Interest rate proper

Seawater Evaporators The production of potable water from saline waters represents a large and growing field of application for evaporators. Extensive work done in this field to 1972 was summarized in the annual Saline Water Conversion Repoi ts of the Office of Sahne Water, U.S. Department of the Interior. Steam economies on the order of 10 kg evaporation/kg steam are usually justified because (1) unit production capacities are high, (2) fixed charges are low on capital used for pubhc works (i.e., they use long amortization periods and have low interest rates, with no other return on investment considered), (3) heat-transfer performance is comparable with that of pure water, and (4) properly treated seawater causes httle deterioration due to scahng or fouhng. 

The key to the discounted cash flow methods is the determination of a proper interest rate. For this, two factors must be known. One is how much does it cost to obtain money The second is what is a reasonable amount of profit to expect from a plant The first depends on the source of money. This can be corporation earnings, the sale of stock, the issuance of bonds, the selling of assets, or borrowing from some outside source. The second depends on economic conditions. 

In the preceding treatment of discounted cash flow, the procedure has involved the determination of an index or interest rate which discounts the annual cash flows to a zero present value when properly compared to the initial investment. This index gives the rate of return which includes the profit on the project, payoff of the investment, and normal interest on the investment. A related approach, known as the method of net present worth (or net present value or venture worth), substitutes the cost of capital at an interest rate i for the... 

Much of this earlier work is largely of historical interest because proper kinetic expressions have not been proposed for representing the reaction rate nor have sufficient data been provided to develop such an interpretation a posteriori. In more recent studies of solid-solid reactions, notably by Rao [6, 7], Kondo et al. [8, 9], and El-Guindy and Davenport [10], the relationship between solid-solid reactions and the previously discussed gas-solid systems has been recognized and therefore the interpretation of these data may be more readily made. A somewhat more detailed discussion of these results will be made after a brief review of the earlier theoretical work on solid-solid reaction systems. 

In these equations, Dmax is the larger of the summed values of STERIMOL parameters, Bj, for the opposite pair 68). It expresses the maximum total width of substituents. The coefficients of the ct° terms in Eqs. 37 to 39 were virtually equal to that in Eq. 40. This means that the a° terms essentially represent the hydrolytic reactivity of an ester itself and are virtually independent of cyclodextrin catalysis. The catalytic effect of cyclodextrin is only involved in the Dmax term. Interestingly, the coefficient of Draax was negative in Eq. 37 and positive in Eq. 38. This fact indicates that bulky substituents at the meta position are favorable, while those at the para position unfavorable, for the rate acceleration in the (S-cyclodextrin catalysis. Similar results have been obtained for a-cyclodextrin catalysis, but not for (S-cyclodextrin catalysis, by Silipo and Hansch described above. Equation 39 suggests the existence of an optimum diameter for the proper fit of m-substituents in the cavity of a-cyclodextrin. The optimum Dmax value was estimated from Eq. 39 as 4.4 A, which is approximately equivalent to the diameter of the a-cyclodextrin cavity. The situation is shown in Fig. 8. A similar parabolic relationship would be obtained for (5-cyclodextrin catalysis, too, if the correlation analysis involved phenyl acetates with such bulky substituents that they cannot be included within the (5-cyclodextrin cavity. 

It is of interest to examine how the manipulated variables (Min, I., and Q) behave in order to yield results such as those of Figure 7. Unless proper limits are imposed by the model, the manipulations required may be difficult or even impossible to achieve in practice (for example, negative concentrations or flow rates). In this case all three manipulated variables were restricted to positive values. In addition, M n was given an upper bound. No restrictions were placed on rates of change of the variables. 

---