• Journal of ILASS-Korea
• /
• v.28 no.2
• /
• pp.97-104
• /
• 2023

A sprinkler is a fire suppression system that extinguishes combustible materials in the early stages of a fire, creating a spray. However, spray formation method of the sprinkler can result in an uneven distribution of water spray on the surface of combustible materials. It is necessary to ensure a consistent water flux density regardless of the spray direction and angle. In this study, the water flux distribution was analyzed for the various types of sprinkler head: circular, flush, pendent, and upright types. All sprinkler heads have a K-factor of 80 LPM/(0.1MPa)^0.5. In this study, water collection cubes were used to examine the water flux distribution. The upright type sprinkler head showed a low standard deviation in total sprayed area, indicating a high level of uniformity. The upright type head showed the lowest standard deviation in the radial direction, and also showed the lowest standard deviation in the azimuthal direction. Upright sprinkler head has no obstructing structure along the path of droplets after they are generated. For this reason, upright sprinkler head showed the most uniform water flux distribution on the floor.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.16 no.1
• /
• pp.77-83
• /
• 2004

In this study, the spray cooling heat transfer and working characteristics of the screen wick heat pipe with ultrasonic spray cooling system in condenser were experimentally investigated. The heat pipe was made of copper tube 300 mm long with inner diameter of 11.1 mm. The evaporator and condenser lengths of heat pipe were 40, 200 mm and the wick structure consists of two layer of 100 mesh copper screen. The experimental results show that the ultrasonic spray cooling increases the heat transfer rate on the condenser surface, and the total thermal resistance of heat pipe system decreases remarkably. A comparison is made for the two working fluids, water and ethanol. The surface temperature of the ethanol tube in evaporator section becomes higher than that of the water tube. Thus, the experimental result shows that water is more useful than ethanol as the working fluid because of increasing the operational limit within this experimental conditions.

• Journal of ILASS-Korea
• /
• v.3 no.4
• /
• pp.8-15
• /
• 1998

The spray characteristics of emulsified fuel of W/O type has been experimentally investigated. The mixture of light oil and water by using ultrasonic energy adding system is used as the emulsified fuel. The SMD of sprayed droplet of emulsified fuel is measured by using the particle size analyzer. Major parameters of the present experimental study are the volume fraction of water in emulsified fuel, $0\sim30%$ by 5%, injection pressure, $10kg_f/cm^2\sim18kg_f/cm^2$ by $2kg_f/cm^2$, and the measurement distance, $10\sim100mm$, between injection nozzle tip and analyzer beam. Compared with light oil, the SMD of emulsified fuel is larger gradually by increasing the volume fraction of water in emulsified fuel, heightening injection pressure and increasing the spray distance. Also, In considering the fact that the pattern of drop size distribution of emulsified fuel is alike that of light oil, the real time spray in coincidence with making emulsified fuel by adding ultrasonic energy can stabilize spray pattern without modificating the injection system used by now.

• Food Quality and Culture
• /
• v.2 no.1
• /
• pp.55-60
• /
• 2008

This study examined the effects of lactic acid spray, hot water spray, or their combined treatment, as well as the effects of acidified sodium chlorite (ASC), for the decontamination of Escherichia coli on beef carcass surfaces using a commercial intervention system. With this system, the effects of 2 or 4% lactic acid (v/v), hot water ($89{\pm}1^{\circ}C$), or their combined treatment, were examined in terms of reducing inoculated E. coli. ASC (266 ppm), which was adjusted to pH 2.5 using acetic acid or citric acid, was applied using a hand-held spray system. When the beef carcasses were treated with 2 or 4% lactic acid for 10.4 s, less than 1 log reductions of inoculated E. coli were observed. A hot water spray treatment for 9.8 s resulted in a 2.1 log reduction of inoculated E. coli. However, when the hot water was followed with either 2 or 4% lactic acid, no difference in E. coli reduction was found between the hot water alone or the combined treatment with lactic acid. When ASC was adjusted to pH 2.5 with acetic acid and citric acid, 3.8 and 4.1 log reductions of E. coli were observed, respectively. Overall, the lactic acid spray treatment was least effective, and the ASC treatment was most effective, for the E. coli decontamination of beef carcasses. Therefore, these data suggest that ASC would be a more effective intervention against E. coli than most of the methods currently being used. However, more research is required to evaluate the effects of ASC on other organisms, as well as to identify application methods that will not affect meat quality.

• Journal of computational fluids engineering
• /
• v.12 no.1
• /
• pp.28-34
• /
• 2007

This study evaluates the performance of the packed bed scrubber and proposes the optimization of spray system for improvements of collection efficiency. The packed bed scrubber is used primarily in the semiconductor manufacturing process. The mean diameter of entering solid particles in scrubber is the submicron. The impaction between water droplets and solid particles is an important factor in removing the solid particles. Thus, the coverage area of spray system influences on the collection efficiency. The collection efficiency of a single droplet is calculated through the mathematical model and numerical calculations are performed for coverage area for each nozzle type (Droplet diameters: 500, 319.5, $289.5{\mu}m$) and injected directions (0, 15, $30^{\circ}$). In case of nozzle type 3, the collection efficiency of a single droplet is highest but the collection efficiency of spray system has lowest value because the ratio of flow rate between the gas and water is below 0.1. The results show the coverage area ratio is about 85% in the case of nozzle type 3 and downward sirection $15^{\circ}$. It was shown that a coverage area increase by two times than an existing spray system. In simulation of demister, collection efficiency by demister is predicted about 80% and the pressure drop in demister is below 3.5 Pa.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2002.05a
• /
• pp.61-65
• /
• 2002

The present study was numerically and experimentally performed to investigate the fire suppression performance of water mist spray subjected to thermal radiation in closed space. Downward-directed water mist sprays to interact with an under kerosine pool fire were investigated in test facility. The mass mean diameters of water mist droplet were measured by PMAS under various flow conditions. The developed water mist spray nozzle was satisfied to the criteria of NFPA 750, Class 1. The mechanism of the fire suppression by water mist was concluded to be cooling of the fire surface which lead to suppressed of fuel evaporation. It was proved that the water mist spray system under lower pressures could be applied to underground fire protection system.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.12 no.4
• /
• pp.341-347
• /
• 2010

The performance of water spray system installed to reduce risks of tunnel fire is investigated by a real tunnel fire test. In case of A class fire, Pool fire, and car fire, the nozzle of water spray has had a marvelous effect to reduce the temperature of hot smoke. And it is verified to have remarkable cooling effects when there is the air flow in a tunnel. Though this results, water spray system will be able to prevent a fire jump to decrease the air temperature in a tunnel and to protect tunnel facilities by the fire control.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.25 no.2
• /
• pp.55-63
• /
• 2013

For a large-scale semiconductor manufacturing clean room, the energy consumed in an outdoor air conditioning system to heat, humidify, cool and dehumidify incoming outdoor air is very large. In particular, the energy requirement to humidify outdoor air in the winter season is generally known to be high. Recently, in order to overcome the high energy consumption nature of a steam generator in a conventional steam humidification type outdoor air conditioning system, an air washer is often introduced instead of the steam generator in the outdoor air conditioning system, which can be called a water spray humidification type outdoor air conditioning system. Therefore, the assessment and comparison of the annual energy consumed in the steam humidification type and the water spray humidification type outdoor air conditioning systems deserves to be examined in order to reduce the outdoor air conditioning load of a clean room. In the present study, a numerical analysis was conducted to obtain the annual electric power consumption of the two outdoor air conditioning systems. It was shown from the comparison of the numerical results that the water spray humidification type outdoor air conditioning system can reduce about 30% of annual electric power consumption of the steam humidification type outdoor air conditioning system.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2016.10a
• /
• pp.50-51
• /
• 2016

Ozone is a strong oxidizing materials in the advanced water treatment facilities. However, due to such a strong oxidation, Ozone eroded waterproofing/corrosion on the concrete surface and caused performance degradation. Therefore, in this study, permeability experiment of metal spraying system by concrete surface treatment was conducted.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.11 no.6
• /
• pp.81-90
• /
• 2008

Recently, geofiber(polyester) reinforced soil was added on soil-seed mixture spray to control erosion and to improve vegetation growth on rocky slope sites. This research was conducted to compare vegetation effects and soil hardness on three types of soil-seed mixture spray on stone gabion river bank [A type : soil-seed mixture spray underlying 30cm thick sand with geofiber(geofiber reinforced soil system), B type : soil-seed mixture spray underlying 30cm thick sand without geofiber, C type : soil-seed mixture spray]. Evaluation were made concerning vegetation coverage, soil hardness and moisture content. The results of this study showed that A type system was effective for the growth of vegetation and soil hardness when compareed to B type and C type. A type and B type showed higher covering rate than C type on stone gabion river bank, and especially A type showed the highest covering rate. Soil hardness and water content were high on A type vegetation system compared to B type and C type. We noted that high soil hardness and high moisture content with geofiber(geofiber reinforced soil system) were effective both to control erosion from water current impact and to be high coverage and species of vegetation on stone gabion river bank.