Experimental and numerical study of impact dynamics and heat transfer in spray cooling process

• Grant number: 25/01107-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: June 01, 2025
• End date: January 31, 2028
• Field of knowledge: Engineering - Mechanical Engineering - Transport Phenomena
• Principal Investigator: Arthur Vieira da Silva Oliveira
• Grantee: Jefferson David Salamanca Cárdenas
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated research grant: 21/01897-0 - Experimental study of droplets impact onto heated walls using combined optical techniques: single droplets, multiple droplets and sprays, AP.JP

Abstract

Spray cooling is a widely used and highly effective technique in industrial applications. This process plays a crucial role in a range of operations, such as tempering and other heat treatments, where precise temperature control is essential to achieve enhanced mechanical properties in treated parts. Despite its widespread application, important theoretical gaps persist in understanding the underlying physical mechanisms. Although numerous studies have successfully modeled the hydrodynamics and heat transfer associated with a single droplet impacting a hot surface, reliable physical models capable of accurately estimating the heat flux in spray cooling processes are still lacking. The objective of this research is to develop a robust computational model-one that can estimate the heat flux during spray cooling reliably, based on measurable physical parameters. To achieve this, existing models related to the impact dynamics of a single droplet must be validated. For that, we have experimental data, then, we must relate the theory of drop impact with spray, and validate it with new experimental data. In the experimental phase, optical measurement techniques will be employed to capture critical parameters, including the size and velocity of the droplets, as well as the temperature distribution across the test surface. Optical methods are favored in this context due to their non-invasive nature. In the modeling phase, we will use the Monte Carlo method to simulate the impact of the droplets on the wall. These simulations will progressively contribute to the wall cooling. We will then validate the new method with experimental data by comparing measured and estimated cooling curves under different experimental conditions. This work focuses particularly on the Leidenfrost regime, where there is no direct contact between the droplet and the surface, and on diluted sprays, where there is no significant interaction between droplets.