Conversion efficiencies, warm

Impact of Fuel Sulfur on Three-Way Catalyst Performance (warmed-up conversion efficiency at conditions shown during exposure to sulfur at the concentrations shown). 

For both catalysts, the rate of increase in bed temperature was greater for smaller converter volumes although there was little difference between the 600- and 1300-cm3 converters. Catalyst temperature increased more rapidly with the platinum catalyst. Greater conversion efficiencies (Table V) and hence greater energy release rates were attained with this catalyst during warm-up cycles 1-5 of the FTP. The fraction converted by the platinum catalysts was maximum at the 1300-cm3 converter volume. Conversion efficiencies with the base metal catalysts increased continuously as volume increased. 

Table V. Average Warm-Up Conversion Efficiencies FTP Cycles 1-5...

Thermal Effects. As expected, the smaller converter volumes warmed up more rapidly because of their smaller thermal mass (Figures 3 and 4). With the platinum catalysts, the conversion efficiencies achieved during the first five cycles of vehicle operation agreed generally with the 1975 FTP emission trends. A minimum in the emissions (Figures 1 and 2) and a corresponding maximum in the warm-up conversions (Table V) occurred at a converter volume of 1300 cm3. 

Two tests to determine the conversion efficiency of the catalyst are conducted. One is the light-off test to examine the conversion efficiency of the catalyst itself by slowly raising exhaust gas temperature at the rate of lO C/min, as shown in Figure 13.1.8. The other test is the warm-up test to examine the conversion efficiency of the catalyst including its heat mass factors in order to simulate the cold-start of engines. Hence, the exhaust gas temperature is raised quickly at the rate of 160°C/ min, also shown in Figure 13.1.8. 

Figure 13.1.10 shows the effects of bulk density of 400 cpi catalysts on warmup characteristics after engine aging. To examine the effects of heat mass of catalysts, 4, 6, and 8 mil catalysts are used. As catalyst bulk density increase, inlet gas temperature at 50% conversion efficiency (T5o%) increases, and conversion efficency during the initial 3 min (rj min) decreases in the HC, CO, and NO warm-up tests. Consequently, reducing the heat mass of catalysts presumably improves warm-up characteristics. 

Effect of DPF thermal inertia The effect of the thermal inertia of the components upstream of the SCR is expected to be more pronounced in the case where the SCR is located after the DPF. In this case, it is not only the thermal inertia of the DOC which delays the SCR warm-up but also the thermal mass of the DPF. To examine this effect, four different DPF formulations, with alternating substrate material and volume, were considered along the baseline DOC. The simulated DPF s were the baseline (SiC, 2.5 1), a (Cordierite, 2.5 1), a (SiC, 3.75 1), and a (Cordierite, 3.75 1). The effect of the thermal response on the average NO , conversion efficiency is illustrated in Fig. 13.20. For the basehne DPF volume of 2.5 1, the substrate material of the DPF appears to have an impact of up to 5 % in the... 

Figure 6. Variation of 0 and 455 Rco2 with temperature for cultivars of (a) cabbage, a cool-climate plant, and (b) tomato, a warm-climate plant. Differences in the temperature dependences of the heat and COi rates lead to constantly changing substrate carbon conversion efficiencies of these plants as temperature changes. Specific growth rate is proportional to the difference between the curves for > 455 / co2, growth stops.

C14-0128. What is the efficiency of the metabolic conversion of palmitic acid to ATP Compute the number of grams of palmitic acid that would have to be metabolized to provide the heat to warm a swimmer from whose skin 75 g of water evaporates. 

Since the oceans comprise over 70% of the earth s surface area, the absorbed solar energy that is stored as latent heat of the oceans represents a very large potential source of energy. As a result of variation in the density of ocean water with temperature, the ocean water temperature is not uniform with depth. Warm surface ocean water with low density tends to stay on the surface and cold water with high density within a few degree of 4°C tends to settle to the depths of the ocean. In the tropics, ocean surface temperatures in excess of 25° C occur. The combination of the warmed surface water and cold deep water provides two different temperature thermal reservoirs needed to operate a heat engine called OTEC (ocean thermal energy conversion). Since the temperature difference of the OTEC between the heat source and the heat sink is small, the OTEC power plant cycle efficiency... 

The use of iodoacetic acid as an aryl radical trapping agent has confirmed the intermediacy of aryl radicals in some hydrodediazoniation reactions, whether these are initiated or not.4 Spontaneous hydrodediazoniation of aryldiazonium fluoroborates occurs in warm dimethylformamide (DMF). Detailed study5 of the conversion of the 4-nitro derivative into nitrobenzene indicates a homolytic mechanism in which H-atom abstraction occurs from both sites in DMF with a formyl methyl preference of 3.5 1.0. High yields of mixed perfluorinated biaryls may be obtained by the catalytic dediazoniation of pentafluorobenzenediazonium ions in acetonitrile containing aromatic substrates and small amounts of iodide salts. The catalytic role of iodide and the isomeric product distributions indicate that arylation proceeds through the pentafluorophenyl radical in an efficient homolytic chain process.6... 

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