Heat transfer during surface boiling of water. The left ordinate axis Ξ / 0.49 corresponds to major subcooling (light markers). Right axis Ξ / 0.095: subcooling does not affect heat transfer or affects it slightly (black markers). Ξ = Nuboil×(Re×∆tsub)0.63/[Pr0.43(Prliq/Prwall)0.25q0.7p0.25]. Pressure markers: circle – 7 ATA; triangle – 16 ATA; square – 41 ATA.