Hi all, is this project still active? I really would like to work on it, there are tons of applications, how hot can be the water generated by a geothermal heat pump?

Hi all, is this project still active? I really would like to work on it, there are tons of applications, how hot can be the water generated by a geothermal heat pump?

How common and deep are these hot water sources, and how do you get enough thermally conductive tubing into one to generate enough heat transfer to the cold side?

Hi, in that case we are not speaking of usual 90°C hot sources from at least 100m depth, but a constant temperature differential of between 5°C and 10°C to allow convection of a propylene based heat exchange fluid for direct stirling coupling

If we account that common soil-air heatpumps usually rely on ~15°C for a drilling depth of 20~30m, drilling 50m~100m more for the 5~10°C differential would cost less than the equivalent photovoltaic setup... added bonus if you have a hot water vein under your property

As those heat exchangers are already widely spread for common soil heatpumps the components should be readily available, and only mid-scale installations (more than 15kW) would require larger heat exchangers in my opinion

I currently have no means of testing or whatsoever so I cannot give more arguments, but discussions with a friend whose field is geothermy and geology gave me the few pointers that let me say it should be viable in many places

Currently looking for pointers on which existing stirling engine or model scale 2 stroke explosion engine would cope with propylene glycol as moving fluid... I would like, if possible and lower enough costs, to construct a hundred watt stirling engine to test heat exchanger topologies (series or parallels)

Next steps: draw figures, think numbers and delta T

Once that done, designing two constant temperature water cabins, and feed a scale model stirling engine for feasability!

Seriously great project idea. I would bet this has potential to place in the contest

This project is for inspiring other people,

This is evident that I do not have a giant drill in my attic nor enough spare plumbing to make fancy heat exchangers, so please be free to inspire of this project as long as you credit the idea ;)