the heat exchanger. It can be (for instance with the door open or while steam is being fed in) closed practically without any delay, which saves up to 10% of the heating energy.
Less water = less energy
Because the steam must only fill the baking chamber and not the heat exchanger as well, you will also create significantly more steam with the same water quantity (or get by with less water = energy for the same quantity of steam). And just in case, the slider can be opened with a handle so that you can easily continue to bake even in case of a malfunction.
Fine and individual adjustment
The position of the MIWE aircontrol and therefore the volume of the recirculated air can be individually preset in the baking oven's control unit for each baking phase in order to create optimal baking conditions for each product.
In the MIWE impulse, you can find more information on this topic.