Application of Entransy Optimization to One-Stream Series-Wound and Parallel Heat Exchanger Networks

Abstract

Entransy theory has developed in recent years to describe heat transfer behavior from another point of view. Entransy dissipation is proposed to evaluate the irreversibility of heat transfer and is used to optimize heat transfer processes. We apply this theory to the one-stream series-wound and parallel heat exchanger (HE) networks. The heat transfer optimization for the HE networks includes the distribution of the heat transfer area or heat load. The distribution of the cold fluid flow rate in parallel HE networks can also be optimized. For these problems, physical and mathematical models are set up, analyzed, and discussed with the entransy theory. It is found that the optimization objectives of these problems and the optimization directions of the extremum entransy dissipation principle are consistent. The optimized results for the distribution optimization problem with given heat load are in agreement with the uniformity principle of temperature difference field. Examples of simple one-stream HE networks are given; the distributions of the heat transfer area or heat load are optimized by the extremum entransy dissipation method.

Uniformity principle of temperature difference field in heat transfer optimization*

“…A one-stream series-wound heat exchanger network. [13] For the i-th thermal component, we can assume that [12,13]…”

“…( 3) is equivalent to the entransy dissipation minimization. [13] Therefore, we can find the optimal distributions of the total heat transfer area and the total released heat flow rate that lead to the entransy dissipation minimization below. For the i-th thermal component, the entransy dissipation rate is…”

“…Furthermore, we can analyze a case in which the values of E i are fixed, and the limiting condition is expressed by Eq. (13). In this case, we can also set up a function…”

“…4 and 6, the consistence between the optimization objective and the entransy dissipation minimization has already been proved. [13,14] For the radiative heat transfer analyzed in Section 5, the entransy dissipation rate is…”