In this article, influences of input current frequency in an induction heating system were studied by using numerical methods. We used finite element method to solve the governing equations. Obtained results say that this parameter has great influences on the distribution and the amount of generated heat in different parts of induction heating systems. These results also will help us to select the best frequency range for different applications.
Induction heating is one of the most popular heating processes for electrical conductive materials (usually a metal) by electromagnetic induction. Induction heating provides many advantages such as: quick heating, high production rates, ease of automation and control, safe and clean working. This process has many applications in material processing, such as heat treating, joining, welding, brazing, soldering, melting and crystal growth. An induction heating installation has three important parts: a source of high-frequency alternating current, an induction coil (RF-coil) and a workpiece (metallic material) to be heated (figure 1).
In induction heating process, an induction coil surrounds the workpiece and an electrical alternative current passes through it. This current produces a time-varying magnetic field in the surrounding environment (Ampere’s law) that generates an electric field (Faraday’s law). These fields penetrate the metallic parts of system, such as workpiece and induction coil. The penetration depth depends on electrical conductivity, relative magnetic permeability and frequency of input current. As a result of electric field penetration, eddy currents will be produced in the workpiece and other metallic parts. Then electrical resistance of material leads to Joulean heati...
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...that the efficiency of induction heating process in different workpiece thicknesses has unpredictable changes. This subject demonstrates the necessity of numerical calculations in designing systems using induction heating process.
5. Changes of frequency can shift the location of maximum point of generated heat on the outer surface of the workpiece wall. In low frequencies, the maximum amount of heat is located at the middle portions of outer surface of workpiece wall and by frequency increasing the maximum point is shifted to the two corners of surface of workpiece wall. In the other word, by frequency increasing, the heat patterns become wider and shallower. Also a uniform heat distribution can be produced on outer wall by choosing a special frequency which depends on workpiece thickness. This particular frequency decreases by workpiece thickness increasing.
Friction stir welding is a solid state welding process; this remarkable up-gradation of friction welding was invented in 1991 in The Welding Institute [1]. Figure 1 shows the schematic representation of the Friction Stir Welding process. The process starts with clamping the plates to be welded to a backing plate, so that the plates do not fly away during the welding process. A rotating wear resistant tool is plunged on the interface between the plates to a predetermined depth and moved forward in the interface between the plates to form the weld. The external tool has a probe and shoulder which stirs the material to be joined and forges the surface. FSW comes together with forging and extrusion processes. The probe and shoulder extrudes the material by stirring and the shoulder alone forges the material surface to be joined.
The first type of forced induction system is the turbocharger. A turbocharger is essentially the same as a supercharger, except where they get their power from. A turbocharger is powered by exhaust gasses that have been produced by the engine and are forcing their way through the turbofold, or the exhaust manifold that the turbo is housed in. The exhaust gas pushes its way through the turbocharger and hit the turbine wheel. Vehicles that usually find the need for a turbocharger from the factory are four or six cylinder engines. Standard in most European vehicles such as Mercedes, Audi, Volkswagen and Volvo. These cars are known for their small displacement motors, and great gas efficiency, due to this setup...
Iqbal, M. K. (2013, March 27). NED University of Engineering and Technology. Retrieved from Department of Metallurgy Engineering: http://www.neduet.edu.pk/myd/TE/MY%20302.pdf
on how long it takes to heat up. If we heat a large volume of water it
good emitter of heat radiation so a lot of heat will be lost to the
Many odd energy supplies are used for welding including a gas fire, an electric arc, a laser, an electron beam, friction, and ultrasound.In an industrial process, welding may be performed in many various environments, including in open
idea was that electrical current flow was similar to that of heat flow, and by
In Friction stir welding process melting does not occur and joining takes place below the melting temperature of the material. Frictional heat is generated between the wear-resistant welding tool and the material of the workpieces. This heat causes the workpieces to soften without reaching the melting point and allows the tool to traverse along the weld line. Defect free copper welds are achieved by friction stir welding carried out at a constant welding speed of 100 mm/min.[1]. The effect of various input speed on microstructure and mechanical properties of friction stir welded Cu–30Zn brass alloy is investigated [2]. Friction stir welding of 5mm thick pure copper plates were done. The characteristics of the microstructure, different heat zones and mechanical properties of welded joints are investigated [3]. The temperature distributions of the weld, Brinell's hardness test, tensile test and microstructure analysis are performed on the welded aluminium alloy
Other electrical systems around the EAF are the delta closure, the power cables, the current conduction arm, and the electrode holders. The power cables provide a connection between the delta closure and the current conducting arm. It is usually made of copper wires, with a rubber water jacket around the outside for water-cooling the cables. The power cable is connected with the current conducting arm, usually made of copper clad steel or aluminum alloys. This system weighs a lot less than the old bus-bar design that a lot of the older furnaces used. The current conducting arm conducts current directly from the power cable to the electrode holders. The electrode holders must withstand thermal cycling (not so much for our furnace, since our furnace should have a continuous feed) and severe mechanical loading and wear due to vibrations, torsion forces and such.
The basis for the understanding of the heat treatment of steels is the Fe-C phase diagram. Because it is well explained in earlier volumes of Metals Handbook and in many elementary textbooks, the stable iron-graphite diagram and the metastable Fe-Fe3 C diagram. The stable condition usually takes a very long time to develop, especially in the low-temperature and low-carbon range, and therefore the metastable diagram is of more interest. The Fe-C diagram shows which phases are to be expected at equilibrium for different combinations of carbon concentration and temperature. We distinguish at the low-carbon and ferrite, which can at most dissolve 0.028 wt% C at 727 oC and austenite which can dissolve 2.11 wt% C at 1148 oC. At the carbon-rich side we find cementite. Of less interest, except for highly alloyed steels, is the d-ferrite existing at the highest temperatures. Between the single-phase fields are found regions with mixtures of two phases, such as ferrite + cementite, austenite + cementite, and ferrite + austenite. At the highest temperatures, the liquid phase field can be found and below this are the two phase fields liquid + austenite, liquid + cementite, and liquid + d-ferrite. In heat treating of steels the liquid phase is always avoided. Some important boundaries at single-phase fields have been given special names. These include: the carbon content at which the minimum austenite temperature is attained is called the eutectoid carbon content. The ferrite-cementite phase mixture of this composition formed during cooling has a characteristic appearance and is called pearlite and can be treated as a microstructural entity or microconstituent. It is an aggregate of alternating ferrite and cementite particles dispersed with a ferrite matrix after extended holding close to A1. The Fe-C diagram is of experimental origin. The knowledge of the thermodynamic principles and modern thermodynamic data now permits very accurate calculations of this diagram.
Life changed immensely in the 20th century as air conditioning and refrigeration systems became more efficient and controllable. Air Conditioning and Refrigeration play important roles in providing human comfort, food processing, storage, and many other industrial processes. We chose this topic because our life would be difficult without AC and Refrigeration. This paper will talk about the history of air conditioning and refrigeration, the role of engineers in designing and building it, people’s life before and after air conditioning and refrigeration, and finally Applications in the area of achievements and future developments.
The phenomenon called electromagnetic induction was first noticed and investigated by Michael Faraday, in 1831. Electromagnetic induction is the production of an electromotive force (emf) in a conductor as a result of a changing magnetic field about the conductor and is a very important concept. Faraday discovered that, whenever the magnetic field about an electromagnet was made to grow and collapse by closing and opening the electric circuit of which it was a part, an electric current could be detected in a separate conductor nearby. Faraday also investigated the possibility that a current could be produced by a magnetic field being placed near a coiled wire. Just placing the magnet near the wire could not produce a current. Faraday discovered that a current could be produced in this situation only if the magnet had some velocity. The magnet could be moved in either a positive or negative direction but had to be in motion to produce any current in the wire. The current in the coil is called an induced current, because the current is brought about (or “induced”) by a changing magnetic field (Cutnell and Johnson 705). The induced current is sustained by an emf. Since a source of emf is always needed to produce a current, the coil itself behaves as if it were a source of emf. The emf is known as an induced emf. Thus, a changing magnetic field induces an emf in the coil, and the emf leads to an induced current (705). He also found that moving a conductor near a stationary permanent magnet caused a current to flow in the wire as long as it was moving as in the magnet and coiled wire set-up.
Autoclave processing is widely used for producing high quality thermoset composites, these are used in various industries to process a wide variety of thermoset and thermoplastic materials [10]. Almost any shape of the composite parts can be cured in autoclaves as the gas pressure is applied isostatically, the only limitations is the size of the autoclave and require high capital to install autoclaves. Autoclaves are normally pressurized with inert gas like nitrogen or carbon dioxide and air, but air is prone to danger of a fire within the autoclave during the elevated cure temperatures. It is observed that the heated pressurized gas strikes the front door and flow back down the center of the vessel to heat the part, as the gas strikes the door it produces considerable turbulence in the gas flow which results in higher velocities and stabilizes as it flows towards the rear of the autoclave.
In 1831, using his "induction ring", Faraday made one of his greatest discoveries - electromagnetic induction: the "induction" or generation of electricity in a wire by means of the electromagnetic effect of a current in another wire. The induction ring was the first electric transformer. In a second series of experiments in September he discovered magneto-electric induction: the production of a steady electric current. To do this, Faraday attached two wires through a sliding contact to a copper disc. By rotating the disc between the poles of a horseshoe magnet he obtained a continuous direct current. This was the first generator. From his experiments came devices that led to the modern electric motor, generator and transformer.
Electrical motors play an important role in today’s society, from powering domestic appliances like blenders to industrial equipment such as trains. It almost seems impossible to not use an electric motor in our daily lives. In the comfort of our home, electric motors will operate fans, refrigerators, and air conditioners to just name a few. Researchers are constantly looking for new ways to incorporate electrical motors into our lives. Electrical motors function by converting electrical energy into mechanical energy by using the energy stored in the magnetic field (Sarma, 1981).