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Following is not the use of dielectric heating
Plastic industry
Food processing
Medical
Textile industry
Textile industry
Dielectric heating involves heating non-conducting (insulating) materials by placing them in a high-frequency alternating electric field. Textile processing, which typically involves mechanical spinning, weaving, or wet processing like dyeing and bleaching, does not primarily rely on dielectric heating for its core operations.
Dielectric heating involves heating non-conducting (insulating) materials by placing them in a high-frequency alternating electric field. Textile processing, which typically involves mechanical spinning, weaving, or wet processing like dyeing and bleaching, does not primarily rely on dielectric heating for its core operations.
P=2╧АfV2Ctan╬┤ тАФ Power developed in dielectric heating
C=d╬╡0тАЛ╬╡rтАЛAтАЛ тАФ Capacitance of the dielectric slab
When a non-conducting material (dielectric) is placed between two metal electrodes subjected to high-frequency AC voltage, the molecular dipoles within the material attempt to align with the rapidly changing electric field. This molecular friction generates heat internally throughout the material, which is expressed by the formula P=2╧АfV2Ctan╬┤.
Dielectric heating is suitable for insulators like plastics, wood, and ceramics.
The heating effect is proportional to the frequency of the supply voltage.
Materials with high dielectric loss factor are ideal for this heating method.
Textile industry predominantly uses convective or radiant heating for drying processes.
Uniform heating throughout the material
Rapid heating process
Clean and easy control of temperature
No conduction losses
High initial cost of equipment
Limited to insulating materials only
Risk of radio frequency interference
Maintenance of high-frequency generators
Preheating of plastic preforms
Drying of wood and glue setting
Food pasteurization and defrosting
Medical diathermy for deep tissue heating
Dielectric heating is specifically useful for materials with low thermal conductivity where surface heating would be ineffective.
Option A, B, and C are valid applications: Plastic industry (welding/molding), Food (thawing/drying), and Medical (diathermy).
D is correct тАФ The textile industry primarily relies on convective heating or steam-based drying rather than dielectric heating methods.
In competitive exams, always link dielectric heating to 'insulators' and induction heating to 'conductors'.