Subject: Re: Help creating a heating element from resistor.
Date: Tue, 10 Dec 2002 01:02:42 +0000 (UTC)
NNTP-Posting-Date: Tue, 10 Dec 2002 01:02:42 +0000 (UTC)
User-Agent: tin/1.5.14-20020926 ("Soil") (UNIX) (Linux/2.4.19 (i686))
Sam Nichols wrote:
> In article ,
>> Sam wrote:
>> > In article ,
>> > "George R. Gonzalez" wrote:
>> >> "Sam" wrote in message
>> >> news:sizam-6B65B5.firstname.lastname@example.org...
>> >> > Hello,
>> >> > I'd like to create a small heating element running on as low a
>> >> > voltage/current as possible and heats up to about 250 deg C. I'd like
>> >> > to pump a fluid over it and have that fluid vaporize.
>> >> We need a bit more info. How much fluid do you want to vaporize
>> >> per unit time? What's the heat capacity of the fluid? What is its
>> >> boiling point temperature? What is its heat of vaporization?
>> >> Witht hat info we can calculate how many watts is required.
>> > I'm not quite sure what the flow rate will be yet, pretty low, I'll be
>> > using as small a pump as possible. Everything togeather should weigh
>> > 3oz or less and another 2oz of liquid, the 3oz includes a battery to run
>> > this on. The fluid is oil, don't konw what the heat capacity is, flash
>> > point is 240 deg F, API gravity is 38.3. I was looking at a site that
>> > carries Nichrome wire and they had some tables to help figure out what
>> > you need (http://www.wiretron.com/nicrdat.html). It looks like if I
>> > used AWG 40 wire I could get by with only needing to generate about 8
>> > watts which I could get from 2 1.2V batteries at 3 amps. Is Nichrome
>> > more efficient at generating heat from electricity then a resistor?
>> Why do you want to evaporate oil?
>> Off-hand, I'd say it's not going to happen, as the battery would be
>> too heavy.
> Sure it could happen, I have 1000 mAh NiMhs that weigh 0.75 oz each,
> which leaves 1.5 oz for a pump which will be mostly plastic and a tiny
> motor, and some Nichrome wire which seems like it'll weigh close to
> nothing. I guess it might be closer to 4 oz which could still work. I
> want to vaporize oil for a tiny smoke machine.
> Anybody know a place that carries Nichrome in the Bay Area?
Oh, it'll work.
I'm just unsure as to for how many seconds.
My gut says there is no way in hell you'r going to get enough energy from
a battery that small to vapourise three times it's weight in oil.
However, numbers are good.
The first fog generator numbers I found were 20Kw evaporating 40l/hour,
or 1Kw=2l/h. Maybe 1Kw/Kg/h.
So, 60g of oil...
Say you want to use it all in 6 mins.
So, you need a power source of 600W.
That AA cell won't supply 500A, and it certainly won't do it for
The energy in an AA cell is about a watt hour, so you can evaporate a
whole gram of fog. The oil container won't need to be very big.
It'll produce about 20 cubic feet of fog a minute for 6 minutes.
http://inquisitor.i.am/ | mailto:email@example.com | Ian Stirling.
If it can't be expressed in figures, it is not science, it is opinion.
-- Robert A Heinlein.