dry ice – A DIY effort shows how low-pressure CO2 can be cooled into puck-like dry-ice blocks, using a specialized cryocooler and gas processing steps.
Cold has a way of turning curiosity into experimentation, and one recent project leans into that impulse: making large, block-like CO2 “dry ice” using low-pressure gas and a custom cooling setup.
The maker argues that the usual term “dry ice” can be misleading for what most people end up producing.. Instead of true solid CO2 blocks in the strictest sense. the material can behave more like very tightly compressed “dry snow.” In this approach. the goal is to push the process far enough that the output shifts from fluffy compressed dry ice toward more solid-looking ice pucks or cubes.
To begin, the CO2 has to be chilled in a pressure chamber before it can deposit as ice.. The project uses a Joule-Thomson cryocooler cooled with a mixed refrigerant stream: 15% butane, 35% propane, and 50% ethylene.. That mix is part of what allows cooling to proceed efficiently for the task at hand. even though not all components are easy or affordable to obtain in everyday quantities.
Ethylene is singled out as the difficult-to-source ingredient.. Rather than relying on purchased ethylene, the maker describes generating it themselves from ethanol.. The method involves boiling ethanol and then using aluminum oxide at roughly 400°C to capture the ethylene produced in the process.. It is a chemical preparation step layered on top of an already demanding engineering challenge: producing cryogenic conditions with the right gases and temperatures.
With the pressure chamber cooled in a refrigerated bath. the project then moves into the moment of opening and checking results.. The time required for the deposition step is described as relatively short once the system is properly chilled. suggesting the key hurdle is getting the cooling stage working consistently rather than waiting for an extended reaction.
When the pressure chamber was opened, the output showed mixed formation patterns.. Along the sides of the chamber—where the metal surface is closest—the CO2 formed definite ice.. Toward the center. the material increasingly resembled the familiar fluffy. compressed dry ice many people associate with CO2 cooling and storage.
That difference across the chamber is an important clue.. It indicates the process can produce the desired phase more reliably near surfaces that provide better conditions for solid deposition. while the central region may be experiencing conditions that favor the softer. snow-like result.. For anyone attempting to scale up or improve the yield. this kind of spatial pattern can point directly to where insulation. flow conditions. thermal contact. or pressure uniformity may need adjustment.
The overall outcome is still described as encouraging.. The maker interprets the results as proof that it is possible to create ice pucks or cubes using this low-pressure CO2 approach.. At the same time. the method is not presented as fully optimized. with the next step being refinement to produce more ice overall and reduce the share that remains “snow” rather than block-like solid.
If you want to see the process in action, the project includes a video walkthrough embedded with the experiment, showing the setup and the results after the chamber is opened.
dry ice blocks low pressure CO2 Joule-Thomson cryocooler CO2 cooling cryogenics DIY ethylene from ethanol