Influence of injection method on the fire extinguishing efficiency of liquid nitrogen in urban underground utility tunnel

As a highly effective and environmentally benign suppression agent, liquid nitrogen (LN2) has been widely used for fire extinguishing in plants, dwellings, enclosed underground tunnels, and other confined spaces through cooling and inerting. It is of great significance to understand the cooling and inerting effects of LN2 injected into a confined space. A confined-space experimental platform was developed to study the injecting LN2 into the platform with different injection parameters, such as mass flux, pipe diameter, and inclination angle. In addition, a mathematical model of quantitatively assessing cooling and inerting effects was proposed by using heat transfer capacity, inerting coefficient, and cooling rate. Results showed that the inerting effect was gradually enhanced with a mass flux increasing from 0.014 to 0.026 kg/s and then tended to level off; an appropriate pipe diameter of 12 mm was optimal for the cooling and inerting effects in this experiment. In addition, a positively increasing inclination angle could contribute to the cooling and inerting effects. However, there was little effect on the cooling and inerting with an inclination angle less than 0°. This study can provide technical guidances for environmentally friendly fire extinguishing with LN2 in a confined space.

Download Full-text

Electron Probe Microanalysis of Frozen Hydrated Kidneys, Isolated Cells, and Cultured Cells

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100054595 ◽

1982 ◽

Vol 40 ◽

pp. 402-403 ◽

Cited By ~ 1

Author(s):

Claude Lechene

Keyword(s):

Liquid Nitrogen ◽

Electron Probe Microanalysis ◽

Electron Probe ◽

Cultured Cells ◽

Liquid Nitrogen Temperature ◽

Elemental Content ◽

Isolated Cells ◽

Renal Tubular Cells ◽

Diamond Saw ◽

Saw Blade

Electron probe microanalysis of frozen hydrated kidneysThe goal of the method is to measure on the same preparation the chemical elemental content of the renal luminal tubular fluid and of the surrounding renal tubular cells. The following method has been developed. Rat kidneys are quenched in solid nitrogen. They are trimmed under liquid nitrogen and mounted in a copper holder using a conductive medium. Under liquid nitrogen, a flat surface is exposed by sawing with a diamond saw blade at constant speed and constant pressure using a custom-built cryosaw. Transfer into the electron probe column (Cameca, MBX) is made using a simple transfer device maintaining the sample under liquid nitrogen in an interlock chamber mounted on the electron probe column. After the liquid nitrogen is evaporated by creating a vacuum, the sample is pushed into the special stage of the instrument. The sample is maintained at close to liquid nitrogen temperature by circulation of liquid nitrogen in the special stage.

Download Full-text

A Liquid Nitrogen Cooled Stage for STEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052237 ◽

1974 ◽

Vol 32 ◽

pp. 444-445

Author(s):

Louis T. Germinario

Keyword(s):

Electron Microscope ◽

High Resolution ◽

Liquid Nitrogen ◽

Room Temperature ◽

Objective Lens ◽

Thermal Drift ◽

Specimen Holder ◽

Resolution Capability ◽

Focal Position

A liquid nitrogen stage has been developed for the JEOL JEM-100B electron microscope equipped with a scanning attachment. The design is a modification of the standard JEM-100B SEM specimen holder with specimen cooling to any temperatures In the range ~ 55°K to room temperature. Since the specimen plane is maintained at the ‘high resolution’ focal position of the objective lens and ‘bumping’ and thermal drift la minimized by supercooling the liquid nitrogen, the high resolution capability of the microscope is maintained (Fig.4).

Download Full-text

Field-Ion Microscopy of BCC Metals: A Study of Image Differences and Topographical Variations

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071016 ◽

1973 ◽

Vol 31 ◽

pp. 114-115

Author(s):

O. T. Inal ◽

L. E. Murr

Keyword(s):

Liquid Nitrogen ◽

Liquid Nitrogen Temperature ◽

Surface Atom ◽

Image Brightness ◽

Field Ion Microscopy ◽

Topographic Features ◽

Bcc Metals ◽

Electron Orbital ◽

Ion Microscopy ◽

Field Ion Microscope

When sharp metal filaments of W, Fe, Nb or Ta are observed in the field-ion microscope (FIM), their appearance is differentiated primarily by variations in regional brightness. This regional brightness, particularly prominent at liquid nitrogen temperature has been attributed in the main to chemical specificity which manifests itself in a paricular array of surface-atom electron-orbital configurations.Recently, anomalous image brightness and streaks in both fcc and bee materials observed in the FIM have been shown to be the result of surface asperities and related topographic features which arise by the unsystematic etching of the emission-tip end forms.

Download Full-text

The Effects of Drying Techniques on Clay-Rich Soil Texture

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052341 ◽

1974 ◽

Vol 32 ◽

pp. 466-467

Author(s):

T. G. Naymik

Keyword(s):

Critical Point ◽

Liquid Nitrogen ◽

Liquid Nitrogen Temperature ◽

Drying Methods ◽

Air Drying ◽

Freeze Dried ◽

Critical Point Drying ◽

Set Up ◽

The Relationship ◽

Quartz Grains

Three techniques were incorporated for drying clay-rich specimens: air-drying, freeze-drying and critical point drying. In air-drying, the specimens were set out for several days to dry or were placed in an oven (80°F) for several hours. The freeze-dried specimens were frozen by immersion in liquid nitrogen or in isopentane at near liquid nitrogen temperature and then were immediately placed in the freeze-dry vacuum chamber. The critical point specimens were molded in agar immediately after sampling. When the agar had set up the dehydration series, water-alcohol-amyl acetate-CO2 was carried out. The objectives were to compare the fabric plasmas (clays and precipitates), fabricskeletons (quartz grains) and the relationship between them for each drying technique. The three drying methods are not only applicable to the study of treated soils, but can be incorporated into all SEM clay soil studies.

Download Full-text

Si(Li) detector for microanalysis cooled by thermoelectric device

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010013331x ◽

1992 ◽

Vol 50 (2) ◽

pp. 1736-1737

Author(s):

Shaul Barkan

Keyword(s):

Solid State ◽

Liquid Nitrogen ◽

Thermoelectric Device ◽

Peltier Cooler ◽

Complicated Process ◽

The Common

Cooling down solid state detecors, with other different way then liquid Nitrogen, is a goal of many vendors and customers since the invention of these detectors. THe disadvantage of the common way of liquid Nitrogen is first the inavailibility of the LN in many uses (like space military and any other applications that are not done inside a well organize Laboratory). The use of LN also considers as a Labor consumer in addition to the big dewar that has to be added to any detector for storing the LN, the boiling of the LN, may cause microphonics problesm and the refiling of the dewar in many Labs is a complicated process due to inconvenience location of the microscope.In this paper I will show a spectra result of 10mm2 SiLi detector for microanalysis use, cooled by peltier cooler. The peltier cooler has the advantage of non-microphonics and non-labor needed (like adding LN to the dewar).

Download Full-text