State any two applications of each for the following types of electrical heating : (i) Direct resistance heating(ii) Indirect induction heating (iii) Direct.arc heating (iv) Dielectric heating
(i) Direct resistance heating:- 1. This type of heating used for industrial purpose 2. Salt bath heating: This utilized for the purpose of carbonizing, tempering, quenching and hardening of steel tools 3. Heating of water in boiler
(ii) Indirect induction heating: 1. For heating as well as melting 2. Production of carbon free ferrous alloys. 3. For vacuum melting. 4. For melting non-ferrous metals for e.g. copper, aluminum, nickel etc. 5. For duplexing steel products. 6. Heating of non-conducting material is also possible if crucible is made from conducting material.
(iii) Direct.arc heating:- 1. Used for continuous and large production of high quality steel. 2. For Ferro-alloy manufacturing
(iv) Dielectric heating:- 1) In food processing industry, dielectric heating is used for Baking of cakes & biscuits in bakeries. 2) Cooking of food without removing outer shell (e.g.-boiled egg) and pasteurizing of milk. 3) For Rubber vulcanizing. 4) In Tobacco manufacturing industry for dehydration of tobacco. 5) In wood industry for manufacturing of ply wood. 6) In plastic Industry for making different containers. 7) In cotton industry for drying & heating cotton cloths for different processes. 8) In tailoring industry for producing threads. 9) For manufacturing process of raincoats & umbrellas. 10)In medical lines for sterilization of instruments & bandages. 11)For heating of bones & tissues of body required for certain treatment to reduces paints & diseases. 12)For removal of moisture from oil. 13)For quick drying gum used for book binding purpose. 14)In foundry for heating of sand, core, which are used in molding processes.