More Thermoregulation, PLSS, and Heaters
Hey Folks! Finished work today on body thermoregulation, as well as starting on heaters for life support.
After a good night's sleep, I eventually decided on a somewhat simplified system for dealing with the body's thermoregulation. Basically, a human has a safe range of temperatures within which the body will gradually approach ideal core temperature (rate is about 15 degrees K per hour, or roughly what hospitals aim for when restoring hypothermic patients). Anything outside of that range gradually gains or loses heat based on a cubic function. The further outside of safe temperatures, the faster the core body temp changes.
It's still a function a lot like the graph I showed yesterday, except I fudged the numbers to arrive at something that would freeze a human to death in about 3 hours at 0C if they were naked. As always, there's room for tweaking later.
Once that was done, I took a brief break from code to add a Primary (or Portable) Life Support System (PLSS) to my orange EVA suit. Since we have an O2 supply, heater, cooler, and power, there's gotta be somewhere to put all that junk. So if you look at today's screenshot, you'll see it now has a PLSS backpack. I also decided to make the helmet transparent, along with a few other tweaks, so it looks a bit nicer.
After a few minor bug fixes and debugging tweaks, I moved on to my next system: heating.
The spaceship's rooms are going to need thermal regulation, too, since we won't be in EVA suits all the time. So that means something to heat and cool. Initially, I was going to delve into specific heats, conduction, radiation, and try to tie it all together. But thermodynamics is a fairly complex topic, and trying to do too much at once is likely to fail.
So for now, I'm sticking with a simple space heater similar to a radiator. It allows me to setup something that'll work in an HVAC system, as well as model things like body heat and fires affecting room temperature.
Heat is expressed in Watts, much like you'd see on a consumer heater. And then I use a fairly simple equation with molar specific heat to get delta-T for the room's gas. Then, any item with a stat for heat output gets this heater component added, and voila! The room gets warmer when it's there.
However, there are still some kinks to sort out.
For one thing, I had to adjust the heat output for the volume of the room. Since not all gas molecules are in contact with the heater at once, I had to scale down the heating effects based on the size of the heater compared to the room. A heater in a tiny box will heat the air faster than in a cavernous room, assuming the same number of moles in each container.
It seems to work for rooms now, but I'm seeing some weird effects still in the EVA suit. The wearer's body heat is superheating the air in the suit. So it appears I still have a bug in the code.
Hopefully, though, once this is sorted out, we'll be a step closer to a complete life support system. Both on ships and in EVA suits!