Special Issue "Progress in Energy Conversion Systems and Emission Control"

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Energy Systems".

Deadline for manuscript submissions: closed (15 January 2021).

Special Issue Editors

Dr. Anthony Anukam
E-Mail Website1 Website2
Guest Editor
Environmental and Energy Systems, Department of Engineering and Chemical Sciences, Karlstad University, SE-651 88 Karlstad, Sweden
Interests: energy systems optimization; emission control; combustion kinetics; biochemical and thermochemical conversion of biomass, biomass upgrade and characterization
Dr. Muhammad R Naqvi
E-Mail Website1 Website2
Co-Guest Editor
Environmental and Energy Systems, Department of Engineering and Chemical Sciences, Karlstad University, SE-651 88 Karlstad, Sweden
Interests: renewable energy; biomass conversion technologies; combined heat and power (CHP) plants; characterization and pyrolysis of agricultural residues; sustainability aspects of biofuels; carbon dioxide capture
Dr. Sampson Mamphweli
E-Mail Website1 Website2
Co-Guest Editor
Centre for Renewable and Sustainable Energy Studies, Faculty of Engineering, Stellenbosch University, Cnr Joubert and Banghoek Road, Matieland 7600, South Africa
Interests: biomass and bioenergy; renewable energy; emission measurements; anaerobic digestion; gasification; energy efficiency

Special Issue Information

Dear Colleagues,

We would like to take this opportunity to invite you to participate in a Special Issue on “Progress in Energy Conversion Systems and Emission Control”, to be published in Processes. Processes (ISSN 2227-9717; CODEN: PROCCO, 2018 Impact Factor: 1.963) is an international peer-reviewed open access journal on processes in chemistry, biochemistry, biology, materials, and related process/systems engineering research fields.

With the rapid increase in world population and industrialization, as well as the associated rise in demand for energy, the development of methods for optimizing energy conversion systems will continue to attract interest among many researchers. Key issues to complement energy demand and supply include the design and operation of energy conversion systems. In addition to the energy challenges, other issues of major global concern are the emissions from the energy conversion systems and their environmental impact, which requires greater attention because of the effects on health. However, a host of factors are responsible for the successful operation and performance of energy conversion systems, particularly thermal energy conversion systems, which includes the physical and chemical properties of the material used as feedstock, the conversion rate and residence time, as well as system operating conditions. Post-conversion concentrations of certain emitted gases, such as nitrogen oxides, sulfur oxides, hydrogen chloride, and volatile organic compounds, are influenced by the composition of the final product gas of the energy system and the material used as feedstock in the conversion process. For instance, in conversion technologies involving thermal energy systems, excessive volatile organic compounds are generated as a result of incomplete combustion and improper mixing of air–fuel in the conversion process, which can cause gradual deterioration of functional characteristics of vegetation. This Special Issue on “Progress in Energy Conversion Systems and Emission Control” seeks high-quality works and topics focusing on progress made not just in conventional energy conversion systems but also alternative systems with significant potential, as well as the environmental impact of the emissions from these systems and control measures. The Special Issue will publish both original research and review articles.

The potential non-exhaustive list of topics to be covered includes:   

  • Energy systems for biomass conversion
  • Modelling and simulation of energy systems
  • Algal systems
  • Biochemical systems
  • Thermochemical systems
  • Combustion kinetics
  • Emission measurements
  • Syngas analysis
  • Life cycle analysis
  • Technoeconomic analysis

Dr. Raza Naqvi
Dr. Muhammad R Naqvi
Prof. Sampson Mamphweli
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Processes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • energy systems
  • thermochemical systems
  • combustion kinetics
  • emission measurements
  • biochemical processes
  • algal conversion
  • life cycle assessments
  • biomass upgrade
  • biomass characterization
  • technoeconomic analysis

Published Papers (15 papers)

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Research

Open AccessFeature PaperArticle
Influence of Air Infiltration on Combustion Process Changes in a Rotary Tilting Furnace
Processes 2020, 8(10), 1292; https://doi.org/10.3390/pr8101292 - 15 Oct 2020
Cited by 1 | Viewed by 586
Abstract
Air infiltration into the combustion chambers of industrial furnaces is an unwanted phenomenon causing loss of thermal efficiency, fuel consumption increase, and the subsequent increase in operating costs. In this study, a novel design for a rotary tilting furnace door with improved construction [...] Read more.
Air infiltration into the combustion chambers of industrial furnaces is an unwanted phenomenon causing loss of thermal efficiency, fuel consumption increase, and the subsequent increase in operating costs. In this study, a novel design for a rotary tilting furnace door with improved construction features is proposed and tested experimentally in a laboratory-scale furnace, aimed at air infiltration rate reduction by decreasing the gap width between the static furnace door and the rotating body. Temperatures in the combustion chamber and oxygen content in the dry flue gas were measured to document changes in the combustion process with the varying gap width. Volumetric flow values of infiltrating air calculated based on measured data agree well with results of numerical simulations performed in ANSYS and with the reference calculation procedure used in relevant literature. An achievable air infiltration reduction of up to 50% translates into fuel savings of around 1.79 to 12% of total natural gas consumption of the laboratory-scale furnace. The average natural gas consumption increase of around 1.6% due to air infiltration into industrial-scale furnaces can thus likewise be halved, representing fuel savings of almost 0.3 m3 per ton of charge. Full article
(This article belongs to the Special Issue Progress in Energy Conversion Systems and Emission Control)
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Open AccessArticle
Study of Performance, Emissions, and Combustion of a Common-Rail Injection Engine Fuelled with Blends of Cocos nucifera Biodiesel with Diesel Oil
Processes 2020, 8(10), 1287; https://doi.org/10.3390/pr8101287 - 14 Oct 2020
Cited by 1 | Viewed by 441
Abstract
Renewable alternatives to fossil fuels, such as biodiesel, are necessary to lessen emission of greenhouse gases that are causing climate change. Using a high-pressure, medium-duty, common-rail, turbocharged four-cylinder diesel engine, this work studies the effect of adding Cocos nucifera biodiesel to conventional diesel [...] Read more.
Renewable alternatives to fossil fuels, such as biodiesel, are necessary to lessen emission of greenhouse gases that are causing climate change. Using a high-pressure, medium-duty, common-rail, turbocharged four-cylinder diesel engine, this work studies the effect of adding Cocos nucifera biodiesel to conventional diesel on exhaust emissions, engine performance, and combustion characteristics. An analysis and characterization of the key physicochemical properties of diesel, biodiesel, and biodiesel–diesel blends were carried out. The engine was fuelled with pure petroleum diesel and blended diesel containing a 10%, 20%, 30%, and 50% volume of coconut oil at full throttle and six different speed settings, respectively. The results showed relatively close physicochemical properties between the biodiesel blend and conventional petroleum fuel. Observations made over the entire speed range indicated that a higher coconut oil biodiesel (COB) content lowers the torque and brake power compared to diesel. In the case of engine exhaust gas, a reduction in carbon monoxide (CO) and smoke emissions were observed. Notably, COB50 gives out the highest nitrogen oxides (NOx) but it is raised even for other blends. The experimental results also demonstrated that a higher COB content achieves a lower peak pressure while the peak heat release rate (PHRR) was lower than that of conventional diesel as the speed of the engine increases. Full article
(This article belongs to the Special Issue Progress in Energy Conversion Systems and Emission Control)
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Open AccessArticle
Alexandrian Laurel for Biodiesel Production and its Biodiesel Blends on Performance, Emission and Combustion Characteristics in Common-Rail Diesel Engine
Processes 2020, 8(9), 1141; https://doi.org/10.3390/pr8091141 - 12 Sep 2020
Viewed by 542
Abstract
A two-step transesterification process was employed in the biodiesel production from non-edible Alexandrian Laurel. The key physicochemical properties of the Alexandrian Laurel biodiesel (ALB), diesel and blends of both fuels were compared and analyzed. The effects of blending biodiesel (ALB) and petroleum [...] Read more.
A two-step transesterification process was employed in the biodiesel production from non-edible Alexandrian Laurel. The key physicochemical properties of the Alexandrian Laurel biodiesel (ALB), diesel and blends of both fuels were compared and analyzed. The effects of blending biodiesel (ALB) and petroleum diesel on engine performance, combustion and exhaust emissions were investigated in a turbocharged, high-pressure common-rail diesel engine under six different speed operations and at full load conditions. The test fuels comprised a conventional diesel fuel and four different fuel blends of ALB. The results showed relatively close physicochemical properties of ALB and its blends when compared with petroleum diesel. However, the use of ALB-blended fuel resulted in penalties engine brake power, brake specific fuel consumption (BSFC) despite slightly improved brake thermal efficiency (BTE). Brake specific nitrogen oxide (BSNOx) was found worsened with higher ALB content in the blends. Nonetheless, consistent improvements in brake specific carbon monoxide (BSCO), brake specific carbon dioxide (BSCO2), and smoke were noticed when ALB blends were used. Additionally, ALB blends contributed to reduction in peak combustion pressure, peak heat release rate (HRR) and combustion duration. In general, the findings suggest satisfactory operation with ALB biodiesel-diesel blends in an unmodified diesel engine. Full article
(This article belongs to the Special Issue Progress in Energy Conversion Systems and Emission Control)
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Open AccessArticle
Technical Route to Achieve Ultra-Low Emission of Nitrogen Oxides with Predictive Model of Nitrogen Oxide Background Concentration
Processes 2020, 8(9), 1104; https://doi.org/10.3390/pr8091104 - 04 Sep 2020
Cited by 1 | Viewed by 495
Abstract
As the most mature denitration technology in the cement clinker burning process, selective non-catalytic reduction (SNCR) has been unable to meet the requirements of ultra-low nitrogen oxide (NOX) emissions under low ammonia escape, thus a hybrid denitration process based on SNCR [...] Read more.
As the most mature denitration technology in the cement clinker burning process, selective non-catalytic reduction (SNCR) has been unable to meet the requirements of ultra-low nitrogen oxide (NOX) emissions under low ammonia escape, thus a hybrid denitration process based on SNCR was established. The process had three steps: reducing the NOX background concentration (NBC), implementing staged combustion, and optimizing the effect of the SNCR. One of the keys to this process was the real-time acquisition of the NBC. In this paper, a multivariate linear regression model for the prediction of NBC was constructed and applied to one 12,000 t/d production line and one 5000 t/d production line. For the 12,000 t/d production line, NBC had a positive correlation with the temperature of the calciner outlet, the pressure, and the temperature of the kiln hood, and it had a negative correlation with the quantity of the kiln coal, the temperature of the smoke chamber, and the main motor current of the kiln. The influence degree of each parameter on the NBC is gradually weakened according to the above order. The determination coefficient (R2) of the model was 0.771, and the mean absolute error and maximum relative error between the predicted and measured NBC were 6.300 mg/m3 and 18.670 mg/m3 respectively. Full article
(This article belongs to the Special Issue Progress in Energy Conversion Systems and Emission Control)
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Open AccessArticle
Performance, Emissions, Combustion and Vibration Analysis of a CI Engine Fueled with Coconut and Used Palm Cooking Oil Methyl Ester
Processes 2020, 8(8), 990; https://doi.org/10.3390/pr8080990 - 15 Aug 2020
Cited by 1 | Viewed by 829
Abstract
Biodiesels from coconut and palm cooking oil are viable alternatives to diesel fuel due to their environmental sustainability and similar physicochemical properties compared to diesel. In the present study, these fuels were tested separately in a diesel engine by blending with fossil diesel [...] Read more.
Biodiesels from coconut and palm cooking oil are viable alternatives to diesel fuel due to their environmental sustainability and similar physicochemical properties compared to diesel. In the present study, these fuels were tested separately in a diesel engine by blending with fossil diesel in proportions of 10%, 20%, 30% and 40% by volume. Experiments were conducted under a constant brake mean effective pressure (BMEP) of 400 kPa and at 2000 rpm. The results revealed similarities in engine performance, emissions, combustion and engine block vibration for used palm cooking oil methyl ester (UPME) fuel blends and coconut methyl ester (CME) fuel blends. Most blends resulted in slight improvements in brake specific energy consumption (BSEC) and brake thermal efficiency (BTE). A maximum reduction of 54%, 89% and 16.8% in pollutant emissions of brake specific hydrocarbons (BSHC), brake specific carbon monoxide (BSCO) and brake specific nitrogen oxides (BSNOx), respectively, was observed with UPME and CME in the blends. The cylinder pressure profiles when UPME-diesel and CME-diesel blends were used were comparable to a standard diesel pressure trace, however, some deviations in peak pressure were also noticed. It was also apparent from the results that engine vibration was influenced by the type of methyl ester used and its blend composition. Notably, the rate of pressure increase was maintained within an acceptable limit when the engine was fueled with both of the methyl ester blends. Full article
(This article belongs to the Special Issue Progress in Energy Conversion Systems and Emission Control)
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Open AccessFeature PaperArticle
Experimental Investigation of Primary De-NOx Methods Application Effects on NOx and CO Emissions from a Small-Scale Furnace
Processes 2020, 8(8), 940; https://doi.org/10.3390/pr8080940 - 05 Aug 2020
Cited by 3 | Viewed by 674
Abstract
Nitrogen oxides (NOx) from combustion contribute significantly to atmospheric pollution. An experimental setup was employed to investigate the application of three primary denitrification methods, i.e., reburning (staged combustion), overfiring air (OFA), and flue-gas recirculation (FGR), individually and in combination, combusting natural [...] Read more.
Nitrogen oxides (NOx) from combustion contribute significantly to atmospheric pollution. An experimental setup was employed to investigate the application of three primary denitrification methods, i.e., reburning (staged combustion), overfiring air (OFA), and flue-gas recirculation (FGR), individually and in combination, combusting natural gas (NG) and propane–butane gas (PBG). Fuel heat inputs of 16 and 18 kW and air excess coefficients of 1.1 and 1.2, respectively, were tested. The highest individual denitrification efficiency of up to 74% was obtained for FGR, followed by reburning and OFA. A denitrification efficiency between 8.9% (reburning + OFA) and 72% (reburning + OFA + FGR) with NG combustion was observed. Using a 20% FGR rate yielded denitrification efficiency of 74% for NG and 65% for PBG and also led to a significant decrease in carbon monoxide (CO) emissions, so this can be recommended as the most efficient denitrification and de-CO method in small-scale furnaces. Reburning alone led to a sharp, more than 12-fold increase in CO emissions compared to the amount without any other method application. The presented results and the difference between our experimental data and the literature data acquired in some other studies indicate the need for further research. Full article
(This article belongs to the Special Issue Progress in Energy Conversion Systems and Emission Control)
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Open AccessArticle
Research on Combustion Characteristics of Air–Light Hydrocarbon Mixing Gas
Processes 2020, 8(6), 730; https://doi.org/10.3390/pr8060730 - 24 Jun 2020
Cited by 1 | Viewed by 637
Abstract
Air–light hydrocarbon mixing gas is a new type of city gas which is composed of light hydrocarbon with the main component of n-pentane and air mixed in a certain proportion. To explore the dominant reactions for CO production of air–light hydrocarbon mixing [...] Read more.
Air–light hydrocarbon mixing gas is a new type of city gas which is composed of light hydrocarbon with the main component of n-pentane and air mixed in a certain proportion. To explore the dominant reactions for CO production of air–light hydrocarbon mixing gas with different mixing degrees at the critical equivalence ratios, a computational study was conducted on the combustion characteristics, including the ignition delay time, laminar flame speed, extinction residence time, and emission of air–light hydrocarbon mixing gas at atmospheric pressure and room temperature in the present study. The calculated results indicate that the ignition delay time of air–light hydrocarbon mixing gas at temperatures of 1000–1118 K is greater than that of n-pentane, while the opposite at temperatures of 1118–1600 K. From the study of the laminar flame speed and ignition delay time, it was found that the essence of air–light hydrocarbon mixing gas is that its attribute parameter is determined by the ratio of n-pentane to the total amount of air at the moment of combustion. The changes in the extinction residence time and the CO emission index of air–light hydrocarbon mixing gas are not synchronized, that is the CO emission index is not necessarily small for air–light hydrocarbon mixing gas with excellent extinction residence time. CO sensitivity analysis and CO rate of production identified key species and reactions that are primarily responsible for CO formation and annihilation. The mixing degree plays a key role in the CO emission index of air–light hydrocarbon mixing gas, which has a constructive opinion on the future experiment and application of air–light hydrocarbon mixing gas. Full article
(This article belongs to the Special Issue Progress in Energy Conversion Systems and Emission Control)
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Open AccessArticle
Image-Based Model for Assessment of Wood Chip Quality and Mixture Ratios
Processes 2020, 8(6), 728; https://doi.org/10.3390/pr8060728 - 23 Jun 2020
Cited by 1 | Viewed by 738
Abstract
This article focuses on fuel quality in biomass power plants and describes an online prediction method based on image analysis and regression modeling. The main goal is to determine the mixture fraction from blends of two wood chip species with different qualities and [...] Read more.
This article focuses on fuel quality in biomass power plants and describes an online prediction method based on image analysis and regression modeling. The main goal is to determine the mixture fraction from blends of two wood chip species with different qualities and properties. Starting from images of both fuels and different mixtures, we used two different approaches to deduce feature vectors. The first one relied on integral brightness values while the latter used spatial texture information. The features were used as input data for linear and non-linear regression models in nine training classes. This permitted the subsequent prediction of mixture ratios from prior unknown similar images. We extensively discuss the influence of model and image selection, parametrization, the application of boosting algorithms and training strategies. We obtained models featuring predictive accuracies of R2 > 0.9 for the brightness-based model and R2 > 0.8 for the texture based one during the validation tests. Even when reducing the data used for model training down to two or three mixture classes—which could be necessary or beneficial for the industrial application of our approach—sampling rates of n < 5 were sufficient in order to obtain significant predictions. Full article
(This article belongs to the Special Issue Progress in Energy Conversion Systems and Emission Control)
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Open AccessArticle
Oxidation and Characterization of Low-Concentration Gas in a High-Temperature Reactor
Processes 2020, 8(4), 481; https://doi.org/10.3390/pr8040481 - 21 Apr 2020
Viewed by 821
Abstract
To achieve the efficient utilization of low-concentration mine gas, reduce resource waste and alleviate environmental pollution, the high-temperature oxidation of low-concentration gas at a concentration range of 1.00% to 1.50%, which is directly discharged into the atmosphere during coal mine production, was carried [...] Read more.
To achieve the efficient utilization of low-concentration mine gas, reduce resource waste and alleviate environmental pollution, the high-temperature oxidation of low-concentration gas at a concentration range of 1.00% to 1.50%, which is directly discharged into the atmosphere during coal mine production, was carried out to recover heat for reuse. The gas oxidation equipment was improved for the heating process and the safety of low-concentration gas oxidation under a high-temperature environment was evaluated. The experimental results showed that the reactor could provide a 1000 °C high-temperature oxidation environment for gas oxidation after installing high-temperature resistant ceramics. The pressure variation curves of the reactor with air and different concentrations of gas were similar. Due to the thermal expansion, the air pressure slightly increased and then returned to normal pressure. In contrast, the low-concentration gas exhibited a stable pressure response in the high-temperature environment of 1000 °C. The outlet pressure was significantly greater than the inlet pressure, and the pressure difference between the inlet and outlet exhibited a trend to increase with the gas concentration. The minimum pressure difference was 4 kPa (air) and the maximum was 11 kPa (1.50% gas). The explosion limit varied with the temperature and the blend of oxidation products. The ratio of measured gas pressure to air pressure after oxidation was below the explosion criterion, indicating that the measured concentration of gas is still safe after the shift of the explosion limit, which provides a safe concentration range for the efficient use of low-concentration gas in the future. Full article
(This article belongs to the Special Issue Progress in Energy Conversion Systems and Emission Control)
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Open AccessArticle
Mathematical Model of a Heating Furnace Implemented with Volumetric Fuel Combustion
Processes 2020, 8(4), 469; https://doi.org/10.3390/pr8040469 - 16 Apr 2020
Cited by 2 | Viewed by 887
Abstract
Heating flame furnaces are the main type of furnaces used for heating and heat treatment of metal products in metallurgy and mechanical engineering. In the working chamber of a modern heating furnace, there should be neither high-temperature nor stagnation zones. One of the [...] Read more.
Heating flame furnaces are the main type of furnaces used for heating and heat treatment of metal products in metallurgy and mechanical engineering. In the working chamber of a modern heating furnace, there should be neither high-temperature nor stagnation zones. One of the methods used to provide such combustion conditions is the application of distributed (volumetric) combustion. Owing to this method, heating quality is ensured by creating a uniform temperature field and equivalent heat exchange conditions, regardless of the placement of the charge in the working chamber of the furnace. In this work, we numerically study the volumetric combustion and influences of small- and large-scale recirculation ratios of furnace gases, the influence of temperature fluctuation on the regenerator nozzle, and the working parameters at the starting phase and reverse. Full article
(This article belongs to the Special Issue Progress in Energy Conversion Systems and Emission Control)
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Open AccessFeature PaperArticle
Impact of Varying Load Conditions and Cooling Energy Comparison of a Double-Inlet Pulse Tube Refrigerator
Processes 2020, 8(3), 352; https://doi.org/10.3390/pr8030352 - 19 Mar 2020
Cited by 2 | Viewed by 1448
Abstract
Modeling and optimization of a double-inlet pulse tube refrigerator (DIPTR) is very difficult due to its geometry and nature. The objective of this paper was to optimize-DIPTR through experiments with the cold heat exchanger (CHX) along the comparison of cooling load with experimental [...] Read more.
Modeling and optimization of a double-inlet pulse tube refrigerator (DIPTR) is very difficult due to its geometry and nature. The objective of this paper was to optimize-DIPTR through experiments with the cold heat exchanger (CHX) along the comparison of cooling load with experimental data using different boundary conditions. To predict its performance, a detailed two-dimensional DIPTR model was developed. A double-drop pulse pipe cooler was used for solving continuity, dynamic and power calculations. External conditions for applicable boundaries include sinusoidal pressure from an end of the tube from a user-defined function and constant temperature or limitations of thermal flux within the outer walls of exchanger walls under colder conditions. The results of the system’s cooling behavior were reported, along with the connection between the mass flow rates, heat distribution along pulse tube and cold-end pressure, the cooler load’s wall temp profile and cooler loads with varied boundary conditions i.e. opening of 20% double-inlet and 40-60% orifice valves, respectively. Different loading conditions of 1 and 5 W were applied on the CHX. At 150 K temperature of the cold-end heat exchanger, a maximum load of 3.7 W was achieved. The results also reveal a strong correlation between computational fluid dynamics modeling results and experimental results of the DIPTR. Full article
(This article belongs to the Special Issue Progress in Energy Conversion Systems and Emission Control)
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Open AccessArticle
Increased Energy Efficiency of a Backward-Feed Multiple-Effect Evaporator Compared with a Forward-Feed Multiple-Effect Evaporator in the Cogeneration System of a Sugar Factory
Processes 2020, 8(3), 342; https://doi.org/10.3390/pr8030342 - 16 Mar 2020
Cited by 5 | Viewed by 929
Abstract
The cogeneration system of a sugar factory consists of boiler, steam turbine, and sugar juice evaporation process. The multiple-effect evaporator used for the conventional sugar juice evaporation process is the forward-feed multiple-effect evaporator, in which steam and sugar juice flow in the same [...] Read more.
The cogeneration system of a sugar factory consists of boiler, steam turbine, and sugar juice evaporation process. The multiple-effect evaporator used for the conventional sugar juice evaporation process is the forward-feed multiple-effect evaporator, in which steam and sugar juice flow in the same direction. The main objective of this paper is to investigate the energy efficiency of the backward-feed multiple-effect evaporator, in which steam and sugar juice flow in opposite directions, compared with that of the forward-feed multiple-effect evaporator. Mathematical models are developed for both multiple-effect evaporators, and used to compare the performances of two cogeneration systems that use the forward-feed and backward-feed multiple-effect evaporators. The forward-feed multiple-effect evaporator requires extracted steam from a turbine at one pressure, whereas the backward-feed multiple-effect evaporator requires steam extraction at two pressures. Both evaporators have the same total heating surface area, process the same amount of sugar juice, and operate at the optimum conditions. It is shown that the cogeneration system that uses the backward-feed multiple-effect is more energy efficient than the cogeneration system that uses the forward-feed multiple-effect because it yields more power output for the same fuel consumption. Full article
(This article belongs to the Special Issue Progress in Energy Conversion Systems and Emission Control)
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Open AccessArticle
Laser-Induced Ignition and Combustion of Individual Aluminum Particles Below 10 μm by Microscopic High-Speed Cinematography
Processes 2020, 8(3), 280; https://doi.org/10.3390/pr8030280 - 28 Feb 2020
Cited by 3 | Viewed by 826
Abstract
Metal aluminum has been widely used as an ingredient in propellant, gunpowder and thermite, but there is less understanding of the combustion mechanism of aluminum particles from submicron to several microns in diameter. This paper proposes to experimentally investigate the ignition and combustion [...] Read more.
Metal aluminum has been widely used as an ingredient in propellant, gunpowder and thermite, but there is less understanding of the combustion mechanism of aluminum particles from submicron to several microns in diameter. This paper proposes to experimentally investigate the ignition and combustion characteristics of individual aluminum particles below 10 μm. A specific in situ diagnostic experimental apparatus was first designed for directly observing the ignition and combustion behaviors of individual aluminum particles, with a submicrometer spatial resolution and a temporal resolution of tens of microseconds. Direct observation through microscopic high-speed cinematography demonstrated that, when heated by a continuous laser, individual aluminum particles thermally expanded, followed by shell rupture; the molten aluminum core overflowed and evaporated, leading to ignition and combustion. Further results showed that, when the laser power densities were gradually increased (5.88, 7.56 and 8.81 × 105 W/cm2), the durations of thermal expansion, melting and evaporation were shortened. The required time for the aluminum particles to expand to 150% of their initial diameter was shortened (34 s, 0.34 s and 0.0125 s, respectively). This study will be beneficial to further extend the investigation of other individual metal particles and reveal their combustion mechanism by direct observation. Full article
(This article belongs to the Special Issue Progress in Energy Conversion Systems and Emission Control)
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Open AccessArticle
Thermodynamic Performance Analysis of Hydrofluoroolefins (HFO) Refrigerants in Commercial Air-Conditioning Systems for Sustainable Environment
Processes 2020, 8(2), 187; https://doi.org/10.3390/pr8020187 - 05 Feb 2020
Cited by 2 | Viewed by 1529
Abstract
Global warming is one of most severe environmental concerns that our planet is facing today. One of its causes is the previous generation of refrigerants that, upon release, remain in the atmosphere for longer periods and contribute towards global warming. This issue could [...] Read more.
Global warming is one of most severe environmental concerns that our planet is facing today. One of its causes is the previous generation of refrigerants that, upon release, remain in the atmosphere for longer periods and contribute towards global warming. This issue could potentially be solved by replacing the previous generation’s high global warming potential (GWP) refrigerants with environmentally friendly refrigerants. This scenario requires an analysis of new refrigerants for a comparison of the thermodynamic properties of the previously used refrigerants. In the present research, a numerical study was conducted to analyze the thermodynamic performance of specifically low GWP hydrofluoroolefens (HFO) refrigerants for an actual vapor compression refrigeration cycle (VCRC) with a constant degree of 3 K superheat. The output parameters included the refrigeration effect, compressor work input, the coefficient of performance (COP), and the volumetric refrigeration capacity (VRC), all of which were calculated by varying the condenser pressure from 6 to 12 bars and vapor pressure from 0.7 to 1.9 bars. Results showed that R1234ze(Z) clearly possessed the desired thermodynamic performance. The drop in refrigeration effect for R1234ze(Z) was merely 14.6% less than that of R134a at a 12 bar condenser pressure; this was minimum drop among candidate refrigerants. The drop in the COP was the minimum for R1234ze(Z)—5.1% less than that of R134a at a 9 bar condenser pressure and 4.7% less than that of R134a at a 1.9 bar evaporator pressure, whereas the COP values of the other refrigerants dropped more drastically at higher condenser pressures. R1234ze(Z) possessed favorable thermodynamic characteristics, with a GWP of 7, and it can serve as an alternative refrigerant for refrigeration systems for a sustainable environment. Full article
(This article belongs to the Special Issue Progress in Energy Conversion Systems and Emission Control)
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Open AccessFeature PaperArticle
Use of Gasoline, LPG and LPG-HHO Blend in SI Engine: A Comparative Performance for Emission Control and Sustainable Environment
Processes 2020, 8(1), 74; https://doi.org/10.3390/pr8010074 - 06 Jan 2020
Cited by 12 | Viewed by 1968
Abstract
The rising global warming concerns and explosive degradation of the environment requires the mainstream utilization of alternative fuels, such as hydroxy gas (HHO) which presents itself as a viable substitute for extracting the benefits of hydrogen. Therefore, an experimental study of the performance [...] Read more.
The rising global warming concerns and explosive degradation of the environment requires the mainstream utilization of alternative fuels, such as hydroxy gas (HHO) which presents itself as a viable substitute for extracting the benefits of hydrogen. Therefore, an experimental study of the performance and emission characteristics of alternative fuels in contrast to conventional gasoline was undertaken. For experimentation, a spark ignition engine was run on a multitude of fuels comprising of gasoline, Liquefied petroleum gas (LPG) and hybrid blend of HHO with LPG. The engine was operated at 60% open throttle with engine speed ranging from 1600 rpm to 3400 rpm. Simultaneously, the corresponding performance parameters including brake specific fuel consumption, brake power and brake thermal efficiency were investigated. Emission levels of CO, CO2, HC and NOx were quantified in the specified speed range. To check the suitability of the acquired experimental data, it was subjected to a Weibull distribution fit. Enhanced performance efficiency and reduced emissions were observed with the combustion of the hybrid mixture of LPG with HHO in comparison to LPG: on average, brake power increased by 7% while the brake specific fuel consumption reduced by 15%. On the other hand, emissions relative to LPG decreased by 21%, 9% and 21.8% in cases of CO, CO2, and unburned hydrocarbons respectively. Incorporating alternative fuels would not only imply reduced dependency on conventional fuels but would also contribute to their sustainability for future generations. Simultaneously, the decrease in harmful environmental pollutants would help to mitigate and combat the threats of climate change. Full article
(This article belongs to the Special Issue Progress in Energy Conversion Systems and Emission Control)
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