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13 pages, 2974 KiB

Open AccessArticle

Microwave Heating Improvement: Permittivity Characterization of Water–Ethanol and Water–NaCl Binary Mixtures

by Fabio Fanari, Giacomo Muntoni, Chiara Dachena, Renzo Carta and Francesco Desogus

Energies 2020, 13(18), 4861; https://doi.org/10.3390/en13184861 - 17 Sep 2020

Cited by 6 | Viewed by 2625

Abstract

Microwave heating offers a lot of advantages compared to conventional heating methods in the chemical reactions field due to its positive effects on reaction time and selectivity. Dielectric properties, and in particular permittivity, of substances and mixtures, are important for the optimization of [...] Read more.

Microwave heating offers a lot of advantages compared to conventional heating methods in the chemical reactions field due to its positive effects on reaction time and selectivity. Dielectric properties, and in particular permittivity, of substances and mixtures, are important for the optimization of microwave heating processes; notwithstanding this, specific databases are poor and far from being complete, and in the scientific literature very little data regarding these properties can be found. In this work, impedance measurements were carried out using a specially designed system to get the real and imaginary parts of the dielectric constant. The apparatus was tested in the estimation of permittivity of water–ethanol and water–NaCl mixtures, varying their composition to obtain a wide range of permittivity values. The results were compared to literature data and fitted with available literature models to verify the correspondence between them, finding that permittivity dependence on mixture composition can be effectively described by the models. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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18 pages, 3115 KiB

Open AccessArticle

Optimal Design of Welded Plate Heat Exchanger for Ammonia Synthesis Column: An Experimental Study with Mathematical Optimisation

by Leonid Tovazhnyanskyy, Jiří Jaromir Klemeš, Petro Kapustenko, Olga Arsenyeva, Olexandr Perevertaylenko and Pavlo Arsenyev

Energies 2020, 13(11), 2847; https://doi.org/10.3390/en13112847 - 3 Jun 2020

Cited by 10 | Viewed by 3244

Abstract

The production of ammonia, consuming up to 5% of natural gas global production, accounts for about 2% of world energy. Worldwide, the Haber–Bosch process is the mainly used method of ammonia catalytic synthesis, involving temperatures up to 600 °C and pressures up to [...] Read more.

The production of ammonia, consuming up to 5% of natural gas global production, accounts for about 2% of world energy. Worldwide, the Haber–Bosch process is the mainly used method of ammonia catalytic synthesis, involving temperatures up to 600 °C and pressures up to 32 MPa. In this paper, the results of the development and study of the special welded construction of plate heat exchanger (WPHE) for a column of ammonia synthesis are presented. The heat transfer and hydraulic performance of developed WPHE are investigated on a one-pass model in laboratory conditions. An equation for the relation between heat transfer effectiveness and the number of heat transfer units is proposed. A mathematical model of multi-pass WPHE is developed using these results. The validity of this model is confirmed by results of industrial tests performed with the prototype WPHE installed in operating column of ammonia synthesis at temperatures about 500 °C and pressure about 32 MPa. The tests confirmed the reliability of WPHE and its efficiency compared to a tubular heat exchanger. A method of optimal design of WPHE that allows finding the optimal height of corrugations and the number of passes in WPHE for specified conditions of operation is developed. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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18 pages, 2572 KiB

Open AccessArticle

Carbon Emissions Constrained Energy Planning for Aluminum Products

by Rok Gomilšek, Lidija Čuček, Marko Homšak, Raymond R. Tan and Zdravko Kravanja

Energies 2020, 13(11), 2753; https://doi.org/10.3390/en13112753 - 1 Jun 2020

Cited by 13 | Viewed by 3323

Abstract

The production of primary aluminum is an energy-intensive industry which produces large amounts of direct and indirect greenhouse gas emissions, especially from electricity consumption. Carbon Emissions Constrained Energy Planning proved to be an efficient tool for reducing energy-related greenhouse gas emissions. This study [...] Read more.

The production of primary aluminum is an energy-intensive industry which produces large amounts of direct and indirect greenhouse gas emissions, especially from electricity consumption. Carbon Emissions Constrained Energy Planning proved to be an efficient tool for reducing energy-related greenhouse gas emissions. This study focuses on energy planning constrained by CO₂ emissions and determines the required amount of CO₂ emissions from electricity sources in order to meet specified CO₂ emission benchmark. The study is demonstrated on and applied to specific aluminum products, aluminum slugs and aluminum evaporator panels. Three different approaches of energy planning are considered: (i) an insight-based, graphical targeting approach, (ii) an algebraic targeting approach of cascade analysis, and (iii) an optimization-based approach, using a transportation model. The results of the three approaches show that approximately 2.15 MWh of fossil energy source should be replaced with a zero-carbon or 2.22 MWh with a low-carbon energy source to satisfy the benchmark of CO₂ emissions to produce 1 t of aluminum slug; however, this substitution results in higher costs. This study is the first of its kind demonstrated on and applied to specific aluminum products, and represents a step forward in the development of more sustainable practices in this field. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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14 pages, 4018 KiB

Open AccessArticle

An Extended Grid Diagram for Heat Exchanger Network Retrofit Considering Heat Exchanger Types

by Bohong Wang, Jiří Jaromír Klemeš, Petar Sabev Varbanov and Min Zeng

Energies 2020, 13(10), 2656; https://doi.org/10.3390/en13102656 - 24 May 2020

Cited by 34 | Viewed by 3596

Abstract

Heat exchanger network (HEN) retrofit is a vital task in the process design to improve energy savings. Various types of heat exchangers such as shell and tube, double-pipe, compact plate, and spiral tube have their working temperature ranges and costs. Selecting suitable types [...] Read more.

Heat exchanger network (HEN) retrofit is a vital task in the process design to improve energy savings. Various types of heat exchangers such as shell and tube, double-pipe, compact plate, and spiral tube have their working temperature ranges and costs. Selecting suitable types of heat exchangers according to their temperature ranges and costs is a crucial aspect of industrial implementation. However, considering the type of heat exchangers in the HEN retrofit process is rarely seen in previous publications. This issue can be solved by the proposed Shifted Retrofit Thermodynamic Grid Diagram with the Shifted Temperature Range of Heat Exchangers (SRTGD-STR). The temperature ranges of six widely used heat exchanger types are coupled in the grid diagram. This diagram enables the visualisation of identifying the potential retrofit plan of HEN with heat-exchanger type selection. The retrofit design aims to minimise utility cost and capital cost. An illustrative example and a case study are presented to show the effectiveness of the method. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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20 pages, 756 KiB

Open AccessArticle

Renewable Energy Integration for Steam Supply of Industrial Processes—A Food Processing Case Study

by Ron-Hendrik Hechelmann, Jan-Peter Seevers, Alexander Otte, Jan Sponer and Matthias Stark

Energies 2020, 13(10), 2532; https://doi.org/10.3390/en13102532 - 16 May 2020

Cited by 14 | Viewed by 6306

Abstract

This study highlights the

C O_{2, e}

-emission reduction potentials and related economic consequences for changing steam generation from fossil to renewable. Seven different utility concepts are developed, including a steam accumulator for load management. Peculiarities for the integration of biogas [...] Read more.

This study highlights the

C O_{2, e}

-emission reduction potentials and related economic consequences for changing steam generation from fossil to renewable. Seven different utility concepts are developed, including a steam accumulator for load management. Peculiarities for the integration of biogas boilers, biomass-fuelled boilers, electrode steam boilers, biomethane-fuelled solid oxide fuel cells, micro gas turbine, solar energy systems, heat pumps and steam accumulators into a steam system with fluctuating steam demand are explained and the energy balance based models for the simulation study are described. The characteristics of batch processes, start up times and part load efficiency are considered via an annual dynamic simulation. Based on a detailed process analysis and dimensioning of the utilities and the accumulator a comprehensive simulation study is conducted for a pet food processing company having an average steam demand of 18,000 MWh at around 9 bar and 3 t/h. The results show that the highest

C O_{2, e}

-emissions reduction of up to 63% is achieved by the transition to a solid biomass-fuelled boiler system. This leads to an increase of the operating costs by 27.8%. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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15 pages, 1639 KiB

Open AccessArticle

Determination of Various Parameters during Thermal and Biological Pretreatment of Waste Materials

by Robert Hren, Aleksandra Petrovič, Lidija Čuček and Marjana Simonič

Energies 2020, 13(9), 2262; https://doi.org/10.3390/en13092262 - 4 May 2020

Cited by 7 | Viewed by 2315

Abstract

Pretreatment of waste materials could help in more efficient waste management. Various pretreatment methods exist, each one having its own advantages and disadvantages. Moreover, a certain pretreatment technique might be efficient and economical for one feedstock while not for another. Thus, it is [...] Read more.

Pretreatment of waste materials could help in more efficient waste management. Various pretreatment methods exist, each one having its own advantages and disadvantages. Moreover, a certain pretreatment technique might be efficient and economical for one feedstock while not for another. Thus, it is important to analyze how parameters change during pretreatment. In this study, two different pretreatment techniques were applied: thermal at lower and higher temperatures (38.6 °C and 80 °C) and biological, using cattle rumen fluid at ruminal temperature (≈38.6 °C). Two different feedstock materials were chosen: sewage sludge and riverbank grass (Typha latifolia), and their combinations (in a ratio of 1:1) were also analyzed. Various parameters were analyzed in the liquid phase before and after pretreatment, and in the gas phase after pretreatment. In the liquid phase, some of the parameters that are relevant to water quality were measured, while in the gas phase composition of biogas was measured. The results showed that most of the parameters significantly changed during pretreatments and that lower temperature thermal and/or biological treatment of grass and sludge is suggested for further applications. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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25 pages, 10160 KiB

Open AccessArticle

A Comparative Techno-Economic Analysis of Different Desalination Technologies in Off-Grid Islands

by Michael Castro, Myron Alcanzare, Eugene Esparcia, Jr. and Joey Ocon

Energies 2020, 13(9), 2261; https://doi.org/10.3390/en13092261 - 4 May 2020

Cited by 35 | Viewed by 6877

Abstract

Freshwater in off-grid islands is sourced from rain, groundwater, or mainland imports, which are unreliable, limited, and expensive, respectively. Sustainable freshwater generation from desalination of abundant seawater is another alternative worth exploring. Model-based techno-economic simulations have focused on reverse osmosis desalination due to [...] Read more.

Freshwater in off-grid islands is sourced from rain, groundwater, or mainland imports, which are unreliable, limited, and expensive, respectively. Sustainable freshwater generation from desalination of abundant seawater is another alternative worth exploring. Model-based techno-economic simulations have focused on reverse osmosis desalination due to its low energy consumption and decreasing costs. However, reverse osmosis requires frequent and costly membrane replacement. Other desalination technologies have advantages such as less stringent feedwater requirements, but detailed studies are yet to be done. In this work, a techno-economic comparison of multi-effect distillation, multi-stage flash, mechanical vapor compression, and reverse osmosis coupled with solar photovoltaic-lithium ion-diesel hybrid system was performed by comparing power flows to study the interaction between energy and desalination components. Optimization with projected costs were then performed to investigate future trends. Lastly, we used stochastic generation and demand profiles to infer uncertainties in energy and desalination unit sizing. Reverse osmosis is favorable due to low energy and water costs, as well as possible compatibility with renewable energy systems. Multi-effect distillation and multi-stage flash may also be advantageous for low-risk applications due to system robustness. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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28 pages, 3433 KiB

Open AccessArticle

Thermodynamics-Based Process Sustainability Evaluation

by Petar Sabev Varbanov, Hon Huin Chin, Alexandra-Elena Plesu Popescu and Stanislav Boldyryev

Energies 2020, 13(9), 2132; https://doi.org/10.3390/en13092132 - 28 Apr 2020

Cited by 20 | Viewed by 4064

Abstract

This article considers the problem of the evaluation of the sustainability of heterogeneous process systems, which can have different areas of focus: from single process operations to complete supply chains. The proposed method defines exergy-based concepts to evaluate the assets, liabilities, and the [...] Read more.

This article considers the problem of the evaluation of the sustainability of heterogeneous process systems, which can have different areas of focus: from single process operations to complete supply chains. The proposed method defines exergy-based concepts to evaluate the assets, liabilities, and the exergy footprint of the analysed process systems, ensuring that they are suitable for Life Cycle Assessment. The proposed concepts, evaluation framework and cumulative Exergy Composite Curves allow the quantitative assessment of process systems, including alternative solutions. The provided case studies clearly illustrate the applicability of the method and the close quantitative relationship between the exergy profit and the potential sustainability contribution of the proposed solutions. The first case study demonstrates how the method is applied to the separation and reuse of an acetic-acid-containing waste stream. It is shown that the current process is not sustainable and needs substantial external exergy input and deeper analysis. The second case study concerns Municipal Solid Waste treatment and shows the potential value and sustainability benefit that can be achieved by the extraction of useful chemicals and waste-to-energy conversion. The proposed exergy footprint accounting framework clearly demonstrates the potential to be applied to sustainability assessment and process improvement while simultaneously tracking different kinds of resources and impacts. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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24 pages, 3583 KiB

Open AccessArticle

A Method for Analyzing Energy-Related Carbon Emissions and the Structural Changes: A Case Study of China from 2005 to 2015

by Honghua Yang, Linwei Ma and Zheng Li

Energies 2020, 13(8), 2076; https://doi.org/10.3390/en13082076 - 21 Apr 2020

Cited by 23 | Viewed by 5324

Abstract

To systematically analyze energy-related carbon emissions from the perspective of comprehensive energy flow and allocate emissions responsibility, we introduce energy allocation analysis to carbon flow process based on Sankey diagrams. Then, to quantitatively compare different diagrams and evaluate the structural changes of carbon [...] Read more.

To systematically analyze energy-related carbon emissions from the perspective of comprehensive energy flow and allocate emissions responsibility, we introduce energy allocation analysis to carbon flow process based on Sankey diagrams. Then, to quantitatively compare different diagrams and evaluate the structural changes of carbon flow, we define changes from three dimensions including total amount change, relative growth rate and occupation ratio change (TRO), propose TRO index. The method is applied to China’s case study from 2005 to 2015. We map China’s energy-related carbon flow Sankey diagrams with high technical resolution from energy sources, intermediate conversion, end-use devices, passive systems to final services, and conduct TRO index decomposition by stages. The results indicate that in energy sources, the emission share of coal has declined due to energy transition although coal is still the largest contributor to China’s energy-related carbon emissions. In passive systems, the factory passive systems are the largest contributors, among them, emission reduction should focus on the steel, non-ferrous and chemical industries; the building passive systems should pay attention to household appliances; the vehicle passive systems should focus on cars. In final services, the demand for structural materials is the strongest driving force for carbon emissions growth. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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17 pages, 2187 KiB

Open AccessArticle

Biowaste Treatment and Waste-To-Energy—Environmental Benefits

by Martin Pavlas, Jan Dvořáček, Thorsten Pitschke and René Peche

Energies 2020, 13(8), 1994; https://doi.org/10.3390/en13081994 - 17 Apr 2020

Cited by 28 | Viewed by 8196

Abstract

Biowaste represents a significant fraction of municipal solid waste (MSW). Its separate collection is considered as a useful measure to enhance waste management systems in both the developed and developing world. This paper aims to compare the environmental performance of three market-ready technologies [...] Read more.

Biowaste represents a significant fraction of municipal solid waste (MSW). Its separate collection is considered as a useful measure to enhance waste management systems in both the developed and developing world. This paper aims to compare the environmental performance of three market-ready technologies currently used to treat biowaste—biowaste composting, fermentation, and biowaste incineration in waste-to-energy (WtE) plants as a component of residual municipal solid waste (RES). Global warming potential (GWP) was applied as an indicator and burdens related to the operation of facilities and credits obtained through the products were identified. The environmental performance of a WtE plant was investigated in detail using a model, implementing an approach similar to marginal-cost and revenues, which is a concept widely applied in economics. The results show that all of the treatment options offer an environmentally friendly treatment (their net GWP is negative). The environmental performance of a WtE plant is profoundly affected by its mode of its operation, i.e., type of energy exported. The concept producing environmental credits at the highest rate is co-incineration of biowaste in a strictly heat-oriented WtE plant. Anaerobic digestion plants treating biowaste by fermentation produce fewer credits, but approximately twice as more credits as WtE plants with power delivery only. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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14 pages, 1883 KiB

Open AccessArticle

Reducing Energy Requirements in the Production of Acrylic Acid: Simulation and Design of a Multitubular Reactor Train

by Kiara Capreece Premlall and David Lokhat

Energies 2020, 13(8), 1971; https://doi.org/10.3390/en13081971 - 16 Apr 2020

Cited by 6 | Viewed by 6953

Abstract

Acrylic acid, a versatile chemical intermediate, is typically manufactured via a two-step process involving the selective oxidation of propylene and acrolein. This work presents an optimized simulation on Aspen Plus^® (AspenTech, Bedford, MA, USA) of the production of acrylic acid, with focus [...] Read more.

Acrylic acid, a versatile chemical intermediate, is typically manufactured via a two-step process involving the selective oxidation of propylene and acrolein. This work presents an optimized simulation on Aspen Plus^® (AspenTech, Bedford, MA, USA) of the production of acrylic acid, with focus on the optimum design and operation of the reactor train, and modification for reduction in energy usage. In the propylene oxidation reactor, an inert pre-heating zone was designed to make use of the excess energy present in the exothermic process fluid and carried within the molten salt cooling fluid circuit. In the acrolein oxidation reactor, injection of cold air was used as a means to absorb the reaction heat. The optimization methodology employed aimed to minimize the total capital expenditure (i.e., equipment sizing) and operating costs (heat exchange network) for the required acrylic acid production and design constraints. The design constraints were based on the selected reaction kinetics and design heuristics for an optimum reactor design in this service from literature. Sensitivity analyses conducted on Aspen Plus^® (AspenTech, Bedford, MA, USA) were used to determine both the interactions between and grouping of the critical parameters for the optimization. Elimination of the conventional fired preheater from the propylene oxidation reactor resulted in energy savings of almost 7 MW, with the reduction in cooling fluid pumping power for the acrolein oxidation reactor amounting to 5 kW. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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15 pages, 5129 KiB

Open AccessArticle

Numerical Study of Heat Transfer in Gravity-Driven Particle Flow around Tubes with Different Shapes

by Xing Tian, Jian Yang, Zhigang Guo, Qiuwang Wang and Bengt Sunden

Energies 2020, 13(8), 1961; https://doi.org/10.3390/en13081961 - 16 Apr 2020

Cited by 13 | Viewed by 2502

Abstract

In the present paper, the heat transfer of gravity-driven dense particle flow around five different shapes of tubes is numerically studied using discrete element method (DEM). The velocity vector, particle contact number, particle contact time and heat transfer coefficient of particle flow at [...] Read more.

In the present paper, the heat transfer of gravity-driven dense particle flow around five different shapes of tubes is numerically studied using discrete element method (DEM). The velocity vector, particle contact number, particle contact time and heat transfer coefficient of particle flow at different particle zones around the tube are carefully analyzed. The results show that the effect of tube shape on the particle flow at both upstream and downstream regions of different tubes are remarkable. A particle stagnation zone and particle cavity zone are formed at the upstream and downstream regions of all the tubes. Both the stagnation and cavity zones for the circular tube are the largest, and they are the smallest for the elliptical tube. As the particle outlet velocity (v_out) changes from 0.5 mm/s to 8 mm/s at d_p = 1.72 mm/s, when compared with the circular tube, the heat transfer coefficient of particle flow for the elliptical tube and flat elliptical tube can increase by 20.3% and 15.0% on average, respectively. The proper design of the downstream shape of the tube can improve the overall heat transfer performance more efficiently. The heat transfer coefficient will increase as particle diameter decreases. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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15 pages, 5184 KiB

Open AccessArticle

Thermal Effects of Natural Gas and Syngas Co-Firing System on Heat Treatment Process in the Preheating Furnace

by Piotr Jóźwiak, Jarosław Hercog, Aleksandra Kiedrzyńska, Krzysztof Badyda and Daniela Olevano

Energies 2020, 13(7), 1698; https://doi.org/10.3390/en13071698 - 3 Apr 2020

Cited by 6 | Viewed by 3493

Abstract

Preheating furnaces, which are commonly used in many production sectors (e.g., iron and steel), are simultaneously one of the most energy-intensive devices used in the industry. Partial replacement of natural gas with biomass-derived synthesis gas as a fuel used for heating would be [...] Read more.

Preheating furnaces, which are commonly used in many production sectors (e.g., iron and steel), are simultaneously one of the most energy-intensive devices used in the industry. Partial replacement of natural gas with biomass-derived synthesis gas as a fuel used for heating would be an important step towards limiting industrial CO₂ emissions. The time dependent computational fluid dynamics (CFD) model of an exemplary furnace was created to evaluate whether it is possible to obtain 40% of energy from syngas combustion without deterioration of thermal parameters of the treated load. As an outcome, a promising method to organize co-firing in the furnace was indicated. The obtained results show that the co-firing method (up to 40% thermal natural gas replacement with syngas), assuming low air-to-fuel equivalence ratio (λ_NG = 2.0) and even distribution of power among the furnace corners, lead to satisfactory efficiency of the heat treatment process—the heat transferred to the load exceeds 95% of the heat delivered to the load in the reference case), while carbon dioxide emission is reduced from 285.5 to 171.3 kg CO₂/h. This study showed that it is feasible (from the heat transfer point of view) to decrease the environmental impact of the process industries by the use of renewable fuels. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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13 pages, 2909 KiB

Open AccessArticle

Isomerization of n-C₅/C₆ Bioparaffins to Gasoline Components with High Octane Number

by Jenő Hancsók, Tamás Kasza and Olivér Visnyei

Energies 2020, 13(7), 1672; https://doi.org/10.3390/en13071672 - 3 Apr 2020

Cited by 10 | Viewed by 3988

Abstract

The thermal and catalytic conversion processes of alternative feedstocks (e.g., waste and biomass) to different engine fuels can result in the formation of a significant amount of light hydrocarbons as by-products in the boiling range of gasoline. The properties of these C₅ [...] Read more.

The thermal and catalytic conversion processes of alternative feedstocks (e.g., waste and biomass) to different engine fuels can result in the formation of a significant amount of light hydrocarbons as by-products in the boiling range of gasoline. The properties of these C₅/C₆ hydrocarbons need to be improved due to many reasons, e.g., their benzene content, and/or poor oxidation stability (high olefin content) and low octane number (<60). The aim of the research work was to increase the octane number of benzene containing C₅/C₆ bioparaffin fractions by catalytic isomerization. These by-products were obtained from special hydrocracking of waste cooking oil to hydrocarbons in the boiling range of aviation turbine fuels (JET fuels)/diesel fuels. Experiments were carried out in a reactor system containing down-flow tubular reactors over Pt/Al₂O₃/Cl and Pt/H-Mordenite/Al₂O₃ catalysts at 115–145 °C and 230–270 °C, respectively. Based on the results obtained at different process parameter combinations, it was concluded that the hydrogenation of benzene was complete over both catalysts, and the liquid yields were higher (ca. 98% > ca. 93 %) in the case of Pt/Al₂O₃/Cl. In addition, the octane number was also enhanced (ca. 32 > ca. 27 unit) in the products compared to the feedstock. This was because a higher isoparaffin content can be obtained at a lower operating temperature. Moreover, cracking side reactions take place to a lesser extent. The utilization of these isomerized bio-origin light fractions can contribute to the competitiveness of second-generation biofuels. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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20 pages, 6109 KiB

Open AccessArticle

Nonlinear Finite Element Analysis-Based Flow Distribution and Heat Transfer Model

by Tomáš Létal, Vojtěch Turek, Dominika Babička Fialová and Zdeněk Jegla

Energies 2020, 13(7), 1664; https://doi.org/10.3390/en13071664 - 2 Apr 2020

Cited by 4 | Viewed by 3132

Abstract

A new strategy for fast, approximate analyses of fluid flow and heat transfer is presented. It is based on Finite Element Analysis (FEA) and is intended for large yet structurally fairly simple heat transfer equipment commonly used in process and power industries (e.g., [...] Read more.

A new strategy for fast, approximate analyses of fluid flow and heat transfer is presented. It is based on Finite Element Analysis (FEA) and is intended for large yet structurally fairly simple heat transfer equipment commonly used in process and power industries (e.g., cross-flow tube bundle heat exchangers), which can be described using sets of interconnected 1-D meshes. The underlying steady-state model couples an FEA-based (linear) predictor step with a nonlinear corrector step, which results in the ability to handle both laminar and turbulent flows. There are no limitations in terms of the allowed temperature range other than those potentially stemming from the usage of fluid physical property computer libraries. Since the fluid flow submodel has already been discussed in the referenced conference paper, the present article focuses on the prediction of the tube side and the shell side temperature fields. A simple cross-flow tube bundle heat exchanger from the literature and a heat recovery hot water boiler in an existing combined heat and power plant, for which stream data are available from its operator, are evaluated to assess the performance of the model. To gain further insight, the results obtained using the model for the heat recovery hot water boiler are also compared to the values yielded by an industry-standard heat transfer equipment design software package. Although the presented strategy is still a “work in progress” and requires thorough validation, the results obtained thus far suggest it may be a promising research direction. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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24 pages, 1595 KiB

Open AccessArticle

A Framework for Flexible and Cost-Efficient Retrofit Measures of Heat Exchanger Networks

by Christian Langner, Elin Svensson and Simon Harvey

Energies 2020, 13(6), 1472; https://doi.org/10.3390/en13061472 - 20 Mar 2020

Cited by 12 | Viewed by 2733

Abstract

Retrofitting of industrial heat recovery systems can contribute significantly to meeting energy efficiency targets for industrial plants. One issue to consider when screening retrofit design proposals is that industrial heat recovery systems must be able to handle variations, e.g., in inlet temperatures or [...] Read more.

Retrofitting of industrial heat recovery systems can contribute significantly to meeting energy efficiency targets for industrial plants. One issue to consider when screening retrofit design proposals is that industrial heat recovery systems must be able to handle variations, e.g., in inlet temperatures or heat capacity flow rates, in such a way that operational targets are reached. Consequently, there is a need for systematic retrofitting methodologies that are applicable to multi-period heat exchanger networks (HENs). In this study, a framework was developed to achieve flexible and cost-efficient retrofit measures of (industrial) HENs. The main idea is to split the retrofitting processes into several sub-steps. This splitting allows well-proven (single period) retrofit methodologies to be used to generate different design proposals, which are collected in a superstructure. By means of structural feasibility assessment, structurally infeasible design proposals can be discarded from further analysis, yielding a reduced superstructure. Additionally, critical point analysis is applied to identify those operating points within the uncertainty span that determine necessary overdesign of heat exchangers. In the final step, the most cost-efficient design proposal within the reduced superstructure is identified. The proposed framework was applied to a HEN retrofit case study to illustrate the proposed framework. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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17 pages, 3048 KiB

Open AccessArticle

Simultaneous Synthesis of Heat Exchanger Networks Considering Steam Supply and Various Steam Heater Locations

by Yao Sheng, Linlin Liu, Yu Zhuang, Lei Zhang and Jian Du

Energies 2020, 13(6), 1467; https://doi.org/10.3390/en13061467 - 20 Mar 2020

Cited by 4 | Viewed by 2823

Abstract

In process industries, the heating gap in heat exchanger networks (HENs) is normally compensated by the steam generated from a utility system, thus these two mutually influencing systems should be designed as a whole through establishing structural interrelationships. In this work, an improved [...] Read more.

In process industries, the heating gap in heat exchanger networks (HENs) is normally compensated by the steam generated from a utility system, thus these two mutually influencing systems should be designed as a whole through establishing structural interrelationships. In this work, an improved stage-wise superstructure of HENs is proposed to integrate with a Rankine cycle-based utility system. Inner- and inter-stage heaters are considered in the new structure. Furthermore, the selection of steam in different levels is also investigated, extending the possibilities of steam utilization in HENs and generation in utility systems. The presented methodology is able to realize the optimal design of HENs by considering the supply and utilization of steam. Heaters’ allocations, matches of streams, steam distribution and utilization are optimized accompanying with the trade-off amongst equipment investment, fuel consumption and power generation in objective, which is highly related to the final structure of the system. The optimization problem is formulated into a mixed-integer non-linear programming (MINLP) model and solved towards the lowest total annual cost (TAC) of the entire system. Finally, a case study with two scenarios is studied. The detailed results are given and analyzed to demonstrate the benefit from structural improvement. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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16 pages, 1463 KiB

Open AccessArticle

Techno-Economic and Environmental Evaluations of Decarbonized Fossil-Intensive Industrial Processes by Reactive Absorption & Adsorption CO₂ Capture Systems

by Ana-Maria Cormos, Simion Dragan, Letitia Petrescu, Vlad Sandu and Calin-Cristian Cormos

Energies 2020, 13(5), 1268; https://doi.org/10.3390/en13051268 - 9 Mar 2020

Cited by 38 | Viewed by 5133

Abstract

Decarbonization of energy-intensive systems (e.g., heat and power generation, iron, and steel production, petrochemical processes, cement production, etc.) is an important task for the development of a low carbon economy. In this respect, carbon capture technologies will play an important role in the [...] Read more.

Decarbonization of energy-intensive systems (e.g., heat and power generation, iron, and steel production, petrochemical processes, cement production, etc.) is an important task for the development of a low carbon economy. In this respect, carbon capture technologies will play an important role in the decarbonization of fossil-based industrial processes. The most significant techno-economic and environmental performance indicators of various fossil-based industrial applications decarbonized by two reactive gas-liquid (chemical scrubbing) and gas-solid CO₂ capture systems are calculated, compared, and discussed in the present work. As decarbonization technologies, the gas-liquid chemical absorption and more innovative calcium looping systems were employed. The integrated assessment uses various elements, e.g., conceptual design of decarbonized plants, computer-aided tools for process design and integration, evaluation of main plant performance indexes based on industrial and simulation results, etc. The overall decarbonization rate for various assessed applications (e.g., power generation, steel, and cement production, chemicals) was set to 90% in line with the current state of the art in the field. Similar non-carbon capture plants are also assessed to quantify the various penalties imposed by decarbonization (e.g., increasing energy consumption, reducing efficiency, economic impact, etc.). The integrated evaluations exhibit that the integration of decarbonization technologies (especially chemical looping systems) into key energy-intensive industrial processes have significant advantages for cutting the carbon footprint (60–90% specific CO₂ emission reduction), improving the energy conversion yields and reducing CO₂ capture penalties. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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19 pages, 3226 KiB

Open AccessArticle

Comparison of the Evaporation and Condensation Heat Transfer Coefficients on the External Surface of Tubes in the Annulus of a Tube-in-Tube Heat Exchanger

by Weiyu Tang, David John Kukulka, Wei Li and Rick Smith

Energies 2020, 13(4), 952; https://doi.org/10.3390/en13040952 - 20 Feb 2020

Cited by 12 | Viewed by 3661

Abstract

An experimental study was carried out to explore the heat transfer characteristics on the outside of smooth and enhanced tubes, during evaporation and condensation of R134A in the annulus of a tube-in-tube heat exchanger. The three-dimensional enhanced surface tube consisted of primary enhancement [...] Read more.

An experimental study was carried out to explore the heat transfer characteristics on the outside of smooth and enhanced tubes, during evaporation and condensation of R134A in the annulus of a tube-in-tube heat exchanger. The three-dimensional enhanced surface tube consisted of primary enhancement patterns and secondary patterns; results were compared to the performance of an equivalent smooth tube. The equivalent external diameter of the inside horizontal copper tubes used in this study was 19.05 mm, while the outer tube varied in size, allowing a comparison of heat transfer for different annulus dimensions. Tests were conducted with a fixed inlet/outlet vapor quality and a constant saturation temperature for varied mass velocities in the range of 30 to 100 kg/(m²∙s). For condensation, the ratio of heat transfer coefficient enhancement (enhanced tube/ smooth tube) was up to 1.78; this can be attributed to the turbulence increase, as well as liquid film re-distribution, produced from the dimples. Furthermore, the condensation heat transfer coefficient increased rapidly with increasing mass flux. For flow boiling in the annulus between the 1EHT tube and outer tube, the heat transfer coefficient during boiling was 11–36% higher when compared to the smooth tube at x_ave = 0.35, while the performance of the 1EHT tube was not as good as the smooth tube at x_ave = 0.5. The heat transfer deterioration can be explained by decreased effective nucleate flow boiling heat transfer area and the flow pattern transition between a slug/wavy-stratified flow to wavy-stratified flow. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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25 pages, 3867 KiB

Open AccessArticle

Critical Analysis of Process Integration Options for Joule-Cycle and Conventional Heat Pumps

by Limei Gai, Petar Sabev Varbanov, Timothy Gordon Walmsley and Jiří Jaromír Klemeš

Energies 2020, 13(3), 635; https://doi.org/10.3390/en13030635 - 3 Feb 2020

Cited by 17 | Viewed by 3302

Abstract

To date, research on heat pumps (HP) has mainly focused on vapour compression heat pumps (VCHP), transcritical heat pumps (TCHP), absorption heat pumps, and their heat integration with processes. Few studies have considered the Joule cycle heat pump (JCHP), which raises several questions. [...] Read more.

To date, research on heat pumps (HP) has mainly focused on vapour compression heat pumps (VCHP), transcritical heat pumps (TCHP), absorption heat pumps, and their heat integration with processes. Few studies have considered the Joule cycle heat pump (JCHP), which raises several questions. What are the characteristics and specifics of these different heat pumps? How are they different when they integrate with the processes? For different processes, which heat pump is more appropriate? To address these questions, the performance and integration of different types of heat pumps with various processes have been studied through Pinch Methodology. The results show that different heat pumps have their own optimal application range. The new JCHP is suitable for processes in which the temperature changes of source and sink are both massive. The VCHP is more suitable for the source and sink temperatures, which are near-constant. The TCHP is more suitable for sources with small temperature changes and sinks with large temperature changes. This study develops an approach that provides guidance for the selection of heat pumps by applying Process Integration to various combinations of heat pump types and processes. It is shown that the correct choice of heat pump type for each application is of utmost importance, as the Coefficient of Performance can be improved by up to an order of magnitude. By recovering and upgrading process waste heat, heat pumps can save 15–78% of the hot utility depending on the specific process. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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Review

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25 pages, 1775 KiB

Open AccessReview

Emerging Tools for Energy System Design Increasing Economic and Environmental Sustainability

by Yee Van Fan, Zorka Novak Pintarič and Jiří Jaromír Klemeš

Energies 2020, 13(16), 4062; https://doi.org/10.3390/en13164062 - 5 Aug 2020

Cited by 42 | Viewed by 3948

Abstract

Energy is a fundamental element supporting societal development, particularly with the increasing dependency on the Internet of Things. It is also the main contributor to environmental impacts and subsequently, a potential sector for mitigation. Sustainable energy system design considers energy savings and energy [...] Read more.

Energy is a fundamental element supporting societal development, particularly with the increasing dependency on the Internet of Things. It is also the main contributor to environmental impacts and subsequently, a potential sector for mitigation. Sustainable energy system design considers energy savings and energy efficiency, waste and consumption reduction, process efficiency enhancement, waste heat recovery, and integration of renewable energy. Emerging tools range from advanced Process Integration, modelling, simulation, and optimisation, to system analysis and assessment. This review covers selected emerging studies promoting sustainable system design, including the recent developments reported in the Special Issue (SI) of the 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction (PRES’19). The primary emphasis was to enhance the economic and environmental performance. However, social factors were also highlighted as essential for future sustainable development. The discussion and analysis in this review focus on the most recent developments of (a) heat integration and heat transfer; (b) integrated and newly developed heat exchangers, (c) integration of renewables, and (d) roles in economic and environmental sustainability. The key results are highlighted, and future research ideas are suggested according to their links to a broader context. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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26 pages, 1621 KiB

Open AccessReview

Operational Management Implemented in Biofuel Upstream Supply Chain and Downstream International Trading: Current Issues in Southeast Asia

by Hoo Poh Ying, Cassendra Bong Phun Chien and Fan Yee Van

Energies 2020, 13(7), 1799; https://doi.org/10.3390/en13071799 - 8 Apr 2020

Cited by 23 | Viewed by 6389

Abstract

Bioenergy is one of the alternatives to secure energy demand, despite increasing debate on the sustainability of using bioenergy as a renewable source. As the source is disseminated over a large area and affected by seasonality, the potential benefit is highly dependent on [...] Read more.

Bioenergy is one of the alternatives to secure energy demand, despite increasing debate on the sustainability of using bioenergy as a renewable source. As the source is disseminated over a large area and affected by seasonality, the potential benefit is highly dependent on other cost and benefit trade-offs along the supply chain. This review paper aims to assess operational management research methods used in biofuel supply chain planning, including both upstream production and international downstream trading. There have been considerable operational management studies done on upstream processes in biofuel production based on different strategic and tactical decision making of a single or multiple feedstocks, considering economic and environmental factor. However, the environmental consideration is often limited to carbon emission where the other environmental impact such as land-use change, biodiversity loss, irrigation and fertilisation are often being overlooked. Biofuel supply chain and trading at international level remain as an apparent research potential where only limited numbers of global energy models explicitly simulate international bioenergy trade. The leading biofuel producing countries in Southeast Asia: Malaysia, Indonesia and Thailand, are selected as a case study to investigate further on how the supply chain management model could be applied considering the existing biofuel support policies. This study is expected to contribute to the selection of operational management research methods used for decision making under robust policy context, followed by several recommendations. Full article

(This article belongs to the Special Issue Selected Papers from PRES’19: The 22nd Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction)

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