Novi pristup optimizaciji brzina fluida kod višecevnih razmenjivača toplote sa aspekta troškova

Abstract

This paper deals with the optimum velocity of a fluid through the pipes and shell for the characteristic groups of the multiple heat exchanger in the presence of sections, starting from the total cost function, containing fixed costs, energy costs, or the force for transporting the fluid. Components optimization functions are expressed in suitable units, which enabled the establishment of a mathematical model which involves both the fluid speeds, which are optimized. For this purpose were used the mathematical transformation of thermodynamic and hydraulic relations. The optimum value of the fluid velocity is obtained by minimization of the complex functions total costs, wherein the used theorems of differential calculus that are compared with two variables function. The resulting function, as the two-dimensional problem is examined in detail by the method of mathematical analysis. During this process is taken into account and the limitations of certain parameters. By partial differentiating the optimization function, obtained a complex system of equations that can be solved by numerical mathematical method with the support of a computer program, with respect to optimized parameters which cannot be expressed explicitly. In order to efficiently obtain solutions, in addition to the analytical, was used and graphic procedure. This techno-economic approach to the problem set due to imposed additional conditions, require the iterative determination of the parameters necessary for the design. The reason for this is because had to be satisfied greater number of equations with respect to certain restrictions.