Direct resistance heating pdf

In this study, heating properties of carbon fiber ncf were evaluated for the development of cfrtp molding technique using direct resistance heating. When current is passed through a resistance element i2r loss takes place which produces heat. The following sections address fundamental heat transfer concepts used to arrive at a general formula that is used in heat loss calculations. This chapter is necessarily vaguer than chapters 2225 because there are fewer established uses of direct resistance heating drh. Before looking at dc, let us discuss some reasons for the neglect. In this method the material or charge to be heated is treated as a resistance and current is passed through it. Direct resistance heating dh is a type of resistance heating that passes electric current directly though an electricallyconductive heated object to directly heat.

Us20140339210a1 direct resistance heating apparatus and. In fact, resistance and current are inversely proportional in this case. Shrinkfit once a support ring is added to the end of the tube, either a hand operated or an electric. A direct resistance heating method includes placing a first electrode and a second electrode on a plateshaped workpiece such that the first electrodes and the second electrode extend across the workpiece in a direction substantially perpendicular to a center line of a heating target region of the workpiece, the center line connecting a middle portion of one side of the heating target region. Heating properties of carbon fibers by using direct. Methods of electrialc heating resistance, arc, induction and dielectric heating. It is thus better to use direct resistance heating for lowcost cfrtp molding. By generating heat within the workpiece rather than in a furnace, direct resistance offers a number of benefits over fuelfired furnaces. Room heaters can consist of electric baseboard heaters, electric wall heaters, electric radiant heat, or electric space heaters. Machine was configured with a miyachi 500a medium frequency direct current mfdc power supply, coupled with a 140kva transformer. The electric current is made to pass through the substance to be heated or charge itself. A process of cfrtp molding is here proposed using direct resistance heating of carbon fibers in noncrimp fabric ncf. Electrofusion in this method the pipe and special fittings are heated by means of electrical resistance and fused together. Carbon fiber reinforced thermoplastics molding by using.

Abbs insubsea direct electrical heating deh system provides a reliable solution for preventing formation of hydrate and wax in the flowlines and pipelines. In direct resistive heating electric current flows directly through the charge. This chapter deals with direct resistance heating drh installations used for heating electrical conductive materials, metallic or nonmetallic, by means of an electrical current flowing directly in the workpiece to be heated. Application of direct resistance treatment to localized areas. The direct resistance heating method is desirable from a cost perspective, because this method can heat the mould directly without using any coils. Ac supply is used having voltage varies from 2 to 20 volts and currents upto 2500 amps. This paper presents results of the research project local heating in robotbased incremental forming, funded by the german research foundation dfg, where the heating of the current forming zone by means of direct resistance heating is examined as a variation of the roboforming process. There are two types of resistance heating, namely, direct resistance heating and indirect resistance heating. Hardcoupled model of local direct resistance heating of thin sheets. As here the charge itself provides the path for passing current and heat gets produced in the charge itself, the efficiency of the system is. Operating under ideal conditions, the resistance of a high quality silicon carbide may increase by as much as 300% before it reaches the end of its useful life. In order to promote public education and public safety, equal justice for all, a better informed citizenry, the rule of law, world trade and world peace, this legal document is hereby made available on a noncommercial basis, as it is the right of all humans to know and speak the laws that govern them.

For example, electric current is applied directly to suitable materials to achieve direct resistance heating. Indirect resistance heating current is passed through a wire or other high resistance material forming a heating element. There is a wide range of electric showers, with various types of heating controls. If enough heat is transferred out of the pipe, the pipe contents may thicken or solidify resulting in damage to pipes or pumping equipment. Electric resistance heating is 100% energy efficient in the sense that all the incoming electric energy is converted to heat. The substance which to be heated in an electric heating system is called charge. In air, 0 5 10 15 20 25 30 0 100 200 300 400 500 600 mm of sag hours figure 4. The basic principle of resistance heating is that, when current passes through some resistance, power loss takes place which appears in the form of heat. Request pdf induction and direct resistance heating. Heating properties of carbon fibers subjected to direct.

To clarify the heating properties of carbon fibers by direct resistance heating. Electrical resistance heating is used by the environmental restoration industry for remediation of contaminated soil and groundwater. Resistance heating according to the joules law the resistance loss i2rt is used to producing the heat from electrical energy for various industrial purposes like welding, heating of buildings etc. In this study, the pipe moulding process of cfrtp using direct resistance heating was developed. Electricitybased process heating systems also transform materials through direct and indirect processes. Electric resistance heat can be supplied by centralized forcedair electric furnaces or by heaters in each room. Direct and encased resistance heating p2 infohouse. What, then, is the effect of resistance on power consumption. However, most electricity is produced from coal, gas, or oil generators that convert only about 30% of the fuels energy into electricity. Theory and numerical modeling this book offers broad, detailed coverage of theoretical. In this process the current is passed through the substances to be heated. Incremental sheet metal forming with direct resistance.

This resistive heating is the result of friction, as created by microscopic phenomena such as retarding forces and collisions involving the charge carriers usually electrons. In this study, we develop the cfrtp molding method by using direct resistance heating to cnfcf in the hot press molding. A monolithic model of local direct resistance heating of thin sheets is presented. This is sad because, as shown in chapters 16, there are great advantages, especially if dc is used.

In the direct resistance heating, the electric current passes through the charge itself. In many cases the transfer of heat from one medium to another is desired. The model respects all material nonlinearities of the system such as the. Ohmic heating sometimes also referred to as joule heating, electrical resistance heating, direct electrical resistance heating, electroheating, and electroconductive heating is defined as the process of passing electric currents through foods or other materials to heat them. Resistance heating an overview sciencedirect topics. When ac current pass through a wire resistor, inductor, capacitor, then current produces a magnetic field across that wire which opposes the flow of ac current in it along with the resistance of that wire. It is also possible to use electric thermal storage systems to avoid heating during times of peak power demand. The courses of power input, temperature and losses at direct resistive heating of a.

In the direct resistance heating, the current flows directly through the substance to be heated. This heating method heats up the mould by joule heating using skin effect of highfrequency current. By using direct resistance electrical heating through the materials, efficient molding process of cfrtp can be achieved. In the equipment for direct resistance heating, heat emerges by direct. Whenever an electric current flows through a material that has some resistance i. Aleksandr aliferov this book offers broad, detailed coverage of theoretical developments in induction and direct resistance heating and presents new material on the solution of problems in the application of such. Induction and direct resistance heating theory and. The resistance heating trials were done on a pedestal type resistance welding frame with nominally 12kn force capacity. The deh system is based on abbs proven and reliable standard components. In contrast, the direct resistance heating is performed with a simple piece of equipment and low power consumption. Erh consists of constructing electrodes in the ground, applying alternating current ac electricity to the electrodes and heating the subsurface to temperatures that promote the evaporation of contaminants. Cooking is an everyday example of intended heat transfer. Resistance heating, direct heating system, long life heater, k type thermocouple, digital controller, tong. In this method of heating, the material or charge to be heated is taken as resistance and current is passed.

Difference between ac and dc resistance which one is more. Induction and direct resistance heating are presented in an unified theory that, starting from the solution of maxwells equations, gives the basic quantities that characterizes thermal. Direct electrical heating system subsea power subsea abb. The key here is that resistive heating depends on the square of the current, meaning that the power is more sensitive to changes in current than resistance. The power and heating time is supplied through an electrofusion control unit. The heating element of an electric shower is immersed in the water stream, using a nichrome resistance element which is sheathed and electrically isolated, like the ones used in oil heaters, radiators or clothes irons, providing safety. The final two chapters consider analytical solutions and numerical modeling of problems in the application of induction and direct resistance heating, providing industrial engineers with the knowledge needed in order to use numerical tools in the modern design of installations. This principle is used in heating water by means of an electrode boiler. In the indirect electric resistance heating, the current is passed through a highly resistive material placed inside an oven, for example, domestic cooking, room heaters, and so on.

Download citation direct resistance heating this chapter deals with direct resistance heating drh installations used for heating electrical conductive. The following are the 2 methods employed in resistance heating. Resistance heating, direct heating system, long life heater, k type thermocouple, digital controller, tong holder hooks, crucible stand, melting 30 minutes, melts gold, silver, brass. The system was operated in secondary feedback constant current control mode. Automatic stirring action is produced in the charge to be heated and no external method of stirring is required to get uniform heating. The overall resistance resistance, inductive reactance and capacitive reactance in ac circuits is called impedance z. The rate of heat transfer is dependent upon how much resistance exists between objects of differing temperatures. In direct electric resistance heating, the current is passed directly through the material that has to be heated, for example, resistance welding. Induction and direct resistance heating springerlink. Although the salt is a good conductor when molten, the bath must be started up from cold by using an auxiliary starting electrode to draw a localised arc. Download induction and direct resistance heating pdf ebook induction and direct resistance heating induction and direct heating dac guidance heating our churches. At temperatures above about 800c direct resistance heating as opposed to the use of sheathed elements or external heat sources is the only usable method. A direct resistance heating method includes steps of providing a workpiece having a heating target region, a resistance of which per unit length in one direction thereof varying along the one direction, placing a first electrode and a second electrode on the heating target region, and moving at least one of the first electrode and the second.