BIZOMAT MAKEOS · Materials
Heating Energy and Time
How much energy and time does it take to heat this material or liquid?
Energy to raise a mass through a temperature range from its specific heat, and the heating time with a given heater power and efficiency.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Mass to heat | kg | Mass of the material or liquid (water: 1 kg per litre). |
| Specific heat capacity | kJ/(kg·K) | Specific heat over the range (water about 4.18, steel about 0.49, aluminium about 0.90 kJ/kg·K). |
| Start temperature | °C | Starting temperature. |
| Final temperature | °C | Target temperature. |
| Heater power | kW | Rated heater power. |
| Heating efficiency (heat reaching the load) | % | Share of heater output that reaches the load (losses to surroundings reduce it). |
| Energy price | AUD/kWh | Energy tariff for cost per batch. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Mass to heat
- What it is
- The mass of the material or liquid being heated in one batch, from weighing or from volume times density.
- Units and format
- Enter a number in kg: kilograms. The form accepts 0.000001 kg or more. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 500 kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Energy, heating time and cost rise in direct proportion.
- Get it right
- For water, one litre is about one kilogram; for other liquids multiply volume by density.
What this means: Specific heat capacity
- What it is
- The heat needed to raise one kilogram of the material by one degree, from material data over the temperature range used.
- Units and format
- Enter a number in kJ/(kg·K): kilojoules per kilogram per kelvin. The form accepts 0.000001 kJ/(kg·K) to 100 kJ/(kg·K). Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 4.18 kJ/(kg·K) as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Energy, heating time and cost rise in direct proportion.
- Get it right
- Enter kJ per kg per kelvin; values in J/(kg·K) are a thousand times larger.
What this means: Start temperature
- What it is
- The temperature of the material at the start of heating.
- Units and format
- Enter a number in °C: degrees Celsius. The form accepts -273 °C to 3000 °C. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 15 °C as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A lower start raises the temperature rise, energy and time.
- Get it right
- Use the real starting temperature, which may be lower in winter.
What this means: Final temperature
- What it is
- The temperature the whole mass must reach at the end of heating.
- Units and format
- Enter a number in °C: degrees Celsius. The form accepts -273 °C to 3000 °C. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 60 °C as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A higher target raises the temperature rise, energy and time.
- Get it right
- It must be above the start temperature, and below any melting or boiling point, as phase change is not included.
What this means: Heater power
- What it is
- The rated output of the heater, from its nameplate or data sheet.
- Units and format
- Enter a number in kW: kilowatts. The form accepts 0.000001 kW to 1000000 kW. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 9 kW as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- More power shortens heating time in proportion; energy and cost do not change.
- Get it right
- Enter kilowatts; the heater must run at full power for the whole time for the result to hold.
What this means: Heating efficiency (heat reaching the load)
- What it is
- The share of the heater’s output that actually ends up in the load, after losses to the vessel, air and surroundings.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 1% to 100%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 85% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A lower efficiency raises energy drawn, heating time and cost.
- Get it right
- Type the percentage itself; an uninsulated open tank loses much more than a lagged vessel.
What this means: Energy price
- What it is
- What you pay for one kilowatt-hour of the energy used, from your energy bill or contract.
- Units and format
- Enter a number in AUD/kWh: Australian dollars per kilowatt-hour. The form accepts 0 AUD/kWh to 100 AUD/kWh. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.3 AUD/kWh as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Cost per batch rises in direct proportion; energy and time do not change.
- Get it right
- Use the tariff at the time of day heating runs, including network charges if they vary with use.
Method and formulas
- Q = m c (T₂ − T₁) (kJ); in kWh ÷ 3600.
- Time = Q ÷ (P × η) (hours when Q is in kWh).
- Energy drawn = Q ÷ η; cost = energy drawn × price.
- Example: 500 kg of water from 15 to 60 °C needs 26.125 kWh, about 3.415 h with 9 kW.
Limitations
- No phase change (melting or boiling) is included; add latent heat separately.
- Heat loss during heating is represented only by the efficiency.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Size a tank or oven heater
- Estimate warm-up time
- Compare energy cost of heating batches
Who it is for
- Process engineers
- Maintenance engineers
What you get
- Heat energy required
- Heating time
- Energy drawn and cost per batch
Interpreting the result
- Heat losses rise with temperature; use a lower efficiency for long, hot warm-ups.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 371–374. Topic reference; no source tables or recommended settings are reproduced.
Learn the Concepts Behind This Tool
These BIZOMAT Library readings explain the method this tool uses, with worked examples.
Method explained here · BIZOMAT original book
Water in the flue gas and condensing heat recovery
What it covers: How much water burning gas makes, the flue gas dew point and how excess air moves it, recovering latent heat with a condensing exchanger, and a flue that was never meant to be wet.
Method explained here · BIZOMAT original book
Heat capacity, cooldown and warm-up
In Cryogenic Design by the Numbers
What it covers: The enthalpy CT-40's cold mass gives up, a cooldown time integrated against the cryocooler's real capacity curve, why rated capacity misleads, a warm-up heater, and a cryostat opened while still cold.
Method explained here · BIZOMAT original book
The nitrogen a part needs
In Cryogenic Liquids by the Numbers
What it covers: Why specific heat collapses on cooling, the enthalpy a steel shaft gives up on the way to −196 °C, the nitrogen an open bath boils, the cost of a warm bath, and a large shaft that ran it dry.
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