A flexible and robust modelling framework for multi-stream heat exchangers

Skaugen, Geir; Kolsaker, Kjell; Walnum, Harald Taxt; Wilhelmsen, Øivind

doi:10.1016/j.compchemeng.2012.10.006

Cited by 36 publications

(12 citation statements)

References 11 publications

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“…This modelling framework itself is described in more detail by Skaugen et al [17]. It can be used to model and analyze the performance of almost any type of heat exchanger.…”

Section: Flexible Heat Exchanger Modeling Frameworkmentioning

confidence: 99%

Investigation of Non-ideal Behavior of Plate-fin Heat Exchangers in LNG Services

2015

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Using a heat exchanger with several parallel channels in boiling services, static instabilities like the Ledinegg instabilities can occur, resulting from a combination of unfortunate operating conditions and the heat exchanger design. Ledinegg instability is characterized by different flow rates in parallel channels that share common inlet and outlet manifolds. Oscillations between different conditions may also occur. In a thermodynamic system like liquefaction of natural gas, the fluids can exhibit a large temperature glide during condensation and evaporation and the actual local fluid temperature inside a heat exchanger will then be directly dependent of the local mass-flow. This means that mass-flow oscillations also imply thermal oscillations. This study shows how this type of non-ideal behavior can be predicted for a plate-fin heat exchanger by requiring all channels for each stream to have equal pressure drop. These nonlinear equations are solved on top of the thermo-hydraulic simulation model for the heat exchanger core.

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“…This modelling framework itself is described in more detail by Skaugen et al [17]. It can be used to model and analyze the performance of almost any type of heat exchanger.…”

Section: Flexible Heat Exchanger Modeling Frameworkmentioning

confidence: 99%

Investigation of Non-ideal Behavior of Plate-fin Heat Exchangers in LNG Services

2015

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“…In practical applications, e.g., the modeling of transient pipeline flow, or multiphase heat exchangers [2,3,46], one is interested in the overall effect of the interface, and thus a description of the interface which is applicable on the macroscopic level. This has been successfully accomplished using excess thermodynamic variables.…”

Section: The Gibbs Surface and Local Equilibriummentioning

confidence: 99%

Extending the nonequilibrium square-gradient model with temperature-dependent influence parameters

et al. 2014

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Nonequilibrium interface phenomena play a key role in crystallization, hydrate formation, pipeline depressurization, and a multitude of other examples. Square gradient theory extended to the nonequilibrium domain is a powerful tool for understanding these processes. The theory gives an accurate prediction of surface tension at equilibrium, only with temperature-dependent influence parameters. We extend in this work the nonequilibrium square gradient model to have temperature-dependent influence parameters. The extension leads to thermodynamic quantities which depend on temperature gradients. Remarkably the Gibbs relation proposed in earlier work is still valid. Also for the extended framework, the "Gibbs surface" described by excess variables is found to be in local equilibrium. The temperature-dependent influence parameters give significantly different interface resistivities (∼9%-50%), due to changed density gradients and additional terms in the enthalpy. The presented framework facilitates a more accurate description of transport across interfaces with square gradient theory.

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“…For a heat exchanger model to be useful for optimization purposes, it is necessary the this model is very robust and reasonably fast. The modeling framework are described by [17]. A short description of the hierarchy and modules is following.…”

Section: Heat Exchanger Modelingmentioning

confidence: 99%

From Droplets to Process: Multilevel Research Approach to Reduce Emissions from LNG Processes

et al. 2015

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In the Enabling Low-Emission LNG Systems project, SINTEF Energy Research and NTNU have since 2009 been developing knowledge and tools with the aim to enable environmental safe, cost-effective, and energy efficient LNG processes. The project has employed a multilevel approach, where studies of fundamental phenomena, component modeling, and process optimization have been performed in parallel. Detailed models for two-phase flow in heat exchangers (HXs) have been developed, and falling films and droplet behavior relevant for LNG HXs have been studied experimentally. Further, the project work has generated robust and accurate HX models that can describe instabilities and include geometrical considerations. Finally, the project has improved the basis for optimization of LNG process through investigating of optimization tools and careful analysis and formulation of the optimization problem.

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A flexible and robust modelling framework for multi-stream heat exchangers

Cited by 36 publications

References 11 publications

Investigation of Non-ideal Behavior of Plate-fin Heat Exchangers in LNG Services

Investigation of Non-ideal Behavior of Plate-fin Heat Exchangers in LNG Services

Extending the nonequilibrium square-gradient model with temperature-dependent influence parameters

From Droplets to Process: Multilevel Research Approach to Reduce Emissions from LNG Processes

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