Fuel losses

Wall losses through most refractory walls are ca 10% of the heat suppHed by the fuel. Losses increase with rising operating temperature. In special cases, eg, in glass tanks, losses can be as high as 30—35%. In these instances, very high values are requked to maintain the refractory at a temperature below which it does not melt or coUapse. 

Zhang X, Robertson M, Deces-Petit C, Qu W, Kesler O, Marie R et al. Internal shorting and fuel loss of a low temperature solid oxide fuel cell with SDC electrolyte. J. Power Sources 2007 164 668-677. 

Running loss emissions are emissions from the fuel tank during vehicle operation due to heating of the fuel, losses from the evaporative canister, or losses due to permeation of fuel through elastomeric fuel lines. 

Small but continuous fuel loss by permeation through polymeric parts of the fuel system ... 

The minimum loss point in Figure 2.2 is not where excess 02 is zero, but a minimum positive value. This is because no burner is capable of providing perfect mixing. This is why the theoretical minimum loss point is to the left of the actual one in the bottom part of Figure 2.2. This actual minimum loss or maximum efficiency point is found by lowering the excess 02 as far as possible, until opacity or carbon monoxide (CO) readings indicate that the minimum has been reached. At this minimum loss point, the flue gas losses (heat lost through the stack) and the unburned fuel losses are the same. 

The rate of fuel loss is the flux density multiplied by g... 

Lbs Degraded to Fuel/lb Premium Products Fuel Value Loss t/lb of Fuel Fuel Value Loss i/lb of Premium Products Capital Charge 20%/lb of Products Total Fuel Loss plus Capital Charge/lb of Product... 

A. H. Jazwinski, A Technique of Evaluating Fuel Losses Due to Meteoroid Puncture and Some Timely Examples, paper presented at Am. Rocket Soc. Lunar Missions Meeting in Cleveland, Ohio (July 17-19, 1962). 

To tackle the problem of fuel loss through the tank walls, polar barrier layers were tested. Among the methods tried were fluorination and sulfonation, as well as epoxy resin or polyamide powder coatings on the fuel tank walls. Again, cost and process safety were the issues begging for solutions, and fluorination and sulfonation proved to be the processes of choice for enhancing barrier properties. Both inline and offline processing approaches were tested, and fluorination with fluorine... 

In comparable experimental conditions, the DEFCs with the Pd-(Ni-Zn)/C and Pd-(Ni-Zn-P)/C anodes delivered 102 mA for 10.9 and 10.4 h, producing 10 and 9.6 mmol of acetate, respectively, at remarkably higher overpotentials than those provided by the Pd/MWCNT anode." " According to the analytical data, ca. 4 mmol of EtOH were lost by evaporation irrespective of the anode catalyst. Since the anode compartments were accurately sealed during the experiments, the fuel losses have been attributed mostly to the evaporation of the cross-over ethanol from the cathode side. 

In severe cases, fuel rod failures may lead to fuel losses from the rod, with their magnitude depending on the size of the defect and on the question of whether liquid water or only steam has entered the rod. Operational experience has shown that after one year of prolonged operation of a failed rod one has to expect the following fuel losses to the coolant (Assmann and Stehle, 1984 Beslu et al., 1984) ... 

The last-mentioned fuel loss may be caused either by mechanical action of the coolant (erosion) or by chemical leaching of the fuel pellet. Often the UO2 loss to the coolant depends on the orientation of the defect to the coolant flow, with this being higher when the long axis of the defect is oriented parallel to the coolant flow. Erosion of fuel particles is facilitated by UO2 oxidation at the grain boundaries (Lewis et al., 1993). Fuel losses of 10 to 15 g U during a 3-year operation period from the area around artificial defects of 1 mm diameter have been reported by Hiittig et al. (1990). 

In the late 1990s and early 2000s, nonfluorinated homopolymers were studied as promising alternatives. In simplified terms, however, reduced methanol permeation and reduced conductivity are combined in these materials to achieve a DM FC performance comparable to that of Nafion-based MEAs, and the membranes had to be so thin that it was not possible to reduce substantially the absolute value for fuel loss by permeation. Table 1.3 provides an overview of the most significant membrane modifications. 

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