A phase-change slurry (PCS) is a carrier fluid — here water — loaded with microencapsulated phase-change-material (PCM) beads. As the slurry absorbs heat along a pipe, the beads don't just warm up: they melt across a narrow temperature band, storing energy as latent heat instead of raising temperature. That lets the same pipe carry far more thermal energy per °C of temperature rise than a single-phase fluid at the same flow rate — the working principle behind PCM slurry district-cooling and electronics-cooling loops.
This sim solves the steady 1-D energy balance along the pipe. With mass flow rate ṁ and wall heat flux per unit length q′, the mixture enthalpy rises linearly with position x:
H(x) = H_in + q′·x / ṁ
The mixture's enthalpy–temperature curve is piecewise linear in three segments (sensible heating of the solid core, the melting plateau where the apparent specific heat spikes with the latent heat L, then sensible heating of the melted core), weighted by the capsule mass fraction φ:
c_app(T) = (1-φ)·c_water
+ φ·c_solid (T below melt band)
+ φ·(L/ΔT_melt + c_pcm,avg) (inside melt band)
+ φ·c_liquid (T above melt band)
Because H(x) is monotonic and piecewise linear, temperature is recovered directly by inverting the matching segment — no iteration needed. Each capsule you see is coloured by where it sits on that curve as it travels from inlet to outlet.
- Flow rate — more mass per second means less time (and less enthalpy) per unit length, so a lower outlet temperature for the same heater power.
- PCM fraction φ — higher φ means more of the pipe's length is spent inside the melting plateau, flattening the temperature rise there.
- Wall heat flux — the heating power injected per metre of pipe; higher flux pushes more capsules past full melt before the outlet.
- Water-only baseline — recomputes the same energy balance with φ = 0, showing the temperature rise you'd get from sensible heat alone.