saltxbattery for heating a tub (outdoors)  

(@tobias)
Active Member

Hi!

Wouldn't it be alot easier to heat a outdoor tub (1500 l) of water with a saltx battery than using wood as fuel? You just add your battery to the water and lets it do its job for a couple of hours. It would be alot easier to insulate the tub since theres is no fire and no maintainence during heatup. I did some calucalation and it seems more complicated than I imagined. It depends on how fast and how much (degrees) you want to heat the tub, the tubs insulation (heat loss),  volume of water and the energy density of the salt.

One calculation was 150 litres of salt and the other one was 33 litres. After that I accepted my lack of knowledge...Maybe someone thats actully good at this and like to play around with numbers can calculate the volume of saltx needed. 😛

Have a good day! /Tobias

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Posted : 24/08/2018 9:59 am
(@liudasmikal)
Admin

Hi @tobias! Very good application indeed! I might add that on top of all the benefits listed you can also heat the water much more rapidly than with wood. I would say that with the right salt you could have a hot water tub in 20 minutes.

Now going to the calculations it really depends on how large your water tub is and what is the temperature difference you're trying to achieve.

Just for the sake of interest - an average hot tub holds about 1500 liters of water. Let's say we need to raise the temperature from 0C to 70C. What I found online - it takes about 1.16kWh to raise 100l by 10 degrees. Then it would take 8.16kWh to raise 100l by 70 degrees. Lastly, to calculate for the whole volume - it takes about 123kWh to heat 1500 liters.
SaltX salts have about 400 kWh/m3 energy density. So you would need about 0.3 cubic meters or about 300 liters of pure salt. The whole installation with heat exchangers will take more space than that though.

If you decide to manufacture this as a business partner, you could buy salt for about 2-5EUR per liter which would make the material costs of about 600EUR/6000SEK per one rapid hot tub heater.

Now that I did the calculations - I will make this the case of the week sometime in the future.

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Posted : 24/08/2018 2:08 pm
(@tobias)
Active Member

hehe good! 🙂 I think you only need to heat the water to around 40 degrees but then you got the heatloss + duration (to keep the water hot for a prolonged time). So I guess having the extra kWh charged is good.

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Posted : 24/08/2018 7:32 pm
(@liudasmikal)
Admin

Yes, I think the finished product will have to have extra kWh because it's never known from what temperature one needs to heat the water.

Also, I think that for maintaining the temperature electricity connection will be needed because there are too many variables. The salt will need to be recharged with electricity anyway so it's best to have the temperature maintenance done with it as well.

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Posted : 26/08/2018 10:37 am
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