Interakce vodních kapek s infračerveným zářením

Abstract

It is commonly known that water droplets contained in the water spray have the ability to prevent the transfer of radiant heat, mainly due to absorption and scattering. This property is generally used to protect against ignition of flammable materials and to reduce thermal stress of firefighters. In terms of protection of property there is used the separation of fire sections by water curtain in certain cases (e.g. an opening for a belt conveyor or a closure of a hopper in technological structures). In case of human safety it is possible to use the properties of water droplets to protect firefighters particularly against thermal radiation. This dissertation focuses on the interaction of thermal radiation, especially in the infrared region of the spectrum, with water droplets. The main objective is to assess the decrease of heat flux or intensity of infrared radiation by positioning the water curtain of various parameters between radiation source and the detector. Changing the parameters of the water curtain, affecting the attenuation of thermal radiation, was ensured by five nozzles with different spraying characteristics. The thesis is divided into two main parts, theoretical and practical. The theoretical part deals with the physical and chemical properties of water, water mist, the free fall and terminal velocity of droplets, removing heat by means of water droplets and the interaction of infrared radiation with water droplets. The practical part is focused on the principle of creating water mist, the decrease of the heat flux through a defined water curtain or decrease in intensity of infrared radiation passing through the water curtain. The practical part also deals with measurement of the characteristics of water mist produced by tested nozzles.