Concrete heat accumulator for a tent

[camper]

Hello,

I am looking to make a camping heat accumulator that will charge during the day, keep it at night, then restore heat in the morning when I wake up. But I lack the data to do tests and prototypes.

To avoid having to manage liquids, I would like to make the accumulator if possible by pouring concrete into a polystyrene case with crosslinking to pass an air flow at low speed with a fan. The heating system could simply be aluminum can panels.

The need would be to add 5 ° to 10 ° to the volume of the tent (2m3 of air) in 15 minutes of heating and maintain it for about 30 minutes.
But I don't see how to calculate the crosslinking, the volume of concrete or the power of the fan to manage the air flow.

Thank you in advance to everyone who can help me.

[Ahmed]

As a first approach, the use of concrete in nomadic use appears contraindicated, moreover its storage capacity remains low, relative to the weight.
Maybe a phase change body would better meet the requirements of this specific job?

[Christophe]

Yes or even simpler because it is available everywhere: use water with a specific thermal capacity greater than that of concrete!

[Gaston]

To give an order of magnitude:

The specific heat of the air is approximately 1000 J / (kg.K)
2m3 of air represents a mass of around 2,4 kg
To heat 2m3 of air from 10 °, you therefore need: 2,4 * 1000 * 10 = 24000 J.

The specific heat of the concrete is 880 J / (kg.K).
If we assume that the temperature delta of the concrete mass is 5 ° (by cooling it from 30 to 25 ° for example), it will therefore be necessary 24000 / (880 * 5) = 5,4 kg of concrete.

Obviously, this is only valid in a perfectly isolated enclosure.
In a tent, as soon as the indoor air starts to heat up, the losses through the walls of the tent increase and the energy required to only maintain the temperature in the tent increases.

In practice, I think you have to rely on a minimum of 20 kg of concrete for the heating system to work.

Then you have to ask yourself the question of daily heating of the concrete block (how to heat it to 30 ° on days when there is no sun, for example, what insulation to keep the block warm throughout the night, .. .?)

[camper]

Thank you for your calculations and advice!

The device would be an aid from the campsite (mine) made available to campers. Sorry I did not specify. So it doesn't have to be nomadic and I would like not to have to deal with water leakage problems if possible. If that proves impossible, we will do it with water.

For the polystyrene box, I thought of a fish-style box 3cm thick which would have two outlets: one to the outside pipe to the heating system and the other to the inside. Both can be plugged overnight. But I don't know if that would be enough.

Then if there was no bcp of sun the previous afternoon, simply there is no heating in the morning.

Indeed it would be oversized to compensate for the losses of the tent to the outside. Do you know how to calculate the theoretical crosslinking in an almost square volume of concrete so that energy can be taken from concrete quickly?

We look forward to seeing you!

[A.D. 44]

Hello,

I'm looking to make a heat accumulator camping

I would like if possible to make the accumulator while running concrete in a polystyrene case

It will be untransportable !!!

concrete weight: 2.3 T per m3.

just an 85L case (or a good big backpack, with a capacity all in all not so rare), there would be 200kg !!! Who to move something like that?

You have to be at least 4 strong fellows with the risk of farting your back and ruining your hands as a bonus ... Not to mention the car that will make the face when you have succeeded (by shitting hat circles) to climb the baby in the trunk. And then bike !!! ??? !!!

A priori, it doesn't seem very in line with the principle of camping!

[AXEAU]

Hello camper, at school we stuck to the radiator because the class was cold. For a tent that is not insulated, it must be placed above the concrete slab. the campers will be warm all the night being in contact directly but in summer period it will be necessary to plant it beside.

jlg

[camper]

Hello,

Thank you for your suggestions.

In fact, I specified my request in the following message. The system does not have to be transportable, that's why we allow ourselves to do it in concrete. The need is to restore the heat in the morning on waking, not overnight.

What I would need is to know how to do the calculations to size the solar collection system (black pipe panel, aluminum cans, small fan?) And that of restitution in the morning.

We look forward to seeing you!