Electrical Heating of a Mass

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Electrical heating of a mass can be expressed with the equation:

V I t μ = c m dT     (1)

where

V = potential difference (Volt)

I = electrical current (Amps)

t = time (sec)

μ = heating efficiency

c = specific heat of the heated substance (J/kg.^oC)

m = mass of the heated substance (kg)

dT = temperature differance (^oC)

Example - 12 Volt Car Water Heater

The temperature change in a 12 Volts 10 Amps Car Water Heater with 0.4 kg water and 5 minutes heating period can be calculated by modifying (1) to

dT = V I t μ / c m

   = (12 Volts) (10 Amps) (300 sec) 1 / (4200 J/kg.^oC) (0.4 kg)

   = 21.4 ^oC

Note! The mass of the water heater and the heat loss from the heater during heating is neglected in this calculation. In reality the mass of the heater and the heat loss from the heater during the heating process influences on the temperature change.

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Related Topics

• Electrical - Amps and electrical wiring, AWG - wire gauge, electrical formulas, motors and units
• Thermodynamics - Thermodynamics of steam and condensate applications

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