Electrical drives

The electrical power required to drive a compressor (or pump) can be calculated from a knowledge of the motor efficiency  

The efficiency of the drive motor will depend on the type, speed and size. The values given in Table 3.1 can be used to make a rough estimate of the power required. 

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Variable Flow Rate Conventional variable clearance volume and valve lifting devices are impracticable at high pressures and, should it be necessary to vary the flow rate, use has to be made of variable speed electric drives or magnetic clutches. Integral steam and gas engines have been used and Burckhardt (168) developed an hydrauhc drive to provide an integrated variable capacity machine, but its efficiency is less than that of a straight mechanical drive. 

Compressed air or hydrauHcally driven reciprocating piston or rotary exciters are sometimes used in short conveyors. They are particularly useflil where explosion hazards limit the use of electrical drives. 

The cost of an electric-drive rotaiy-cutter sample of the smallest size manufactured—suitable for gravity sampling of fine particulate solids or shiny flow—including timer and control unit was approximately 5,000 in 1996. 

An electric-drive linear-traversing sampler of minimum standard manufactured size with cutter ana controls will range upwards of 8,000. 

Pneumatic as well as electric-drive samplers are available. Generally, pneumatic-drive samplers are lower in cost. 

Cross-belt samplers of minimum size for 24-in (600-mm) conveyors cost approximately 15,000 with controls using an electric drive, and about 12,500 with pneumatic drive. 

Electric drive systems have been tried as a means of achieving propulsion without harmful emissions. Currently, most battery-operated vehicles use... 

Instrument and Plant Air Systems. A typical setup for a large plant could include three to four 50% instrument air compressors and two 100% plant air compressors, with steam drives for normally operated units and electrical drives for spares. Common practice would provide an interconnection to allow makeup from plant air into instrument air, but not vice versa, and two sets (two 100% driers per set—one on-stream and one regenerating) of 1007c instrument air driers. Two main receivers on instrument air near the compressors with several minutes holdup time and satellite receivers at process trains would be likely and proper for feasibility cost estimating. 

Fine-motion of control rods is provided by hydraulic and electric drives. 

Ranade, S. M., W. E. Robert, and A. Zapata-Suarez, Evaluate Electric Drive Applications Quickly, Hydro. Proc., p. 41, Oct. (1988). 

Torque converters used in most drawworks are designed to absorb shocks from the prime movers or the driven equipment and to multiply the input torque. Torque converters are used in conjunction with internal combustion prime movers when these engines are used directly to drive the drawworks. More modern drawworks are driven by electric drives since such prime movers usually simplify the drawworks. 

Pallets are now mostly standardized at 1.2 X 1.0 m and the total weight will be between 4 and 1 t, depending on the product. Handling in small cold stores can be by hand pallet trucks or hand-steered electric drive trucks. These can transport but not lift one pallet onto another. The usual fork-lift truck is a ride-on vehicle, electric driven, and can lift to form a stack of two, three, four or even five pallets high, according to the length of the telescopic lift and the skill of the driver. 

The economics of the heat pump are dependent on the relative costs of the drive power and heat energy from other sources. In the UK, where electricity is currently about three times the price of natural gas, the electric drive heat pump needs to have a COP of 3 to break even, and 4 or more to be competitive. This price ratio will change as fossil fuels run out in the next century. 

The fifth of the color methods places the three emitting structures in a stack one on top of the other, rather than side by side ]20l ]. Clearly there is a requirement here that the two electrodes in the middle of the structure must be transparent. The advantages are that the display can be made much brighter with up to three times the luminance from each pixel, and the requirements for high resolution patterning are relaxed by a factor of three. The disadvantages are that three times as many layers must be coated (without defects) over the area of the display and electrical driving circuitry must make contact with four sets of elec- trades. It will be extremely difficult to incorporate a stacked OLED into a active matrix array. 

Electron-transfer reactions occur all around us. Objects made of iron become coated with mst when they are exposed to moist air. Animals obtain energy from the reaction of carbohydrates with oxygen to form carbon dioxide and water. Turning on a flashlight generates a current of electricity from a chemical reaction in the batteries. In an aluminum refinery, huge quantities of electricity drive the conversion of aluminum oxide into aluminum metal. These different chemical processes share one common feature Each is an oxidation-reduction reaction, commonly called a redox reaction, in which electrons are transferred from one chemical species to another. 

When an electrostatic field of field strength E is applied, each type j of ion carrying charge ZjF (per mole) finds itself under the effect of an electric driving force... 

In 1998 the auto industry turned from weak commitments to a solid move toward fuel cells and EVs. All the auto companies are pursuing hydrogen fuel cells in some way. But, the new cars on the road in the near future are likely to be a mix of vehicles including those with electric drive, including battery EVs, hybrids with gasoline and direct-injection diesels, turbo generators and fuel cells. 

The timetables announced by government and industry have generally been proven too conservative. Many auto companies already have running drivable fuel cell prototypes and it appears likely that some moderate commercialization will be achieved in the next decade. Hybrids are already here and proving to be popular because of their efficiency. They are providing valuable data on the type of electric drives that would be used in hydrogen fuel cell vehicles. 

Besides fuel-cell (electric) vehicles (FCV), there are other vehicle concepts under development, which are also based on electric drives ranked by increasing battery involvement in the propulsion system, and thus extended battery driving range, these are hybrid-electric vehicles (HEV), plug-in hybrid-electric vehicles (PHEV) - which both incorporate an ICE - and, finally, pure battery-electric vehicles (BEV), without an ICE. While electric mobility in its broadest sense refers to all electric-drive vehicles, that is, vehicles with an electric-drive motor powered by batteries, a fuel cell, or a hybrid drive train, the focus in this chapter is on (primarily) battery-driven vehicles, i.e., BEV and PHEV, simply referred to as electric vehicles in the following. 

Duvall, M. (2004). Advanced Batteries for Electric-Drive Vehicles A Technology and Cost-effectiveness Assessment for Battery Electric Vehicles, Power Assist Hybrid Electric Vehicles, and Plug-in Hybrid Electric Vehicles. Report 1009299. Palo Alto, CA Electric Power Research Institute (EPRI). 

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