Laboratory scale experiments

As noted earlier there have been extensive studies in fire wind tunnels of fire propagation through porous fire beds made of a variety of different depths of natural and artifical materials. Unfortunately, little of this work is directly applicable to the simulation within urban fires or forests including crown fires. One minor exception is the limited work of Lee and Otto, 1975 [364], 

The interaction of the fire between the two structures that resulted during fire whirl formation and subsequent sucking of flames out of openings (windows and doors) is similar to that assumed by the Himmoto and Tanaka [264] fire propagation model. 

No additional examples of intense heat sources or actual fires released within model forest or simulated urban environments are known to this author. 

---

The model is able to predict the influence of mixing on particle properties and kinetic rates on different scales for a continuously operated reactor and a semibatch reactor with different types of impellers and under a wide range of operational conditions. From laboratory-scale experiments, the precipitation kinetics for nucleation, growth, agglomeration and disruption have to be determined (Zauner and Jones, 2000a). The fluid dynamic parameters, i.e. the local specific energy dissipation around the feed point, can be obtained either from CFD or from FDA measurements. In the compartmental SFM, the population balance is solved and the particle properties of the final product are predicted. As the model contains only physical and no phenomenological parameters, it can be used for scale-up. 

Some information exists regarding the potential for emissions of organotin compormds from landfills, including laboratory-scale experiments as well as measured concentrations of organotins in landfill leachate. 

The DNS in turbulent combustion has evolved from two-dimensional computations with simple chemistry to duplicate laboratory-scale experiments with detailed... 

Although the asymmetric hydrogenation route to 3,3-diphenylalanine via this modified substrate preparation was not developed further, Dowpharma had a requirement to rapidly develop and scale up the manufacture of a related 3,3-diarylalanine product. The work to 3,3-diphenylalanine centred around substrate preparation and removal of impurities leading to high activity associated with the PhanePhos catalyst system allowed for a facile transfer from laboratory scale experiments to the commercial manufacture of the related diphenylalanine derivative by a robust, reproducible and scaleable procedure. 

In a series of laboratory scale experiments, streams of oxygen and sulfur dioxide were fed at different rates to a differential reactor containing 2.372 g of catalyst. The data below were recorded under essentially isothermal conditions... 

The Jacobs-Gould intramolecular cyclization of diethyl N-(6-methyl-2-pyridyl)amino-methylenemalonate to 3-ethoxycarbonyl-7-methyl-l,8-naphthyrid-4-one is another reaction ideally suited to microwave heating, although conductively heated equipment was employed for laboratory-scale experiments [45]. The product is a key intermediate in the synthesis of nalidixic acid, the first of the quinolone antibacterials. The process usually is conducted at temperatures of 200-250 °C and in high dilution, with heat transfer oils such as the eutectic mixture of diphenyl ether and biphenyl. However, it proceeded rapidly, predictably and controllably under solvent-free conditions. 

This procedure was scaled up from 50 mmol to the 2 mol scale (i.e. from 15.6 to 622.4 g total starting materials) in a larger batch reactor (Synthewave 1000) [12]. Yields were equivalent to those obtained under the original conditions (5 min, 160 °C) in the laboratory-scale experiment (Synthewave 402) (Tab. 5.2). 

For example, a well defined inertial range exists only for R, > 240. Thus the proportionality constant in (5.251) should depend on the Reynolds number in most laboratory-scale experiments. 

It is difficult to deduce the size of tower required for an absorption combined with a chemical reaction, and a laboratory scale experiment should be carried out in all cases. Stephens and Morris(41) have used a small disc-type tower illustrated in Figure 12.15 for preliminary experiments of this kind. It was found that a simple wetted-wall column was unsatisfactory where chemical reactions took place. In this unit a series of discs, supported by means of a wire, was arranged one on top of the other as shown. 

The stability of the treated slurries was linearly related to the oxygen consumed during treatment, which could be calculated using an expression for nitrification derived in the present study and one for COD changes produced by Evans et al (4) from laboratory scale experiments. 

If there are no detrimental organic side reactions, a cell current density in excess of the limiting current density - and as result a loss of current efficiency - may be acceptable for laboratory scale experiments. For example, a hydrogen evolution parallel to an electroorganic cathodic reduction can even be advantageous as it improves the mass transfer by moving gas bubbles and thus enhances the organic cathodic reduction. 

Constant current electrolysis is an easy way to operate an electrochemical cell. Usually, it is also applied in industrial scale electrolysis. For laboratory scale experiments, inexpensive power supplies for constant current operation are available (also a potentiostat normally can work in galvanostatic operation). The transferred charge can be calculated directly by multiplication of cell current and time (no integration is needed). 

In many cases, it will be impossible to prevent unwanted reactions at the counter electrode. Then a separation of the anolyte and catholyte is needed. An optimal compromise has to be found for the separator between separation effectiveness and ion conductivity, that is, minimized electrical resistance and low energy consumption. Moreover, chemical, thermal, and mechanical stability and price of the separator have to be considered. Naturally, a complete separation is impossible, because a slight diffusion rate is inevitable. In laboratory scale experiments, probably a high cell voltage is acceptable in order to realize a maximal separation. 

The upper-limit temperature of the hot liquid where RPTs are not probable and film boiling occurs is less definite. Data from laboratory-scale experiments shown below indicate that a value equal to l.lOTsi is not a bad approximation. 

Quantifying adsorption of contaminants from gaseous or liquid phases onto the solid phase should be considered valid only when an equilibrium state has been achieved, under controlled environmental conditions. Determination of contaminant adsorption on surfaces, that is, interpretation of adsorption isotherms and the resulting coefficients, help in quantifying and predicting the extent of adsorption. The accuracy of the measurements is important in relation to the heterogeneity of geosorbents in a particular site. The spatial variability of the solid phase is not confined only to field conditions variability is present at all scales, and its effects are apparent even in well-controlled laboratory-scale experiments. 

Conditions of constant potential are frequently employed in laboratory scale experiments. In these experiments, the cunent tlirough the cell falls with time due to depletion of the substrate. Under conditions of constant diffusion layer thickness, the current it at time t is given by Equation 1.4 [17] where D is the diffusion coeffi-... 

Alkanes are functionalised by anodic oxidation in acetonitrile, methanol, acetic acid and more acidic solvents such as trifluoracetic acid and fluorosulphuric acid. Reaction requires very positive electrode potentials (see Table 2.1) and platinum has generally been used as anode materials in laboratory scale experiments. On a larger scale carbon is used as anode material. The first stage in these reactions in-... 

Electrochemically generated nickei(lll) oxide, deposited onto a nickel plate, is generally useful for the oxidation of alcohols in aqueous alkali [49]. The immersion of nickel in aqueous alkali results in the formation of a surface layer of nickel(ll) oxide which undergoes reversible electrochemical oxidation to form nickel(lll) oxide with a current maximum in cyclic voltammetry at 1.13 V vj. see, observed before the evolution of oxygen occurs [50]. This electrochemical step is fast and oxidation at a prepared oxide film, of an alcohol in solution, is governed by the rate of the chemical reaction between nickel oxide and the substrate [51]. When the film thickness is increased to about 0.1 pm, the oxidation rate of organic species increases to a rate that is fairly indifferent to further increases in the film thickness. This is probably due to an initial increase in the surface area of the electrode [52], In laboratory scale experiments, the nickel oxide electrode layer is prepared by prior electrolysis of nickel sulphate at a nickel anode [53]. It is used in an undivided cell with a stainless steel cathode and an alkaline electrolyte. 

In 1995, the vendor estimated the cost of in sitn remediation based on laboratory-scale experiments. The estimate was approximately 50/yd of soil treated (D126089, p. 12). 

The increase in microbe populations that can be caused by direct application of surfactants leads to an increased need for oxygen (an increase in the biological oxygen demand, or BOD). This increased demand for oxygen was handled in a laboratory-scale experiment where the soil was easily mixed each day for aeration however, it was implied that oxygen could act as a limiting factor in a full-scale apphcation where aeration would be more difficult. 

The developers estimate the operating costs for a full-scale version of the PST process will typically be less than the value of the recovered oil. Estimates are that the operating costs will be about 25 per ton. Installed capital costs are estimated to be about 2 million, or 10 to 15 per wet ton feed sludge capacity (D15507H, p. 1 D13883U, p. 41). However, the actual costs of the technology may vary from this because at this point in time these estimates are based only on laboratory-scale experiments. 

Figure 15. Laboratory-scale experiment for studying the behavior of de Broglie waves.

Recent laboratory-scale experiments (5, 6) on the partial hydrogenation and carbonization of bituminous and lower-rank coal in a fluidized bed at hydrogen pressures of 1000 pounds per square inch or less have indicated that ... 

Certain criteria and assumptions were used in the development of analytical methods. It was assumed that 1 L of water spiked with model compounds would be used in the laboratory-scale experiments. It was also assumed that the extracts taken for analysis could be reduced to 1 mL prior to analysis. The objective of the analyses would be to permit measurement at all values in excess of 1-2 of the concentration levels specified (i.e., for those compounds specified at 50 /zg/L, one should be able to detect and measure concentrations in the range 1-50 /zg/L). 

Laboratory-scale experiments which used L. casei symbiotically with Propionibacterium freudenreichii in the fermentation of whey gave an average yield of 2.2 mg of vitamin per liter the maximum was 4.3 mg/liter. Production of vitamin Bi2 is not species-specific. All species of Propionibacterium, when cultivated under the same conditions, produce active substances, but in different quantities. P freudenreichii and P zeae synthesized sufficient quantities to warrant their consideration for commercial exploitation. Because propionic acid bacteria are active during Swiss cheese ripening, it was anticipated, and actually demonstrated, that production of vitamin Bi2 in Swiss cheese is influenced by the same factors that influence its production in pure culture, particularly by the cobalt content of milk (Hargrove and Leviton 1955). 

---