Seawater Can be Used for Blocking out Radiation from Fires
Leonid Dombrovsky, UTMN researcher, together with his colleagues from the Moscow Power Engineering Institute, Moscow State University, and the Universities of Warwick and Kingston (UK), has studied situations where there is no fresh water, and one needs to use seawater to protect against fire.
The international research team has proven that seawater can be used to protect people and equipment on oil platforms from thermal emissions caused by fire. This will help individuals escape from a fire when there is a lack of fresh water nearby. The research results were published in the International Journal of Thermal Sciences.
According to experts, to protect against infrared and visible fire radiation, large fresh water resources are used to create mist curtains from small droplets of water. These curtains absorb and scatter the incident radiation. This method is called shielding. The mist curtains are formed when water is supplied through numerous nozzles pre-installed at the right height in dangerous places.
“We are talking about a possible fire on an oil platform, sea vessel or on land, not far from the sea, but far from fresh water sources. It was important to understand whether seawater could be used instead of fresh water, and how effective such a solution is“, Leonid Dombrovsky, the lead author of the study, researcher at the Microhydrodynamic Technologies Laboratory from the UTMN Institute of Environmental and Agricultural Biology, said.
According to the researcher, a physical model of the process was developed. The scientists, moreover, solved coupled equations taking into account the special evaporation features of seawater droplets under the influence of thermal radiation in a fire with temperature of about 1,500 Kelvin.
The scientist said that a solid crust forms on the surface of evaporating seawater droplets with an initial diameter of 0.1-0.2 mm. When pressure inside the droplets increases due to evaporation, the remaining saltwater is removed through the hole formed in the crust.
“Together with water vapour, a stream of concentrated sea salt solution is released into the surrounding air, and a lot of small crystals of sea salt are formed. As a result, using saltwater instead of freshwater, we will get relatively large hollow spherical salt particles, as well as small salt crystals“, Leonid Dombrovsky added.
The calculations showed that hollow salt particles are sufficient to attenuate the flame radiation. As a result, seawater can be used to create a protective curtain if a fire occurs on an oil platform, experts believe.
Theoretical and computational work was supported by The Leverhulme Trust foundation (UK).