Ethylene Glycol

Reference data and engineering information about ethylene glycol for hvac systems applications.

ethyleneglycol

Overview

Engineering reference data for Ethylene 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

Expansion Volume Calculations

The density of ethylene glycol solutions changes with temperature, affecting the volume in a system. This must be accounted for in expansion tank sizing.

Key Formulas for Volume Expansion

The mass of the fluid remains constant between installation (cold) and operation (hot) states: $m_{inst} = m_{op}$ $\rho_{inst} V_{inst} = \rho_{op} V_{op}$

Therefore, the operational volume can be calculated from the installation conditions: $V_{op} = V_{inst} \left( \frac{\rho_{inst}}{\rho_{op}} \right)$

The expansion volume, $\Delta V$ , is the difference between the operational and installation volumes: $\Delta V = V_{op} - V_{inst} = V_{inst} \left( \frac{\rho_{inst}}{\rho_{op}} - 1 \right)$

Variables:

$V_{inst}$ : Liquid volume at installation (m³)
$V_{op}$ : Liquid volume during operation (m³)
$\rho_{inst}$ : Density at installation temperature (kg/m³)
$\rho_{op}$ : Density at operation temperature (kg/m³)
$m_{inst}, m_{op}$ : Mass of liquid at installation and operation (kg)

Important Engineering Notes

Viscosity: The dynamic viscosity of an ethylene glycol solution is significantly higher than that of clean water. This increases the head loss (pressure drop) in piping systems.
Specific Gravity & Density: These properties are also increased compared to water, affecting system weight and pressure calculations.
Freezing Point: Solutions should not be used in conditions very close to their listed freezing point, as slush formation can occur.

Data Tables

10 rows

Freezing Points of Ethylene Glycol-Water Solutions
Ethylene Glycol(% by volume)	Freezing Point(°F)	Freezing Point(°C)
0	32	0
10	25.9	-3.4
20	17.8	-7.9
30	7.3	-13.7
40	-10.3	-23.5
50	-34.2	-36.8
60	-63	-52.8
80	-51	-46
90	-22	-30
100	9	-12.8

Source: engineeringtoolbox.com

6 rows

Dynamic Viscosity of Ethylene Glycol-Water Solutions (Note: Viscosity values at 0°F for 25% and 30% solutions are above the freezing point; values at 240°F are above the boiling point of the solution).
Temperature(°F)	Viscosity (25%)(cP)	Viscosity (30%)(cP)	Viscosity (40%)(cP)	Viscosity (50%)(cP)	Viscosity (60%)(cP)	Viscosity (65%)(cP)	Viscosity (100%)(cP)
0	—	—	15	22	35	45	310
40	3	3.5	4.8	6.5	9	10.2	48
80	1.5	1.7	2.2	2.8	3.8	4.5	15.5
120	0.9	1	1.3	1.5	2	2.4	7
160	0.65	0.7	0.8	0.95	1.3	1.5	3.8
200	0.48	0.5	0.6	0.7	0.88	0.98	2.4

Source: engineeringtoolbox.com

7 rows

Specific Gravity of Ethylene Glycol-Water Solutions
Temperature(°F)	SG (25%)(-)	SG (30%)(-)	SG (40%)(-)	SG (50%)(-)	SG (60%)(-)	SG (65%)(-)	SG (100%)(-)
-40	—	—	—	1.12	1.13	—	—
0	—	1.08	1.1	1.11	1.12	1.16	—
40	1.048	1.057	1.07	1.088	1.1	1.11	1.145
80	1.04	1.048	1.06	1.077	1.09	1.095	1.13
120	1.03	1.038	1.05	1.064	1.077	1.082	1.115
160	1.018	1.025	1.038	1.05	1.062	1.068	1.1
200	1.005	1.013	1.026	1.038	1.049	1.054	1.084

Ethylene Glycol

Overview

Key Formulas

Sensible Heat

Latent Heat

COP (Cooling)

Variables

Expansion Volume Calculations

Key Formulas for Volume Expansion

Important Engineering Notes

Data Tables

Interactive Charts

Water with ethylene glycol - freezing points

Antifreeze - Ethylene Glycol Volume vs. Temperature Rating

Calcium Chloride Water Solutions

References