Radiation and direction

The principal dangers of a flash fire are radiation and direct flame contact. The size of the flammable cloud determines the area of possible direct flame contact... 

A massive amount of propane is instantaneously released in an open field. The cloud assumes a flat, circular shape as it spreads. When the internal fuel concentration in the cloud is about 10% by volume, the cloud s dimensions are approximately 1 m deep and 100 m in diameter. Then the cloud reaches an ignition source at its edge. Because turbulence-inducing effects are absent in this situation, blast effects are not anticipated. Therefore, thermal radiation and direct flame contact are the only hazardous effects encountered. Wind speed is 2 m/s. Relative humidity is 50%. Compute the incident heat flux as a function of time through a vertical surface at 100 m distance from the center of the cloud. 

Heat transfer is always from hot to cold. The main mechanisms of heat transfer in a hydrocarbon are thermal radiation and direct flame contact (convection). Heat transfer to personnel can cause burns. Heat transfer to equipment and structures can lead to failure of hydrocarbon-containing equipment that can further feed the fire. 

Debromination of deca-BDE occurs through light exposure (both UV radiation and direct sunlight) and biological activity. These pathways lead to a variety of degradation products. 

The design of the IBS facility is based on an off-axis paraboloidal mirror with a focal length of 25 mm mounted above the heater, which captures the infrared radiation and directs the radiation into the spectrometer. The assembly of the heating block and platinum hot-plate is located such that the surface of the platinum is slightly above the focal point of the off-axis paraboloidal mirror. By... 

Fire transmits heat in several ways, which need to be understood in order to prevent, plan escape from, and fight fires. Heat can be transmitted by convection, conduction, radiation and direct burning (Figure 15.3). 

A flash fire is the nonexplosive combustion of a vapor cloud resulting from a release of flammable material into the open air. Experiments have shown (AIChE, 1994) that vapor clouds only explode in areas where intensely turbulent combustion develops and only if certain conditions are met. Major hazards from flash fires arc fi om thermal radiation and direct flame contact. 

Evidence of 1 fire spread When examining a fire scene it is often not clear how the fire has spread, particularly if there are a variety of materials involved. Reference to the mechanisms of fire spread will help the consideration of conduction, convection, radiation and direct burning as methods of how the fire as spread. This will also help to confirm the location of the seat of the fire. 

The source is reflected equally onto mirrors so that beams pass through the sample and reference areas. These beams are then selected alternately by a rotating mirror and each beam follows a conunon path to the diffraction grating, which disperses the radiation and directs it onto the detector. The width of the... 

Certain types of equipment are specifically excluded from the scope of the directive. It is self-evident that equipment which is already regulated at Union level with respect to the pressure risk by other directives had to be excluded. That is the case with simple pressure vessels, transportable pressure equipment, aerosols and motor vehicles. Other equipment, such as carbonated drink containers or radiators and piping for hot water systems are excluded from the scope because of the limited risk involved. Also excluded are products which are subject to a minor pressure risk which are covered by the directives on machinery, lifts, low voltage, medical devices, gas appliances and on explosive atmospheres. A further and last group of exclusions refers to equipment which presents a significant pressure risk, but for which neither the free circulation aspect nor the safety aspect necessitated their inclusion. 

Since there is a definite phase relation between the fiindamental pump radiation and the nonlinear source tenn, coherent SH radiation is emitted in well-defined directions. From the quadratic variation of P(2cii) with (m), we expect that the SH intensity 12 will also vary quadratically with the pump intensity 1 ... 

In the previous section we defined several characteristic properties of electromagnetic radiation, including its energy, velocity, amplitude, frequency, phase angle, polarization, and direction of propagation. Spectroscopy is possible only if the photon s interaction with the sample leads to a change in one or more of these characteristic properties. 

Heat is often removed by simply allowing it to escape by convection, radiation, and conduction. However, such uncontrolled escape can lead to very large temperature fluctuations. It is better to surround the entire container, heaters and all, with a controUed-temperature cooled chamber. Even then, buoyancy-driven free convection from the ampul can lead to small temperature fluctuations. Jets of air or cooling water appHed directly onto the ampul adjacent to the heater have been employed. Both temperature and flow rate of the coolant should be controlled. 

Determination of the Temperature of the Evaporating Surface in Direct-Heat Tray Dryers When radiation and conduction are negligible, the temperature of the evaporating surface approaches the wet-bulb temperature and is readily obtained from the humidity and diy-bulb temperature. Frequently, however, radiation and conduction cause the temperature of the evaporating surface to exceed the wet-bulb temperature. When this occurs, the true surface temperature must be estimated. 

A planar polished surface reflects heat radiation in a similar manner with which it reflects light. Rough surfaces reflect energy in a diffuse manner hence radiation is reflected in all directions. A blackbody absorbs all incoming radiation and therefore has no reflection. A perfect blackbody does not exist a near perfect blackbody surface such as soot reflects 5% of the radiation, making it the standard for an ideal radiator. 

FIGURE 11.31 Radiaiion fluxes at the buildirtg facade the solar radiation components (direct or beam, diffuse, and reflected radiation from the ground or other buildings) and the components of the radiation back from the building facade (reflected solar and thermal infrared radiation from the building envelope). 

T he total or global solar radiation has a direct part (beam radiation) and a diffuse part (Fig. 11.31). In the simulation, solar radiation input values must be converted to radiation values for each surface of the building. For nonhorizontal surfaces, the diffuse radiation is composed of (a) the contribution from the diffuse sky and (b) reflections from the ground. The diffuse sky radiation is not uniform. It is composed of three parts, referred to as isotropic, circumsolar, and horizontal brightening. Several diffuse sky models are available. Depending on the model used, discrepancies for the boundary conditions may occur with the same basic set of solar radiation data, thus leading to differences in the simulation results. 

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