This is the 2D cutaway counterpart to the 3D orbiting-camera version. Instead of a rendered scene you get the drum drawn in schematic cross-section — drag it to tilt and rotate — plus three data panels that make the governing physics legible directly: a g-force dial, the Clausius–Clapeyron boiling curve, and a live compressor/vacuum-pump energy breakdown. A real closed-loop habitat's Water Recovery System does not just boil wastewater — that would spend roughly 2260 kJ per kilogram of water evaporated (its latent heat). Instead a Vapor Compression Distillation (VCD) drum spins the wastewater into a thin liquid film against its wall using centrifugal force (needed because there is no buoyancy-driven boiling in microgravity), boils it under vacuum at low temperature, then mechanically re-compresses the vapor and condenses it against the still-boiling liquid — reusing almost all of that latent heat as the actual boiler heat source.
Boiling point at pressure P (Clausius-Clapeyron):
1/T(P) = 1/T_ref - (R / L)*ln(P / P_ref)
T_ref = 373.15 K, P_ref = 101.325 kPa, L = 2260 kJ/kg, R = 0.4615 kJ/(kg*K)
Specific energy (compressor + vacuum pump only, latent heat is recycled):
E = c_p,vapor * dT_transfer / eta_comp + k_vac * ln(P_ref / P)
Drum g-force at radius r: g = omega^2 * r / 9.81, omega = 2*pi*RPM/60
Concentration factor & recovery:
CF = feed processed / brine remaining
recovery R = 1 - 1/CF (bounded by the CF limit before scaling risk forces a canister purge)
Fix applied vs. the 3D source: its own flavour text says the drum needs "roughly 2-3g at the wall" to separate cleanly, but it computed g-force with a 0.14 m physical radius — at its own RPM_MIN_G (260 RPM) that formula gives ~10.6g, not 2-3g, and ~42g at RPM_FULL_G (520 RPM). A standalone numerical check (Node, not shipped) confirmed the mismatch. This 2D version uses a corrected radius (~0.033 m) that actually reproduces 2-3g in the 260-520 RPM band the UI describes, so the g-force dial and the text agree.
- Feed rate — how fast wastewater (urine + humidity condensate) enters the drum; sets how quickly particles move through the loop.
- Drum speed — the RPM of the centrifuge. Real ISS-style units need roughly 2-3 g at the drum wall for the liquid film to separate cleanly from the vapor; drop below that and liquid gets entrained into the vapor stream, degrading recovery and product quality. Drag the drum panel to tilt/rotate the view of the spinning film.
- Cabin/boiler pressure — a deeper vacuum lowers the boiling point (Clausius–Clapeyron above) but costs more vacuum-pump energy, so specific energy is a trade-off, not monotonic in one direction — watch the stacked energy panel invert as you sweep the slider.
- Max concentration factor — how far the brine is allowed to concentrate before mineral scaling risks clogging the drum; hit the limit and the canister purges, resetting the concentrate.
Real hardware (ISS's UPA/WPA and the newer Brine Processor Assembly) pushes overall water recovery from wastewater into the high-80s to mid-90s percent — this model uses the same governing relationships at a simplified, visually-legible scale.