An local ice rink has a permafrost layer under the concrete slab.
I seek a rink operator's forum or equivalent, that I can join without paying money, on which to ask a question about an idea I have for removing the permafrost.
Background:
The (government-run) rink was built about 40 years ago as an refrigerated outdoor facility that stayed open for half the year. Later they enclosed the rink, and keep it open 10 months/year. This is near DC and two months should be enough to defrost the ground underneath the concrete slab, that acts as a foundation and contains the cooling pipes, to prevent frost heaves. But they stay open during the hottest part of the summer, to run a popular summer camp.
An engineering study found that there is a permafrost layer extending deep beneath the concrete slab. It would take a long time to defrost by simply turning off the rink, much longer than two months. Although the slab is said to be in very good condition for a 40 year old facility, and has no cracks, the study found it is likely to crack in 5-6 years, and that the best option was to replace the rink by a new facility on another site.
The study was performed by a company that builds rinks. In addition, the rangers at the park containing the current facility would like to use the rather nice building as their office, so it would not be surprising if they hinted that it was not essential to find the cheapest solution. (In government agencies and the government service industry, managers benefit from controlling as many employees and as large a budget as possible.) But I doubt there is fraud - I expect that the conclusions are correct, by prudent engineering standards, if the rink continues to operate in the current manner.
I have an idea. The cooling pipes must comprise an efficient heat exchanger, to freeze the ice above. So if the glycol is heated instead of cooled before being pumped into the pipes in the slab, during the two months the rink is closed, it should defrost the permafrost much more quickly than if they let it defrost passively. They would have to tap into the pipes before and after the compressor, and add a heater and a few valves.
Questions:
1. Does "glycol" means ethylene glycol, like in car radiators, and can it take fairly high temperatures? A manager said the glycol runs at 9 degrees F in normal operation.
2. How hot glycol can the the system safely take?
3. Does permafrost mean that ice has displaced the ground - in which case melting the ice would leave the slab unsupported, and it might collapse and crack? If so, is it practical and economical to pump in mud to support the slab? Or does permafrost just mean the ground water is frozen?
4. Is there anything else that could go wrong?
5. Has anyone tried this before? What were the results?