economicol diameters in pipeline systems at given supply and outlet pressures

摘要

In this paper the subject is a pipeline consisting of several parts, there being at the end of each part an outlet or an additional supply;pressures at the beginning and at the end of the pipeline are supposed to be given and recompression is not assumed. The object of this paper is to find conditions of minimum in¬vestment.nIt is shown that in this case there is always an optimum and there is only one principal condition:the diameters of the consecutive parts of pipeline must be proportionate to the desired capacities of these parts to a certain power. A formula is given to compute each diameter. Also a formula is given to compute the optimum investment forthwith.nSince application of the rule of proportionality which has been found leads to any value of diameter, a method of correction is given to find practical diameters as a multiple of (one or) two inches. This correction will as a rule cost less than a 5 % additional investment.nFurther conditions of pressure are discussed. A formula is given for the computation of intermediate pressures. Lastly, the effects of branches on optimum conditions are considered.nIt appears strange that in literature there has often been mention of the problem of the economical dia-meter, but what was really meant then was the economical pressure, while the present problem, viz. the economical diameters (with the stress on the plural), has, hitherto, not or scarcely been dealt with and has even hardly been seen as a totally separate problem.nThe method of optimization is applied in such a way as to show how it may also be applied in other techno-economic fields.