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About

Designing thermal systems requires balancing energy input against thermal mass and heat loss. This calculator estimates the electrical power (Wattage) required to heat a specific volume of fluid within a target timeframe. It is an essential utility for process engineers and DIY enthusiasts designing brew kettles, water heaters, or industrial tanks.

The core calculation relies on the Specific Heat Capacity (Cp) of the medium. The tool accounts for the energy delta required to raise the temperature from start to finish and integrates a "Safety/Loss Factor" to compensate for imperfect insulation. It then back-calculates the required electrical Resistance (R) for the heating element based on the supply voltage.

thermodynamics heater design specific heat physics wattage

Formulas

The thermal energy Q required is calculated as:

Q = m Cp ΔT

Power (P) is Energy per unit Time (t):

P = Qt (1 + Loss%)

Reference Data

MaterialSpecific Heat (J/g°C)Density (g/cm³)
Water4.1861.00
Olive Oil1.9700.92
Aluminum0.9002.70
Ethanol2.4400.789
Glycerin2.4301.26
Air (dry)1.0050.0012

Frequently Asked Questions

For an insulated plastic tank, 10-15% is standard. For uninsulated metal pots, heat loss can exceed 30%. Always overestimate the required power to ensure the target temperature is reached.
A heating element is a resistor. Its power output is fixed by the voltage applied (P = V²/R). If you design a 2000W element for 240V but plug it into 120V, it will only produce 500W (1/4 of the power).
This tool calculates the energy to reach the target temperature (Sensible Heat). It does not include the Latent Heat of Vaporization required to turn liquid into gas once the boiling point is reached.