# RCAIDE/Library/Components/Thermal_Management/Heat_Exchangers/Cross_flow_Heat_Exchanger.py
#
# Created: Apr 2024, S. Shekar
# ----------------------------------------------------------------------------------------------------------------------
# IMPORT
# ----------------------------------------------------------------------------------------------------------------------
# RCAIDE Imports
from RCAIDE.Framework.Core import Data, Units
from RCAIDE.Library.Components import Component
from RCAIDE.Library.Attributes.Coolants.Glycol_Water import Glycol_Water
from RCAIDE.Library.Attributes.Gases import Air
from RCAIDE.Library.Methods.Thermal_Management.Heat_Exchangers.Cross_Flow_Heat_Exchanger import cross_flow_hex_rating_model, append_cross_flow_heat_exchanger_conditions, append_cross_flow_hex_segment_conditions
from RCAIDE.Library.Plots.Thermal_Management.plot_cross_flow_heat_exchanger_conditions import plot_cross_flow_heat_exchanger_conditions
import os
import numpy as np
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# Cross Flow Heat Exchanger
# ----------------------------------------------------------------------------------------------------------------------
[docs]
class Cross_Flow_Heat_Exchanger(Component):
"""
A class representing a cross-flow heat exchanger with strip fins for thermal
management systems.
Attributes
----------
tag : str
Unique identifier for the heat exchanger, defaults to 'cross_flow_heat_exchanger'
coolant : Glycol_Water
Coolant properties for calculations, defaults to Glycol_Water()
air : Air
Air properties for calculations, defaults to Air()
design_heat_removed : float
Design heat removal capacity, defaults to 0.0
minimum_air_speed : float
Minimum air velocity through exchanger, defaults to 105 knots
heat_exchanger_efficiency : float
Overall heat transfer effectiveness, defaults to 0.8381
density : float
Material density in kg/m^3, defaults to 8440
thermal_conductivity : float
Material thermal conductivity in W/m.K, defaults to 121
specific_heat_capacity : float
Material specific heat in J/kg.K, defaults to 871
stack_length : float
Length of heat exchanger core, defaults to 1
stack_width : float
Width of heat exchanger core, defaults to 1
stack_height : float
Height of heat exchanger core, defaults to 1
t_w : float
Plate thickness in meters, defaults to 5e-4
t_f : float
Fin thickness in meters, defaults to 1e-4
fin_spacing_cold : float
Cold side fin spacing in meters, defaults to 2.54e-3
fin_spacing_hot : float
Hot side fin spacing in meters, defaults to 2.54e-3
fin_metal_thickness_hot : float
Hot side fin metal thickness in meters, defaults to 0.102e-3
fin_metal_thickness_cold : float
Cold side fin metal thickness in meters, defaults to 0.102e-3
fin_exposed_strip_edge_hot : float
Hot side exposed strip edge in meters, defaults to 3.175e-3
fin_exposed_strip_edge_cold : float
Cold side exposed strip edge in meters, defaults to 3.175e-3
fin_area_density_hot : float
Hot side fin area density in m^2/m^3, defaults to 2254
fin_area_density_cold : float
Cold side fin area density in m^2/m^3, defaults to 2254
finned_area_to_total_area_hot : float
Hot side fin area ratio, defaults to 0.785
finned_area_to_total_area_cold : float
Cold side fin area ratio, defaults to 0.785
coolant_hydraulic_diameter : float
Coolant passage hydraulic diameter in meters, defaults to 1.54e-3
air_hydraulic_diameter : float
Air passage hydraulic diameter in meters, defaults to 1.54e-3
fin_conductivity : float
Fin thermal conductivity in W/m.K, defaults to 121
wall_conductivity : float
Wall thermal conductivity in W/m.K, defaults to 121
Notes
-----
The cross-flow heat exchanger uses strip fins and is based on the 1/8-19.86
surface designation. The design includes:
* Liquid coolant passages with strip fins
* Air passages with strip fins
* Counter-flow arrangement for maximum effectiveness
**Assumptions**
* Coolant is 50-50 Glycol Water mixture
* Constant entrance and exit loss coefficients
* Surface designation of 1/8-19.86 with strip fins
**Definitions**
'Strip Fin'
Interrupted fin design that enhances heat transfer while reducing pressure drop
'Hydraulic Diameter'
Characteristic dimension for internal flow calculations
References
----------
[1] Kays, W.M. and London, A.L. (1998) Compact Heat Exchangers. 3rd Edition,
McGraw-Hill, New York.
See Also
--------
RCAIDE.Library.Components.Thermal_Management.Heat_Exchangers.Cryogenic_Heat_Exchanger
Alternative heat exchanger for cryogenic applications
"""
def __defaults__(self):
"""
Sets default values for the cross-flow heat exchanger attributes.
"""
self.tag = 'cross_flow_heat_exchanger'
self.coolant = Glycol_Water()
self.air = Air()
self.design_heat_removed = 0.0
self.minimum_air_speed = 105 * Units.knots
# heat exchanger: thermophysical properties
self.heat_exchanger_efficiency = 0.8381
self.density = 8440 # kg/m^3
self.thermal_conductivity = 121 # W/m.K
self.specific_heat_capacity = 871 # J/kg.K
self.stack_length = 1
self.stack_width = 1
self.stack_height = 1
self.design_air_flow_rate = None
self.design_air_inlet_pressure = None
self.design_coolant_inlet_pressure = None
# heat exchanger: geometric properties
# Plate thickness
self.t_w = 5e-4 # m
# Fin Thickness
self.t_f = 1e-4 # m
self.fin_spacing_cold = 2.54e-3 #m
self.fin_spacing_hot = 2.54e-3 #m
# Fin metal thickness
self.fin_metal_thickness_hot = 0.102e-3 #m
self.fin_metal_thickness_cold = 0.102e-3 #m
# Strip edge exposed
self.fin_exposed_strip_edge_hot = 3.175e-3 #m
self.fin_exposed_strip_edge_cold = 3.175e-3 #m
# Finned area density
self.fin_area_density_hot = 2254 # m^2/m^3
self.fin_area_density_cold = 2254 # m^2/m^3
# Ratio of finned area to total area
self.finned_area_to_total_area_hot = 0.785
self.finned_area_to_total_area_cold = 0.785
# Hydraullic Diameter
self.coolant_hydraulic_diameter = 1.54e-3 #m
self.air_hydraulic_diameter = 1.54e-3 #m
# Fin and wall Conductivity
self.fin_conductivity = 121 # W/m.K
self.wall_conductivity = 121 # W/m.K
# Fan
self.fan = Data() # Replace with RCAIDE Fan
self.fan.efficiency = 0.7
self.fan.active = True
# Pump
self.pump = Data() # Replace with RCAIDE Fan
self.pump.efficiency = 0.7
# Operating Conditions
self.percent_operation = 1.0
self.atmospheric_air_inlet_to_outlet_area_ratio = 0.5
self.duct_losses = 0.98 # Inlet, Duct and Nozzle Losses
self.fan_operation = True
# Limiting Pressure Drop
self.pressure_drop_hot = 9.05e3 #Pa
self.pressure_drop_cold = 8.79e3 #Pa
# Enterance and Exit pressure loss coefficients
self.kc_values = load_kc_values()
self.ke_values = load_ke_values()
return
[docs]
def append_operating_conditions(self, segment, coolant_line):
"""
Adds operating conditions for the heat exchanger to a mission segment.
Parameters
----------
segment : Data
Mission segment to which conditions are being added
coolant_line : Data
Cooling system flow path information
"""
append_cross_flow_heat_exchanger_conditions(self, segment, coolant_line)
return
[docs]
def append_segment_conditions(self, segment, bus, coolant_line, conditions):
"""
Adds specific segment conditions to the heat exchanger analysis.
Parameters
----------
segment : Data
Mission segment being analyzed
bus : Data
Electrical bus data
coolant_line : Data
Cooling system flow path information
conditions : Data
Operating conditions for the segment
"""
append_cross_flow_hex_segment_conditions(self, segment, bus, coolant_line, conditions)
return
[docs]
def plot_operating_conditions(self, results, coolant_line, save_filename, save_figure,
show_legend, file_type, width, height):
"""
Creates visualization plots of the heat exchanger operating conditions.
Parameters
----------
results : Data
Simulation results data
coolant_line : Data
Cooling system flow path information
save_filename : str
Path for saving the plot
save_figure : bool
Flag to save the figure
show_legend : bool
Flag to display plot legend
file_type : str
Output file format
width : float
Plot width
height : float
Plot height
"""
plot_cross_flow_heat_exchanger_conditions(self, results, coolant_line, save_filename,
save_figure, show_legend, file_type, width, height)
return
[docs]
def load_kc_values():
"""
Loads entrance loss coefficient data from file.
Returns
-------
ndarray
Array of entrance loss coefficients
"""
ospath = os.path.abspath(__file__)
separator = os.path.sep
rel_path = os.path.dirname(ospath) + separator
x = np.loadtxt(rel_path + 'rectangular_passage_Kc.csv', dtype=float,
delimiter=',', comments='Kc')
return x
[docs]
def load_ke_values():
"""
Loads exit loss coefficient data from file.
Returns
-------
ndarray
Array of exit loss coefficients
"""
ospath = os.path.abspath(__file__)
separator = os.path.sep
rel_path = os.path.dirname(ospath) + separator
x = np.loadtxt(rel_path +'rectangular_passage_Ke.csv', dtype=float,
delimiter=',', comments='Ke')
return x
