Source code for RCAIDE.Library.Attributes.Coolants.Glycol_Water
# RCAIDE/Library/Attributes/Coolants/Glycol_Water.py
#
#
# Created: Mar 2024, M. Clarke
# ----------------------------------------------------------------------------------------------------------------------
# Imports
# ----------------------------------------------------------------------------------------------------------------------
from .Coolant import Coolant
# ----------------------------------------------------------------------------------------------------------------------
# Glycol_Water
# ----------------------------------------------------------------------------------------------------------------------
[docs]
class Glycol_Water(Coolant):
"""
Implementation of a 50-50 ethylene glycol-water mixture coolant properties.
This class provides thermophysical properties and calculation methods for a standard
ethylene glycol-water mixture commonly used in cooling systems.
Attributes
----------
tag : str
Identifier set to 'Glycol_Water'
percent_glycol : float
Mass fraction of glycol in the mixture (default: 0.5)
density : float
Mass per unit volume [kg/m³]
specific_heat_capacity : float
Heat capacity at constant pressure [J/kg·K]
thermal_conductivity : float
Heat conduction coefficient [W/m·K]
dynamic_viscosity : float
Absolute viscosity [Pa·s]
Prandtl_number : float
Dimensionless number for heat transfer characteristics
kinematic_viscosity : float
Ratio of dynamic viscosity to density [m²/s]
Notes
-----
All properties are currently implemented as constant values, though the method
structure allows for future implementation of temperature and pressure dependence.
**Major Assumptions**
* Mixture is exactly 50% water and 50% ethylene glycol by mass
* Standard atmospheric pressure conditions
* Single-phase liquid mixture
**Extra modules required**
None
References
----------
[1] The Engineering ToolBox (2003). Ethylene Glycol Heat-Transfer Fluid Properties. [online] Available at: https://www.engineeringtoolbox.com/ethylene-glycol-d_146.html [Accessed 8 January 2025].
[2] Microelectronics Heat Transfer Laboratory. (1997). Fluid Properties Calculator. Fluid properties calculator. http://www.mhtl.uwaterloo.ca/old/onlinetools/airprop/airprop.html
See Also
--------
RCAIDE.Library.Components.Thermal_Management : Thermal management system components
"""
def __defaults__(self):
"""This sets the default values.
Assumptions:
Mixture is 50% water-50% ethylene-glycol
Source:
Engineering Toolbox: https://www.engineeringtoolbox.com/ethylene-glycol-d_146.html
University of Waterloo: http://www.mhtl.uwaterloo.ca/old/onlinetools/airprop/airprop.html
"""
self.tag = 'Glycol_Water'
self.percent_glycol = 0.5
self.density = 1075 # kg/m^3
self.specific_heat_capacity = 3300 # J/kg.K
self.thermal_conductivity = 0.387 # W/m.K
self.dynamic_viscosity = 0.0019 # Pa.s
self.Prandtl_number = self.specific_heat_capacity * self.dynamic_viscosity / self.thermal_conductivity
self.kinematic_viscosity = self.dynamic_viscosity / self.density
[docs]
def compute_cp(self,T=300):
"""
Calculate specific heat capacity of glycol-water mixture at given temperature.
Parameters
----------
T : float, optional
Temperature [K] (default: 300)
Returns
-------
cp : float
Specific heat capacity [J/(kg·K)]
Notes
-----
Currently returns constant value of 3300 J/(kg·K), based on the default value, regardless of temperature.
**Major Assumptions**
* Temperature independence
* 50-50 water-glycol mixture
References
----------
[1] The Engineering ToolBox (2003). Ethylene Glycol Heat-Transfer Fluid Properties. [online] Available at: https://www.engineeringtoolbox.com/ethylene-glycol-d_146.html [Accessed 8 January 2025].
"""
return self.specific_heat_capacity
[docs]
def compute_absolute_viscosity(self,T=300.,p=101325.):
"""
Calculate dynamic viscosity of glycol-water mixture at given conditions.
Parameters
----------
T : float, optional
Temperature [K] (default: 300)
p : float, optional
Pressure [Pa] (default: 101325)
Returns
-------
mu : float
Dynamic viscosity [kg/(m·s)]
Notes
-----
Currently returns constant value of 0.0019 Pa·s, based on the default value, regardless of conditions.
**Major Assumptions**
* Temperature and pressure independence
* 50-50 water-glycol mixture
References
----------
[1] The Engineering ToolBox (2003). Ethylene Glycol Heat-Transfer Fluid Properties. [online] Available at: https://www.engineeringtoolbox.com/ethylene-glycol-d_146.html [Accessed 8 January 2025].
"""
return self.dynamic_viscosity
[docs]
def compute_density(self,T=300.,p=101325.):
"""
Calculate density of glycol-water mixture at given conditions.
Parameters
----------
T : float, optional
Temperature [K] (default: 300)
p : float, optional
Pressure [Pa] (default: 101325)
Returns
-------
rho : float
Density [kg/m³]
Notes
-----
Currently returns constant value of 1075 kg/m³ based on the default value.
**Major Assumptions**
* Temperature and pressure independence
* 50-50 water-glycol mixture
References
----------
[1] The Engineering ToolBox (2003). Ethylene Glycol Heat-Transfer Fluid Properties. [online] Available at: https://www.engineeringtoolbox.com/ethylene-glycol-d_146.html [Accessed 8 January 2025].
"""
return self.density
[docs]
def compute_thermal_conductivity(self,T=300.,p=101325.):
"""
Calculate thermal conductivity of glycol-water mixture at given conditions.
Parameters
----------
T : float, optional
Temperature [K] (default: 300)
p : float, optional
Pressure [Pa] (default: 101325)
Returns
-------
k : float
Thermal conductivity [W/(m·K)]
Notes
-----
Currently returns constant value of 0.387 W/(m·K), based on the default values,
regardless of conditions.
**Major Assumptions**
* Temperature and pressure independence
* 50-50 water-glycol mixture
References
----------
[1] Microelectronics Heat Transfer Laboratory. (1997). Fluid Properties Calculator. Fluid properties calculator. http://www.mhtl.uwaterloo.ca/old/onlinetools/airprop/airprop.html
"""
return self.thermal_conductivity
[docs]
def compute_prandtl_number(self,T=300.):
"""
Calculate Prandtl number of glycol-water mixture at given temperature.
Parameters
----------
T : float, optional
Temperature [K] (default: 300)
Returns
-------
Pr : float
Prandtl number [dimensionless]
Notes
-----
Calculated using the relationship:
Pr = (μ·Cp)/k
where:
- μ is dynamic viscosity
- Cp is specific heat capacity
- k is thermal conductivity
**Major Assumptions**
* Temperature independence of constituent properties
* 50-50 water-glycol mixture
References
----------
[1] Microelectronics Heat Transfer Laboratory. (1997). Fluid Properties Calculator. Fluid properties calculator. http://www.mhtl.uwaterloo.ca/old/onlinetools/airprop/airprop.html
"""
Cp = self.compute_cp(T)
mu = self.compute_absolute_viscosity(T)
K = self.compute_thermal_conductivity(T)
return mu*Cp/K
