Ventilation experiments

Figure 13.11 South Atlantic distributions of (A) nitrate (pmol kg ) and (B) DIN s (pmol kg ) on (7e surface 26.8. Data collected in the South Atlantic Ventilation Experiment (SAVE) project. Dots are station locations.

The Atlantic basin, particularly the North Atlantic, is the most studied of the global oceans, yet there are several important processes and issues remaining to be addressed. Arguably, the most important issue is the paucity of data from the South Atlantic. There have been excellent expeditionary efforts there (i.e., the WOCE sections and the South Atlantic Ventilation Experiment), so the hydrographic system and the nutrient provinces can now be assessed in greater detail. However there has been little focus on processes of the nitrogen cycle in the basin. 

Finsterle and Pruess (1995) obtained by backanalysis of a ventilation experiment the... 

Different inlet and return air pressure are carried out for four U-shaped ventilation experiments. Along goaf tendency the distance for x = 0 cm side is the inlet side, and x = 160 side is the return air-side. The mined negative pressure and gas content for each point are tested respectively. Use MAT-LAB to analyze the pressure and gas concentration values and draw a three-dimensional contour map. The conditions of the gas concentration and pressure distribution get under differential pressure between inlet and return airway. 

An ideal outcome would be to provide a ventilation experience that would not suspend partides whose size is 10 miaons or larger (to keep dean parts dean), have a relative humidity not exceeding 50% (to minimize water intmsion into the degreaser with the parts), provide an adequate volumetric turnover of fresh air of 5 to 10 changes per hour (for employee comfort), and not exceed a laminar face velodty from a unidirectional diffuser greater than 30 ft/min (0.15 m/s) (to minimize solvent diffusion from the degreaser). 

Most European centers supervise less than 50 patients. This limits the ventilator experience of the staff. But these small centers can provide the patient greater accessibility. The solution to the dilemma between accessibility and expertise is the creation of networks of centers. The centers with more expertise, technology, and specialists can give support to local centers with less technological resources but who are able to provide closer attention to the patient. Eventually the patient may be transferred from the local center to the center with more technological support for a more complex evaluation, but the routine care is given in the most accessible place. Moreover, in the context of a network the introduction of innovations is easier and permits a more homogeneous dissemination. 

Ethyl alcohol is a flammable Hquid requiring a red label by the DOT and Coast Guard shipping classifications its flash point is 14°C (Tag, closed cup). Vapor concentrations between 3.3 and 19.0% by volume in air are explosive. Liquid ethyl alcohol can react vigorously with oxidi2ing materials. Ethyl alcohol has found wide appHcation in industry, and experience shows that it is not a serious industrial poison (273—275). If proper ventilation of the work environment is maintained, there is Httle likelihood that inhalation of the vapor will be ha2ardous. 

At high pressure experiments the reactor should be installed in a pressure cell. All check valves before it, and the filter with the flow controller after it, can be kept in the vented operating room. As a minimum, the bypass valve and the flow controller must be accessible to the operator. This can be done by extended valve stems that reach through the protecting wall. Both the operating room and the pressure cell should be well ventilated and equipped by CO alarm instruments. 

Please notice that in a well-ventilated laboratory and a pressure cell, these experiments can be executed safely. In seven years of graduate research activity at the Chemical Engineering Department of the University of Akron, only one catalyst ignition and one real CO alarm occurred. Several false CO alarms were sounded until someone noticed that they always happened about 2 30 PM. As it turned out, one maintenance employee parked his old car right in front of the air intake to the lab ventilation. He warmed up his car for a while before he started to go home after his shift, and the motor exhaust gas set off the false alarms. 

If available government agencies do not have personnel with the appropriate skills to assist in solving your lAQ problem, they may be able to direct you to firms in your area with experience in indoor air quality work. Note that even certified professionals from disciplines closely related to lAQ issues (such as industrial hygienists, ventilation engineers, and toxicologists) may not have the specific... 

This chapter covers a description of conventional measurement techniques used in ventilation as well as othei related topics such as flow visualization, laser- based measurement techniques, and scale model experiments. 

The results clearly indicated that the ventilation noise was perceived as most acceptable when the tone was situated in the low er part of the frequency range. The experience of disturbance and the associated effects occur at exposure levels above the auditory perception threshold. Above this level, the risk of these effects increases as the perceived loudness increases, provided that the other conditions remain constant. Since the loudness can be predicted relatively accurately by means of technical measurements, any differences in the degree of disturbance can also be predicted by reference to these measurements, provided that they are dependent on differences in the loudness. 

The extent to which a ventilation noise is perceived as disturbing depends not only on its dB(A) level, but also on the spectral distribution and the presence of tones or intermittent components in the noise. From an experiment carried out on respondents exposed to ventilation noises with different characteristics in a simulated office room, it emerged that the highest acceptable level was about 7 dB higher for ventilation noise with a superimposed tone at 30 Fiz than for other types of noise. In another experiment, it was found that the tolerance level was much higher for a tone than for a noise at 100 Hz, whereas the opposite tendency applied at 1000 Hz. ... 

Earlier experiments indicate clearly that a lowered sound pressure level can be an effective measure to reduce the inconvenience reactions due to a ventilation noise, provided that it is targeted at the most critical frequency range from the point of view of influence or that the measure results in a general lowering over the entire spectral range of the ventilation noise. 

A detailed method of determining pressure coefficients is to perform experiments with a wind tunnel facility. Cochran and Cermak compared wind tunnel pressure coefficient measurements with field measures on a test building and found excellent results, with the exception of small areas beneath the vortices near the upwind roof corner for winds approaching at 45 . For infiltration and natural ventilation designs, wind tunnel results should be sufficiently accurate. 

The most popular approach to solve these problems is to use experience and good engineering judgment. A quick experiment may be another solution. A computer simulation is a third option. All those approaches may eventually lead to success. This chapter presents various methods of computer simulation for industrial ventilation design. 

Experiment or simulation. A decision may be based on the following considerations, but the final choice rests with the ventilation engineer ... 

The study shows, however, that the air curtain in the original design is bent off the wall due to the presence of the open oven with induced airflow inside the oven. This unexpected flow feature finally leads to a recirculation zone below the oven, and dust particles on the floor can be carried into the oven (class B quality). This effect was then also confirmed by smoke experiments in the real room and the existing ventilation system. 

One of the first simulations of displacement ventilation was presented in refs, 34 and 35. The predictions were compared with water-model experiments, and hence radiation was not taken into account. In ventilated rooms radiation should be taken into account. In ref. 36 plumes related to displacement ventilation were numerically studied. 

Aro T., and Koivula K. Learning from experience with industrial ventilation. CADDFIT Analyses Series No. 10, 1993. Atlanta, GA American Society of Heating, Refrigeration and Air-Conditioning Engineers. 

Model Experiments in Connection with Local Ventilation in the Industrial... 

Laboratory Experiments with General and Local Ventilation 1186... 

The carrying out of visualization techniques or measurements is one approach to obtain answers to these questions. Computer simulation is another method that is now becoming a more exact science. A third, essential approach is to depend on experience and good engineering judgment. All the above methods may eventually lead to success however, the effort and cost of the work may differ considerably. This chapter describes the measurement and visualization techniques that can be applied in industrial ventilation problems. 

In addition to their widespread use in research and development in fluid dynamics, laser-based techniques ° are also suited to experiments in industrial ventilation. The use of these advanced experimental methods is reasonable when their advantages in comparison with traditional measurement techniques counterbalance the significantly higher expenses of instrumentation. 

In industrial ventilation applications, LDA experiments fulfill the following needs ... 

One of the methods used for the determination of airflow in large spaces is model experiments. This method is also useful in the study of local ventilation around a working area in the industrial environment. 

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