Heat Transfer Coefficients in the Surface Temperature Range of 400 to 800°C during Water-spray Cooling of Hot Steel Product

Abstract

Heat transfer coefficients (α) of water-spray cooling in the region of steel surface temperature (θ_s) 400 to 800°C are numerically expressed as a function of θ_s and impinged water flux (W), by using published water-spray cooling data (7 papers, 112 data) measured with scale-coated steel specimens by many researchers. In the region of θ_s : 400 to 800°C and W: 10 to 2 000 l/m₂ · min, α_w is represented by the following equation,
α_w=2.292 × 10⁸ · W^0.616θ_s ^2.445
where α_w is value of α without radiation heat transfer, [α_w] being kcal/m²· h ·°C.
In addition, are discussed features of exponents of W and θ_s, comparison of the above equation with other researchers' one, α in the film boiling region, and α calculation methods for θ_s between 125°Cand about 1 200°C.