[roosterk0031]

Not familiar with the salts, the one linked is for cold storage Freeze/thaw temp of 47 dF wouldn't work well for heat storage, but the latent heat of fusion of 50 btu/lb if that is the same or close for a mixture the that has a freeze/thaw of 180 would work well and obviously give 50 more btu per lbs vs the normal 1 or less btu/lb/dF. I've seen the plastic balls filled with water used inside tanks for chilled storage, I think it would have to be similar here with solid salt inside plastic balls inside a tank circulating anti-freeze to get the heat from exhaust to heat then melt the salt.

So energy wise, to get the same 1 gallon worth of LP (ignoring the antifreeze) assuming the same 140 dF delta + 50 btus latent heat of fusion we get 190 btus/lb, so it would take 481 lbs of brine balls.

Obviously we cold heat it up to 220-240 dF and store a little more heat.

Actually thinking about it now, it would probably work better to us a small liquid to liquid heat exchanger and use the engine coolant on one side and the heat storage anti-freeze on the other side. That would automatically limit max temperature to engine temperature to make controlling it easier. Not sure how to limit max temperature using the exhaust.

I wonder if those plastic bags for water storage have large enough openings to get the balls in. It would form fit to the trunk when filled up and wouldn't need an expansion tank since it's flexible.