Automatic Evolution of Heat Exchanger Networks With Simultaneous Heat Exchanger Design

Liporace, Fábio S.; Pessoa, Fernando; Queiroz, Eduardo M.

doi:10.1590/s0104-66321999000100004

Cited by 6 publications

(2 citation statements)

References 3 publications

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“…After the synthesis of the initial HEN that accomplishes the minima consumption of utilities, the HEN is evolved in order to decrease the HEN TAC. This evolutionary optimization is performed with the help of the Simulation Matrix in order to restore the MTD and the stream's target temperature when they are violated by the loop-breaking procedure (Liporace et al, 1999). As the process streams are not, in fact, split, the HEN structure presented in Figure 6 must be rearranged in order to show the matches of the original streams ( Figure 7 and Table 14), so as a comparison between the final HENs obtained by the traditional and proposed procedures can be performed.…”

Section: Example Equations and Resultsmentioning

confidence: 99%

Heat Exchanger Network Synthesis Considering Changing Phase Streams

Liporace¹,

Pessoa²,

Queiroz³

2004

RETERM

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The Pinch Design Method was developed considering one-phase streams, with constant specific heats (Cp) throughout streams temperature ranges. Its first stage, the determination of utilities targets and pinch point (PP), is ruled by the number of streams, their temperatures and MCp. But, for changing phase streams, the usual description of the Cp behavior by a constant value can lead to errors in this stage and, hence, in the synthesis one. This work proposes a procedure to deal with these streams and discusses its results through an example involving multicomponent streams. First, bubble (BP) and dew (DP) points of the streams are estimated. Then, changing phase streams are split into sub-streams, using BP and DP as bounds. For each one, an effective Cp is estimated as the division of the enthalpy change by the respective temperature difference. Results obtained show significant changes on the PP, utilities targets and network proposed structure.

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Section: Example Equations and Resultsmentioning

confidence: 99%

Heat Exchanger Network Synthesis Considering Changing Phase Streams

Liporace¹,

Pessoa²,

Queiroz³

2004

RETERM

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“…One of the first studies to investigate the effects of the detailed heat exchanger designs upon the network synthesis was Liporace et al 14,15 In their work they first used Pinch Technology to derive a network before assessing the individual exchangers. Noticing that certain exchangers were very small or had many shells, they excluded these matches in subsequent network solutions.…”

Section: Introductionmentioning

confidence: 99%

Heat exchanger network synthesis with detailed exchanger designs—2. Hybrid optimization strategy for synthesis of heat exchanger networks

et al. 2020

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We propose a new strategy to synthesize heat exchanger networks with detailed designs of individual heat exchangers. The proposed strategy uses a multistep approach by first obtaining a heat exchanger network topology through solving a modified version of the mixed integer nonlinear programming (MINLP) stage‐wise superstructure of Yee and Grossmann, which includes a smoothed LMTD approximation and pressure drops. In a second nonlinear programming (NLP) suboptimization step, we allow for nonisothermal mixing to solve problems with or without exchanger bypasses. The selected heat exchangers along with the mass and energy balances obtained are then used to design the network with detailed exchanger designs through solving a sequence of NLPs for individual heat exchanger designs. The NLPs are based on the detailed discretized optimization models of Kazi et al., which solve quickly and reliably to obtain heat exchangers based on rigorous, first‐principles derived coupled differential equations. These models solve a differential algebraic equation system and do not rely on usual assumptions associated with other heuristic‐based exchanger design methods, such as log mean temperature difference and FT correction factors. These detailed exchanger designs are then used to update the network optimization model through sets of correction factors on heat exchanger area, number of shells, heat transfer coefficients, and pressure drops of each exchanger design, in a method based on that of Short et al. The method solves reliably, guaranteeing feasible exchangers for every potential network generated by the shortcut models, through validation with rigorous heat exchanger models at every iteration. In addition, the method does not increase the nonlinearity of the MINLP model, nor does it require any manual intervention or initialization from the user. Three examples are solved and the results are compared to those obtained in the literature.

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