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nzjetboating.com Forums => Engines => Tech Library => Cooling System => Topic started by: callan FNQ on October 21, 2013, 17:43:27 PM

Title: heat exchanger - pipe expander tool
Post by: callan FNQ on October 21, 2013, 17:43:27 PM

hi guys,
has anyone used rolling tube expanders when building their heat exchangers ?
have a look at the youtube link,
http://www.youtube.com/watch?v=LsfRQGm4-Lc (http://www.youtube.com/watch?v=LsfRQGm4-Lc)


I was considering building a multi tube exchanger similar to the run of the mill mercuiser/savage units,
probably in 100mm stainless pipe, around 600mm long.

I am worried our warm waters in FNQ wont keep up with the single long 20mm inner/ 40mm outer copper pipe style heat exchangers used in NZ.

I'm happy to be proven otherwise though if anyone has experience with heat exchangers in warmer waters.
my motor is a twin turbo subaru ej20.

also, what would one consider to be the smallest pipe diameter to use ?
3/8th has an ID of 7.5mm
1/2 " has an ID of 10.7mm
both ends of the exchanger will be able to be removed for cleaning should there be a blockage.
I am also running a sand trap before the exchanger.

the pipe expanding tool makes neat work of building an exchanger, bar the outlay for a tool that will be lucky to be used again.

open to your thoughts.

thanks.






Title: Re: heat exchanger - pipe expander tool
Post by: Paul on October 21, 2013, 18:06:35 PM
Stainless is:
- abysmal for heat transfer rate;
- work hardens then cracks;
- is many times more difficult to work than copper\brass.
Title: Re: heat exchanger - pipe expander tool
Post by: callan FNQ on October 21, 2013, 18:11:18 PM
sorry paul i didnt explain myself clearly.

my intention was to use copper pipe for the heat exchanger tubes,
the stainless outer was just for presentation.
Title: Re: heat exchanger - pipe expander tool
Post by: Hacky on October 21, 2013, 18:26:15 PM
Have you considered putting a vane at the start of the copper pipes to start the water spiralling to improve the heat transfer.
Title: Re: heat exchanger - pipe expander tool
Post by: Matthewf/Norbert/TuiDog on October 21, 2013, 18:35:34 PM
20/40mm tube works fine. just go 20% longer
Title: Re: heat exchanger - pipe expander tool
Post by: Tones on October 21, 2013, 19:20:40 PM
I have boated in 30C surface water temp with a Mercruiser heat X on a 350 Chev with no problems.
Title: Re: heat exchanger - pipe expander tool
Post by: callan FNQ on October 22, 2013, 11:05:54 AM
thanks for the responses fellas.