Investigation of entropy generation in a helically coiled tube in flow boiling condition under a constant heat flux

Abdous, Mohammad Ali; Saffari, Hamid; Avval, Hasan Barzegar; Khoshzat, Mohsen

doi:10.1016/j.ijrefrig.2015.07.026

Cited by 34 publications

(8 citation statements)

References 42 publications

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“…The structural theory to model and minimize entropy generation has been used. Abdous et al . analyzed the same problem in helically coiled tubes under flow boiling conditions under a constant heat flux.…”

Section: Introductionmentioning

confidence: 99%

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Optimization of a Thermal Cracking Reactor Using Genetic Algorithm and Water Cycle Algorithm

Saffari¹,

Salarian

Lohrasbi

et al. 2022

ACS Omega

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With the global production of 150 million tons in 2016, ethylene is one of the most significant building blocks in today’s chemical industry. Most ethylene is now produced in cracking furnaces by thermal cracking of fossil feedstocks with steam. This process consumes around 8% of the main energy used in the petrochemical industry, making it the single most energy-intensive process in the chemical industry. This paper studies a tubular thermal cracking reactor fed by propane and the molecular mechanism of the reaction within the reactor. After developing the reaction model, the existing issues, such as the reaction, flow, momentum, and energy, were resolved by applying heat to the outer tube wall. After solving the entropy generation equations, the entropy generation ratio of the sources was evaluated. The temperature of the tube/reactor was tuned following the reference results, and processes were replicated for different states. The verification of the modeling and simulation results was compared with the industrial case. The Genetic Programming (GP) machine learning approach was employed to generate objective functions based on key decision variables to reduce the computational time of the optimization algorithm. For the first time, this study has proposed a systematic approach for optimizing a thermal cracking reactor based on a combination of Genetic Programming (GP), Water Cycle Algorithm (WCA), and Genetic Algorithm (GA). In this regard, multiobjective optimization was performed based on the maximization of the products and entropy generation with the generation of GP objective functions. The key decision variables in this study included inlet gas temperature, inlet gas pressure, air mass flow rate, and wall temperature. The results showed that the weighted percentage of products after optimization increased to 61.13% and the entropy production rate of the system decreased to 899.80 J/s, displaying an improvement of 0.85 and 16.51% compared with the base case, respectively, with the multiobjective GA algorithm. In addition, by applying the multiobjective WCA, the weighted percentage of products increased to 61.81%. The entropy production rate of the system decreased to 882.72 J/s. So, an improvement of 1.97% in weights of products and an improvement of 18.77% in entropy generation have been achieved compared with the base case.

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Section: Introductionmentioning

confidence: 99%

“…The structural theory to model and minimize entropy generation has been used. Abdous et al 20 analyzed the same problem in helically coiled tubes under flow boiling conditions under a constant heat flux. Kurnia et al 21 applied this analysis to various cross-sections.…”

Section: Introductionmentioning

confidence: 99%

Optimization of a Thermal Cracking Reactor Using Genetic Algorithm and Water Cycle Algorithm

Saffari¹,

Salarian

Lohrasbi

et al. 2022

ACS Omega

View full text Add to dashboard Cite

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“…The principles of the structural theory have also been used in modeling and minimizing the entropy generation in a reactor . Abdous analyzed the entropy generation in helically coiled tubes in the flow boiling condition under a constant heat flux. Kurnia et al replicated this analysis for various cross sections.…”

Section: Introductionmentioning

confidence: 99%

Entropy Generation Analysis of a Thermal Cracking Reactor

et al. 2021

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The present paper analyzes the entropy generation of a tabular thermal cracking reactor with propane feed, as well as the molecular mechanism of the reaction. The reaction model is obtained and the flow, reaction, momentum, and energy are determined with knowledge of the outer wall temperature. Then, the equations of entropy generation in the tabular reactor are solved and the rate of entropy generated by three sources along the reactor is determined. After that, the temperature of the tube or reactor is changed using the reference results, and the results and procedures are replicated. The results obtained for two states show that the three factors are in the order of chemical reactions, heat transfer, and pressure loss in terms of their contribution to entropy generation. The decrease in input feed temperature does not influence the weight percent of the products considerably, but when the wall temperature is reduced, as is the case with the optimal wall temperature state, the conversion percent in the reactor is reduced. The entropy generated by heat transfer in reactors with lower feed temperature is much higher at the beginning of the reaction. These variations do not affect the pressure-induced entropy considerably. The variation of input feed temperature does not affect the entropy generated by the chemical reactions, but the entropy produced in the reactor with optimal wall temperature is the lowest. At the inlet of the reactor, the entropy is higher when the wall has optimal temperature, which can be attributed to its higher rate of reactions than the other two states of input feed temperature.

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“…About the optimization of SHE's two works that converge to the stated by Caputo et al [11] may be useful, Bidabadi et al [12] and Turgut and Ç oban [1], where minimization from the economic and the maximization from the thermal point-of-view are implemented. Another work that deserves attention about the thermal point-of-view is Abdous et al [13], where helically coiled heat exchanger was investigated under the entropy generation. Important to notice that some works considered special cases where the spiral heat exchangers could be treated as flat plate heat exchanger [14] and, in that case, other correlations for heat transfer and pressure drop could be applied [15].…”

Section: Introductionmentioning

confidence: 99%

Design of spiral heat exchanger from economic and thermal point of view using a tuned wind-driven optimizer

Segundo

Mariani

Coelho

2018

J Braz. Soc. Mech. Sci. Eng.

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This paper presents an optimization of spiral heat exchangers by wind-driven optimization and a novel variant of this algorithm by the insertion of a statistic distribution to self-adapting of the evolution parameters of the algorithm. Spiral heat exchangers are the ideal type for cooling slurries and fluids that presents high viscosity and is very common in food and petrochemical industries. The variables used for the optimization were the spacing channels for hot and cold streams, the length, the width and the thickness of the heat exchanger. Two case studies were presented where the minimization of the cost and the maximization of the overall heat transfer coefficient were implemented. Reductions about 4.46 and 23% were obtained for the cost and increases about 18.8 and 16.4% were reached for the overall heat transfer coefficient for each case study in comparison to previous works. The proposed technique reached better results in all the simulations, in some cases with GA, but performed better accuracy among all the simulations. Keywords Spiral heat exchanger Á Wind-driven optimization Á Minimization of total cost Á Maximization of overall heat transfer coefficient Á Optimization

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Investigation of entropy generation in a helically coiled tube in flow boiling condition under a constant heat flux

Cited by 34 publications

References 42 publications

Optimization of a Thermal Cracking Reactor Using Genetic Algorithm and Water Cycle Algorithm

Optimization of a Thermal Cracking Reactor Using Genetic Algorithm and Water Cycle Algorithm

Entropy Generation Analysis of a Thermal Cracking Reactor

Design of spiral heat exchanger from economic and thermal point of view using a tuned wind-driven optimizer

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