Thermal effects on a pressure swirl nozzle in spray cooling

Pressure swirl nozzles are widely used in industries due to their good atomization quality at relatively low operating pressure. This paper experimentally investigates the thermal effects on the spray cone formation of a pressure swirl nozzle in spray cooling. Particle image velocimetry (PIV) is used to reflect the thermal effects on global spray behaviour of the spray cone impinging on a heated surface, while Phase-Doppler Interferometry (PDI) is used to investigate the thermal effects on droplet sizes, droplet velocity and flux distributions. It is found that temperature of the impinged surface plays an important role in the formation of spray cone in spray cooling. The spray cone expands under impinging on a heated surface with high surface temperatures, which consequently influences the spatial distributions of the droplet flux and velocity, as well as the probability density distributions of the diameter and velocity of the impinging droplets and secondary droplets. The heat transfer experiments reveal that the expansion of spray cone under impinging on the surface with difference temperatures have significant effects on the surface temperature non-uniformity and heat transfer coefficient in spray cooling.