Numerical Comparisons on Heat-Source-Targeted and Large-Area Spray Cooling for an Impinging Jet at High Temperature in a Confined Space

Abstract

Impinging jets with high temperature can be commonly found among industrial applications, such as exhaust gas from turbine engines that used for ships, heavy trucks or aircrafts. When the heating source is in a confined space, i.e., a garage or a machine room, additional cooling method, e.g., spray cooling, usually needs to be applied to decrease the temperature of the impinging jet, to minimize damages to the interior structure. In this paper, numerical simulation is used to study the cooling effect of water spray on an impinging jet at ~800 K. The confined space also incorporates an exhaust fan to remove the generated gas. The cooling effect of both local cooling (i.e., directly spraying at the heat source) and large-area cooling (i.e., spraying spread out the whole space) are investigated. Six cases were designed. In the first case, there were no nozzles were set. In the next 5 cases, the total number of nozzles were 65 and remained unchanged, by changing the number of nozzles used for larger-area cooling and local cooling, the cooling effect of different installation scheme of nozzles was obtained thorough computational method. For all the cases, the flow rate of the flue gas is 28.0 kg/s, and hourly water consumption of each nozzle is ~0.8 m³/h. The results show that increasing the number of nozzles that used for local cooling result in a better cooling effect, but the increment of cooling effect will be slightly when the number of local cooling nozzles up to ~20.