I'm researching Geothermal Heating energy and I am curious as to why hundreds to thousands of feet of coiled Polyethylene piping is preferred over perhaps a buried aluminum heat exchanger. Aluminum has great corrosion resistance (unlike copper) and thermal conductivity. In my opinion, using a well designed aluminum exchanger drastically reduces the size of the excavation needed to bury so much pipe (in a horizontally laid system), which should offset any material price increase by using a metal over a polymer. Your comments are appreciated.
Also, I'm wondering if anyone is familiar with a more passive geothermal heat exchange, using the temperature gradient in the pipeline to drive fluid motion (slowly) rather than constantly pumping the fluid. I'm sure it works somewhat in theory, but I haven't seen practical use.
Aaron A. Spearin
ASQ CSSBB
Engineering Six-S'$
"The only constant in life is change." -Bruce Lee
Also, I'm wondering if anyone is familiar with a more passive geothermal heat exchange, using the temperature gradient in the pipeline to drive fluid motion (slowly) rather than constantly pumping the fluid. I'm sure it works somewhat in theory, but I haven't seen practical use.
Aaron A. Spearin
ASQ CSSBB
Engineering Six-S'$
"The only constant in life is change." -Bruce Lee