A Numerical Approach of the Influence of Water Temperature in the Extinction of Fire Developed in Closed Spaces

The aim of this work is to make a visual investigation of the fire behavior during the extinguish process with water mist at different temperatures, different diameters of the nozzle and different angles of diffusion jet, too. It was used a numerical simulation approach to analyze 24 scenarios regarding the influence of mist water in fire extinguish process. The main test was focused on a given enclosure with dimensions of 1.0 × 1.0 × 3.0 m and the fire source placed inside, in the middle. The enclosure is considered opened on the upper part. From the numerical simulation values, we concluded the best scenario in fire extinguish process using water mist.

Experimental Investigation on Filtration and Cooling Effect of Kitchen Hood Ventilation System from Water-Mist Recirculation Spray: Water-Mist Spray Cycle

A Water-mist spray system in several heavy-duty kitchen hood canopies is installed to efficiently control the high heat loads and grease emissions produced from the cooking process and for safety purposes. The main purpose of this study is to reduce water consumption by introducing the water-mist recirculation system to replace the current method water-mist system since it is working as water loss. A standard ASTM 2519 and UL 1046 full-scaled experiment is developed in the laboratory. An existing Halton Europe/Asian water-mist operating system is adopted in this study. Twelve (12) cycles (at 24 hours of water-mist activation) have been studied to determine the maximum water-mist activation cycle. The data are collected at two (2) hours water-mist activation at every water-mist recirculation cycle. The water-mist spray fluids viscosity is 0.7 cP from fresh water until the 4th cycle (8 hours water-mist spray) and increase 14.29% (0.8 cP) at the 5th cycle to the 12th cycle. On average, the difference in gas emissions percentage for CO concentration between fresh water until the 4th cycle is 10.81 – 18.92% while the CO2 concentration is 12.33 – 18.22%. On average, the difference in cooling effects percentage for ducting temperature between fresh water until the 4th cycle is 5.55% while the hood temperature is 2.33%. From the study, the water-mist recirculation system could save up to 611,667 litres per year and 466,798.5 litres per year water for all U.S, European, and Asian kitchen hood designs per hood length. By adopting the new water-mist recirculation system to the current water-mist kitchen hood, the water operational cost for water successfully reduced to RM 4,889.63 per year and RM 6,977.86 per year for U.S design and European or Asian design per hood length respectively. The water-mist recirculation system has great potential to improve the current water-mist system for the commercial kitchen hood.

An experimental study of the fire extinguishing ability of modular fire extinguishing installations if astralene-modified water mist is used

Introduction. The aim of the research project is to study the effect produced by one type of carbon nanostructures, or astralenes, on processes of extinguishing oil product flame using finely sprayed water. Materials and research methods. The research is focused on fire extinguishing suspensions used in modular water mist installations for the fire extinguishing of oil products. Astralene-modified distilled water, having the volumetric concentration of nanostructures equal to 0.05–1.0 percent, was used as a fire extinguishing substance under research. The experiment was focused on the study of thermophysical characteristics of fire extinguishing liquids, such as density, dynamic viscosity, surface tension, specific heat of vaporization. Also, studies were carried out to identify the rate of evaporation, the distribution of droplet sizes of sprayed fire extinguishing compositions, and the time needed to extinguish the model source of ignition of oil products.Research results. The dispersion of nanostructures of fire-extinguishing liquids allows to increase their density, surface tension by 20.6 %, increase the specific heat of vaporization if the volumetric concentration of astralenes is equal to 0.25 and 0.5 %, and boost the dynamic viscosity by 6.68–15.38 % at the temperature of 20 °С. The research was carried out to find the rate of evaporation of droplets of the modified fire-extinguishing liquid. It was found that an increase in the volumetric concentration of nanostructures from 0.05 to 0.5 % causes reduction in the evaporation rate.The droplet speed increases if the volumetric dispersion of astalenes goes up to 0 to 0.25 %. However, a further increase in the volumetric concentration of astralenes to 1.0 % causes a reduction in their speed. The extinguishing time was identified using a laboratory fire extinguishing installation. The distribution of droplet sizes of fire-extinguishing compositions is in the range of 20 to 160 microns. The fire extinguishing capacity of the installation was highest if a fire extinguishing composition had a 0.5 % volumetric concentration of astralenes.Conclusions. The modification of a fire extinguishing composition by carbon nanostructures leads to a change in its thermophysical characteristics. The addition of this composition to the installation, used at facilities involved in the processing of petroleum products, will increase its fire extinguishing ability. Further areas of research may include the development of astralene stabilization methods for suspensions and adaptation to low temperatures.