Range, vehicle

Despite the environmental benefits of natural gas vehicles, large numbers of compressed natural gas stations need to be built or compressed natural gas will never be more than a niche fuel servicing large fleets of buses, cabs, and delivei y trucks that can be fueled at a central location. Nonroad short-range vehicles such as forklifts, backhoes, street sweepers, and airport ground support equipment are also ideally suited for natural gas use. 

Thus far it has not been demonstrated that acceptable driveability can be achieved for a vehicle operating at 20-22 1 A/F other than by a very high level of equipment, i.e. total electronic closed loop management with multipoint fuel injection. However, even at that level, it is not possible to achieve severe legislation limits without provision of a COC to remove hydrocarbon species (ref. 13). Nevertheless, it is evident that substantial progress has been achieved and that in the European context a fourth control strategy is potentially available for mid-range vehicles. 

Assumes 14,000 mi/yr driving and 350 mile range (except the Battery EV that has 120 mile range) vehicle costs are adjusted for resale value with monthly payments over 5 years at 4% finance rate insurance, tax, and license costs are excluded. 

VOLTEC GM propulsion system for extended-range vehicles... 

Figure 3.1 The weight and volume of various fuels and tank systems required for a 500 km range vehicle. Reprinted with permission from Ref 2.

PC/ABS remains a popular choice for manufacture of instrument panels, particularly for top of the range vehicles. OEMs are also starting to use more PC/ABS for middle of the range car instrument panels because of its better quality compared with other polymers such as polypropylene. There is also a possibility that PC/ABS blends may be one of the candidates being considered by OEMs to replace SMA in some interior applications. Manufacturers are known to be looking for alternatives to SMA copolymers. 

Phospholipid molecules form bilayer films or membranes about 5 nm in thickness as illustrated in Fig. XV-10. Vesicles or liposomes are closed bilayer shells in the 100-1000-nm size range formed on sonication of bilayer forming amphiphiles. Vesicles find use as controlled release and delivery vehicles in cosmetic lotions, agrochemicals, and, potentially, drugs. The advances in cryoelec-tron microscopy (see Section VIII-2A) in recent years have aided their characterization [70-72]. Additional light and x-ray scattering measurements reveal bilayer thickness and phase transitions [70, 71]. Differential thermal analysis... 

The sum of the downstream costs adds roughly 7.9 cents per Hter (300/gal) and the adjustment of the final cost for an amount of methanol fuel equivalent ia distance driven to an equal volume gasoline involves a multiplier ranging from 1.6 to 2.0, depending on fuel specification and the assumed efficiency for methanol light-duty vehicles as compared to gasoline vehicles. The California Advisory Board has undertaken such cost assessment (11). 

The first methanol bus in the world was placed in revenue service in Auckland, New Zealand in June 1981. It was a Mercedes O 305 city bus using the M 407 hGO methanol engine. This vehicle operated in revenue service for several years with mixed results. Fuel economy on an equivalent energy basis ranged from 6 to 17% mote than diesel fuel economy. Power and torque matched the diesel engine and drivers could not detect a difference. ReHabiUty and durabihty of components was a problem. Additional demonstrations took place in Berlin, Germany and in Pretoria, South Africa, both in 1982. 

Vehicle volatihty requirements are a strong function of ambient temperatures. ASTM has defined five volatihty classes based on expected minimum and maximum daily temperatures. These classes and their ranges are shown in Table 3. Each month, each state is assigned a volatihty class, depending on its temperature history. Table 3 also shows the ASTM volatihty specifications for each class. 

AH corrosion inhibitors in use as of this writing are oil-soluble surfactants (qv) which consist of a hydrophobic hydrocarbon backbone and a hydrophilic functional group. Oil-soluble surfactant-type additives were first used in 1946 by the Sinclair Oil Co. (38). Most corrosion inhibitors are carboxyhc acids (qv), amines, or amine salts (39), depending on the types of water bottoms encountered in the whole distribution system. The wrong choice of inhibitors can lead to unwanted reactions. Eor instance, use of an acidic corrosion inhibitor when the water bottoms are caustic can result in the formation of insoluble salts that can plug filters in the distribution system or in customers vehicles. Because these additives form a strongly adsorbed impervious film at the metal Hquid interface, low Hquid concentrations are usually adequate. Concentrations typically range up to 5 ppm. In many situations, pipeline companies add their own corrosion inhibitors on top of that added by refiners. 

In the United States, CNG s initial use is in captive, centrally refueled fleets which require limited range, such as deHvery vans, taxis, or school buses. Such vehicle fleets can afford the capital cost of refueling equipment and can tolerate the slightly longer refueling times. Many utiHty companies, such as Brooklyn Union Gas (New York), have purchased CNG vehicles as a way of encouraging the development of this fuel. AH three domestic automobile manufacturers offer CNG vehicles for sale. 

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