Calculation 1: Wattage required for heat-up:
Weight of material (lbs) x Specific Heat x Temperature Rise ?F
3.412 x Time (in hours or fraction of hours)
For specific heat and weights of each material being heated, see
Properties of Metals,
Properties of Non-metallic Solids, and
Properties of Gases charts.
Calculation 2: Wattage losses at operating temperature:
Wattage loss/sq. ft. x Area in sq. ft. (see/click on heat loss curves below).
Calculation 3: Wattage for melting or vaporizing:
Weight of material (lbs) x Heat of fusion or vaporization (BTU/lb)
3.412 x Heat up time (in hours or fraction of hours)
When the specific heat of a material changes at some temperature during the heat-up, due to melting (fusion) or evaporation (vaporization), perform Calculation 1 for heat absorbed from the initial temperature up to the temperature at the point of change, add Calculation 2, then repeat Calculation 1 for heat absorbed from the point of change to the final operating temperature. See Properties of Metals, Properties of Non-metallic Solids, and Properties of Gases charts for heats of fusion and vaporization and temperatures at which these changes in state occur.
Losses through insulated walls
Losses from molten surfaces
Losses from surfaces of oil baths
Losses from open water tanks
Losses from uninsulated surfaces
Properties of Gases
Properties of Metals
Properties of Non-metallic Solids
