1

Computer Assisted Induction

Aluminum Brazing

R. C. Goldstein, V. S. Nemkov, R. T. Ruffini

Centre for Induction Technology, Inc.

www.induction.org

2

Overview

• Automotive Heat Exchangers

• Pipe to Tube Brazing

• Computer Simulation of Induction Brazing

of Pipe to Tube Joints

• Optimization of Induction Coil

• Conclusions

3

Automotive Heat Exchangers

• Used for thermal

management in many

areas of the car

– Oil Coolers

– Powertrain

– Air Conditioning

– Dehumidifiers

– etc.

4

Heat Exchanger Manufacturing

• Assembling of heat exchanger bodies

• Brazing of body in a controlled atmosphere furnace

• Attachment of various components for connection to different cars

– Nylon tanks

– Aluminum pipes with connection blocks (most common)

5

Pipe to Tube Brazing

• Clamshell Inductors

– Problems with electrical contacts

– Complicated mechanical design

• “Horseshoe-Hairpin” Inductors

– Non-uniform heating in circumference

– Complicated magnetic field distribution

6

Pipe to Tube Induction Brazing Installation

using “Horseshoe-Hairpin” Coil

Connection Block

Pipe

Tube

Header

Body

Joint

Copper Coil

Fluxtrol A Magnetic

Flux Controller

7

Computer Simulation of Pipe to

Tube Brazing

• Not possible to simulate all processes due to

process complexity

• 2-D approach can not be used for

Horseshoe-Hairpin inductors

• 3-D electromagnetic simulation used to

study heat sources (most controllable factor)

8

1/4 of a Heat Exchanger Brazing

Coil

Fluxtrol A Magnetic

Flux Controller

Copper Coil

Heat Exchanger

Header

Tube

Pipe

9

Main Variables in this System

• Coil and Concentrator Dimensions

• Coil Position

• Contact in the Brazing Joint

• Coil Crossover

10

Different Crossovers

+ + . +

. . . +

11

Existing Induction Coil with

Diagonal Crossover

No Contact Good Contact

12

Existing Induction Coil with

Horizontal Crossover

No Contact Good Contact

13

Current Density Distribution for

Optimized Induction Coil

14

New Induction Coil

15

Conclusions

• Induction aluminum brazing of heat exchanger joints can be a very complicated process

• 3-D computer electromagnetic simulation provided good information regarding the heating process

• Optimized induction coil and process was more robust and produced higher quality joints

• Further study should be made using 3-D coupled electromagnetic plus thermal simulation