Fuel-controlled

Both friction and wear measurements have been used to study boundary lubrication of fuel because sticking fuel controls and pump failures are primary field problems in gas turbine operation. An extensive research program of the Coordinating Research Council has produced a baH-on-cylinder lubricity test (BOCLE), standardized as ASTM D5001, which is used to qualify additives, to investigate fuels, and to assist pump manufacturers (21). 

The performance of the catalytic converter is affected by the conditions of air/fuel control provided by the fuel metering system. A slowly responding fuel metering system can dramatically decrease the conversion efficiency of the converter compared to a fast response multipoint fuel injection system. 

Technical Support Document Revisions to the Malfunction and Diagnostic System Requirements Applicable to 1994 and later New California Passanger Cars, Eight-Duty Trucks, andMedium Duty Vehicles with Feedback Fuel Control Systems (OBD-II), California Air Resources Board, Sacramento, Sept. 14,1989. 

Probably the most significant control technology breakthrough came m 1977, when Volvo released a computer-controlled, fuel-mjected vehicle equipped with a three-way catalyst. The new catalytic converters employed platinum, palladium, and rhodium to simultaneously reduce NO and oxidize CO and HC emissions under carefully controlled oxygen conditions. The new Bosch fuel injection system on the vehicle provided the precise air/fuel control necessary for the new catalyst to perform effectively. The combined fuel control and three-way catalyst system served as the foundation for emissions control on the next generation of vehicles. 

The energy produced in a nuclear reactor vessel is the result of a nuclear fission (atom splitting) process that occurs when sufficient nuclear material is brought together (critical mass). Under these circumstances, a chain reaction occurs and an external supply of neutrons is not required. A nuclear fuel control rod system raises or lowers the nuclear fuel (which is contained within fuel rods) inside the reactor vessel. 

Oxygen sensors for air/fuel control in combustion engines (niobium oxide, Nb205, is also used for this application). 

A microcomputer periodically reads the sensor signal and adjusts the fuel control signal to bring the air-fuel ratio, and thus the exhaust composition, closer to the stoichiometric point. 

For the second item ignition to lead to flashover, the area involved must equal or exceed the total critical area needed for the second item. The time for ignition depends inversely on the exposure heat flux (Equation (11.51)). Figure 11.21 shows the behavior for ignition of the second item, where Af,i is the fixed area of the first item and AF c is the critical area needed. The energy release rate of both fuels controls the size of the jump at criticality and depends directly on AFAhc/L. No flashover will occur if the jump in energy for the second item is not sufficient to reach the critical area of fuel, AFjc- The time to achieve the jump or to attain flashover is directly related to the fuel property,... 

Techniques are available to calculate conditions under which enclosed fires are ventilation- or fuel- controlled. Computer models are available to estimate compartment fire growth and temperature effects. In particular, the zone fire model C-FAST (Jones et al., 2000) is widely used. Additional information on models is contained in Appendix C. 

A lean NOx trap (LNT) (or NOx adsorber) is similar to a three-way catalyst. However, part of the catalyst contains some sorbent components which can store NOx. Unlike catalysts, which involve continuous conversion, a trap stores NO and (primarily) N02 under lean exhaust conditions and releases and catalytically reduces them to nitrogen under rich conditions. The shift from lean to rich combustion, and vice versa, is achieved by a dedicated fuel control strategy. Typical sorbents include barium and rare earth metals (e.g. yttrium). An LNT does not require a separate reagent (urea) for NOx reduction and hence has an advantage over SCR. However, the urea infrastructure has now developed in Europe and USA, and SCR has become the system of choice for diesel vehicles because of its easier control and better long-term performance compared with LNT. NOx adsorbers have, however, found application in GDI engines where lower NOx-reduction efficiencies are required, and the switch between the lean and rich modes for regeneration is easier to achieve. 

Here I is the total current, F is the Faraday constant, M is the molecular weight. The energy equations for the air and fuel control volumes shown by dashed lines in Figure 5.6 are given by ... 

As a fuel-controlled fire grows in size and involves more fuel surface area and more fuel packages, it can reach a condition where the entire fuel load in the compartment burns at once. When this condition takes place as a transition suddenly, it is termed as flashover. The transition from fuel-controlled to ventilation-controlled conditions usually takes place at flashover event. 

Just as with other furnaces, fuel control is based on the boiler ten erature. This means that the thermal output momentarily used is measured, and on the basis of this thermal output and a supposed calorific value combustion efficiency, the required quantity of combustibles is calculated by an approximate method and finally set. On the basis of the temperature curve of Ae boiler, this calculated quantity of fuel is permanently adjusted. 

The advantage of such a control system is that the feeding of fuel can be adapted to the time curve of the thermal output almost instantaneously. This ensures stable controlling which is necessary for a continuous operation without on/off-operation. On the other hand, a fuel control reacting exclusively to the boiler temperature or the flow temperature, only allows a very slow adjustment of the fuel quantity to the load curve, as a change in load becomes effective only after a certain time. Due to this dead time, there is in general no stable control without disturbance value feed-forward... 

The oil tube/atomizer section was removed from the dual fuel burner and an oxy/fuel burner was inserted in its place. The burner retrofit package including the natural gas and oxygen flow control trains were prefabricated to prevent furnace downtime. The oxy/fuel flow controls and safety switches were interlocked to the conventional air/fuel controls, thus creating a hybrid air-oxy/fuel combustion system. 

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