The effects of spray characteristic on heat transfer during spray quenching of aluminum alloy 2024

A spray quenching apparatus was performed and hot aluminum alloy 2024 thin sheets were spray quenched by two symmetrically arranged nozzles. The influence of spray nozzle distance on heat transfer was experimentally investigated. The results show that there is no film boiling regime and Leidenfrost point at different nozzle distance. Both critical heat flux (CHF) value and surface temperature at which CHF occurs first decrease to the minimum value with increased nozzle distance, and then increase until reach the maximum value. Finally, CHF value and surface temperature decrease with further increase of nozzle distance. However, the maximum CHF value is observed when nozzle distance is 70 mm, and the highest surface temperature at which CHF occurs is obtained at nozzle distance of 80 mm. A nozzle distance of 80 mm is better since there exists a longer nucleate boiling regime and a relatively higher CHF value. This phenomenon may have guiding significance for industrial production.