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17 pages, 3280 KiB

Open AccessFeature PaperArticle

A Practical Approach for Biochemical Modeling in the CFD Evaluation of Novel Anaerobic Digester Concepts for Biogas Production

by Mario Miana, Ana Martínez Santamaría, Jose B. Carbajo, Cristina Bengoechea, Gorka García and Salvador Izquierdo

Processes 2023, 11(10), 2851; https://0-doi-org.brum.beds.ac.uk/10.3390/pr11102851 - 27 Sep 2023

Cited by 1 | Viewed by 747

Abstract

The detailed physics-based description of anaerobic digesters is characterized by their multiscale and multiphysics nature, with Computational Fluid Dynamics (CFD) simulations being the most comprehensive approach. In practice, difficulties in obtaining a detailed characterization of the involved biochemical reactions hinder its application in [...] Read more.

The detailed physics-based description of anaerobic digesters is characterized by their multiscale and multiphysics nature, with Computational Fluid Dynamics (CFD) simulations being the most comprehensive approach. In practice, difficulties in obtaining a detailed characterization of the involved biochemical reactions hinder its application in the design of novel reactor concepts, where all physics interplays in the reactor must be considered. To solve this limitation, a practical approach is introduced where a calibration step using actual process data was applied for the simplified biochemical reactions involved, allowing us to efficiently manage uncertainties arising when characterizing biochemical reactions with lab scale facilities. A complete CFD modeling approach is proposed for the anaerobic digestion of wastewater, including heat transfer and multiphasic flow. The proposed multiphase model was verified using reference data and, jointly with the biochemical modeling approach, applied to a lab-scale non-conventional anaerobic digester for winery wastewater treatment. The results showed qualitative improvement in predicting methane production when the diameter of the particles was reduced, since larger particles tend to move downwards. The biochemistry of the process could be simplified introducing a preexponential factor of 380 (kmol/m³)^{(1 – n)}/s for each considered chemical reaction. In general, the proposed approach can be used to overcome limitations when using CFD to scale-up optimization of non-conventional reactors involving biochemical reactions. Full article

(This article belongs to the Special Issue Technologies for Climate-Neutral Energy Systems)

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29 pages, 5145 KiB

Open AccessFeature PaperArticle

On the Energy Performance and Energy Saving Potential of the Pharmaceutical Industry: A Study Based on the Italian Energy Audits

by Giacomo Bruni, Chiara Martini, Fabrizio Martini and Marcello Salvio

Processes 2023, 11(4), 1114; https://0-doi-org.brum.beds.ac.uk/10.3390/pr11041114 - 05 Apr 2023

Cited by 1 | Viewed by 1991

Abstract

The growing attention towards environmental sustainability in the pharmaceutical industry and increased awareness of the potential for improving energy performance are justified by the fact that the sector is energy intensive. However, the variety of the processes and the lack of data about [...] Read more.

The growing attention towards environmental sustainability in the pharmaceutical industry and increased awareness of the potential for improving energy performance are justified by the fact that the sector is energy intensive. However, the variety of the processes and the lack of data about production and energy consumption make it difficult to calculate Energy Performance Indicators (EnPIs) as much as to list Energy Performance Improvements Actions (EPIAs). This work elaborates data, such as final energy consumption and site characteristics, from 84 mandatory Italian Energy Audits (EAs) to calculate the mean and standard deviation of site-level EnPIs. Additionally, the suggested and implemented EPIAs are analyzed to describe achieved and potential savings. The results show what follows. In the typical pharmaceutical plant, around 70% of energy is used in auxiliary services, and its use is not related to production. For this reason, EnPIs calculated both with respect to mass production and plant surfaces have a mid-to-wide standard deviation; the mean primary energy EnPI calculated with respect to plant surface area is 0.38 ± 0.22 toe/m². Most suggested EPIAs regard cold and hot energy production, as well as on-site energy production, from renewables and Combined Heat and Power (CHP) plants. The payback time is less than 4 years for many EPIAs, including both technical and managerial ones. According to the results, plant energy managers should calculate site EnPIs with respect to the site surface and increase monitoring of energy consumption at the process level. The last recommendation is also likely to be associated with more effective planning of EPIAs, allowing their introduction where the saving potential and economic indicators are more promising. Full article

(This article belongs to the Special Issue Technologies for Climate-Neutral Energy Systems)

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22 pages, 4728 KiB

Open AccessFeature PaperArticle

Evaluation of Technical Feasibility of Solar Heat Integration in Agri-Food Industries

by Julio Guillen-Angel and Ignacio Julian

Processes 2023, 11(3), 696; https://0-doi-org.brum.beds.ac.uk/10.3390/pr11030696 - 25 Feb 2023

Viewed by 1460

Abstract

This work assesses the use of different solar heating integration configurations and heating storage solutions for three different agri-food industries located in southern Europe. TRNSYS is employed to model different Solar Heat for Industrial Process (SHIP) integration options and to quantify the solar [...] Read more.

This work assesses the use of different solar heating integration configurations and heating storage solutions for three different agri-food industries located in southern Europe. TRNSYS is employed to model different Solar Heat for Industrial Process (SHIP) integration options and to quantify the solar thermal share with respect to the overall thermal demand, as well as to estimate the avoided consumption of fuels and CO₂ emissions in the existing boiler units as a result of the solar system integration. The SHIP integration is complemented with the evaluation of selected phase-change materials (PCM) to promote latent heat storage under the specific conditions of the considered agri-food demo sites and solar irradiation characteristics. The arrangement of flat-plate solar collectors coupled with latent heat storage was found to enhance the yearly averaged solar share of the SHIP solutions, reaching 13% of the overall thermal demand for an average Spanish winery demo site. Furthermore, the estimation of the gross solar heat production for a mid-size Italian spirits distillery yielded 400 MWh/y, leading to annual fossil fuel savings of 32 tons and yearly avoided CO₂ emissions of up to 100 tons. Similarly, the SHIP integration model for an average French charcuterie predicted a 55% solar share of the thermal demand required for plant cleaning purposes, resulting in roughly 50 tons of CO₂ emissions avoided per year. The estimated payback period (PBP) for the Italian spirits demo case under the current economic scenario is below 9 years, whereas the PBP for the other demos does not exceed the expected lifetime of the solar plants (25 years). Full article

(This article belongs to the Special Issue Technologies for Climate-Neutral Energy Systems)

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15 pages, 3053 KiB

Open AccessFeature PaperArticle

Design, Development, and Performance Evaluation of a New Photovoltaic-Thermal (PVT) Air Collector: From Lab Testing to Field Measurements

by Raquel Simón-Allué, Raúl Villén, Gonzalo Brun, Yolanda Lara and Isabel Guedea

Processes 2023, 11(2), 588; https://0-doi-org.brum.beds.ac.uk/10.3390/pr11020588 - 15 Feb 2023

Viewed by 1402

Abstract

Over the last decade, the market has experienced a growing interest in hybrid photovoltaic-thermal (PVT) technologies, although more long-term studies are needed before air-based PVT panels are fully implemented. In this paper, we present the experimental framework developed around an air-based PVT collector, [...] Read more.

Over the last decade, the market has experienced a growing interest in hybrid photovoltaic-thermal (PVT) technologies, although more long-term studies are needed before air-based PVT panels are fully implemented. In this paper, we present the experimental framework developed around an air-based PVT collector, consisting of a high-quality photovoltaic laminate and a newly designed thermal absorber. The experimental performance of the collector was measured both in lab testing and in a pilot plant during one of the field operations. Results show an almost constant electrical performance of 15–19%, and a thermal performance that changes a lot, ranged between 15–52% for the individual panel and 11–35% for the system of 2.5 panels in series (to maximize output temperature). Field operation presents average thermal and electrical efficiencies ranged between 16–20% with an electrical–thermal generation ratio close to 1:1. Full article

(This article belongs to the Special Issue Technologies for Climate-Neutral Energy Systems)

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24 pages, 8760 KiB

Open AccessFeature PaperArticle

CFD Modeling and Validation of Blast Furnace Gas/Natural Gas Mixture Combustion in an Experimental Industrial Furnace

by Jorge Arroyo, Luis Pérez and Víctor Cuervo-Piñera

Processes 2023, 11(2), 332; https://0-doi-org.brum.beds.ac.uk/10.3390/pr11020332 - 19 Jan 2023

Cited by 3 | Viewed by 2482

Abstract

The use of residual gases from steel production processes as fuel for steel treatment furnaces has attracted great interest as a method for reducing fossil fuel consumption and the steel footprint. However, these gases often have a low calorific value, and a direct [...] Read more.

The use of residual gases from steel production processes as fuel for steel treatment furnaces has attracted great interest as a method for reducing fossil fuel consumption and the steel footprint. However, these gases often have a low calorific value, and a direct substitution can lead to low temperatures or combustion instability issues. CFD simulations of the combustion of these gases can help steel producers forecast the results of the substitution before real testing and implementation. In this study, a CFD model of an industrial experimental furnace in the steel sector is developed and validated. The results are calculated using the combustion, radiation, and heat transfer models included in the software Ansys Fluent. The validation of the simulated results is performed with data acquired from experimental tests under the same simulated conditions at three air-to-fuel equivalence ratios, which vary from an excess of 0% to an excess of 5% oxygen at the outlet. The model is adjusted to the results, capturing the trends of the measured physical variables and pollutant concentrations. In the case of the combustion temperature, the differences between the simulated and measured values vary from 0.03% to 6.9. Based on the simulation results, the use of blast furnace gas as fuel produces temperatures inside the chamber between 1004 °C and 1075 °C and high stream velocities because of the high flow needed to keep the power constant. Flames exhibit straight movements since the high flows absorb the effect of the swirling flames. The addition of natural gases increases the combustion temperature up to 1211 °C and reduces the flow and length of the flames. Finally, temperatures up to 1298 °C and shorter flames are reached with natural gas enriched with a stream of oxygen, but in this case, NOx emissions need to be controlled. Full article

(This article belongs to the Special Issue Technologies for Climate-Neutral Energy Systems)

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15 pages, 2152 KiB

Open AccessFeature PaperArticle

Catalytic Hydrothermal Liquefaction of Brachychiton populneus Biomass for the Production of High-Value Bio-Crude

by Ikram Eladnani, Maria Paola Bracciale, Martina Damizia, Seyedmohammad Mousavi, Paolo De Filippis, Rajae Lakhmiri and Benedetta de Caprariis

Processes 2023, 11(2), 324; https://0-doi-org.brum.beds.ac.uk/10.3390/pr11020324 - 19 Jan 2023

Cited by 3 | Viewed by 1482

Abstract

The current study focused on the heterogenous catalytic hydrothermal liquefaction (HTL) of Brachychiton populneus biomass seed, using Ni as hydrogenation catalyst and Fe as active hydrogen producer. The activity of Ni metal and of Ni/Al₂O₃ in the HTL of seed [...] Read more.

The current study focused on the heterogenous catalytic hydrothermal liquefaction (HTL) of Brachychiton populneus biomass seed, using Ni as hydrogenation catalyst and Fe as active hydrogen producer. The activity of Ni metal and of Ni/Al₂O₃ in the HTL of seed (BS) and of a mixture of seed and shell (BM) was studied. To establish the best operating process conditions, the influence of variation of temperature and reaction time on the product yields was also examined. The highest bio-crude yields of 57.18% and 48.23% for BS and BM, respectively, were obtained at 330 °C and 10 min of reaction time, in the presence of Ni/Al₂O₃ as catalyst and Fe as hydrogen donor. Elemental analysis results showed that at these operative conditions, an increase of the higher heating value (HHV) from 25.14 MJ/kg to 38.04 MJ/kg and from 17.71 MJ/kg to 31.72 MJ/kg was obtained for BS and BM biomass, respectively, when the combination of Fe and Ni/Al₂O₃ was used. Gas chromatography–mass spectrometry (GC-MS) and Fourier transform infrared spectroscopy (FT-IR), used to determine the oils’ chemical compositions, showed that the combined presence of Fe and Ni/Al₂O₃ favored the hydrodeoxygenation of the fatty acids into hydrocarbons, indeed their amount increased to ≈20% for both biomasses used. These results demonstrate that the obtained bio-crude has the capacity to be a source of synthetic fuels and chemical feedstock. Full article

(This article belongs to the Special Issue Technologies for Climate-Neutral Energy Systems)

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36 pages, 1392 KiB

Open AccessFeature PaperArticle

Technological Energy Efficiency Improvements in Glass-Production Industries and Their Future Perspectives in Italy

by Alessandra Cantini, Leonardo Leoni, Saverio Ferraro, Filippo De Carlo, Chiara Martini, Fabrizio Martini and Marcello Salvio

Processes 2022, 10(12), 2653; https://0-doi-org.brum.beds.ac.uk/10.3390/pr10122653 - 09 Dec 2022

Cited by 4 | Viewed by 7573

Abstract

The glass industry is highly energy-intensive, consuming approximately 500–700 million GJ each year. Replacing inefficient equipment with better-performing equipment is a good strategy to reduce the energy consumption of a glass plant. Since there are many alternative solutions, the choice of which technological [...] Read more.

The glass industry is highly energy-intensive, consuming approximately 500–700 million GJ each year. Replacing inefficient equipment with better-performing equipment is a good strategy to reduce the energy consumption of a glass plant. Since there are many alternative solutions, the choice of which technological improvement to implement is usually difficult. Therefore, a review of solutions to reduce energy consumption in a glass plant is pivotal. The literature offers similar studies, but they are not sufficiently up-to-date and do not represent the actual state of the art, which should be updated. Thus, this paper aims to provide an updated list of alternative solutions, clustering them into different categories (e.g., the process stage). Moreover, this paper investigates the current applicability of energy-saving solutions in Italy. Specifically, a sample of 103 Italian companies is considered and the type of interventions that the companies recently implemented or that they intend to adopt is analyzed. Quantitative statistical and economic analyses were conducted to highlight the most popular solutions and determine their cost-effectiveness. The results show that most interventions consist of replacing machinery with more efficient ones, mainly in auxiliary systems (132 out of 426). The outcome of this paper could represent a guide to select energy-saving solutions. Full article

(This article belongs to the Special Issue Technologies for Climate-Neutral Energy Systems)

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Review

Jump to: Research

18 pages, 1838 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Renewable Power and Heat for the Decarbonisation of Energy-Intensive Industries

by Alessandro A. Carmona-Martínez, Alejandro Fresneda-Cruz, Asier Rueda, Olgu Birgi, Cosette Khawaja, Rainer Janssen, Bas Davidis, Patrick Reumerman, Martijn Vis, Emmanouil Karampinis, Panagiotis Grammelis and Clara Jarauta-Córdoba

Processes 2023, 11(1), 18; https://0-doi-org.brum.beds.ac.uk/10.3390/pr11010018 - 22 Dec 2022

Cited by 9 | Viewed by 3637

Abstract

The present review provides a catalogue of relevant renewable energy (RE) technologies currently available (regarding the 2030 scope) and to be available in the transition towards 2050 for the decarbonisation of Energy Intensive Industries (EIIs). RE solutions have been classified into technologies based [...] Read more.

The present review provides a catalogue of relevant renewable energy (RE) technologies currently available (regarding the 2030 scope) and to be available in the transition towards 2050 for the decarbonisation of Energy Intensive Industries (EIIs). RE solutions have been classified into technologies based on the use of renewable electricity and those used to produce heat for multiple industrial processes. Electrification will be key thanks to the gradual decrease in renewable power prices and the conversion of natural-gas-dependent processes. Industrial processes that are not eligible for electrification will still need a form of renewable heat. Among them, the following have been identified: concentrating solar power, heat pumps, and geothermal energy. These can supply a broad range of needed temperatures. Biomass will be a key element not only in the decarbonisation of conventional combustion systems but also as a biofuel feedstock. Biomethane and green hydrogen are considered essential. Biomethane can allow a straightforward transition from fossil-based natural gas to renewable gas. Green hydrogen production technologies will be required to increase their maturity and availability in Europe (EU). EIIs’ decarbonisation will occur through the progressive use of an energy mix that allows EU industrial sectors to remain competitive on a global scale. Each industrial sector will require specific renewable energy solutions, especially the top greenhouse gas-emitting industries. This analysis has also been conceived as a starting point for discussions with potential decision makers to facilitate a more rapid transition of EIIs to full decarbonisation. Full article

(This article belongs to the Special Issue Technologies for Climate-Neutral Energy Systems)

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