Chemistry Bits

Over the years I’ve occasionally noodled on what might be a better working fluid for supercritical turbines than Carbon Dioxide. It turns out the main fixed parameter is the critical temperature, because there’s a strong nonlinearity in density with it going up rapidly as that temperature is approached. The other parameters of note are thermal conductivity, specific heat, and density, with more being better. There’s a very short list of possible fluids to mix which aren’t horribly corrosive, thermally unstable, or otherwise problematic. I’ve put together a tool to play with all the possible options here. You should go play with it. The short of it is that a mix of Neon and Perfluorobenzene tuned to the desired critical temperature is probably optimal, but if Perflueropropane’s decomposition problems aren’t too bad or Titanium Tetrachloride mixes with other things well then combining with some of those may be beneficial. This approach to visualization is probably equally applicable to…