Sensible Heat Calculator

Sensible heat is energy that changes temperature without phase change. For a fixed mass, the sensible heat is:

Q = m · cₚ · ΔT

• Q: sensible heat (J)
• m: mass (kg)
• cₚ: specific heat capacity (J/(kg·K))
• ΔT: temperature change (K)

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For a continuous stream, the sensible heat rate (power) is:

P = ṁ · cₚ · ΔT

• P: heat rate (W)
• ṁ: mass flow rate (kg/s)

In flow mode, total energy over a duration is E = P · t.

1. Select a mode: Energy from mass or Power from mass flow.
2. Enter cₚ for your material and choose its unit.
3. Enter initial and final temperatures, then pick the temperature unit.
4. Provide mass (energy mode) or mass flow plus duration (flow mode).
5. Press Calculate to view results above the form.
6. Use the download buttons to export a CSV or PDF summary.

For best accuracy, use heat capacity at the average temperature of your process.

Examples are illustrative; material properties vary with temperature and composition.

1) Purpose and scope

This calculator estimates sensible heat, the energy linked to a temperature change without a phase change. It supports batch heating or cooling using mass, and continuous streams using mass flow rate. Results are shown in joules, kilojoules, megajoules, watt-hours, kilowatt-hours, and Btu.

2) Core relationship

Sensible heat is modeled with Q = m·c_p·ΔT. For flowing systems the heat rate is P = ṁ·c_p·ΔT, where power is in watts. In the flow mode, total energy over time is computed as E = P·t.

3) Typical property data

The accuracy depends on the selected heat capacity. As practical reference points near room temperature: water is about 4.18 kJ/(kg·K), dry air about 1.005 kJ/(kg·K), aluminum about 0.90 kJ/(kg·K), and carbon steel about 0.49 kJ/(kg·K). Use verified data for critical work.

4) Temperature range considerations

Many materials show noticeable variation of c_p with temperature. For moderate ranges, using c_p at the average temperature often yields good engineering estimates. For wide ranges, consider splitting the process into segments and summing energy, or using tabulated c_p(T).

5) Heating versus cooling sign

The calculator preserves sign based on ΔT. A positive ΔT produces positive Q or P, meaning energy is added to raise temperature. A negative ΔT produces negative values, indicating energy removal during cooling. If you need only magnitude, interpret the absolute value for load sizing.

6) HVAC and process-load use

For HVAC, sensible load is commonly estimated from air mass flow and temperature rise across a coil. Example: 0.50 kg/s of air, ΔT = 10 K, c_p = 1005 J/(kg·K) gives P ≈ 0.50×1005×10 = 5025 W (about 5.0 kW). Similar logic applies to liquid loops and heat exchangers.

7) Unit handling and conversions

Inputs accept common units for mass, mass flow, heat capacity, and temperature scales. Internally, values are converted to SI, then converted back for reporting. The temperature difference is computed from initial and final values, so °C and K differences match numerically, while °F differences are converted consistently.

8) Documentation and exports

The CSV export is useful for lab notebooks, commissioning sheets, and quick audit trails. The PDF export creates a clean calculation summary for reports and approvals. Always record assumptions, especially c_p, mixture composition, and whether any phase change is present, because latent effects are outside the sensible-heat model.

1) What is sensible heat?

Sensible heat is thermal energy that changes temperature without changing phase. It is modeled with Q = m·cₚ·ΔT and is used for heating and cooling load estimates.

2) Why can results be negative?

Negative values occur when final temperature is lower than initial temperature. The sign indicates cooling, meaning heat is removed from the material or stream.

3) Which cₚ should I use for best accuracy?

Use cₚ for your specific material at the relevant temperature range. For moderate ranges, cₚ at the average temperature is a common engineering approximation.

4) Does this include latent heat?

No. Latent heat from melting, boiling, condensation, or freezing is not included. If a phase change occurs, add latent energy separately using appropriate property data.

5) When should I use mass-flow mode?

Use mass-flow mode for continuous processes such as air handlers, liquid loops, or pipelines. It returns power (W, kW) and also energy over a selected duration.

6) How are temperature units handled?

The calculator converts your initial and final temperatures to a common scale and computes ΔT consistently. Differences in °C and K match, while °F is converted to K.

7) What should I include in documentation?

Record material identity, cₚ source, temperature range, and whether properties vary with temperature. For streams, also note flow measurement method and duration used.