Why Induction heating is energy efficient? Fact File 29


The method of Induction heating uses electromagnetic energy to heat an electrically conducting material. The electromagnetic field induces Eddy current in the conducting material thereby causing heat through joule heating. The pot used in induction heater is ferromagnetic so that, it heats up by accepting the electromagnetic energy from the induction heater. The heat generating in the pot is then transferred to the water used for cooking. This is why the pot remains cool while its content is hot. But the cooking pot must be ferromagnetic types, one like Iron or Steel .Non ferromagnetic pots made up of aluminium or copper cannot be used in induction heating.

The induction cooker has a large circular coil made up of enameled copper windings placed under the space for the pot. When AC of a particular frequency passes through the coil, an oscillating magnetic field develops which induces electric current into the pot material. When this Eddy current (Not a shocking one) passes through the material of the pot, friction develops in the molecules (don’t be confused, the molecules of the pot material) and heat develops. This heat is transferred to the water to boil the contents in the pot.

Efficient induction cooking takes place if steel vessels are used because of its magnetic properties and the steel concentrates all the induced current in the surface so that the heating effect becomes stronger. Aluminum and other non magnetic materials are not good for induction cooking, since the induced magnetic field penetrates deep into the material creating only little resistance. In Coil heater, much of the current is wasted and efficiency reduces to 20-40%.But in Induction heating, energy wastage is very low and efficiency is 80-90%.
The following features make induction heating energy efficient

1. Energy level and power consumption can be controlled

2. No wastage of energy through heat loss

3. No shock and burning

4. Only the content of the pot heats. Heat will not pass into the surrounding air.

5. Power usage can be controlled for different types of cooking. This prevents wastage of energy.

6. Cost effective. Electricity consumption is many times lower than the electric heater and cost for electricity is lower than the cost of cooking gas.

7. Less time than gas cooking

Let us go inside the Induction heater then we can learn some tips for efficient cooking and precautions of its use.

Induction cooker has many monitoring systems for efficient functioning. It can detect whether there is a ferromagnetic pot over it by sensing the heat. It can also sense whether there is any content (water or food) inside the pot. It also shut off if any one of these conditions is not satisfied. This prevents hazardous results as found in gas cooking or heater cooking.

The induction heater has an electromagnet through which high frequency AC passes. The frequency of AC used depends on many factors including the material and size of the conductor and coupling of the work coil and conductor. Mains frequency 50Hz or 60Hz is used in many practical applications including Induction Cooker. Iron and alloy conductors respond well with induction heating due to ferromagnetic property.


The structure of induction cooker is very simple and there is no bulky part inside. Besides the large circular coil, it contains a Microprocessor based circuit board to control various functions and to regulate the frequency of AC passing through the coil and a cooling fan . Nothing other than these parts present inside.

Some important features of Induction cooking are:

1. Thermal efficiency- maximum heat generation using small current.

2. Heat consistency- Heat generation is uniform and constant throughout the period.

3. Less time – Duration for cooking is half or less than half than Gas cooking. But the time depends on the quantity and type of food. Stir drying is faster than water boiling.

4. Safer- It is safer since there is no open flame or hot pans.

5. Clean- Pots can be easily cleaned since there is no smoke accumulation and the pot surface is flat.

6. No shock – There is total isolation of heating surface and the internal electric circuit. There is air gap between the underneath coil and the cooking surface.

7. Cool cooking surface- The cooking surface (space for placing the pot) is made up of a poor heat conductor so that heat will not be transferred from the pot to the surface. The cooking surface can be touched easily after removing the pot.

8. Light weight- Portable and easy to handle.

9. Power consumption – Depends on the watts used and duration of cooking. Any way, cost effective than gas cooking or heater cooking.

10. Some interference – Radio frequency instruments, Cardiac pacemakers etc may function erratic near the induction cooker due to strong magnetic field.

Cookware

In induction cooking, cookwares are most important. Not all vessels or pots cannot be used since magnetic induction is required for induction cooking.

1. Black metal or Iron pots are best.

2. If stainless steel pot is used, it should be in the ferromagnetic category.

Current consumption

Many of us doubt that, there is much current consumption in Induction heating. See some facts about current consumption.
In Coil heater, much of the current is wasted and efficiency reduces to 20-40%.But in Induction heating, energy wastage is very low and efficiency is 80-90%.The comparison can be

1. In Coil heater, coil takes huge current (depends on the size, length, resistance etc of the coil) to heat up. In induction heater, current is regulated through the coil by the microcontroller.

2. Heat loss occurs in coil heater through the air space between the coil and pan. In induction heater, the pot material is heating and there is efficient energy transfer through the inner surface of the pot.

3. When the input AC voltage drops, coil heater uses much current and takes long time to cook but in Induction heating, voltage is regulated and current consumption is uniform. Moreover, it takes half of less than half time for cooking.

4. The wattage of the coil heater is fixed (1000- 3000 watts) so that power consumption is same irrespective of the quantity of cooking food. But in induction heater, power can be adjusted from 200 watts to 1800 watts depending on the type of cooking like hot pot or frying.

Precautions

1. Switch on the Induction cooker only after placing the Pot with material.

2. Switch off the device before removing the pot.

3. Do not unplug or switch off the power from AC outlet till the cooling fan stops running. This is necessary for removing all the magnetic field accumulated in the device.

4. Use a Pot having circular flat surface with diameter that exactly matches with the marking of the pot surface of cooker (The pot surface has the same diameter as that of the coil inside). This increases the efficiency of cooking.

5. Always clean the Pot base before placing over the induction cooker.

6. Always clean the cooker surface after cooking.

7. Keep the induction cooker in a well ventilated, moisture free area.

8. Unplug the cooker from the AC outlet after the use.

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