Transient tests

OBSERVATIONS ON TRANSIENT TESTING TECHNIQUES. AN EXAMPLE OF A TRACER TEST... 

The five transient testing techniques outlined above are not independent but simply alternatives by means of which RTDs and system dynamics can be studied in particular situations, one or other method may be preferred. Some of the relationships between these different techniques are discussed in refs. 22, 24 and 25. 

To study the influence of N02 on SCR efficiency, ESC and ETC test cycles with 0% and 50% N02/NOx ratio in front of SCR catalyst were simulated. However, during transient test cycle operating conditions, a constant supply of optimum 50% N02/NOx ratio will be difficult to achieve. NO to N02 conversion over a DOC is dependent on exhaust temperature, space velocity and exhaust composition. Because of transient operating conditions, it becomes furthermore a function of time. Exploiting the fast SCR reaction is thus limited by the realistically achievable N02/NOx ratio in front of the SCR catalyst. To investigate this, ESC and ETC test cycles were also simulated for a combined system of DOC and SCR, where the N02/NOx ratio in front of the SCR is defined by the N02 conversion over the DOC (Fig. 52). 

Tlhis paper describes the physical and radiochemical characteristics of selected debris from the Kiwi Transient Nuclear Test (TNT) (6, 7). This transient test was conducted in Nevada by the Los Alamos Scientific Laboratory (LASL), and produced approximately 3 X 1020 fissions (1). Zero time was 1059 PST on 12 January 1965. About 5% of the reactor core was vaporized, and some 68% was converted to a cloud of particulate. The measured maximum temperature was 4250°K. (7). Large pieces of fuel rods were recovered near ground zero. 

Transient Test Air Bursts Coral Surface Burst Silicate Surface Bursts... 

Although the transient test was orders of magnitude below a nuclear weapon in regard to energy release and temperature achieved, the debris showed many similarities to fallout. These included not only the size and appearance of the particles but also the correlation properties of various radionuclides. Dissimilarities in the correlations and the variation of specific activity with particle type confirm expectations of the importance of escape processes to the formation mechanisms for this type of debris. This study shows that data-correlation techniques developed for fallout characterization are also useful in studying reactor debris. 

The 2002 Mallik well provided an indisputable proof of the concept—namely, it is possible to in transient testing to recover energy from permafrost hydrates upon dissociation. 

One clear reason for this statement is that transient screening, in contrast to steady screening experiments, gives a denser information-content simply because during transient tests a complete function (the kinetics) is recorded instead of single stochastic data. 

The conversions are predicted quite accurately over a wide range of coke levels (from 0.7 to 2.7 wt %). There are some minor discrepancies in the coke predictions. However, these predictions are within the experimental accuracies of the tests. The FFB conversions are reproducible within 2 numbers, with 20% accuracy for coke yields. Similarly, the MAT data are reproducible within 3 numbers with 30% accuracy for coke yields. These comparisons suggest that the models could be used to fit the catalyst intrinsic parameters (kj, A,) from the transient tests and then predict the steady state riser performance. Indeed, we have done this exercise and we predict a reverse ranking for catalysts A and C in going from transient tests to the riser performance, as observed in the riser experimental data. 

The effect of time averaging on yields in transient tests can be minimized by shortening the duration of the test. Also, a fixed bed test is superior to an FFB activity test in that backmixing is minimized. Furthermore, an isothermal fixed bed test would be easier to interpret than the adiabatic MAT test. This work shows that from the point of view of a catalyst characterization test, a small steady state riser will give the most direct information for catalyst performance in a commercial riser. 

Glass transition temperature, Tg, and storage modulus, E , were measured to explore how the pigment dispersion affects the material (i.e. cross-link density) and mechanical properties. Both Tg and E were determined from dynamic mechanical analysis method using a dynamic mechanical thermal analyzer (DMTA, TA Instruments RSA III) equipped with transient testing capability. A minimum of 3 to 4 specimens were analyzed from each sample. The estimated uncertainties of data are one-standard deviation. 

These standards are required to be met over the full life of the vehicle or engine, rather than over half the life as is the case with cars. Also, EPA based the standard on the new "transient" test referenced above rather than on the old "steady-state" test because the transient test is much more representative of the manner in which trucks are driven in cities. 

FIGURE 15.72 Effect of contact angle on transition boiling heat transfer. Transient tests with saturated water on 100-mm copper surface (from Shoji et al. [183], with permission from ASME). 

The isothermal lines on the test surface can be evaluated from the measured dominant wavelength distribution reflected from the liquid crystal surface. In a transient test, the surface temperature can be evaluated from the one-dimensional conduction equation in a semiinfinite domain ... 

J. E. Doorley, Procedures for Determining Surface Heat Flux Using Thin Film Gages on a Coated Metal Model in a Transient Test Facility, ASME J. of Turbomachinery, 110, pp. 242-250,1988. 

Performed steady state and transient testing on gasoline and delivered integrated FCPS to ANL. 

Transient tests have been performed with a fixed bed of 0.125 g catalyst in a 1 mm id, quartz reactor exposed to a series of concentration steps CjHs-He, Fie, Oa+FFe, Fie, CsHg-Fle, etc. This was obtained by distributing the three constant gas flows between the reactor and two parallel ballasts with two couples of three way eletrovalves [6] The concentration of products was determined using a Balzers QMS 420 system based on quadripole mass spectroscopy. The reactor conception was taken from the works of Floffmann and Muller [7]. 

Table lU.S. Heavy/Medium Duty Diesel Emissions Standards (HD U.S. Transient Test Cycle)... 

The emissions test is conducted using the heavy duty U.S. transient (FTP) cycle which reflects a continuous measure of emissions during various speed and loads reflecting urban and expressway driving [2]. The transient test itself and different engines with different power ratings, result in a variety of exhaust temperature and flow conditions. Thus, the catalyst must remove and convert the particulates over a broad range of conditions. 

European diesel passenger car transient test results... 

Figure 2. - European Transient Test Results for Catalyst "C" and Catalyst "D" -Performance for Gas Phase HC and TPM Removal...

Figure 2c shows the HC removal results for Catalyst "C" and Catalyst "D" for the overall Transient Test (Cycle "A") which is the weighted-average of the ECE and EUDC segments. As can be seen Catalyst "D" exhibits very hi overall HC removal because of its excellent low temperature performance. Even at the lowest Pt loading level Catalyst "D" gives HC removal levels to meet the EURO II HC+NOx standards with a comfortable margin and comes quite close to the proposed EURO III standards. 

Figure 2d gives the particulate (TPM) removal of the catalysts over the Transient Test Cycle and it can be seen that high levels of performance (> 40% removal) are attained, especially for the lower Pt loading levels. Overall, these results show that it is possible to achieve good removal and conversion of gas phase HC s and TPM under demanding conditions by the proper choice of base metal oxides and with low levels of platinum on the catalyst. 

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