Input, energy

One can also do work by stirring, e.g. by driving a paddle wheel as in the Joule experiment above. If tire paddle is taken as part of the system, the energy input (as work) is detemiined by appropriate measurements on the electric motor, falling weights or whatever drives the paddle. 

It is evident from the figure that impurities can complicate the use of NMR integrals for quantitation. Further complications arise if the relevant spins are not at Boltzmaim equilibrium before the FID is acquired. This may occur either because the pulses are repeated too rapidly, or because some other energy input is present, such as decoupling. Both of these problems can be eliminated by careful timing of the energy inputs, if strictly accurate integrals are required. 

With continuous lasers (for example an argon ion laser), the energy delivered is usually much less than from pulsed ones, and the focusing is not so acute. Thus, the irradiated area of the sample is more like 10 cm rather than 10" cm, and the energy input is much less, about 100 kW/cm rather than the 100,000 kW/cm described earlier. 

Thermal desorption. The vaporization of ionic or neutral species from the condensed state by the input of thermal energy. The energy input mechanism must be specified. 

Desorption ionization (DI). General term to encompass the various procedures (e.g., secondary ion mass spectrometry, fast-atom bombardment, californium fission fragment desorption, thermal desorption) in which ions are generated directly from a solid or liquid sample by energy input. Experimental conditions must be clearly stated. 

The energy input into a CO2 laser is in the form of an electrical discharge through the mixture of gases. The cavity may be sealed, in which case a little water vapour must be added in order to convert back to CO2 any CO which is formed. More commonly, longitudinal or, preferably, transverse gas flow through the cavity is used. The CO2 laser can operate in a CW or pulsed mode, with power up to 1 kW possible in the CW mode. 

Fig. 20. Energy inputs and outputs to manufacture 3.785 L of anhydrous ethanol from com. (-) denotes system boundary. AH KJ figures are lower...

Ratio and Multiplicative Feedforward Control. In many physical and chemical processes and portions thereof, it is important to maintain a desired ratio between certain input (independent) variables in order to control certain output (dependent) variables (1,3,6). For example, it is important to maintain the ratio of reactants in certain chemical reactors to control conversion and selectivity the ratio of energy input to material input in a distillation column to control separation the ratio of energy input to material flow in a process heater to control the outlet temperature the fuel—air ratio to ensure proper combustion in a furnace and the ratio of blending components in a blending process. Indeed, the value of maintaining the ratio of independent variables in order more easily to control an output variable occurs in virtually every class of unit operation. 

Like the fired heater, the dryer is physically large, and proper insulation of the dryer and its aUied ductwork is critical. It is not uncommon to find 10% of the energy input lost through the walls in old systems. 

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