TECH Solar Thermal Storage Tank?

[Chapulin]

I'm trying to design a new solar unit and will need the Glycol solution (Thermal Fluid). Every storage tank I'm seeing has the Thermal Fluid spiral through a water storage tank.

I'm looking to store more than the Thermal Fluid in the tubing/pipes of my install and actually store the heated Thermal Fluid in its own tank. 40-65 gallons would meet my thoughts. Can I use any water storage tank for Thermal Fluid or do I need a special inside lining?

I understand thermal stratification, but if I can have a higher portion of Thermal Fluid to water, I should be able to keep higher temperatures in the system.

Comments?
Chap

 

[Warm Wisconsin]

I'm trying to design a new solar unit and will need the Glycol solution (Thermal Fluid). Every storage tank I'm seeing has the Thermal Fluid spiral through a water storage tank.

I'm looking to store more than the Thermal Fluid in the tubing/pipes of my install and actually store the heated Thermal Fluid in its own tank. 40-65 gallons would meet my thoughts. Can I use any water storage tank for Thermal Fluid or do I need a special inside lining?

I understand thermal stratification, but if I can have a higher portion of Thermal Fluid to water, I should be able to keep higher temperatures in the system.

Comments?
Chap

Look up solar thermal drain back tanks. Many of the new solar thermal systems drain back to a storage tank so they don't freeze or over heat of the pump fails. There usally cheap and there are a varity of sizes and shapes available. Otherwise there is no special lining needed if your using propylene glycol.

Edit: always have the hot come into the bottom of the tank.

 

[methos]

Prop. glycol, or ethylene glycol for hydronic systems typically contain corrosion inhibitors. They do need to be checked yearly or biannually for proper ph and inhibitor levels.

If you run straight water in a closed system, where you're not bringing in fresh water all the time, carbon steel components will last a long time. Its the oxygen in fresh water that starts the corrosion process.

There are also fold up tanks, think pool liner with insulation. Can't remember the name of the company off the top of my head, and I've seen people fabricate similar tanks themselves using pond liners, styrofoam insulation and reinforced plywood box.

Cool project, have fun and good luck.

 

[mechanic 217]

Take a look at Home Power magazine and builditsolar.com lots of good information, if you are dealing with freezing temps some of the year, a drainback system maybe the way to go IMHO

 

[Chapulin]

Thanks, good advice from the crew!
I think I finally have the fact that the Fluid is chemically stable, its the incoming fresh oxygen in the water that will corrode.

Chap