Jet stirring

Guiraud, P., J. Bertrand, and J. Costes (1991). Laser measurements of local velocity and concentration in a turbulent jet-stirred tubular reactor. Chemical Engineering Science 46, 1289-1297. 

Monte Carlo PDF method for turbulent reacting flow in a jet-stirred reactor. 

Other measurements of Hanratty s p have been made or inferred from various techniques, including a hot film probe just under the water surface (Brumley and Jirka, 1987), particle image velocimetry in a vertical laser sheet leading up to the water surface with a florescent dye to indicate water surface location accurately (Law and Khoo, 2002) and PIV on the water surface (McKenna and McGillis, 2004 Orlins and Gulliver, 2002). The measurements of Law and Khoo (2002) are especially interesting because the following relationship was developed from experiments on both a jet-stirred tank and a wind-wave channel ... 

C.B. Vaughn, W.H. Sun, J.B. Howard, and J.P. Longwell. Measurements and Modeling of Light Hydrocarbons in Rich C2H4 Combustion in a Jet-Stirred Reactor. Combust. Flame, 84 38-46,1991. 

The global rates were determined by direct comparison of predictions, using selected sets of rates, with the near adiabatic data obtained from the Exxon Jet-Stirred Combustor (12). The particular set of rate parameters resulting from this process are given... 

Detailed comparisons for near adiabatic combustion of isooctane are shown in Figures 3 and 4. Figure 3 shows temperature and Figure 4 shows CO, CO2, O2 and unburned hydrocarbons as functions of equivalence ratio. The quality of these comparisons is very good and is similar to that obtained for the toluene experiments. Soot was not observed to form in measurable quantities for iso-octane mixtures which could be stably burned in the Jet-Stirred Combustor. 

Although the prediction of N0X emissions under lean and stoichiometric combustion with the extended Zeldovich mechanism is adequate for certain applications, predictive methods for fuels containing bound nitrogen and for rich combustion conditions require substantial improvement. However, the early studies of Fenimore (13, 14) demonstrated the potential importance of HCN and NH type species in fuel-nitrogen interactions. To illustrate the critical importance of the coupling of nitrogenous species reactions in rich combustion, predictions of NO emissions from rich iso-octane combustion in a jet-stirred combustor are shown in Table III. C2 hydrocarbon fragmentation and oxidation creates... 

Quasiglobal kinetics models, which have previously been shown to represent lean and stoichiometric combustion of a variety of hydrocarbon fuels, have been extended to represent lean and rich combustion of toluene and iso-octane. The model predicts the thermal state of the flow and emissions of CO, soot, and N0X. The thermal state of the flow and the stable species were shown to be accurately predicted for jet-stirred combustor experiments. For rich combustion, hydrocarbon intermediates and soot are additional combustion products. The global reactions and rates were developed to represent near-adiabatic jet-stirred combustor data and were then verified by comparison to the near iso-thermal jet-stirred combustor data. N0X emissions behavior was investigated with the quasiglobal kinetics model to represent rich combustion... 

Engleman, V. S. Bartok, W. Longwell, J. P. Edelman, R. B. "Experimental and Theoretical Studies of N0X Formation in a Jet-Stirred Combustor" Fourteenth Symposium (International) on Combustion, 1973, 755-765. 

A Study ot Fuel Nitrogen Conversion in Jet-Stirred Combustors... 

In this paper we report on factors which affect the conversion of fuel nitrogen to TFN in laboratory jet-stirred combustors which serve to simulate the primary zone in a gas turbine. The independent variables in the experiments were fuel type (aliphatic isooctane vs. aromatic toluene), equivalence ratio (fuel-to-oxygen ratio of combustor feed divided by stoichiometric fuel-to-oxygen ratio), average gas residence time in the combustor, and method of fuel injection into the combustor (prevaporized and premixed with air vs. direct liquid spray). Combustion temperature was kept constant at about 1900K in all experiments. Pyridine, C5,H5N, was added to the fuels to provide a fuel-nitrogen concentration of one percent by weight. 

The LFJSC has a spherical jet-stirred zone (diameter 5.08 cm) followed by a cylindrical plug flow zone (diameter =2.2 cm length - 7.6 cm) both zones are refractory lined. Primary combustion air enters the jet-stirred zone through two nozzles positioned 180° apart. A set of four 1.1 mm diameter air jets from each nozzle is aimed towards the corners of a cube imagined to sit within the spherical zone. One set of air jets is rotated 45° with respect to the other to allow the opposing jets to mesh rather than to collide. Flow rates are chosen to produce near... 

Data from the present set of experiments suggest that the conversion of fuel nitrogen to TFN in jet-stirred combustors depends upon the equivalence ratio and average residence time of gases within the combustor, the fuel type and certain physical characteristics of the combustors. However, the effects of these primary variables on fuel nitrogen conversion appear to be related to their effects on the concentrations of unburned hydrocarbons and soot in the exhaust gases. These effects and their relationships to unburned hydrocarbon and soot concentrations are discussed below. 

An experimental apparatus that under certain conditions approximates closely a well-stirred reactor is a spherical chamber into which premixed reactants are injected centrally through a perforated tube and out of which the reaction products flow through a number of ports located at various positions in the outer shell. The mixing is driven by the fuel-injection jets that are formed at the tube perforations, and the apparatus has been called the jet-stirred reactor. The average residence time of an element of gas in the reactor is... 

The overall rate of consumption of fuel obtained in a well-stirred reactor differs from that of an ignition-delay experiment because the combustion rather than the ignition of the fuel is investigated. Overall rates of other processes, such as pollutant production, also have been obtained in experiments with jet-stirred reactors by measuring levels of the appropriate products in the outlet streams. Results of some experiments on jet-stirred reactors are consistent with the concept of the well-stirred reactor [6], [9] [17]. Some of the more recent work cited has endeavored to account for influences of imperfect mixing. Theoretical aspects of the well-stirred reactor have been presented in a recent book. ... 

CSTR = Continuously-stirred tank reactor, PER = Pressurized flow reactor, RCM = Rapid compression machine, JSR = Jet-stirred reactor, JSFR Jet-stirred flow reactor. 

Fig. 6.1. Variation in measured mole fraction of n-heptane as a function of vessel temperature. Jet-stirred reactor at 1 MPa over a range of fuel oxygen ratios () = 1 3.6 (0.3) ( ), 1 22 (0.5) ( ), 1 11 (1.0) (A) and 1 7.5 (1.5) ( ) at a mean residence time of 1.0s. Reactants diluted with excess N2 to maintain isothermal conditions. (After Dagaut et al.

A complementary ignition diagram to that for n-C4Hio in an unstirred closed vessel was obtained in a jet-stirred flow reactor by Proudler et al. [58]. The reactor was a 500 cm stainless steel cylinder, operated at a mean residence time of 9.4 0.4 s with a reactant mixture [n-C4Hio] [O2] = 1.13 1 (Fig. 6.16). Oscillatory cool-flames and ignitions were detected within narrow temperature ranges, but comparable with those of the closed... 

Typical molecular products of n-heptane and i-octane oxidation over the temperature range 550-1200 K at 1.0 MPa in a jet-stirred flow reactor. The components are listed according to their maximum mole fractions of products below, above or in the vicinity of 850 K [31]... 

As part of the experimental phase of the program, Esso Research and Engineering (2i) is conducting combustion studies under a variety of conditions. The initial work (23) utilized a modification of the Longwell-Weiss reactor (24), termed a jet-stirred combustor (Figure 3). This... 

Figure 4 shows the experimental data taken for hydrogen-air combustion. The solid squares are the result of a complete kinetic calculation (not assuming partial equilibration) (26), treating the jet-stirred reactor as a well stirred system and inputing measured reactor temperature or heat loss rates. The reaction scheme included the following ... 

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