REFRIGERANT BEHAVIOR

"Refrigerants absorb heat by boiling in cold spaces and reject heat by condensing in warm spaces. By controlling pressure, we control when and where phase changes occur — enabling heat to be moved from cold to warm."

Guided Exploration — Step 1 of 5

Click or drag anywhere in the blue liquid region on the phase chart below. Notice how the refrigerant stays liquid when pressure is high relative to temperature.

Assumptions

Thermodynamic Model: Uses the Antoine equation to relate pressure and temperature during phase change. R-134a properties: latent heat ~217 kJ/kg, boiling point -26.1°C at atmospheric pressure, specific heat liquid 1.4 kJ/kg·K, vapor 0.85 kJ/kg·K.

Simplifications: Enthalpy changes represent heat transfer (compression work excluded). Vapor quality (x) is modeled during phase transitions to show the liquid/vapor mixture ratio. All pressures are absolute (bar).

Start Here

This tool shows how R-134a refrigerant behaves under different conditions.

Current state: Your refrigerant is at 20°C and 3.0 bar, making it a superheated vapor.

How to explore: Click or drag on the phase chart to change temperature and pressure simultaneously.

What to watch for: The magic happens at the curved saturation line — that's where phase changes occur and lots of energy moves!

Refrigerant State

Pressure ? 3.0 bar
Temperature ? 20.0 °C
Boiling Point ? -7.4 °C
Enthalpy ? 420.5 kJ/kg
Latent Heat ? 217.0 kJ/kg
Phase
SUPERHEATED VAPOR

Heat Transfer

Current Enthalpy 420.5 kJ/kg
Previous Enthalpy 420.5 kJ/kg
Heat Transfer (ΔH) ? 0.0 kJ/kg
Process Type No Change
Latent Contribution ? 0.0 kJ/kg
NO HEAT TRANSFER
TEMPERATURE (°C) PRESSURE (BAR) LIQUID VAPOR -30 -20 -10 0 10 20 30 40 50 1 2 3 4 5 6 7 8 9 10
Click or drag to explore
Values
PRESS
0 bar
TEMP
0 °C
ENV
0 °C
ENTH
0 kJ/kg
LATENT
0 kJ/kg
REFRIGERANT ENVIRONMENT

Key Terms

Refrigerant

A fluid that easily changes between liquid and gas at useful temperatures. It flows through the system absorbing heat in one place and releasing it in another. R-134a is commonly used in automotive AC systems.

Enthalpy

Total heat energy stored per kilogram of refrigerant — includes both sensible heat (from temperature) and latent heat (from phase changes). Higher enthalpy = more energy stored.

Latent Heat

The "hidden" energy needed to change phase without changing temperature. When water boils at 100°C, the extra energy turning it to steam is latent heat — you can't feel it as temperature, but it moves enormous amounts of energy.

Evaporation

Liquid turning to gas, absorbing heat and cooling surroundings. This is what happens in your AC's indoor unit — refrigerant boils and pulls heat from your room air.

Condensation

Gas turning to liquid, releasing heat and warming surroundings. This happens in your AC's outdoor unit — hot vapor becomes liquid and dumps heat outside.

Sensible Heat

Temperature going up or down without phase change. You can "sense" it because the thermometer moves. Like heating water from 20°C to 80°C — hotter, but still liquid.

Subcooled Liquid

Liquid cooler than its boiling point. Like water at room temperature — stable as liquid with room to absorb more heat before it starts boiling.

Saturated

Right at the boiling point. Any heat added causes boiling; any heat removed causes condensation. Temperature stays constant during the phase change — all energy goes into changing phase, not raising temperature.

Superheated Vapor

Gas hotter than needed to stay gaseous. It has extra heat energy beyond what's needed to be vapor — like invisible steam above boiling water.