Thermals Design

Owner	@Kaden Nguyen
Status	IN PROGRESS
Contributors	@Ava Schraeder @Adam Hathiyari @Niteshwar Dhillon
Decision
On this page	1 Problem statement 2 Questions to Answer 3 Solution hypothesis 4 Design Constraints/Given Architecture 5 Calculations and Scripts 6 Cold Plate Optimization 7 Radiator Optimization 8 Pump Optimization 9 Follow up 10 Source files

Problem statement

Optimized pathing/channel for tubing?
Is the pump powerful enough to support the pathing chosen above? How do we determine that?
Can our radiator dissipate heat from fluid given the chosen fans?

Area	Constraint	Reasoning

Area	Constraint	Reasoning
Nose Intakes	Double NACA cutout placements on aeroshell front	CFD by Aerodynamics optimized holes in area of highest pressure (most airflow in) Nextbreak Shell
Rear Exhausts	Double NACA cutout placements on aeroshell rear	Nextbreak Shell
Ducting	4in. Aluminum ducts	Size Constraints/interferences
Battery Ventilation	Must have exhaust Ducting	Regulations
Cold Plate	Battery base plate quarter in. thickness Round Copper Tubing 0.25in OD	>0.25in base plate is egregious, 0.25in Copper tubing OD constrained by cold plate thickness. Round tubing since no square tubing manufacturer available
Radiator/Pump	Location and tube routing	Already placed so that length is reduced Only place where pump and radiator fits properly

Name	Medium	Results	Notes

Name

Medium

Results

Notes

Kaden Battery Steady State Analysis

Matlab

Q vs. Mass Flow Rate

Conduction through plate

At conditions:

T_cell = 45; % cell surface temperature [C] (ideal)
T_plate = 35; % temperature of cold plate [C] (warm to touch, about 95F)
T_Bair = 35; % ambient temperature inside battery enclosure [C]

Results:

Steady State
- Does not account for Multiple channels and fluid temp increase further down the channels
- Static material and fluid temperatures, assumes all heat is transferred through material
- Assumes constant current draw and heat gen of 600W
Needs time step function to simulate true scenario
- very hard. Can separate tubing into smaller dx? but don’t know how to calculate heat transferred per dx
Solution is to do thermal sims
- idk how

Ava Heat Exchanger Calcs

Python

Plate thickness and tubing OD is locked in place. So the only cold plate optimization that can happen is tube pathing
Note that double channel worked better for rectangular tubing due to larger volume and surface contact
Rectangular to Circular
- 23mm → 20.3mm inner tube cross sectional area (12% decrease in water volume)
- 16.5mm → 10mm cross section contact length with base plate (40% decrease in contact area)
- Need to make up in other areas to make up for losses

		Double Channel	Six Channel	Quad Channel

	Double Channel	Six Channel	Quad Channel
Overview	Manifold Y-Split the flow into two channels. One per four segments	Manifold three way split into three channels.	Manifold four way split into four channels. One per two segments.
Screenshot	Manifold Velocity Distribution
Notes			I made one in the summer but I lost the file
Pros	Lower pressure loss within manifold	Middle ground between lower pressure loss and higher heat transfer rate	Theoretical higher heat transfer rate across shorter channels Easier pipe manufacturability, shorter channel → easier tolerancing
Cons	Lower heat transfer rate (fluid is hotter farther down longer piping)	Harder to split between eight segments to ensure uniform cooling	Inconsistent pressure loss within manifold Inconsistent flowrate into each channel
Criteria	Need to redesign y split to configure with round tubing	Need to design a four channel manifold Simming to optimize flow	Need to design a four channel manifold Lots of simming to optimize flow Takes a lot more time to design
Criteria

Due to space restriction, we are limited to a 2x120mm fan radiator setup with one intake and exhaust duct
Radiator must have copper interior to prevent galvanic corrosion between aluminum and copper
Better if we order from koolance since they’re an approved vendor

		34mm Thick, 17-FPI Copper	54mm Thick, 30-FPI Copper	34mm Thick 30-FPI Copper

	34mm Thick, 17-FPI Copper	54mm Thick, 30-FPI Copper	34mm Thick 30-FPI Copper
Overview
Screenshot
Link	https://koolance.com/hx-240yc-radiator-2-fan-120mm-17-fpi-copper	https://koolance.com/hx-240xc-radiator-2-fan-120mm-30-fpi-copper	https://koolance.com/radiator-2-fan-120mm-30-fpi-copper
Pros
Cons
Criteria	We have ordered this	We have this at pickle	Would need to order
Criteria

Must have extensive documentation especially over PWM control
Can be 12V now since pump controller has a 12v buck Rev B (a lot more options)
Current pump was selected since it was the only 24V pump with proper documentation.

Kaden’s Notes:

Plate size and tubing size is locked into place → only things we can change is pathing, which in turn dictates manifold design. We shouldn’t do less than one “loop” per two segments due to contact area already shrinking due to round tubing.
Need to decide pathing and manifold design
Other points to figure out: pump strength and radiator op

Decision	Status	Next steps

Decision	Status	Next steps
	decided / in review / other

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