Influence of water temperature on spray cooling at high surface temperatures

Abstract

Spray cooling is a common cooling method used in many high-temperature metallurgical processes. Heat transfer in the spray cooling of hot surfaces depends on many parameters, and one of them is cooling water temperature. Especially in the steel industry, the cooling water temperature is influenced by the season, the location in the world and also by the intensity of the manufacturing process. Using an experimental approach, the influence of water temperature on the Leidenfrost temperature and film boiling heat transfer coefficient in spray cooling is investigated. Extensive measurements, taken for two types of nozzles, different water flow rates and different water temperatures (12 °C to 78 °C), are presented. It is shown that the film boiling heat transfer coefficient and the Leidenfrost temperature decrease linearly as the water temperature increases. The obtained results are generalised into correlations and transformation functions, allowing extension of existing correlations, which are mostly valid only for water temperatures around 20 °C, to arbitrary water temperatures. All existing papers, which deal with the influence of the water temperature on spray cooling, only present the measured data and do not provide a generalisation of the results. This is a research gap, and this paper tries to fill it.