high pressure inline electric water heater

[knighty]

pressure washer at work runs on hot water, max 80'C input temperature

and it works great, but I'd like to go a bit hotter if I can

trying to avoid a diesel heater because of the mess/fumes/flue etc.

big 3 phase supply so I can power a big heating element.... but I can't find any made for the pressure, runs about 2600psi but peaks to about 3000psi as the trigger is pulled/let off


anyone have any ideas?

I could have a coil if pipe inside a fluid and heat that... but then I have time lag of it warming up, and then the problem of when we turn the pump off the water pressure in the pipe would fall and the water could boil?


trying to keep things simple too

[countrypaul]

If the hot water could pass through a steel pipe, could you use an induction heater on the pipe? No idea if you can get big induction heaters or howwell it would work - but seems to fit the idea of being simple for an out of box idea.

Something like : https://www.stanelcorftechnologies.com/induction-technology/

Might be a little expensive I suppose...

[knighty]

I was thinking about an induction heater...

I bought a 2kw on ebay cheap to play with but never took it out of the box


there's lots of plans for them online to be built really big for using in a furnace etc.


I wonder how far apart the coper coils can be stretched so the heat isn't all in once place?


just bow thought, I wonder if I could do a pipe in a pipe style heat exchanger, have the water go down the outside double back and the end and back down the middle.... that way there's more pipe/steel/surface area.... induction heater should heat both at the same time?

[countrypaul]

Why make the pumbing compicated? If you use a slightly larger pipe and put some steel rods fastened in it would that not give you the additional steel/surface area?  Using several coils  rather than one large or stretched one might give you some redundancy in case one fails.

What flow rate are you using, and how hot do you want to go?

[knighty]

yes, a rod might be easier

I'm not sure how the length of the coils or how tightly they're wound effects how well an induction heater works... would be best to spread the heat out as much as possible....  maybe have a few winds then a straight to the next few coils, on and on like that?

it's 23litres/min,  start temp is @80'C

as hot as possible really... I think I'll be limited by other factors long before I'm limited by max temp - plenty of diesel fired steam cleaners go to 160'C and above

realistically 120'C would be just nice


I'll have to set up a system to dump hot water for a little while after the pump off button is pressed.... to stop water boiling in the system if the flow stopped inside the hot pipe

[countrypaul]

23L/min increasing from 80 to 120C looks as though it would require about 65KW (+ losses) - so multple heaters might well be appropriate especilly if you want to space them out along a pipe. Looks like close spacing of the turns in a coil is required. Check out: https://sg-induction.com/wp-content/uploads/2021/03/Coil-Design-Induttore.pdf for clearer explanations (the first such document I found).

[knighty]

reading the coil info, almost all of the heat/energy goes to the center of the coils... so if I have a pipe with a rod up the center the rod should take most of the heat - that's a load off my mind because I was worried about the pipe getting too hot and making it weak

I'll see if I can build a little one first, have a bit of practice with that :-)