Hardware · build

A 3D-printed fridge that runs on a flame

Ben Krasnow printed a clear Einstein-Szilard absorption refrigerator in resin, heated it with an open flame, and got it 5 °C below ambient.

Build sheet

Method: Absorption, Einstein-Szilard
Heat source: Open flame
Body: 3D-printed clear resin
Result: 5 °C below ambient

Can I build this?Expert · AI 2/5 · $150–400

Difficulty: Expert
AI-buildability: 2/5
Time: A few weeks
Cost: $150–400

Parts

3D-printed clear resin body copper block perfluoropentane

Tools

3D printersoldering ironpropane torch

Starter prompt

Based on "A 3D-printed fridge that runs on a flame" on Afterware: https://afterware.xyz/p/a-3d-printed-fridge-that-runs-on-a-flame

Help me design a 3D-printable transparent Einstein-Szilard absorption refrigerator model. Give me a single internal fluid path layout for a resin body with a copper boiler block heated by a flame, and list the ammonia-water and perfluoropentane fill steps. Flag where bubbles are most likely to airlock the loop.

Estimates based on the original write-up. How AI-buildability is scored. Building with an AI assistant? Connect it to Afterware (free MCP server).

Story

Most absorption fridges need pressures a glass or plastic body can't hold. The Einstein-Szilard design sidesteps that with a third liquid as the refrigerant, so Ben Krasnow could build the whole thing in clear resin and watch the cycle run.

A copper block carries heat from an open flame into the boiler, which separates ammonia from a strong ammonia-water solution. The ammonia gas lowers the refrigerant's partial pressure so it evaporates and pulls heat away. He used nonflammable perfluoropentane instead of the usual butane, since there's a flame right next to it. The single internal path is finicky: a stray bubble in the wrong place airlocks the whole loop. He got it to 5 °C below ambient.

Copper and ammonia don't mix long term, so this is a demo, not a keeper. It's still the clearest way to see how an absorption cycle works, and the clear body means you can track every bubble.

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