As in the case of gases, the vapours may also be expanded or compressed by different methods as given below: Method # 1. Constant Volume Process (fig. 3-14): An example of constant volume process is the heating of steam in a closed rigid vessel. As there is no change in volume, work done in this process is zero. By the [...]
In this article we will discuss about:- 1. Causes of Overheated and Burnt Steels 2. Detection of Overheated and Burnt Steels 3. Reclamation. Causes of Overheated and Burnt Steels: When steels are heated above the upper critical temperatures, austenite grains coarsen. If the coarsening is not excessive, normalising, or annealing can refine the grains to normal size. If the heating [...]
The main advantages of electric heating over other system of heating such as coal, gas or oil heating are given below: Advantage # 1. Economical: Electric energy is cheaper to use as it is produced on large scale. The electric furnaces run by electric energy are cheaper in initial cost. The maintenance cost is also low as compared to other [...]
In this article we will discuss about the design of heating elements and causes of its failure. Design of Heating Elements: The wire employed for heating element may be circular or rectangular like a ribbon. Knowing the electrical input and its voltage the size and length of wire required as the heating element to produce the given temperature can be [...]
List of top seven appliances used for heating:- 1. Non-Pressure Type Water Heater 2. Electric Iron 3. Electric Radiator 4. Immersion Heater 5. The Electric Toaster 6. Soldering Iron 7. Electrode Boiler 8. Hot Air Circulator. Appliance # 1. Non-Pressure Type Water Heater: The geyser is a non-pressure type water heater. It supplies the hot water continuously to wash basins [...]
In this article we will discuss about:- 1. Types of Resistance Ovens 2. Uses of Resistance Ovens 3. Temperature Control. Types of Resistance Ovens: 1. Resistance Furnace: This type of oven is used for cooling a heated job slowly for removing its brittleness is known as annealing. In this usual process of annealing the job is left covered with a [...]
In this article we will discuss about the design of core and coreless induction furnace. Design of Core Induction Furnace: Fig. 3.12 shows a core type furnace. Core type furnace is essentially a transformer with the charge of metal to be heated as single turn short circuited secondary and magnetically coupled to the primary winding by iron core. The current [...]
In this article we will discuss about the methods of electric heating. The methods are:- 1. Power Frequency Heating 2. High Frequency Heating. Method # 1. Power Frequency Heating: I. Resistance Heating: As we know that whenever current passes through some resistance, power loss takes place which appears in the form of heat, e.g Resistance oven. Properties of Resistance Heating [...]
There are three types of arc furnaces namely: 1. Direct Arc Furnace 2. Indirect Arc Furnace 3. Submerged Arc Furnace. Design of Direct Arc Furnace: Figure 3.16 shows a direct arc furnace. The chamber of the furnace is lined with refractory material. The arc is struck between the electrode and the charge. Three electrodes made of carbon or graphite are [...]
In this article we will discuss about:- 1. Meaning of Eddy Current Heating 2. Advantages of Eddy Current Heating 3. Disadvantages. Meaning of Eddy Current Heating: Eddy current heating is also known as the induction heating. The material to be heated is placed inside the coil. The heat in the material to be heated is produced by eddy currents. Power [...]