Manifold exhaust

M ass Transfer. Exhaust gas catalytic treatment depends on the efficient contact of the exhaust gas and the catalyst. During the initial seconds after start of the engine, hot gases from the exhaust valve of the engine pass through the exhaust manifold and encounter the catalytic converter. Turbulent flow conditions (Reynolds numbers above 2000) exist in response to the exhaust stroke of each cylinder (about 6 to 25 times per second) times the number of cylinders. However, laminar flow conditions are reached a short (- 0.6 cm) distance after entering the cell passages of the honeycomb (5,49—52). 

Sulfur oxides resulting from fuel sulfur combustion often inhibit catalyst performance in Regions II, III, and a portion of Region IV (see Fig. 7) depending on the precious metals employed in the catalyst and on the air/fuel ratio. Monolithic catalysts generally recover performance when lower sulfur gasoline is used so the inhibition is temporary. Pd is more susceptible than Rh or Pt. The last is the most resistant. Pd-containing catalysts located in hotter exhaust stream locations, ie, close to the exhaust manifold, function with Httie sulfur inhibition (72—74). 

Further oxidation of the pollutants outside the combustion chamber. This oxidation may be either by normal combustion or by catalytic oxidation. These systems require the addition of air into the exhaust manifold at a point downstream from the exhaust valve. An air pump is employed to provide this air. Figure 31-2 illustrates an engine with an air pump and distribution manifold for the oxidation of CO and hydrocarbons (HC) outside the engine. 

Water-jcKketed exhaust manifolds eliminate expansion strains and keep engine room temperature down. 

An alternative is a suction provided by an engine exhaust manifold pressure)... 

Vehicle data represents the complex interaction of many variables, including vehicle performance, reactor design and location, as well as catalyst properties. For a catalyst that has failed, one must ponder whether the converter design used in the vehicle is suitable for the catalyst, the quantity of the catalyst used is correct, the distance of the converter from the exhaust manifold is suitable, the catalyst has been inadvertantly overheated to above 2000°F or poisoned by lead and sulfur, or whether the catalyst can be modified to produce a far superior product. 

Heat loss in the exhaust pipe from the exhaust manifold to the converter can also be analyzed by Eq. (30). The flow is turbulent, and Nu depends on (Re)2/S. Assuming a tail pipe that is 3 ft long, and a Reynolds number of 30,000, the results of the computation are also shown in Table VII. Due to the low surface area, only 20% of the temperature above the wall temperature would be lost through the walls, and 80% would arrive at the converter inlet. As the gas velocity increases, heat loss through the... 

The IIEC model was also used to study the importance of various design parameters. Variations in gas flow rates and channeling in the bed are not the important variables in a set of first-order kinetics. The location of the catalytic bed from the exhaust manifold is a very important variable when the bed is moved from the exhaust manifold location to a position below the passenger compartment, the CO emission averaged over the cycle rose from 0.14% to 0.29% while the maximum temperature encountered dropped from 1350 to 808°F. The other important variables discovered are the activation energy of the reactions, the density and heat... 

Evaporation of Samples. Six samples of usually 250 ml. each are simultaneously evaporated to a moist residue in a water bath, shown in Figure 7, which is maintained at 80° to 90° C. The exhaust manifold is connected with the house vacuum. With the assemblies shown a gentle stream of air is drawn over the surface of the evaporating solution and out the vacuum line the air inlet tube is lowered frequently so as to maintain a rippled surface on the benzene extract. In this manner, 250 ml. of benzene can be evaporated completely in 10 minutes or less. 

Internal combustion engines contain several features that pose ignition sources for hydrocarbon vapors. Most obvious is they exhaust hot combustion gases that can ignite vapors, secondary they have hot surfaces - primarily the exhaust manifold and piping, and finally and most overlooked, instrumentation and ignition devices may not be rated for use in an area where combustible gases may be present. 

A catalytic converter is a stainless steel tube located near the exhaust manifold, lined with finely divided metal salts, e.g. of platinum and palladium. 

The car, which he runs on a daily basis, is a restored, eight-cylinder 1978 Chevy Camaro with stock 350 (5.7 litre) engine, no computer controls, automatic transmission, stock 4-barrel carburettor and stock fuel pump. The fuel tank has been replaced with a metal water tank with the filler cap vented to release heat and pressure. The exhaust was replaced with a new 2 inch pipe which is ducted into the water tank. The water tank has baffles inside it which also muffles the exhaust noise. The stock exhaust manifolds were used, but they will rust on the inside - custom stainless steel pipes would be best but these were not used due to their cost. 

Feed the pipe from the exhaust manifold into a water tank with baffles as shown below. 

FUEL RATE BTU / BHP HR. i RATED LOAD RPM MAXIMUM MINIMUM EXHAUST MANIFOLD WATERCOOL ED [7] INSULATED TACHOMETER... 

The autoignition temperature of ethanol is significantly higher than that of gasoline or diesel fuel. This should make ethanol less susceptible to ignition when spilled on hot surfaces such as engine exhaust manifolds. 

Figure 6. Above a tool for the superplastic forging of titanium, made entirely from carbon/carbon composites (15) Below aircraft exhaust manifold formed from titanium by superplastic forging with the carbon/carbon tool.

Many gas-fired compressors that pump natural gas through millions of miles of pipelines are also equipped with exhaust catalysts to clean emissions at moderate conditions. Even fast-food restaurants are being equipped with catalysts to eliminate odors from the cooking process. The most widely used treatment of exhaust pollutants is that of the catalytic converter present in the exhaust manifold that cleans emissions from the internal combustion engines of gasoline- and diesel-fiieled automobiles and trucks. As modem commercial passenger jets fly above 30,000 feet there is a need to destroy the few ppm ozone that enters the airplane with make-up air to ensure passenger and crew comfort and safety. Radiators on select... 

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