Ethylene Propylene Glycol

Overview

Engineering reference data for Ethylene Propylene Glycol in HVAC systems.

Key Formulas

Sensible Heat

$Q = \dot{m} c_p \Delta T$

Heat causing temperature change.

Latent Heat

$Q = \dot{m} h_{fg} \Delta\omega$

Heat causing moisture change.

COP (Cooling)

$COP = Q_c / W$

Coefficient of performance.

Variables

Symbol	Description	Unit
$Q$	Heat transfer	W
$\dot{m}$	Mass flow rate	kg/s
$c_p$	Specific heat of air	J/(kg·K)
$\Delta T$	Temperature difference	K

Important Notes

• Toxicity: Ethylene glycol is highly toxic upon oral ingestion and targets the kidneys. It must never be used in systems associated with potable water or food processing. Propylene glycol has a lower level of acute toxicity.
• Performance Trade-off: While ethylene glycol offers better heat transfer efficiency due to lower viscosity, propylene glycol has a higher specific heat capacity. This means more ethylene glycol fluid must be circulated to transfer the same amount of energy.
• Environmental Impact: Ethylene glycol degrades faster (10-30 days) than propylene glycol (>20-30 days) and has a lower chemical oxygen demand, meaning less impact on aquatic oxygen levels.

References

• Original Source