Engine load

Figure 10-24 shows a schematic of an actual dry low emission NO combustor used by ALSTOM in their large turbines. With the flame temperature being much closer to the lean limit than in a conventional combustion system, some action has to be taken when the engine load is reduced to prevent flame out. If no action were taken flame-out would occur since the mixture strength would become too lean to burn. 

To counter the elevated emissions associated with enrichment, the EPA has adopted supplemental federal test procedures. The new laboratory test procedures contain higher speeds, higher acceleration and deceleration rates, rapid speed changes, and a test that requires the air conditioning to be in operation. These tests increase the probability that vehicles will go into enrichment under laboratory test conditions. Hence, manufacturers have an incentive to reduce the frequency of enrichment occurrence in the real world. Future catalytic converters and emissions control systems will be resistant to the high-temperature conditions associated with engine load, and will be less likely to require enrichment for protection. Thus, enrichment contributions to emissions will continue to decline. 

The above method is useful in determining internal combustion engine loading conditions. Failure to duplicate former readings at no load and at normal speed indicates that the engine is in poor condition. Failure to duplicate former readings... 

The first requirement in developing the ACC was to control air-fuel mixtures, and in contemporary cars this is maintained at precisely the 19 1 stoichiometric ratio for aU engine loads, using an exhaust O2 sensor that controls the fuel injection system. The composition and location of the catalyst within the reactor are also crucial to proper design. 

Figure 29.4 An unloading pocket reduces engine load and volumetric capacity.

The EPA has proposed an enhanced IM program that would require a dynamometer test under varying engine loads, would test evaporative emissions, and would raise the repair cost limit substantially. The enhanced IM program still has some serious defects. Most notably, it lacks the necessary components of significant on-road, in situ, remote sensing to validate the emission reductions and to catch cars that have been tampered with between inspections. 

Particulate Emissions from Blend Tests. The stack particulate emissions for the baseline and three blend ratios were measured. The effect of blend ratios on the particulate emission rate is shown graphically in Figure 1. In this representation the percent increase of the particulate emission rate over the baseline value for the various blend ratios is plotted for the two higher engine loads at 110° F AMT. 

Figure 1. Particulate mass rate increase as affected by blend ratio, engine load, and AMT.

The effect of EDS/DF-2 blends on particulate emissions was significantly influenced by both blend ratio and engine load. Increasing one or the other or both resulted in an increase in the particulate emissions, though an increase in AMT may reduce the particulate emission rates. No information on particle size or morphology was obtained in this program. 

The results of the exhaust stack measurements of gaseous emissions indicate that the use of EDS/DF-2 fuel blends under engine load conditions resulted in a moderate increase in CO emissions (25%) and a moderate decrease in THC emissions (26-31%) when compared to baseline (0%) tests. The EDS/DF-2 fuel blends all showed substantial increases in both CO and THC emissions at the no-load condition. 

The emissions of N0X from EDS blends are less than or equal to the baseline over all engine loads except for the maximum EDS/DF-2 blend where N0X levels were slightly higher at lower loads. A 150° F AMT slightly increased the N0X for baseline and the 66.7 percent blend at 3600 kw but lowered... 

Diesel Gas Chamber Operation 8.1. Imposing an Engine Load... 

Generally, the Thermofuel fuel gives lower NO than conventional diesel, especially at lower engine load. Particulate emissions from diesel engines rnn on Thermofuel diesel, also at 3000 rpm, varies with the load on the engine [21] as shown in Table 15.6. 

It is apparent from the above data that Thermofuel diesel produces significantly less particulates (smoke) at all engine loadings than conventional diesel. This is environmentally significant, as the particulates formed from diesel combustion contain polycyclic aromatic hydrocarbons (PAH) which have carcinogenic potential. The hotter burning characteristic of the Thermofuel relative to conventional diesel is likely to be responsible for the better burn-out of particulates [21]. 

Engine load NO c (ppm) (Thermofuel fuel) NOx (ppm) (conventional diesel)... 

Thus from equation (3), for an engine load of 4 BHP, CVn must be 127 Btu/ft for EPG to be 100 percent. From equation (1), the engine speed would be 1496 RPM, and from equation (2), brake thermal efficiency e is 16. 5 percent. 

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