Power conversion factors

The conversion factors are presented for ready adaptation to computer readout and electronic data transmission. The factors are written as a number equal to or greater than one and less than 10, with six or fewer decimal places. The number is followed by E (for exponent), a plus or minus symbol, and two digits which indicate the power of 10 by which the number must be multiphed to obtain the correct value. Eor example ... 

Power Number a dimensionless number used to describe the power dissipation of impeller and which is given by Np = Pg,/pN D where P = impeller power dissipation and g, = gravitational conversion factor. 

Designers, manufacturers, and operators of boilers continue to use many of these terms, without undue deference to unit standardization, to define, measure, and report on plant steam-raising capacities power output) and operating parameters. (In continuance of this common practice therefore, many of these various terms are freely used in discussions throughout this book.) However, to familiarize the reader and minimize confusion, some energy terms and notes are provided here. A more complete list of units and conversion factors is provided in the appendix. 

It is often necessary to convert a unit that is raised to a power (including negative powers). In such cases, the conversion factor is raised to the same power. For example, to convert a density of 11 700 kg-m-3 into grams per centimeter cubed (g-cm 3), we use the two relations... 

It should be noted that a dimensional analysis of this problem results in one more dimensionless group than for the Newtonian fluid, because there is one more fluid rheological property (e.g., m and n for the power law fluid, versus fi for the Newtonian fluid). However, the parameter n is itself dimensionless and thus constitutes the additional dimensionless group, even though it is integrated into the Reynolds number as it has been defined. Note also that because n is an empirical parameter and can take on any value, the units in expressions for power law fluids can be complex. Thus, the calculations are simplified if a scientific system of dimensional units is used (e.g., SI or cgs), which avoids the necessity of introducing the conversion factor gc. In fact, the evaluation of most dimensionless groups is usually simplified by the use of such units. 

This section presents sample calculations to aid the reader in understanding the calculations behind the development of a fuel cell power system. The sample calculations are arranged topically with unit operations in Section 10.1, system issues in Section 10.2, supporting calculations in Section 10.3, and cost calculations in Section 10.4. A list of conversion factors common to fuel cell systems analysis is presented in Section 10.5 ans a sample automotive design calculation is presented in Section 10.6. 

Balanced equations, diverse conversion factors, limiting re ents, and percent yield calculations all now tremble before you. Probably. Be sure your powers over them cire as breathtaking as they should be by checking your answers. 

In this section, unless otherwise stated, coal refers to the internationally traded commodity classified as coal ARA CIF AP 2, while gas refers to the high caloric gas (with a conversion factor 35,17 GJ/m3) from the Dutch Gas Union Trade Supply (GUTS). Moreover, prices for power, fuels and C02 refer to forward markets (i.e. year-ahead prices). 

There are a variety of problem-solving strategies that you will use as you prepare for and take the AP test. Dimensional analysis, sometimes known as the factor label method, is one of the most important of the techniques for you to master. Dimensional analysis is a problem-solving technique that relies on the use of conversion factors to change measurements from one unit to another. It is a very powerful technique but requires careful attention during setup. The conversion factors that are used are equalities between one unit and an equivalent amount of some other unit. In financial terms, we can say that 100 pennies is equal to 1 dollar. While the units of measure are different (pennies and dollars) and the numbers are different (100 and 1), each represents the same amount of money. Therefore, the two are equal. Let s use an example that is more aligned with science. We also know that 100 centimeters are equal to 1 meter. If we express this as an equation, we would write ... 

The amplifying power is the product of the conversion factor (number of secondary particles emitted by the conversion dynode for one incoming ion) and the multiplying factor of the continuous dynode electron multiplier. It can reach 107 with a wide linear dynamic range (104-106). Their lifetime is limited to 1 or 2 years because of surface... 

A conversion factor (see below) is used when working with English engineering units no factor is necessary for SI metric units. For a given impeller geometry, the power number is a constant for conditions of turbulent agitation. Values of turbulent power numbers for some agitator impellers are shown in Fig. 12.1. 

At 0.27 hp (0.20 kW), a constant viscous power number can be used to predict an apparent viscosity, with the aid of a 6.11 x 1CV15 units-conversion factor ... 

A principle illustrated in this example is that raising a quantity (in particular, a conversion factor) to a power raises its units to the same power. The conversion factor for h /day is therefore the square of the factor for h/day ... 

Impeller power consumption can be calculated as a product of the direct torque, rotational impeller speed, and a coefficient (usually equal to 2n times a unit conversion factor, if required). 

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