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View Full Version : Chemical heaters, what temperatures?



Canotila
11-24-2009, 03:04 PM
I need a way to generate heat sufficient for cooking or boiling water without open flame or combustion of any type. If it doesn't consume oxygen, that is ideal.

One method that seems like it may work extremely well is the oxidation reaction used in the heater pouch for MREs, with magnesium, iron and sodium chloride.

My only problem with that is the highest temperature I have found that it reaches is 178 F. Would it possible to reach an even higher temperature if a larger quantity than MRE pouches contain is used? Or is that top range overall?

If that is the top range, is there another fairly harmless chemical reaction that could be used to produce enough heat to cook with?

Thanks for reading this, I appreciate it.

Tsu Dho Nimh
11-24-2009, 08:17 PM
Electricity?

The quantity of reactants and the kind of heating vessel counts.

Canotila
11-24-2009, 10:26 PM
Electricity?

The quantity of reactants and the kind of heating vessel counts.

Thanks, I'll look into increasing the quantity. This may involves some hands on research, via several MRE heaters combined and an oven thermometer, heh heh.

It's a fantasy setting. They don't have electricity, and this particular people doesn't have a magical means of generating heat. They do have fairly advanced chemistry and alchemy though, I'm trying to keep their chemistry as true to real life as possible.

MAP
11-25-2009, 12:24 AM
What about a primitive battery? If the society is fairly advanced chemistry, I don't see why they wouldn't discover batteries since they are just an oxidation-reduction reactions connected by a wire.

Alternatively, you can google exothermic chemical reactions to find one that would work for you, but I would just use a battery. I am not sure if I would buy an advanced chemistry world that didn't have some form of electricity.

Canotila
11-25-2009, 12:55 AM
What about a primitive battery? If the society is fairly advanced chemistry, I don't see why they wouldn't discover batteries since they are just an oxidation-reduction reactions connected by a wire.

Alternatively, you can google exothermic chemical reactions to find one that would work for you, but I would just use a battery. I am not sure if I would buy an advanced chemistry world that didn't have some form of electricity.

A battery might work, and they are definitely advanced enough to know about the reactions. The main obstacle I foresee is obtaining enough acid to make enough batteries for everyone to do stuff like cook, heat water, etc. I think primitive batteries used grape juice? What would be some types of acid that would be more plentiful? It seemed like water + sodium chloride + iron/magnesium alloy would be something easy to supply and produce.

Also, they don't have access to rubber for wire insulation which only leaves glass, which is fragile and limiting.

It's not so much the whole world as it's a very isolated culture within the bigger world. There are about 2,000 people living there, they're the descendants of refugees and have been there about 300 years. They have to trade for the bulk of their food, fiber for clothing, etc. Their only commodity is metals and minerals, the land they live in has water and they are pretty much unable to produce anything else so anything else has to be traded for. This creates a lot of problems for them in the story, as trade/supply is disrupted by wars in outlying lands.

benbradley
11-25-2009, 01:44 AM
You must be a reason for not having an open flame, and it makes me curious.

A battery might work, and they are definitely advanced enough to know about the reactions. The main obstacle I foresee is obtaining enough acid to make enough batteries for everyone to do stuff like cook, heat water, etc. I think primitive batteries used grape juice? What would be some types of acid that would be more plentiful? It seemed like water + sodium chloride + iron/magnesium alloy would be something easy to supply and produce.

Also, they don't have access to rubber for wire insulation which only leaves glass, which is fragile and limiting.
If they know how batteries work, they surely know that it's not as efficient as a direct chemical reaction to produce heat. I think even with heat made directly from chemical reactions, it may be a lot of effort to get enough of the right chemicals for cooking.

It's not so much the whole world as it's a very isolated culture within the bigger world. There are about 2,000 people living there, they're the descendants of refugees and have been there about 300 years. They have to trade for the bulk of their food, fiber for clothing, etc. Their only commodity is metals and minerals, the land they live in has water and they are pretty much unable to produce anything else so anything else has to be traded for. This creates a lot of problems for them in the story, as trade/supply is disrupted by wars in outlying lands.
What about a non-chemical source of heat? Do they have a reasonable amount of sunligjht? I'm thinking they could have parabolic mirrors to heat their food with sunlight. These might be costly for them but metal mirrors would be durable and easily cleaned.

Canotila
11-25-2009, 02:35 AM
You must be a reason for not having an open flame, and it makes me curious.

If they know how batteries work, they surely know that it's not as efficient as a direct chemical reaction to produce heat. I think even with heat made directly from chemical reactions, it may be a lot of effort to get enough of the right chemicals for cooking.

What about a non-chemical source of heat? Do they have a reasonable amount of sunligjht? I'm thinking they could have parabolic mirrors to heat their food with sunlight. These might be costly for them but metal mirrors would be durable and easily cleaned.

They take refuge inside a glacier for the worst parts of the year, and they're pretty far north so that is 2.5 out of 4 seasons. The structures carved out inside are carefully engineered with ventilation ducts for good airflow, so there's a standing ban on anything that might unnecessarily consume oxygen or pollute the air.

The mirrors are a good idea, that would work for the summer months for sure. I think a lot of the food they stockpile for the winter might have to be things like cold salt fish (bleh, ha ha).

RobinGBrown
11-25-2009, 12:36 PM
Also, they don't have access to rubber for wire insulation which only leaves glass, which is fragile and limiting.

I'm afraid you've got a possible logical flaw in there:

How do they manage to make glass but can't heat water?

AFAIK glass is made from sand that is melted at a very high temperature, either over an open fire or in a kiln that would logically have to use some sort of burning fuel or other method of attaining a very high temperature.

If they have the tech for making glass they _must_ also have the tech for boiling water.

Canotila
11-25-2009, 09:11 PM
I'm afraid you've got a possible logical flaw in there:

How do they manage to make glass but can't heat water?

AFAIK glass is made from sand that is melted at a very high temperature, either over an open fire or in a kiln that would logically have to use some sort of burning fuel or other method of attaining a very high temperature.

If they have the tech for making glass they _must_ also have the tech for boiling water.

Glass blowing/smelting metal/ore etc. is done above ground in the summer when everything isn't buried in snow and fuel is available. They can't have open flame inside the glacier in the winter, it would consume too much oxygen and mess up air quality if everyone was heating their own water on open flame.

Mike Martyn
11-26-2009, 03:17 AM
Since heat is the issue here's a question. If they are living inside a glacier, which has to be significantly below freezing otherwise it would thaw, how do they keep themselves warm?

icerose
11-26-2009, 03:41 AM
What about using the concept of an igloo on a larger scale? As in your converted glacier. How do those who build igloos melt their water, heat the igloo and cook their food? That research might just answer your dilemna.

All else fails this is a fantasy, you could have a unique fuel or flame or whatever to their world that fits your properties.

Canotila
11-26-2009, 04:33 AM
From what I understand the Inuit people (igloo dwellers) had a strictly carnivorous diet in the wintertime of raw seal and raw whale so they didn't cook their food. Which means I might have to go the salt fish route with them if I can't come up with a cheap enough heat source to cook for 2,000 people.

Their igloos were either heated by body heat alone, or they used oil lamps and burned whale/seal blubber in them which is also how they melted snow for drinking water. Therein is my problem again, these people don't have access to large quantities of burning fuel, and if they did their winter dwellings are not directly on the surface so venting large amounts of smoke outside isn't feasible, and the oxygen consumption problem again.

The inside of glaciers is not that cold. When you get inside, it's right at 32 F. That's pretty manageable with warm clothing. Closer to the surface in winter, it's going to be colder but the deeper inside the warmer it is. A lot of glaciers are melted water/slush on the very bottoms where they touch the ground.

RJK
11-26-2009, 08:05 PM
Wouldn't a glacier be unstable? I could see burrowing into an icecap, but a glacier flows, slowly, I admit, but it would still be unstable, opening and closing fissures. I don't think I'd set up any long term stays in one.

cbenoi1
11-26-2009, 09:48 PM
> {...} for 2,000 people

That's a lot of calories being burned right there, even if they do nothing but sleep all day. Consider that in the cramped space of a modern jet airplane, the temperature rises rapidly when the A/C is turned off. We're talking 200kW (or about 1M BTU/hr) or more just to blow cold air through an Airbus 330. The net net is that with 2K people (about 10x what you normally cram in an airplane), your glacier is melting from the inside out. Fast.

> Wouldn't a glacier be unstable?

Good point. Glaciers move between 1m ot 30m per day. After 2.5 seasons (~225 days), the inhabitat would have moved between 225m and 6.75 Km away from its origin, notwithstanding the huge deformations it would have endured.

-cb

blacbird
11-27-2009, 12:27 AM
Wouldn't a glacier be unstable? I could see burrowing into an icecap, but a glacier flows, slowly, I admit, but it would still be unstable, opening and closing fissures. I don't think I'd set up any long term stays in one.

Icecaps flow, too. Lots of research on this from Greenland and Antarctica. In Antarctica, they have a hell of a time keeping infrastructure from being consumed by the ice.

caw