Rated airflow

A maximum resistance, when clean, of 25 mm WG when operated at rated airflow capacity... 

Rated airflow The flow rate specified by the manufacturer for an item of equipment. 

Test airflow rate The rated airflow in equipment testing. 

Injector temperature Detector temperature Hydrogen flow rate Airflow rate... 

Individual HEPA filter efficiencies are established by an exacting challenge of the filter frame and medium, usually incorporating a cold-boil, polydisperse aerosol of dioctylpthalate (DOP) or equivalent, which is introduced into the upstream plenum-side of the filter in a manner that ensures even distribution of the test aerosol behind the filter, at its rated airflow. 

The total combustion fuel flow rates, airflow rates, and firing stoichiometry for each port during furnace operation are shown in Table 32.2. The fuel flow rates... 

For determination of the drying rates, airflow rates used in the SBD experiments varied from 0.6 to 1.0 m/s for various seeds. The typical drying rate curves also present some information concerning the structure of the material. The curve labeled grass seed 1 in Figure 15.9 is used as an illustration. 

A throwaway extended-pleated-medium dry-type filter with (1) a rigid casing enclosing the Ml depth of the pleats, (2) a minimum particle removal efficiency of 99.97% for thermally generated monodispersed DOP smoke particles with a diameter of 0.3 microns, and (3) a maximum pressure drop of 1 inch water gage when clean and operated at its rated airflow capacity. ... 

For heat transfer directly to solids, predictive equations give directly the volume V or the heat-transfer area A, as determined by heat balance and airflow rate. For devices with gas flow normal to a fluidized-solids bed,... 

A nominal resiilt of this techniqne is that the reqnired airflow rate and eqnipment size is abont two-thirds of that when evaporative cooling is not nsed. See Sec. 20 for eqmpmeut available. 

Design Methods The size of the agitated flash dryer is based on the evaporation rate required. The operating temperatures are product-specific. Once established, they determine the airflow requirements. The diyiug chamber is designed based on air velocity (approximately 3 m/s) and residence time (product-specific). 

Injection of Steam in the Combustor of the Gas Turbines Utilizing Present Dual Fuel Nozzles. Steam injection in the combustor has been commonly used for NO control as seen in Figure 2-43. The amount of steam, which can be added, is limited due to combustion concerns. This is limited to about 2-3% of the airflow. This would provide an additional 3-5% of the rated power. The dual fuel nozzles on many of the industrial turbines could easily be retrofitted to achieve the goal of steam injection. The steam would be produced using an HRSG. Multiple turbines could also be tied into one HRSG. 

If there is substantial airflow through the pathway, the peppermint oil odor could be diluted so that it is imperceptible. Tracer gases such as sulfur hexafluoride (SF ) can provide qualitative and quantitative information on pollutant pathways and ventilation rates. Use of tracer gases to obtain quantitative results requires considerable technical expertise. If it appears that a sophisticated study of pathways (or ventilation rates) is required, you need to use trained investigators. 

Particulate filtration removes suspended liquid or solid materials whose size, shape, and mass allow them to remain airborne at the air velocity conditions present. Filters are available in a range of efficiencies, with higher efficiency indicating removal of a greater proportion of particles and of smaller particles. Moving to medium efficiency pleated filters is advisable to improve lAQ and increase protection for equipment. However, the higher the efficiency of the filter, the more it will increase the pressure drop within the air distribution system and reduce total airflow (unless other adjustments are made to compensate). It is important to select an appropriate filter for the specific application and to make sure that the HVAC system will continue to perform as designed. Filters are rated by different standards which measure different aspects of performance. 

Air Flow Cartridge collectors are currently limited to low air flow capacity applications. Standard cartridge collectors are factory-built, off the shelf units. They may handle airflow rates from less than 0.10 to more than 5 standard cubic meters per second (smVsec) (("hundreds" to more than 10,000 standard cubic feet per minute (scfm)). 

Air-handling units equipped with heat recovery and sophisticated control of the key parameters of HVAC systems, such as temperature, airflow rate, and pressure difference... 

The main target levels inside a building are normally set for temperature, humidity, air velocity, airflow rate (and air distribution), and contaminant concentration.1 -... 

The airflow rate does not interfere with the building or the building materials, and usually not with the process. The air distribution may vary a lot, however, if the building and process layout and sometimes the building materials are not chosen with great care. Lamps, ladders, window shutters, cabins, process equipment, etc. are often placed where the ventilation designer did not expect any obstructions. Thus continuous cooperation between the different designers is necessary to prevent mistakes and to facilitate common solutions to this type of problem (see Chapter 8). 

Normally there is some connection between the airflow rate and noise and vibration generation. This could modify the building construction either to prevent spreading or to diminish the levels of noise and vibrations from the air-handling units. This naturally includes all parts of these units, i.e., fans, pumps, and valves (see Chapters 5 and 9). The demands on noise insulation also include the noise and vibrations from the process equipment, which often has a higher level of noise and vibration than the ventilation system. 

The influence of the building on the ventilation system, and indirectly on the target levels, can take many forms. There are, e.g., emissions from the materials that demand increased airflow rates and also door and window open-... 

In general, it is mandatory to have some kind of partition between different parts of a building because of fire risks and regulations. These partitions can easily change both the airflow rate and the air distribution if proper preventive measures are not taken. 

Local exhausts arc designed to capture air pollutants and heat at the source, and thus their location and the exhausted airflow rate should ensure sufficient capture velocity. 

Entrainment ratio is another jet characteristic commonly used in air distribution design practice. Specifically, it is used in analytical multizone models (see Chapter 8) when one needs to evaluate the total airflow rate transported by the jet to some distance from a diffuser face. Airflow rate in the jet, Q,., can be derived by integrating the air velocity profile within the jet boundaries ... 

Equations for airflow rate computation in compact, linear, and radial jets are presented in Table 7.13. 

TABLE 7.13 Airflow Rate through a Jet Cross-sectional Area... 

Thermal plumes above point (Fig. 7.60) and line (Fig. 7.61) sources have been studied for many years. Among the earliest publications are those from Zeldovich and Schmidt. Analytical equations to calculate velocities, temperatures, and airflow rates in thermal plumes over point and line heat sources with given heat loads were derived based on the momentum and energy conservation equations, assuming Gaussian velocity and excessive temperature distribution in... 

A point source has a convective heat output of 100 W (see Fig. 7, >2). Determine the airflow rate 1 m above the source. 

Calculate the airflow rate along an external wall with a surface temperature 3°C above room remperature, at a height of 4 meters above the lower edge of the surface. 

In reality, heat sources are seldom a point, a line, or a plane vertical surface. The most common approach to account for the real source dimensions is ro use a virtual source from which the airflow rates are calcu-lared " " see Fig. 7.64. The virtual origin is located along the plume axis at a distance on the other side of the real source surface. The adjustment of the point source model to the realistic sources using the virtual stmrce method gives a reasonable estimate of the airflow rate in thermal plumes. The weakness of this method is in estimating the location ol the virtual point source. 

The airflow rate from a heat source can then be calculated as half of the flow from a source with a heat emission of... 

Calculate maximum air velocity, airflow rate, and excessive temperature (relative to the ambient air temperature equal to 20 °C) in thermal plume above the heated cube (0.66 m x 0.66 m x 0.66 m) with convective heat production = 225 W, at heights of 2.0 m and 4.0 m above the floor level. Neglect temperature gradient along the room height. Compare the results with predictions made for the same case using CFD code (Fig. 7.80). 

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