International Forum on Energy, Environment and Sustainable Development (IFEESD 2016)
Resolution and application of electromagnetic induction heating
technology
Haiwei Xu1, a, Jiangping Cao2,b, Gang Li3,c , Yonggang Wu 4,d
Comment: All of the authors are in Chinese
1
Sichuan Zhongceliangyikeji CO., LTD, Chengdu Sichuan province, China
2
Sichuan Zhongceliangyikeji CO., LTD, Chengdu Sichuan province, China
3
Sichuan Zhongceliangyikeji CO., LTD, Chengdu Sichuan province, China
4
Sichuan Zhongceliangyikeji CO., LTD, Chengdu Sichuan province, China
b
email:2479860633@qq.com
Keywords: Electromagnetic, Induction, Heat source
Abstract. This paper shows electromagnetic induction heating technology advantages and great
potential application as a new heat source, which is based on the principle of electromagnetic
induction heating technology, application methods and application fields, and combined with
comparative analysis of the test. The electromagnetic induction heating technology will replace
traditional heat sources in many ways for its unique advantages, upgrade and change the electric
heating technology.
The induction heating bases on the electromagnetic induction discovered by Michael Faraday in 1831,
Then Foucault and Heaviside put forward the theory on eddy current and induction heating. The
energy saving effect of electromagnetic heating is more remarkable than traditional heating methods,
it saves between 30 and 50 percent average wattage, and it also has many relative advantages, such as
heat stableness, rapid heating, long service life, convenient maintenance, etc. So it is usually used for
the energy saving projects across many industries such as plastic rubber products, chemical
engineering, medicine, foodstuff, energy, printing and constructional profiles, and so on. For instance,
the heating of plastic-wire drawing, blowing, prilling and shooting. Cable production extruder heating,
plastic extruding machine, thermoplastic plastic pipes, profile production. Heat tracing pipeline,
thermostatically controlled warming, etc.
Traditional heat source
We require heating equipment in many industry, the traditional heat sources are given priority
with coal, gas, resistance wire, etc. There are five shortcomings to get heat by the form of burning fuel
such as coal, oil and gas. Low efficiency and high energy consumption: A part of fuel burning heat
absorbed by the boiler, and the rest send out into the air. Big environmental temperature rising:
environmental temperature goes up greatly because of the heat loss, it is great influence on production
environment in summer especially. Some companies have to reduce temperature with air-condition,
this also causes secondary waste of energy. Low thermal conductivity: The thermal conductivity of
speed and efficiency is slow and controlled difficultly, inevitable thermal inertia, because this
determined by the material of the boiler thermal conductivity. Fuel storage problem: we should have
special fuel storage space and security. Environmental pollution problems: Fuel combustion
emissions and waste residue caused serious environmental pollution.
The resistance wire heating method is developed in recent decades，and has some advantages
compared with burning fuel mode. They are more accurate temperature control, less environmental
pollution and without considering fuel storage, etc. It has replaced fuel combustion heat sources in
many industries and equipment. However, it doesn’t develop and apply generally because it also has
some disadvantages. High heat loss：Existing enterprises adopt the heating mode, which is winded by
resistance wire, heat double-side (the circle of inside and outside), the inside (close to the cylinder part)
© 2016. The authors - Published by Atlantis Press 1133
of heat transfer into the cylinder, most of the outside heat lost to the air, and result electric energy
waste. The environmental temperature rises for a large number of heating lost, the ambient
temperature has a great influence on production environment especially in summer, the working
temperature is usually more than 45 Celsius, some enterprises have to reduce temperature by
air-condition, it causes secondary waste of energy. A short service life and a large amount of
maintenance: because of using resistance wire heating, the heating temperature will be up to about
300 Celsius, the resistance wire is easy to burn out for high temperature aging, the service life of
common electric heating circle is about half a year. So the maintenance workload is really larger.
Electromagnetic induction heating
The principle of electromagnetic heating is that 50hz alternating current(AC) transforms into
direct current(DC) by internal rectification filter circuit, and then DC changes into 20-30Khz high
frequency and voltage, current by Pulse-Width Modulation(PWM) control circuit, The high speed
change of current produces changing magnetic field through coil , it was generating a myriad of small
eddy current inside heated metal to high fever, when magnetic field lines in magnetic field went
through the heated metal objects.
Many flat heating experiment of electromagnetic heating did test, the data rates were nearly the
same. For example：The test are obtained from 5mm thick carbon steel by real-time monitoring in a
given situation of 22 Celsius, 17khz coil frequency and 15-20m from steel plate( Q235A). The test
data is shown in table 1.
Test time Aver Tem(℃) Max Tem(℃) Elec meter(kw·h) Test current(A)
NO.
1 14:35 22 22 265.4 8.42/8.11/8.62
2 14:36 66 98 7.31/7.22/7.64
3 14:37 128 160 7.06/7.12/7.41
4 14:38 158 272 6.89/6.91/7.25
5 14:40 205 319 6.53/6.65/7.03
6 14:43 211 409 6.27/6.42/6.65
7 14:44 248 424 6.11/6.18/6.41
8 14:46 278 463 5.96/6.02/6.25
9 14:49 297 493 5.91/5.96/6.27
10 14:51 304 496 5.77/5.71/6.24
11 14:53 314 497 5.64/5.58/6.29
12 14:55 315 495 5.59/5.60/6.23
13 15:00 322 495 267.1 5.57/5.63/6.28
Table 1: Heating plate test
To summarize of these experiments, there are many advantages of electromagnetic induction
heating method, such as rapid warming, high thermal efficiency, no open flame, no smoke and no
harmful gases, no heat radiation for surrounding, it also has a small volume and good security. The
individual analysis is following:
More energy efficient：The thermischer of electromagnetic induction heating is usually more
than 80 percent, Traditional heat resources’ is between 40 and 65 percent, so the former is more
energy efficient than the latter nearly one times. The metal appliances are heating rapidly when they
accept magnetic field induced current. Because they have electrical and thermal conductivity (iron,
stainless steel and enamel), their material molecules move a high speed irregularly, and their collision
and friction generate thermal radiation each other.
Better security ：It’s safe to human body that the frequency of electromagnetic oscillation is only
between 20 and 30 Khz.
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Better environmental protection ， No substance is released during the heating process of
magnetic field induction.
More accurate on temperature control：The microcomputer is used to control electromagnetic
heating temperature and automatically deploy an appropriate temperature for needs conveniently and
accurately.
Long service life：Don’t need to change heating ring because of its lasting about 100 Celsius. It
reduces secondary input which compared to resistance wire heating method.
Easier installation：Only require simple support.
Higher output： Improve output because of high heating efficiency and short heating-up time.
Pay attention to the problem of induction heating
To make full use of many of the advantages of induction heating, we need to pay close attention
to some problems on its structure and control system design and implementation.
First: Choose electricity frequency exactly;
Second: Enhance conductor’s end voltage;
Next: Choose induction ring’s electricity density accurately;
Next: Choose good, heat-resisting and thermal baffle materials;
Last: Take full advantage of the conductor’s cooling water.
The other feasible applications of electromagnetic heating technology (developed able industries and
equipment)
The electromagnetic heating advantages have been applied and developed into many industries,
such as rubber production, pharmaceutical and chemical, energy, food, building materials, printing
equipment, and tobacco etc. their theory principles are comfortable in the same function, for instance,
they have universality on drying device between food and pharmaceutical industry. So we only need
to analyses the key structure of different devices, and modify energy research of present heating
equipment, while we popularize this technology to other fields.
Rattler-drying machines or drum ovens
Feasibility analysis：Rattler-drying machines is a little different from a water-removing cylinder
machine of its function and structure, Most of them heat by burning coal and resistance, some of them
heat by infrared technology. The electromagnetic heating is super to another heating ways on saving
effect. It also will be fixed sample and doesn’t need burner, its overall structure is simple. Heating
device which is made into circle or oval shape by heat-resistant cable can be mounted at the cylinder’s
or rotary furnace’s outside, and set aside a certain distance. It is covered by an insulation structure or
body with dehydrating units and feeder-discharge units. Drum ovens work alone and together with
others in assembly line.
This equipment is suitable for many kinds of fields such as drying operation of food,
pharmaceutical and mine industries etc. We only adjust its structure and heating temperature with the
same rationale.
Conveyors and feeding machines with drying and curing effect
Feasibility analysis：There are mesh-belt conveyers and raddle conveyors in this type of
equipment which transport materials with heating to dry and bake. The electromagnetic heating heat
at iron or steel plate with good thermal conductance or convey or with great magnetic permeability. In
the case of materials can be directly baked, its advantage is more remarkable than the present
equipment with burning coal, gas and resistance wire. But, it doesn’t work in the other way.
The heating device can be fixed between conveyer belt and roller which is under conveyer belt, it
is parallel to conveyer belt for keeping a certain distance. Once the equipment work, the materials on
conveyer belt will be dried or baked, and we can control baking temperature by commanding the
frequency of the electric current and power of induction coil.
The equipment can be used in baking food, medicine and paper industries, drying, etc.
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Industrial heaters
Feasibility analysis: It is easy to control the local heating temperature and conducive to the
realization of plastic molding process that use electromagnetic heating mode. For example,
electromagnetic heating can replace the present heat sources of die-casting molding heater. In theory,
the improved heater’s structure can be more simplified. However, we carried it out difficultly,
because the equipment based on traditional plastic molding equipment, we should know and
understand its principle and structure enough, and understand something of plastic molding process.
Industrial heater can be used for plastic and rubber molding equipment, etc.
An electric heating plate
Feasibility analysis：Electric heating plate which equipped with a lot of equipment for heating
work-piece, material or equipment, can be directly placed at the outside of heated object according to
needs, it is easy to use. It is designed a flat structure with resistance wire and infrared tube covered
outer insulation device. The applicability of heating plate is really extensive, the user can choose
different specifications and place where need to be heated according to their own needs.
The electric heating plate can be made of electromagnetic, flat coils are placed its inside. The
magnetic field shielding devices are installed at bottom and sides. The heating plate can be designed
direct heating and indirect heating. The heating plate can be set above a ceramic glass plate, Magnetic
induction line heat the permeable material (steel or iron, etc.) at 25mm distance through this layer of
glass directly；On the other way, The heating plate can be set above a metal plate, induction coil heat
metal plate, metal plate will be heated and then its quantity of heat radiate outward to heat the other
material.
The electric heating plate can be used for textile and printing and dyeing industries, etc.
Conclusions
The electromagnetic heating is attended and known as a new energy by human more and more, and
has started to replace traditional heat sources. The study has a huge area of electromagnetic induction,
heat conduction, electromagnetic shield and their relative control systems. You must study deeply and
test repeatedly to get and apply it expertly. It is really better than traditional heat sources in many ways,
saving effect and losing reduction is remarkable especially. To summarize, electromagnetic heating
application outlook is pretty vast in many kinds of industries and fields, it will replace traditional heat
sources progressively.
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