Flow configurations influence

The exhaust flow rate influences the flow of the jets and some reports recommend a ratio of supply airflow rate to exhaust airflow rate of approximately 0.3. A ratio of 0.2 is unsteady and ratios larger than 0.4 have not been studied. In the cases that have been studied, the exhaust opening was 80 mm in diameter, the distance between the horizontal planes was 750 mm, the tubes were placed in a square w ith side length equal to 670 mm, and the inward angles of the jets were 10 degrees. This configuration resulted in better capture of hot gases than use of an exhaust system alone. 

To examine the effect of turbulence on flames, and hence the mass consumption rate of the fuel mixture, it is best to first recall the tacit assumption that in laminar flames the flow conditions alter neither the chemical mechanism nor the associated chemical energy release rate. Now one must acknowledge that, in many flow configurations, there can be an interaction between the character of the flow and the reaction chemistry. When a flow becomes turbulent, there are fluctuating components of velocity, temperature, density, pressure, and concentration. The degree to which such components affect the chemical reactions, heat release rate, and flame structure in a combustion system depends upon the relative characteristic times associated with each of these individual parameters. In a general sense, if the characteristic time (r0) of the chemical reaction is much shorter than a characteristic time (rm) associated with the fluid-mechanical fluctuations, the chemistry is essentially unaffected by the flow field. But if the contra condition (rc > rm) is true, the fluid mechanics could influence the chemical reaction rate, energy release rates, and flame structure. 

J. Soler, E. Hontanon, and L. Daza. Electrode permeability and flow-field configuration Influence on the performance of a PEMFC. Journal of Power Sources 118 (2003) 172-178. 

Several laboratory studies have contributed to our understanding of turbulent chemical plumes and the effects of various flow configurations. Fackrell and Robins [25] released an isokinetic neutrally buoyant plume in a wind tunnel at elevated and bed-level locations. Bara et al. [26], Yee et al. [27], Crimaldi and Koseff [28], and Crimaldi et al. [29] studied plumes released in water channels from bed-level and elevated positions. Airborne plumes in atmospheric boundary layers also have been studied in the field by Murlis and Jones [30], Jones [31], Murlis [32], Hanna and Insley [33], Mylne [34, 35], and Yee et al. [36, 37], In addition, aqueous plumes in coastal environments have been studied by Stacey et al. [38] and Fong and Stacey [39], The combined information of these and other studies reveals that the plume structure is influenced by several factors including the bulk velocity, fluid environment, release conditions, bed conditions, flow meander, and surface waves. 

The influences of the liquid and gas flow rates, the diameter of the absorption chamber, the distance between nozzles, and the flow configuration on absorption rate were studied by the researchers mentioned above. These will not be discussed in detail here because of the length limitation of the chapter for the details, the reader may refer to the original references as cited in the text above. It should be noted, however, that in all the investigations above, the data for mass transfer coefficients are always correlated with the gas and/or liquid flow rates, but not with the impinging velocity, m0, although the latter is the operation parameter extremely important in every impinging stream device. 

The cause of this is not only that there are many influencing quantities that play a role in boiling processes, but also different types of heat transfer depending on the flow configuration and superheating. These different types of heat transfer will be considered first, followed by an explanation of the physical fundamentals of boiling phenomena. The final part of this section will consist of the calculation of the heat transfer. 

A.ll experiments were conducted at atmospheric pressure in a quartz-glass flow tube reactor (2.-5 cm diameter. 20 cm length). The reaction gases were premixed and flowed perpendicular to the catalytic foil in a stagnation point flow configuration (inset fig. 1).. All experiments were conducted at total gas flow rates between 1 slpm and 6 slpm. which did not influence the results within experimental error. The high-purity platinum foils were resistively heated and the foil temperature was determined by a chromel/alumel thermocouple spotwelded to the back of the foil. Temperature measurements were reproducible within 10 K on the same foil and within 30 K in independent runs with different foils. 

Particle distribution will be influenced by air flow configurations and velocities so that under clean room operating conditions particles may be dispersed further than distances predicted from data derived using... 

Finally, we note that the size and shape of the particles of the packing, the packing technique, and column dimensions and configuration are additional factors which influence a GPC experiment. In addition, the flow rate, the sample size, the sample concentration, the solvent, and the temperature must all be optimized. Details concerning these considerations are found in analytical chemistry references, as well as in the technical literature of instrument manufacturers. 

Whereas there is no universally accepted specification for marketed natural gas, standards addressed in the United States are Hsted in Table 6 (8). In addition to these specifications, the combustion behavior of natural gases is frequently characteri2ed by several parameters that aid in assessing the influence of compositional variations on the performance of a gas burner or burner configuration. The parameters of flash-back and blow-off limits help to define the operational limits of a burner with respect to flow rates. The yeUow-tip index helps to define the conditions under which components of the natural gas do not undergo complete combustion, and the characteristic blue flame of natural gas burners begins to show yellow at the flame tip. These... 

The influence of room transverse cross-section configuration on airflow patterns created by air jets supplied through round nozzles in proximity to the ceiling was studied by Baharev and Troyanovsky and Nielsen (see Fig. 7.37). Based on experimental data, they concluded that when the room width B is less than 3.5H, the jet attaches to the ceiling and spreads, filling the whole width of the room in the manner of a linear jet. The reverse flow develops under the jet. When B > 4H, the reverse flow also develops along the jet sides. Baharev and Troyanovsky indicated that air temperature and velocity distribution in the occupied zone is more uniform when the jet develops in the upper zone and the occupied zone is ventilated by the reverse flow. Thus, they proposed limiting room width to 3-3.5H,. 

Corona discharges have been investigated extensively for NO removal [38-54], The effect of electrodes configuration, electrical circuit, gas composition and flow rate were studied. When the discharge was operated in pulsed mode, the influence of pulse rise time, duration, and repetition frequency, as well as the effect of the voltage polarity on NO conversion, were considered by numerous authors. 

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