System available-energy flows

Figure 1. Skeleton schematic of 1960 system available-energy flows (megawatts). Also shown are the unit costs of the steam and electricity outputs based on the equality method and sunk capital costs.

In the application of this method to a Rankine cycle cogeneration system, generalized costing equations for the major components have been developed. Also, the utility of the method was extended by relaxing the rule that each state variable (and hence each Lagrange constraint) must correspond to an available-energy flow. The applicability was further extended by the introduction of numerical techniques necessary for the purpose of evaluating partial derivatives of steam table data. 

Figure 2. Simple distillation system for the separation of a 45%-55% benzene-toluene feed into 92% benzene distillate and a 95% toluene bottoms product. Available-energy flows and destructions are given in 10° Btu/hr.

On this basis, a cost or value of the available energy flows at the various junctures within the system can be determined (iteratively). Then if, for example, a particular component needs to deliver some specified output, knowing the unit cost of the availability supplied to the component, the component and its operating conditions can be selected (or designed) so that the total costs—of availability supplied thereto and of capital costs thereof, (etc.)—can be minimized. Typical parameters (decision variables) of a component which can be adjusted in order to attain the optimum system are efficiency, operating pressure and temperature, speed, and so on and so forth. 

Af a(j,j is the additional boiler fuel required when the heater is ou of service, cB is the unit cost of steam in the i - 1 bleed line, and cp is the unit cost of boiler fuel (coal). These available-energy flows are calculated in the usual manner and are given in Table II and reference (6). The unit costs are obtained with exactly the same techniques discussed by Reistad and Gaggioli (2)—by applying money balances to each component (boiler, high-pressure turbine,. . . ) of the system of interest to get the dollar flows and then by the subsequent division of the appropriate available-energy flows to obtain the unit costs. 

When cavitation occurs in a pump, its efficiency is reduced. It ean akso cause sudden surges in flow and pressure at the discharge nozzle. The calculation of the NPSITr (the pump s minimum required energy) and the NPSITa (the system s available energy), is based on an understanding of the lic]uid s absolute vapor pressure. 

An inerease in ambient air temperature will deerease the available energy for the generator. This assumes that the fresh feed and eoke burn remains eonstant. The expander horsepower does not ehange, but the air blower horsepower inereases with inereased air temperature, eausing the exeess energy to deerease. Steam and water may need to be added to the flue gas flow at various points in the system to eontrol afterburning. In Figure 4-64, the solid eurves are for a normal flow of steam. The dotted eurves are for inereases in the steam rate by 3.05 times, 4.85 times, and 6.05 times the normal flowrate. 

The system must iteratively collect additional energy from the available but normally wasted enormous Heaviside energy flow component. 

Design of products, processes, and systems must include integration and interconnectivity with available energy and materials flows. 

Perhaps I should say that many of the smaller compartments are mitochondria the typical cell contains about two thousand of them, and they occupy a total of about 20 percent of the cell s volume. Each of the little compartments contains machinery necessary to capture the energy of foodstuffs and store it in a chemically stable, yet readily available, form. The mitochondrial mechanisms that do this are quite complex. The system uses a flow of acid to power its machines, which shuttles electrons among a half-dozen carriers, requiring an exquisitely delicate interaction between many components. 

Riekert, L., in "Flow and Loss of Available Energy in Chemical Processing System" Koeteier, W.T., Ed. Chemical Engineering in A Changing World, Elsevier Scientific New York,.N.Y., 1976. 

Azbel and Liapis (1983) analyzed gas/liquid systems with the assumption that the available energy at steady state is at a minimum. Reh (1971) mentioned the concept of the lowest resistance to fluid flow, and in a somewhat alternate way, the so-called minimum pressure drop was used by Nakamura and Capes (1973) in analyzing the annular structure in dilute transport risers. The instability of a uniform particle-fluid suspension was analyzed by introducing small disturbances into the system (Jackson, 1963 Grace and Tuot, 1979 Batchelar, 1988). 

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