Heating a small fluid stream. 3

[itsmoked]

Anyone got a name or source for really small in-line electric heaters? Something in the sub 500W range for heating H₂O?

Maybe a semicon supplier, or pharmaceuticals, or lab instruments.

I'm having no luck with google, et al.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[danw2]

Onesie?

What kind of heater do these single-cup-of-coffee drip coffee makers use? Cold water resevoir, water heated which drips down through the ground coffee . . .

I've never had one apart to look at it, but you could modulate the heater, if needed, as described in that thread here not so long ago.

 

[itsmoked]

No not a onesie a manyz.

Never have torn one of those apart but that's a good idea.

Ah, here's how a coffee maker works. It doesn't help me in this case.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[IRstuff]

Can't you use a strip heater, ala Minco, or the like?

TTFN

FAQ731-376

 

[ScottyUK]

Infinity?


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If we learn from our mistakes I'm getting a great education!

 

[JimCasey]

Well there are the tankless water heaters for home use.
They sense flow and control the outlet temperature to a preset value. There IS a minimum happy flowrate, but it's pretty small.

 

[itsmoked]

IRstuff; This kind of heater has several issues. Since response is central you need fairly high power to get the show rolling quickly. The best way to get high power is just wrap a tube with Nichrome. This will do it. Except.. The Nicrome winds have to be isolated from each other and from the tube. As soon as you put something between the tube and the wire you've just hammered the response time.

If you turn to the myriad insulated heaters like Minco et al produce,(if that's what you're referring too), they use Kapton and, silicone, and various other materials for the insulation. These materials all have low temperature limits. Limits like 400F. This means you may only have a differential of 400 - 200 = 200F which doesn't lend itself to rapid energy flow.

Scotty that is by far the closest thing I've seen! Nice find. How did you find it?

If you notice the liquid heating curve at the bottom - the lowest flow is about 32oz/min. This is 10x more than I have to deal with. It's good to see the numbers off that chart!!

Keith Cress
kcress -

http://www.flaminsystems.com

 

[IRstuff]

Well, the sheet says "fast", but it looks to still be a heater wrapped around a pipe.

If you really want fast, you might think about an induction heater that puts the heat directly into the piping. I haven't found one for your specific application yet; most appear to be design to actually melt the pipe ;-)

http://www.magneforce.com/page/page/2668503.htm

This one appears to tbe smallest I've found:

http://www.ameritherm.com/PDFs/411-0050-10.pdf

It looks like it'll be dumping full power in about 10 ms.

TTFN

FAQ731-376

 

[itsmoked]

!! I was just thinking about that! You'd be having the water cool the pipe you're trying to melt. Would sure get the job done a little bulky on the power supply.

I've been told about a gas heater that was made by milling a long serpentine path into an aluminum block. The N₂ had to wend its way thru this path providing a lot of surface contact. The two faces of the heater were then heated. It apparently worked very well.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[IRstuff]

They're great for other things. A friend had them installed as cooktops in his house, and I've been to several restaurants that use portable ones for cooking hotpots on your tabletop.

Which brings me to:

http://www.sunpentown.com/srincow.html,

so if you serpentine the pipe across the cooktop, you shuold get some pretty exciting cooking. And at $175 apiece, it's not even that expensive.

TTFN

FAQ731-376

 

[IRstuff]

This one's even cheaper, at $89+free UPS ground:

http://cgi.ebay.com/BRAND-NEW-INDUC...all_Kitchen_Appliances_US?hash=item33582bcdc8

TTFN

FAQ731-376

 

[itsmoked]

Now you're starting to get my serious interest!

Keith Cress
kcress -

http://www.flaminsystems.com

 

[itsmoked]

Groan. I just realized it needs ferrous material. Not stainless. Dang.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[jmw]

Ohmic heating?
I heard about a company that uses the fluid as the heater element... but where? (It was some years ago).

JMW

http://www.ViscoAnalyser.com

 

[ScottyUK]

Keith,

It was a brochure tucked away in a drawer - a long time ago I was involved in the thick film hybrids business and it dates back to then I think. Either that or I've just picked it up at a trade show somewhere along the way and filed it with all that stuff! I'm a hoarder or things that will be useful 'eventually'.


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If we learn from our mistakes I'm getting a great education!

 

[IRstuff]

It's not clear that stainless won't work. It's an eddy-current process, and other non-ferrous metals like aluminum and copper work on those stoves.

TTFN

FAQ731-376

 

[IRstuff]

If you head to the nearest Chinese hotpot restaurant, you might be able to test it for the cost of a meal, but you might have to drive over the mountains into Silicon Valley to get to one...

TTFN

FAQ731-376

 

[ScottyUK]

Stainless will probably work, although maybe not quite as well as carbon steel. Cast iron will work too, although it has a relatively high resistivity. Anecdotal evidence (from my induction hob!) is that 18/8 stainless works pretty well, cast iron works but takes a higher setting to achieve the same results, copper gets blistering hot easily. I don't have a mild steel pan to try though


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If we learn from our mistakes I'm getting a great education!

 

[HEC]

Ohmic heating, I was dealing with a room humidifier many years ago. It had a boiler with electrodes for generating the steam for humidification, I think it was from Spirax Sarco or Honeywell, but the memory is fading now. The company or product line has probably been sold off three times too!

Mark Hutton

 

[IRstuff]

The brute force ohmic heating humidifiers were pretty horrid, after a couple of seasons. I recall having to dismantle the electrodes and cleaning them, or something. I gave up after buying another one with the same design. The hot water/steam environment wreaked havoc on the metal parts. We had a baby bottle heater that was like that; rust was everywhere after a few uses.

The fan evaporation ones ahve their own grossness. The wicks get pretty grotey after one or two seasons, and have to replaced.

TTFN

FAQ731-376