Looking for a chemical reaction to use as a heat source

[Zoobie]

I am looking for a chemical reaction that can be used as a heat source to 'start' another reaction. I have to keep the application confidential but I hope by providing some of the criteria that I need satisfied, I may be able to get some help.

-existing reaction is initiated by an electrical source (no spark, just heat)
-reaction should be capable of producing temperatures of several hundred degrees (ie 400C) without flames or toxic/corrosive fumes (to be used in a classified area).
-an operator should be able to start and control this reaction and should be able to tranport the reactants (separately or together) on his person.
-reaction will be performed outside of a vessel
-reaction does not have to be large. All we want to do is ignite the device (main reaction).

Thanks for any help/suggestions that you may have.

 

[IRstuff]

I really don't see a benefir from using a chemical reaction.

Most reactions, once started, cannot be stopped, which means that your requirement for "control" cannot be met.

Additionally, most exothermic chemical reactions are not reversible, and you will therefore have additional waste materials to dispose of.

TTFN

 

[25362]

Have a look at

http://pubs.acs.org/cen/coverstory/8124/8124achema3.html

it may give you some ideas.

 

[Zoobie]

IRStuff:

There is benefit for using a chemical reaction if the right reaction can be found because of the peculiar nature of the application.

The intent of the application is that only a small amount of reactants will be used so the reaction will stop, providing that a secondary reaction with something in the environment does not occur. This is the extent to which control is required.

I am hoping that waste will not be a major problem as reactant mass will hopefully be on the order of several grams.

 

[IRstuff]

Most reactions strong enough to produce massive amounts of heat involve oxidation reactions, e.g., burning or combustion.

Hydrogen and oxygen.

Elemental sodium in water, OK, no oxygen required

Something rather cool, but not necessarily apropos:

http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA3/MAIN/PHOSPHO/PAGE1.HTM

from

http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA3/BOOKS/SPENCER.HTM

section 7.7 contains references to a number of exothermic reactions.

TTFN

 

[unclesyd]

About the best you can do is a thermite reaction.
Another powerful one is H2O2 + MnO2 hard to handle
Burning Magnesium ribbon is a good starting point. Depending on how it is applied a magnesium flare could supply the heat.
The standard Fusee used on the highway and railroad might work.
There are several type of ignitors for small rocket engines.
There are several used by fire bugs that use KMNO4 + a Glycol or Glycerine.

Here is company that deals in pyrotechnic products you might want to give them a call. The can probably put you on to just the thing you need.

http://www.hummelcroton.com/prod.html

If you do too much enquiry you might invite the FBI and Homeland security to your place.

 

[IRstuff]

I think he is looking for a non-destructive system ;-)

Although, I'm personally very interested in thermite... just for purely acadenic reasons, of course.

TTFN

 

[moltenmetal]

If I understand you correctly, you want 400 C temperatures in a "classified area" (presume you mean an area which is Class 1 Div 2 at least). You're already close to or above the autoignition temperature of many substances, so you're going to have to deal with that potentially combustible atmosphere a different way. If you're above the autoignition temperature, the source of the heat (electric, combustion or other chemical reaction) is irrelevant- you already have your potential source of ignition.

If all you want is a source of localized high temperatures without flame, in a form that is transportable by an operator "on his person", driven by a controllable chemical reaction, the answer is simple: a resistance heating element driven by a battery. Cheap, plentiful and much easier to control than any two-component high-temperature heat-generating flameless reaction I can imagine.

 

[Zoobie]

moltenmetal:

You have basically 'hit the nail on the head' with respect to my problem. Yes, autoignition at those temperatures is a risk and, yes, all I need is a localized heat source. The exisiting method uses a resistance heating element and a battery. Perhaps, this will ultimately be the best solution but we felt that it was worthwhile looking at alternatives.