Effect of Nozzle Location and Nozzle Capacity on Spray Cooling of Hot Gas in a Horizontal Duct

Abstract The modeling of the spray cooling of hot gas in a horizontal duct is carried out. Three nozzle arrangements are considered: the nozzle is located at the duct wall with the injection in favour of and against gravity (cross flows) and at the central axis (parallel flow). The predicted flow and heat transfer performance between different nozzle arrangements are compared for various nozzle capacities and numerical predictions are verified with simplified analytical solutions of outlet temperature. Results show that some non-vaporized droplets flow out of the duct exit. As far as the cooling effect is concerned, the cross flow with the injection against gravity is the best and the parallel flow appears to be the worst. For a given nozzle capacity, the operation may be more stable (with less flow and thermal fields fluctuation in quasi-steady state) and fewer droplets hit the duct wall for the nozzle arrangement with the injection against gravity. For safe operation, the nozzle should be located about ...