Design and Optimization of Waste Heat Recovery Unit Using Carbon Dioxide as Cooling Fluid

Skaugen, Geir; Walnum, Harald Taxt; Hagen, Brede; Clos, Daniel Perez; Mazzetti, Marit J.; Nekså, Petter

doi:10.1115/power2014-32165

Cited by 4 publications

(4 citation statements)

References 3 publications

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“…Other authors evaluate optimal designs based on techno-economic optimization (Pierobon et al, 2013;Nguyen et al, 2014a;Nguyen et al, 2014b;Pierobon et al, 2014a;Pierobon et al, 2014b;Zhang et al, 2018), albeit cost is highly uncertain in off-shore oil and gas applications. Skaugen et al (2014) developed a methodology for optimizing total minimum weight of an off-shore waste heat recovery unit by including both the finned tube bundle and the casing and structures. The result showed a close to quadratic exhaust gas flow area to keep the total weight low.…”

Section: Introductionmentioning

confidence: 99%

Compact Steam Bottoming Cycles: Minimum Weight Design Optimization and Transient Response of Once-Through Steam Generators

et al. 2021

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Compactness and weight minimization are key aspects for successful and widespread implementation of waste heat recovery steam cycles in off-shore oil and gas platforms due to the site weight and volume footprint constraints. The power plant off-shore must be designed for flexibility in its operations to provide varying power demands across multiple time scales. Reliability of the heat and power production units is crucial. Within a case study in an off-shore platform in the Norwegian Continental Shelf, this article conducts design optimization of compact and low-weight steam cycles for power production from gas turbine exhaust and transient analysis of the core of heat recovery steam generators (HRSGs) via dynamic modeling and simulation, considering once-through steam generators (OTSGs) for the HRSGs. A method for simultaneous thermodynamic and heat exchanger geometry optimization design for bottoming cycles is applied, with the main objective being weight minimization and compactness of the cycle heat exchangers. Ten different optimal minimum weight bottoming cycle designs are provided by selecting ten different manufacturable tubes. The resulting bottoming cycle designs are compared in terms of weight, OTSG core weight distribution, heat transfer area, and footprint. The resulting bottoming cycle weight varies from 48.4 to ca. 87.10 ton for designs sensible for off-shore applications, and from 95.8 to 178.9 ton when selecting outer tube diameters typical of onshore applications. Smaller outer tube diameter selection in OTSG bundles is a key driver for low-weight and compact steam cycle designs. Three different designs representing light, normal, and heavy OTSG designs are compared by dynamic trajectory and response time analysis under transient scenarios by means of dynamic modeling and simulation. More compact and lighter designs respond faster to changes in the gas turbine (GT) operation upstream the OTSG. The results in this analysis indicate the need for feedforward control. Feedback control alone is probably not a good option due to the high OTSG open loop stabilization time and large sensitivity to GT exhaust gas variations. More compact and low-weight designs based on the OTSG can reduce potential challenges in controlling and stabilizing bottoming cycles for power production.

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Section: Introductionmentioning

confidence: 99%

Compact Steam Bottoming Cycles: Minimum Weight Design Optimization and Transient Response of Once-Through Steam Generators

et al. 2021

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“…Weight-and volume minimization of the heat exchanger core is vital due to the lack of space on these installations. Earlier work has indicated that overall Waste Heat Recovery Unit (WHRU) skid weight can be reduced by bringing down the tube diameter [1], which calls for an extension of the validity range of existing thermal-hydraulic design correlations. It is also highly desirable to be able to validate the performance of a thermally optimized design by detailed numerical modeling, before investing in fabrication and experimental testing.…”

Section: Introductionmentioning

confidence: 99%

A validated CFD model of plain and serrated fin-tube bundles

Lindqvist

Næss

2018

Applied Thermal Engineering

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This work presents a Computational Fluid Dynamics model of helically wound fin tube bundles and demonstrates its predictive capability for thermal-hydraulic performance. A consistent validation against experimental data is given for four different fin tube geometries, two with plain fins and two with serrated fins. Predicted heat transfer and pressure drop data are within, or very close to, the experimental uncertainty, with maximum root mean square errors of 13.8 % and 14.4 % respectively. The modeled fin temperature distribution is used to evaluate three fin efficiency models, revealing that correction equations can be in significant error for tall plain fins. Three sets of semi-empirical correlations for Nusselt and Euler numbers are also evaluated, showing non-conservative predictions for several of the tested geometries. Results from the study confirm the efficacy of reduced domain modeling, whereby geometric periodicity of the heat exchanger array is exploited to reduce computational cost.

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“…This is particularly true for pressure drop measurements, where uncertainties are larger. Earlier work has shown that the WHRU skid weight can be reduced by scaling down the tube diameter to about 10 mm [4]. This requires new correlations with an extended validity range, to avoid extrapolation.…”

Section: Introductionmentioning

confidence: 99%

A Machine Learning Approach to Correlation Development Applied to Fin-Tube Bundle Heat Exchangers

et al. 2018

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Heat exchanger designers need reliable thermal-hydraulic correlations to optimize heat exchanger designs. This work combines an adaptive sampling method with a Computational Fluid Dynamics (CFD) simulator to obtain increased accuracy and validity range of heat transfer and pressure drop predictions using a limited number of data points. Correlation efficacy was evaluated based on a steam generator case study. The sensitivity to the design parameters was analyzed in detail. The RMSE (root mean square error) of the developed correlations were reduced, through CFD sampling, from 28% to 15% for pressure drop, and from 33% to 25% heat transfer, compared to regression on experimental data only. The best reference correlations have RMSE values of 43% and 33% on pressure drop and heat transfer, respectively, on an independent validation set. Indeed, a radically different fin-tube geometry was suggested for the case study, compared to results using the Escoa correlations.The developed correlations show good to excellent agreement with trends in the CFD model. The quantitative error of predicted heat transfer and pressure drop coefficients at the case study optimum, however, was as large as those of the Escoa correlations. More data are likely needed to improve accuracy for compact heat exchanger designs further.

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Design and Optimization of Waste Heat Recovery Unit Using Carbon Dioxide as Cooling Fluid

Cited by 4 publications

References 3 publications

Compact Steam Bottoming Cycles: Minimum Weight Design Optimization and Transient Response of Once-Through Steam Generators

Compact Steam Bottoming Cycles: Minimum Weight Design Optimization and Transient Response of Once-Through Steam Generators

A validated CFD model of plain and serrated fin-tube bundles

A Machine Learning Approach to Correlation Development Applied to Fin-Tube Bundle Heat Exchangers

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