Quote:
Originally Posted by theoldwizard1
I am certain they work better than what any DIYer can make, but have you compared them to commercial available "shell and tube" or "spiral" heat exchangers.
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When I built my first unit, I started by buying the materials to make a coaxial HX. I didn't get very far along that path, when I started adding up the materials cost and realized that I was going to be very close to the cost of a BPHX, and I was not even sure what the capacity of the homemade HX would be. Then, when I projected what the cost additions might be from successive "cut and fit" iterations, and my time, it was clear to me that BPHX was the way to go.
I totally agree with jeff5may about how particulate matter in an open "pump & dump" type of system would quickly foul a BPHX... because the plates are so tightly spaced.
But I'm not so sure about a coaxial being close to the same performance of a BPHX, all other things being equal. In my opinion, BPHX are a stroke of genius when you have a closed system.
So, from the point of view of engineering, and assembly, and possibly even cost, Randen's final choice of Brazed Plate was seasoned by prudence and experience.
BTW, if you are running R290, the pressures are lower than they are for R22, R134a, R410a, etc. Therefore, lower cost, lower pressure BPHXs may fit your design criterion and budget.
-AC