Study on Ultra-fast Cooling Behaviors of Water Spray Cooled Stainless Steel Plates

Abstract

Spray cooling is an effective tool to dissipate high heat fluxes from hot surfaces. This article thoroughly investigates the effect of thickness of a hot stainless steel plate on the cooling time, cooling rate, heat flux, and heat transfer coefficient under constant mass flow rate maintained at 1 MPa using water as the coolant. Cylindrical samples of stainless steel with constant diameter (D = 25 mm) and thickness (δ = 7.5, 12, 16.5, and 21 mm) were used in the present study. Critical droplet diameter to achieve an ultra-fast cooling rate of 300°C/s was estimated by using an analytical model for samples of varying thicknesses. The analytical model (one side spray cooling) showed good agreement with experimental results with a relative error of 3.2% in the plate thickness range of 1–12 mm. An increasing trend in maximum heat flux was found with increasing thickness of the plate. Maximum heat flux as high as 1,800 kW/m² was achieved for a 21-mm-thick sample. Heat transfer coefficients in the range 0.092–96.24 kW/m²K, 0.111–98.9 kW/m²K, 0.074–63.4 kW/m²K, and 0.127–55.63 kW/m²K were reported for sample of varying thicknesses in the present study. Limited published work is available with reference to water spray cooling dynamics and thickness of stainless steel plate. Therefore, the present study focuses on the correlation between the thickness of the plate and spray dynamics of water spray cooling.

Keywords::

• spray cooling
• ultra-fast cooling rate
• thickness effect
• critical droplet diameter