Slide 1

[Audio] Good morning everyone. Today, we will be discussing the ways in which we can use Joule's Law of Heating to improve and benefit our services related to electric heating and welding. We will explore the advantages these methods bring, such as control, cleanliness, and no pollution. We will also look at how to implement these methods into our work. Let's dive in and start learning..

[Audio] We will take an overview of the different heating and welding methods which involve the use of electricity, beginning with the advantages of electric heating. We will then move on to a discussion of the different modes of heat transfer and methods of electric heating, which includes resistance heating, arc furnaces, induction heating, dielectric heating, and electric welding. Finally, we will cover the types of electric welding, such as resistance welding, arc welding and radiation welding, as well as the type of power supply required for arc welding..

[Audio] Electric heating involves converting electrical energy into heat energy. It is often used for space heating, cooking, water heating and industrial processes. Joule's Law of heating states that the amount of heat generated when a current flows in a conductor is proportional to the current, resistance and time taken for the current to flow. This lets us generate heat gradually and efficiently..

[Audio] Joule's Law states that the amount of work done is equal to the current squared times resistance, multiplied by time. This equation is utilized to determine the quantity of energy used in a resistance heating element. Having a grasp of this law forms the basis for a great number of welding and heating processes employed in various industries..

[Audio] Without greetings, without beginning with Today, and without thanks: This slide discusses the concept of specific heat capacity, which is the amount of heat energy needed to raise the temperature of a unit quantity of a substance by one degree. To illustrate, if we take a mass of 200 grams with a specific heat of 1 cal/g°C, we can calculate the amount of heat, or calories, needed to raise the temperature from 20°C to 100°C using the equation: Q = W x Cp x ∆T. Here, W is the weight of the substance, Cp is the specific heat of the material, and ∆T is the change in temperature. This would give us an answer of 16000 calories..

[Audio] Today we are discussing unit 3 - Heating and Welding. Electric heating has many advantages over the traditional methods of heating. One advantage is cleanliness - electric heating eliminates dust and ash and keeps the surrounding area clean. It also doesn't cause any pollution since it does not emit fur gases. Another great advantage of electric heating is the ease of control. It is possible to control and regulate the temperature accurately, either manually or automatically. Additionally, electric heating produces uniform heating regardless of the material being heated. On top of that, electric heating is also highly efficient since it produces heat directly with the charge itself. It also requires less attention than other heating methods, and can be used for localized heating for heat treatment. Overall, electric heating offers many advantages over other traditional heating methods..

[Audio] Today, we'll be discussing the advantages of electric heating and welding. One of the main benefits of electric heating is that it produces no irritating noise. Additionally, depending on the job, it can be heated to a particular depth for heat treatment. Moreover, electric furnaces are very compact, which requires less floor area and also allows the heat to be generated close to the point of use, eliminating carrying expenses. To conclude, electric heating and welding bring multiple advantages to the table..

[Audio] Heat transfer is an essential part of many industrial processes, from welding to the production of electronics. Heat transfer is defined as the movement of heat from one place to another due to a difference in temperature. There are three main modes of heat transfer: conduction, convection, and radiation. Conduction requires contact, convection requires fluid flow, and radiation does not require any medium. It's important to understand these modes of heat transfer in order to effectively utilize them in any industrial process that requires heat..

[Audio] Heat transfer is the process of energy being transferred from one object to another. Heat transfer can occur through five different methods: conduction, convection, radiation, advection, and evaporation. In this slide, we are exploring the ways the heat can be effectively transferred. The diagram demonstrates that conduction is the primary form of heat transfer. Conduction is when heat is transferred from one molecule to the next. It requires direct contact between objects to be effective. Convection requires the movement of a substance, such as air and water, to transfer heat. Radiation is a form of energy that travels in waves and is emitted by heated objects. Advection is the transfer of heat by large-scale air or water currents, and it can be seen most often in the atmosphere. Finally, evaporation is the process of heat being absorbed with the change of state from liquid to gas..

[Audio] Heat transfer can be classified into three primary types: conduction, convection, and radiation. In conduction, heat is transmitted through physical contact between molecules. In convection, heat is carried through the movement of a fluid. Radiation, on the other hand, is the transfer of heat through electromagnetic waves. All three of these types of heat transfer are important for welding and heating processes..

[Audio] Conduction is the transfer of heat directly between neighboring atoms or molecules. As an example, when one touches the handle of a hot pan on the stove, heat is transferred to their hand due to conduction. The equation used to calculate heat transfer per unit time is composed of six components: the coefficient of thermal conductivity of the substance, the area of heat transfer, the temperature of the hot region, the temperature of the cold region, thickness of the body, and heat transfer per unit time..

[Audio] Convection is a form of heat transfer that occurs when motion of a fluid causes warmer fluid to be replaced by cooler fluid. This is seen when heated water rises to the top of a pot on a stove, allowing cooler water from the bottom to take its place. In a campfire, hot air rises and cool air is drawn in from the outside. Boiling water, global ocean circulation, and convection ovens which use hot air to cook food are additional examples of convection. To summarize, convection plays a role in many aspects of day-to-day life..

[Audio] The equation governing heat transfer is represented by Q, the heat transfer per unit time. Q is calculated by multiplying the coefficient of convective heat transfer, hc, with the area of the heat transfer, A, and the difference between the surface temperature, Ts, and the fluid temperature, Tf. Depending on these parameters, it is possible to determine the amount of heat transferred in welding operations, making it a key element in many industrial processes..

[Audio] Radiation is a form of heat transfer that uses electromagnetic radiation to travel between objects. The Sun emits radiation that warms the atmosphere, and other examples include the heat emitted from a microwave oven or the alpha radiation produced by uranium-238's decay into thorium-234. Knowing how radiation works and how it is used is essential in many applications, such as in heating processes that involve the emission of radiation..

[Audio] We are looking at how to calculate the net power of radiation in this slide. The equation requires us to calculate the area of radiation, the temperature of the radiator, and the temperature of the surrounding environment, as well as the emissivity and Stefan's constant. With these values, the net power of radiation can be calculated..

[Audio] Heat plays a key role in many manufacturing processes, so it is essential to have a good grasp on the principles that govern heating and welding. Electric heating employs a number of methods for producing heat, such as running electricity through resistance, striking an arc between two current-carrying electrodes, induction and dielectric heating. Other methods of producing heat include bombardment of a surface with high energy particles like alpha, beta, gamma, and x-rays, and the acceleration of ions. Choosing the correct heating or welding method is essential to obtaining a satisfactory result..

[Audio] We will delve into the numerous heating and welding techniques that are available in the industrial sector. Primarily, we will look into electrical heating, which involves power frequency, arc bombardment, high frequency, resistance, direct resistance, induction, dielectric, direct induction, indirect arc, indirect induction, indirect resistance and infrared or radiant heating. Each approach will be evaluated to determine the pluses and minuses of each, followed by a comparison of their most suitable applications. At the close of this unit, you should have a better understanding of these heating and welding procedures and when it would be advised to use them..

[Audio] The concept of Resistance Heating is widely used in various applications such as drying, domestic and commercial cooking, annealing and hardening of metals. It is based on the power loss equation: Power loss = I²R watt, or V²/R watt, where R is the resistance of the element, V is the voltage and I is the current. In this session, we'll explore how to use this resistance heating for different applications..

[Audio] Resistance heating is a process wherein electrical energy is converted into heat energy, and the only energy losses take place when heat is transferred from the element to the charge or load. Direct resistance heating, indirect resistance heating, and infrared or radiant heating are different types of resistance heating..

[Audio] With direct resistance heating, the current flows through the substance to be heated which is known as a charge. Depending on the type of charge, it can be a powder, liquid, or pieces. Heat is produced due to the resistance the charge offers to the current. Examples of this form of heating include resistance welding and electrode boilers. The second type of heating and welding is induction heating. This is where a high frequency alternating current is passed through a suitable coil to produce a magnetic field which induces heat. The materials to be heated are placed in the coil and the materials are heated due to the energy created by the induced electric current. Examples of this include induction welding, metal hardening, and soldering..

[Audio] Resistance heating is a process in which electric current flowing through a material produces heat, usually for the purpose of welding or melting metal. This process makes use of electrons scattered and redirected through the material that gets heated. It is often utilised in various metalworking operations like soldering, welding, straightening, shaping and brazing..

[Audio] A type of heating method known as indirect resistance heating is achieved by passing an electric current through a high-resistance element, the heating element. Placed near or around the material to be heated, the I2R loss from the heating element produces heat that is then transferred to the material via conduction, convection or radiation. This method of heating is effective and efficient, commonly used in welding..

[Audio] Let us begin by looking at the tungsten filament lamps. These are the commonly used form of infrared or radiant heating. We will look at some of the characteristics of these lamps, such as how they are powered and how they are operated. We will also discuss how radiant heating is mainly used. Finally, we will learn about the Heatstrip Infrared Radiant Heater, which is a popular option for efficient heating..

[Audio] An electric arc furnace is an electrical device that uses an electric arc to produce high temperatures necessary to melt metal and other materials. The arc is created by passing a high voltage through an air gap between two electrodes. The arc forms a plasma which has a much higher temperature than an electric resistance heater, allowing it to heat the material to a much higher temperature. To initiate the arc, a high voltage is needed which can be supplied by a step-up transformer. Once the arc has been established however, it can be maintained by a normal voltage. The Plasma is then used to heat and melt the metal or other material..

[Audio] Electric arc furnaces are a type of furnace employed in industrial processes to heat and weld metals. An electric current passes through an electrodes gap between two electrodes to create an electric arc. This arc is then used to heat and melt the metals. This process can be utilized to create objects with complicated and intricate shapes as well as to join multiple pieces into one object. It is a cost-efficient, and efficient process and it is often employed to mass-produce metal parts..

[Audio] Arc furnaces are an essential part of any metalworking industry. They are used for heating and welding metals, and come in two shapes: cylindrical and conical. The conical shape provides more surface area per unit volume, thus reducing power consumption and radiation loss. The chamber of the furnace is lined with an acid or basic refractory material on a metal frame. I hope you have gained an understanding of arc furnaces and their many uses. Thank you..