A Reddit Refugee. Zero ragrets.

Engineer, permanent pirate, lover of all things mechanical and on wheels

moved here from lemmy.one because there are no active admins on that instance.

  • 13 Posts
  • 394 Comments
Joined 1 year ago
cake
Cake day: December 22nd, 2023

help-circle













  • “Yes” with the asterisk that there is no phase change, and the flow paths are segregated.

    In a heat pipe, water is installed such that it is kept near it’s liquid-gas phase change point on the pressure-temperature curve. When heated, it turns to “steam”, travels thru the center of the pipe, condenses back to liquid on the cold/fins side (giving off all it’s heat), then returns via capillary action on the metal foam walls of the pipe.

    In a thermosiphon, the water never leaves the liquid phase. It simply relies on the density change based on temperature (hot water becomes less dense, and will rise to the top of a column) to force some circulation to occur. The hot fluid rises out of the heatsink and displaces the cooled water in the radiator, which then flows down the other side to return to the heatsink.

    Very old cars (<1920) used to rely entirely upon the thermosiphon effect, rather than a pump.
    It’s not terribly efficient, especially at higher dissipated power densities. They are also very prone to being overloaded with heat, if the overall loop temperature gets too high and/or the radiator loses some efficiency (e.g clogged with dust), the water can start to boil on the hot plate side and you’ll lose basically all cooling effect when your siphon is blocked with steam.





  • Oregon does all commercial vehicles based on weight-mile-axle taxes. More weight, more axles, more miles, all increase the tax burden proportionally. Then you buy PUC credited diesel with no state gas tax. Works fine and can be extended to electric vehicles fine.

    The issue I’ll take with it is the filing and monitoring system they’ll try to make private citizens do, which options are limited to either direct government GPS tracking (fuckkkk no) or an inefficient bureaucratic hellhole of odometer pictures (will cost additional tens of millions to administer). The Oregon system works fine because commercial vehicles are fairly strictly regulated, but that will break down with the general public.