Life expectation

Life Expectancy of Devices. The expected or average hfe of devices is defined ... 

Li—Al/FeS cells have demonstrated good performance under EV driving profiles and have deUvered a specific energy of 115 Wh/kg for advanced cell designs. Cycle life expectancy for these cells is projected to be about 400 deep discharge cycles (63). This system shows considerable promise for use as a practical EV battery. 

In contrast to segregated flow, in which the mixing occurs only after each sidestream leaves the vessel, under maximum mixedness mixing of all molecules having a certain period remaining in the vessel (the life expectation) occurs at the time of introduction of fresh material. These two mixing extremes—as late as possible and as soon as possible, both consistent with the same RTD—correspond to performance extremes of the vessel as a chemical reactor. 

FIG. 23-13 The two limiting flow patterns with the same RTD. a) Segregated flow, in which all molecules of any exit stream have the same residence time, (h) Maximum mixed flow, in which all molecules of an external stream with a certain life expectation are mixed with all molecules of the internal stream that have the same life expectation. 

Load-carrying capacity and life expectancy of bearings 8/214... 

The life of the insulation will also be affected by an excessive operating temperature. It is halved for every 11°C rise in temperature over its rated value and occurs when a machine is occasionally overloaded. Sometimes the size of the machine may be only marginal when it was initially chosen and with the passage of time, it may be required to perform duties that are too arduous. Every time the machine overheats, the insulation deteriorates, and this is called thermal ageing of insulation. Figure 9.1 illustrates an approximate reduction in life expectancy with a rise in operating temperature. 

Figure 9.1 Reduction in life expectancy of a motor with a rise in operating temperature...

The life expectancy of most hot section parts is dependent on various parameters and is usually measured in terms of equivalent engine hours. The following are some of the major parameters that effect the equivalent engine hours in most machinery, especially gas turbines ... 

Insulation systems were first classified according to the material used, and permissible temperatures were established based on the thermal aging characteristics of these materials. For example. Class B insulation was defined as inorganic materials such as mica and glass with organic binders 130°C was the allowable maximum operating temperature. The present definition of insulation system Class B stipulates that the system be proven. . by experience or accepted tests. .. to have adequate life expectancy at its rated temperature, such life expectancy to equal or... 

Base Metal Catalyst - An alternate to a noble metal catalyst is a base metal catalyst. A base metal catalyst can be deposited on a monolithic substrate or is available as a pellet. These pellets are normally extruded and hence are 100% catalyst rather than deposition on a substrate. A benefit of base metal extruded catalyst is that if any poisons are present in the process stream, a deposition of the poisons on the surface of the catalyst occurs. Depending on the type of contaminant, it can frequently be washed away with water. When it is washed, abraded, or atritted, the outer surface is removed and subsequently a new catalyst surface is exposed. Hence, the catalyst can be regenerated. Noble metal catalyst can also be regenerated but the process is more expensive. A noble metal catalyst, depending on the operation, will typically last 30,000 hours. As a rule of thumb, a single shift operation of 40 hours a week, 50 weeks a year results in a total of 2,000 hours per year. Hence, the catalyst might have a 15 year life expectancy. From a cost factor, a typical rule of thumb is that a catalyst might be 10%-15% of the overall capital cost of the equipment. 

Materials with short life expectancies should not be combined with those of longlife in nonreparable assemblies. 

Life expectation, Of a molecule or aggregate in a vessel at a particular time is the period that it will remain in the vessel before ultimately leaving. The distribution of life expectancies is identical with that of residence times, E(A.) = E(t). 

Maximum mixedness Exists when any molecule that enters a vessel immediately becomes associated with those molecules with which it will eventually leave the vessel. This occurs with those molecules that have the same life expectation. A state of maximum mixedness is associated with every residence time distribution (RTD). 

Cross-comparing the risks of various activities is difficult because of the lack of a common basis of comparison, however Cohen and Lee, 1979 provide such a comparison on the basis of loss of life expectancy. Solomon and Abraham, 1979 used an index of harm in a study of 6 occupational harms - three radiological and three nonradiological to bracket high and low estimates of radiological effects. The index of harm consists of a weighting factor for parametric study the lost time in an industry and the worker population at risk. The conclusions were that the data are too imprecise for firm conclusions but it is possible for a radiation worker under pessimistic health effects assumptions to have as high index of harm as the other industries compared. 

Determine the action level in pg/iiv for an 80 kg person with a life expectancy of 70 years exposed to benzene over a 15-year period. The "acceptable risk is one incident of cancer per 1 million persons or lO ". Assume a breathing (intake) rate of 15 m /d and an absorption factor of 75%. The potency factor for benzene is 1.80 (mg/kg-d)." ... 

The lithium-ion-polymer battery, which uses a cathode that contains lithium instead of cobalt, is likely to eventually replace lithium-ion. Lithium-ion-polymer batteries boast a longer life expectancy (over 500 charge-and-discharge cycles as opposed to around 400), much more versatility (they are flat and flexible and can be cut to fit almost any shape), and better safety (far less likely to vent flames while recharging). 

Unlike the automobile-type battery that is quite portable, the stationaiy lead-acid batteries that provide uninterruptible power to hospitals and other important facilities are not. Some may weigh over several tons because of the much heavier grid structure and other features to extend life expectancy and improve deep discharge capabilities. 

Reduce the amount of change in the electrolyte and electrodes per charge-and-discharge cycle to extend life expectancy. 

Nickel-Hydrogen, Nickel-Iron, and Nickel-Metal Hydride. First developed for communication satellites in the early 1970s, nickel-hydrogen batteries are durable, require low maintenance, and have a long life expectancy. The major disadvantage is the high initial cost. For these batteries to be a viable option for electric vehicles, mass production techniques will have to be developed to reduce the cost. 

Unfortunately, often the EV s efficiency and cost advantages are wiped out by the batteiy s abbreviated life expectancy. When hattei y life expectancy is around 2,(1(10 miles (reported by testers of General Motors s EV, the Impact), then the recharging and replacement hattei y costs of an EV (over 1,500 for the GM Impact) alone can exceed the total operating costs for an ICE vehicle. Energy costs per mile for the GM Impact ( 0.02 electricity plus 0.42 for batteries) were greater than the total operating costs for an ICE vehicle ( 0.42). 

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