07 Jun Induction cooktop
An induction cooker is an electric tool that makes use of the principle of induction home heating of the cooking products.
The hob (food preparation area) of the cooker has a coil that is powered by a large alternating current. The coil is made from copper cord, which is a very good electrical conductor as well as there are no huge losses. An electromagnetic field is produced in the coil, which produces warmth in two different ways:.
1. By the action of an electromagnetic field on the electrically conductive base of the vessel, swirl currents are generated in the vessel, which is exchanged heat because of the electrical resistance of the vessel.
2. A smaller-sized part of the warm can additionally be acquired from the losses caused by the hysteresis of the ferromagnetic material of the vessel during its magnetization. Much less than 10% of the total heat is generated.
The components of the warmed vessel are later on warmed.
The induction flux generating coil has many turns, while the bottom of the pot is essentially a single shorted thread. The coil-pot system acts as a transformer that reduces the voltage and increases the current flowing through the potting material. After all, the entire transfer of electrical energy from the coil to the electrically conductive vessel and the generation of heat is similar to unwanted losses in the transformer.
Most induction cookers used in practice are designed for dishes made of ferromagnetic material. In principle, it is possible to design an induction cooker that works with any electrically conductive and even non-magnetic (for example aluminum or copper) vessel. But steel and iron have much higher permeability. The high permeability of the vessel material in combination with the frequency at which the coils are fed allows the depth of penetration of the magnetic field into the bottom of the vessel to be adjusted. The so-called skin effect is applied here. The eddy currents can close in the ferromagnetic material of the vessel and, due to the high electrical resistance of the iron (higher resistance is advantageous in this case), heat the potting material. The induction cooker cannot work with electrically non-conductive dishes (eg glass or ceramics ).
Induction cookers are faster and more energy-efficient than traditional electric cookers, and they also allow precise regulation of the hob's power, similar to gas cookers. A material with poor thermal conductivity is usually used for the surface of the cooker. Unlike traditional stoves, the container is heated directly (not the surroundings), which reduces the possibility of burns. The highest temperature for induction cooking is usually the pot, not the hot plate as with electric heating or the flame of a gas burner.
Due to the fact that the heat is generated by the induced electric current, the cooker can recognize that the vessel has been removed or its contents have boiled, as such an event is manifested by a change in the current and voltage of the cooker coil. It is thus possible to implement functions such as maintaining the boiling temperature and automatically switching off when the container is removed.
Induction heating provides a number of advantages compared to gas heating or resistance coil cookers. The advantages include very fast heating, better heat transfer efficiency, heating uniformity and better heating control. In situations where it is not possible to use standard heating, induction heating is absolutely ideal, as it does not generate any heat at all.
The time it takes to bring a pot of water to a boil depends on the power of the cooker and the amount of water. The 3600 watt induction cooker will boil a pot of water in three minutes, while the 1200 watt cooker will need ten minutes for the same amount of water. The performance of an induction cooker is reflected, for example, when frying in a thin pan . On this, a few teaspoons of oil are heated to the frying temperature in just ten seconds.
Induction cookers are also much easier to clean, as their surface is flat and smooth, regardless of how many induction zones are built into it. In addition, the food does not burn on the surface of the stove, as its surface is almost cold.
Induction cookers also have their disadvantages. One of the biggest disadvantages is the need to use dishes made of magnetic materials. At the same time, dishes made of copper or aluminum alloys have much better thermal properties than dishes made of steel . Thanks to better thermal conductivity, there is a better and more even heat distribution. Also, containers made of stainless steel may not always be suitable. It is often recommended to use sandwich bottom containers. These have a bottom formed by layers of stainless steel, between which is inserted a plate of ordinary, ferromagnetic steel.
Induction cookers work best with flat-bottomed dishes. Wok pans will not work properly on a flat cooker. Therefore, induction cookers with recesses for wok pans are already being produced.
For people with pacemakers and defibrillators, the induction cooker can be dangerous - large induction currents can endanger any electronics.
There is a risk of heating various metal chains, bracelets or rings.
Induction cookers are more expensive than standard cookers with a resistance spiral.
Induction cookers are noisy. The noise is caused by the fan of the cooling electronics and then by the armor of the coil.
Operating economy and environmental impact
According to the US Department of Energy is the efficiency of energy transfer by induction heating 90%. For non-induction heating with a flat surface, the transfer efficiency is 71%. This means approximately 20% energy savings for the same amount of energy transferred.
To assess the environmental impact, it is necessary to consider the whole cycle, which begins with the production of electricity. If the overall efficiency is taken into account, starting with the production of electricity, its transmission, and finally its conversion into heat, then the efficiency of the induction cooker is comparable to cooking on gas. The efficiency of electricity production produced from gas or coal is around 33% (currently around 80% of electricity is produced in this way). Losses during energy transmission are around 5%, which gives an overall efficiency of around 28% (probably the error at 5% power loss must only apply to that 33% that go into the distribution system). Cooking on a gas stove has an efficiency of around 33% and heat transfer losses to the food are around 6%, giving an overall efficiency of 27.9%.
|Technology||Efficiency||Time required to heat 1.9 liters of water||The energy needed to bring 2 liters of water to a boil (from 20 ° C)|
|Induction cooker||83 to 90%||4 minutes 46 seconds||745 kJ|
|Infra cooker||60%||9 minutes 0 seconds||1120 kJ|
|Heating spiral or cast iron stove||45%||8 minutes 0 seconds||1490 kJ|
|Gas||55%||6 minutes 2 seconds||1220 kJ|
Note: Only the efficiency of the cooker itself is taken into account in the table. It does not take into account the efficiency of production and transmission of the gas and electricity distribution system.
Note_2: we should also take into account the repairability = if a classic glass-ceramic hob breaks down, it can usually be easily repaired at an affordable price, while for an induction hob the repair costs are much higher = an unprofitable repair condemns the induction hob to disposal.
A lot of induction stoves are made use of as built-in kitchen area counters or as a mobile stove. In this embodiment, the coil ( electromagnet ) is encapsulated under the surface area of a glass-ceramic plate that can be easily cleaned. In Japan, induction heating is commonly used in rice cookers.
Less expensive single-plate (single-zone) stoves are offered, mostly from Asian producers. These single-zone stoves are incredibly popular as a result of largely populated cities where the living room is extremely restricted. These dual and solitary hob cookers often have temperature level or power control, programs for preparing numerous usual dishes, and timers for switching off the hobs.