Calculator Inputs
Adiabatic Process Graph
The chart plots pressure against volume across the process path.
Example Data Table
| Case | Initial Pressure | Initial Volume | Initial Temperature | Gamma | Known Final Input | Main Use |
|---|---|---|---|---|---|---|
| Air Compression | 100 kPa | 1.00 m³ | 300 K | 1.40 | 0.60 m³ | Estimate final pressure and temperature |
| Gas Expansion | 300 kPa | 0.40 m³ | 420 K | 1.33 | 150 kPa | Estimate final volume and work |
| Engine Cycle Study | 800 kPa | 0.002 m³ | 650 K | 1.35 | 0.0012 m³ | Compare compression stage behavior |
| Lab Demonstration | 1 atm | 15 L | 25 °C | 1.40 | 8 L | Show practical unit conversion |
Formula Used
Pressure-volume relation: P₁V₁γ = P₂V₂γ
Temperature-volume relation: T₁V₁γ−1 = T₂V₂γ−1
Temperature-pressure relation: T₂ = T₁(P₂/P₁)(γ−1)/γ
Work done by gas: W = (P₂V₂ − P₁V₁) / (1 − γ)
Heat transfer: Q = 0 for an adiabatic process
Here, P is pressure, V is volume, T is absolute temperature, and γ is the specific heat ratio. The calculator uses consistent SI conversions internally before returning values in your chosen units.
How to Use This Calculator
- Select whether the known final input is volume or pressure.
- Enter initial pressure, volume, temperature, and gamma.
- Choose the same display units you prefer for outputs.
- Type the known final pressure or final volume.
- Click Calculate Process to show the result panel.
- Review final state values, work, internal energy, and ratio.
- Use the graph to inspect the pressure-volume trend.
- Export the results with the CSV or PDF buttons.
Frequently Asked Questions
1. What is an adiabatic process?
An adiabatic process exchanges no heat with surroundings. Energy transfer appears as work and internal-energy change. Compression usually raises temperature. Expansion usually lowers temperature.
2. What does gamma mean here?
Gamma is the ratio Cp/Cv. It controls how sharply pressure and temperature change. Dry air often uses 1.4. Other gases can differ noticeably.
3. Why must gamma be greater than 1?
For common ideal gases, Cp exceeds Cv. That makes gamma greater than 1. The work equation also uses 1 − gamma in the denominator.
4. Why does the calculator use Kelvin internally?
Thermodynamic equations require absolute temperature. Kelvin avoids negative offsets used by Celsius and Fahrenheit. The calculator converts your entry automatically and returns your preferred unit.
5. What does positive work mean?
Positive work means the gas does work on surroundings. That usually happens during expansion. Compression often gives negative work because surroundings do work on the gas.
6. Can I use non-SI input units?
Yes. You may enter several pressure, volume, and temperature units. The calculator converts values to consistent internal units before solving the equations.
7. Is this valid for irreversible real processes?
Not exactly. This tool assumes a reversible ideal-gas path. Real systems may show heat leakage, friction, pressure losses, and variable properties.
8. When is this calculator useful?
It is useful in engine analysis, compressor studies, turbine estimates, classroom examples, and quick thermodynamic checks involving idealized adiabatic changes.