Hi,

 

I am after some advice from you guys, it would be much appreciated....

 

I am looking for your recommendation on the best material that when placed out in the sun all day would have heated up very well and then continue to hold that heat with not much loss (or very slowly) all through the night, so that are small area could be heated Any ideas?

 

I have been looking at cast iron which seems good but to be honest it's one of the first I came across! So I thought i'd approach you guys for more expert advice,

 

You suggestions would be much appreciated and thanks in advance.

 

oh, a lightweight material would also be an advantage, thanks

big tank of water painted black would do the trick. iron has a low heat capacity and would not hold heat very long.

 

water has a high heat capacity and can hold heat longer. this is why coastal areas are hotter than inland places in the winter and colder in the summer.

Sounds good but I kind of need it to be as lightweight as possible and portable. Any other ideas?

 

Thanks for your quick reply by the way

if this isn`t possible then use Firebrick, the sort employed in electric storage heaters, they`re not Light, but lighter than Iron and also less expensive.

 

paint them Matt Black also, it`ll help.

well, the thing is, the less stuff you have, the worse it is going be at retaining heat in the manner you want. where you draw the compromise is your desicion and i don't have the details necessary to work out a good one.

 

have a look at this http://en.wikipedia.org/wiki/Storage_heater and google for it to get some more indepth links. this is basically what you want except you want a solar powered one.

excellent guys, thanks. I will do some further searches on your advice.

 

Thanks again

A solar energy architecture book I have uses river stones exposed to direct sun all day.

"Portable", cheap and with great heat mass. The spaces between a wall of them allows circulation to withdraw the there-heated air into a dwelling.

 

Miguel

A solar energy architecture book I have uses river stones exposed to direct sun all day.

"Portable", cheap and with great heat mass. The spaces between a wall of them allows circulation to withdraw the there-heated air into a dwelling.

 

Miguel

 

This seems to be quite a traditional tactic, IIRC having air in the rock is good as it has a high heat capacity, as does the rock. Although traditionally heated using a fire has been used. So paint them black and get a concave mirror or 500...

Sounds good but I kind of need it to be as lightweight as possible and portable. Any other ideas?

 

Thanks for your quick reply by the way

 

Water is still King for heat capacity for it's mass (and cost).

you could use a vacuum flask full of hot water, they weigh less than the materials used to make them and can they retain a lot of heat.

 

you could boil it at home and use it on location or modify the lid to utilise a pool heating type system, lots of black pipe and natural convection, (works both ways)