Boiling
Three modes: heat flux q = h·ΔTsat (with required area for a duty), boiling coefficient h = q/ΔTsat, and the Zuber pool-boiling critical heat flux qmax = 0.131·hfg·ρv·[σg(ρl−ρv)]1/2.
Mode
Boiling
Zuber CHF
Frequently asked
- What is the critical heat flux?
- The peak heat flux a pool-boiling surface can carry before a vapor film blankets it and the surface temperature shoots up (burnout). Zuber's correlation gives the theoretical maximum for a large horizontal heater; wires and small heaters are close to it.
- Why is ΔT saturation excess the driver?
- In nucleate boiling the heat flux is driven by how far the wall sits above the saturation temperature. Newton's law q = h·ΔT_sat is the engineering form used in the solution manual for measured h values.
- Which properties does Zuber need?
- Latent heat h_fg, liquid and vapor densities, and surface tension sigma — all at saturation. For water at 100 C: 2257 kJ/kg, 957.9 and 0.5978 kg/m3, 0.0589 N/m.