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22 pages, 5328 KiB

Open AccessArticle

Modeling and Integrated Optimization of Power Split and Exhaust Thermal Management on Diesel Hybrid Electric Vehicles

by Jinghua Zhao, Yunfeng Hu, Fangxi Xie, Xiaoping Li, Yao Sun, Hongyu Sun and Xun Gong

Energies 2021, 14(22), 7505; https://doi.org/10.3390/en14227505 - 10 Nov 2021

Cited by 4 | Viewed by 1672

Abstract

To simultaneously achieve high fuel efficiency and low emissions in a diesel hybrid electric vehicle (DHEV), it is necessary to optimize not only power split but also exhaust thermal management for emission aftertreatment systems. However, how to coordinate the power split and the [...] Read more.

To simultaneously achieve high fuel efficiency and low emissions in a diesel hybrid electric vehicle (DHEV), it is necessary to optimize not only power split but also exhaust thermal management for emission aftertreatment systems. However, how to coordinate the power split and the exhaust thermal management to balance fuel economy improvement and emissions reduction remains a formidable challenge. In this paper, a hierarchical model predictive control (MPC) framework is proposed to coordinate the power split and the exhaust thermal management. The method consists of two parts: a fuel and thermal optimized controller (FTOC) combining the rule-based and the optimization-based methods for power split simultaneously considering fuel consumption and exhaust temperature, and a fuel post-injection thermal controller (FPTC) for exhaust thermal management with a separate fuel injection system added to the exhaust pipe. Additionally, preview information about the road grade is introduced to improve the power split by a fuel and thermal on slope forecast optimized controller (FTSFOC). Simulation results show that the hierarchical method (FTOC + FPTC) can reach the optimal exhaust temperature nearly 40 s earlier, and its total fuel consumption is also reduced by 8.9%, as compared to the sequential method under a world light test cycle (WLTC) driving cycle. Moreover, the total fuel consumption of the FTSFOC is reduced by 5.2%, as compared to the fuel and thermal on sensor-information optimized controller (FTSOC) working with real-time road grade information. Full article

(This article belongs to the Special Issue Advances in Reduction Technologies of Gas Emissions (CO2, NOx, and SO2) in Combustion-Related Applications)

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15 pages, 5611 KiB

Open AccessArticle

Experimental Investigation of the Ash Deposition Characteristics of Biomass Pretreated by Ash Removal during Co-Combustion with Sub-Bituminous Coal

by Dae-Gyun Lee, Min-Jong Ku, Kyeong-Ho Kim, Jae-Sung Kim, Seung-Mo Kim and Chung-Hwan Jeon

Energies 2021, 14(21), 7391; https://doi.org/10.3390/en14217391 - 5 Nov 2021

Cited by 7 | Viewed by 2106

Abstract

Although replacing biomass, (e.g., wood chips and pellets), with thinning wood and herbaceous biomass is eco-friendly and economically advantageous, their direct utilization in plant boilers is associated with ash-related challenges, including slagging and fouling. The aim of this study is to determine the [...] Read more.

Although replacing biomass, (e.g., wood chips and pellets), with thinning wood and herbaceous biomass is eco-friendly and economically advantageous, their direct utilization in plant boilers is associated with ash-related challenges, including slagging and fouling. The aim of this study is to determine the effects of ash removal treatment (ashless biomass (ALB)) in the context of solid fuel power plant boilers. Ash was removed via neutralization of metal ions and carboxylic acids contained in the biomass ash. The ash removal rate of K, Na, Cl was indicated by assessing the total biomass before and after ash removal treatment, via XRF analysis. Co-combustion with sub-bituminous coal and ALB-treated biomass was analyzed using a drop tube furnace and revealed that NOx and SOx values converged converge toward an approximate 10 ppm error, whereas the Unburned Carbon (UBC) data did not exhibit a specific trend. Factors associated with slagging and fouling, (capture efficiency (CE), and energy based growth rate (GRE)) were calculated. All biomass samples without pretreatment exhibited V-shaped variation. Conversely, for ashless biomass (ALB) samples, CE and GRE gradually decreased. Thus, the ALB technique may minimize slagging and fouling in a boiler, thus, reducing internal corrosion associated with ash deposition and enhancing the economic operation of boilers. Full article

(This article belongs to the Special Issue Advances in Reduction Technologies of Gas Emissions (CO2, NOx, and SO2) in Combustion-Related Applications)

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21 pages, 17304 KiB

Open AccessArticle

NOx Emission of a Correlation between the PEMS and SEMS over Different Test Modes and Real Driving Emission

by Young Soo Yu, Jun Woo Jeong, Mun Soo Chon and Junepyo Cha

Energies 2021, 14(21), 7250; https://doi.org/10.3390/en14217250 - 3 Nov 2021

Cited by 8 | Viewed by 2303

Abstract

The aim of this study is to verify the reliability of NOx emissions measured using Smart Emissions Measurement System (SEMS) equipment in comparison with the NOx emissions measured using certified Portable Emissions Measurement System (PEMS) equipment. The SEMS equipment is simple system, and [...] Read more.

The aim of this study is to verify the reliability of NOx emissions measured using Smart Emissions Measurement System (SEMS) equipment in comparison with the NOx emissions measured using certified Portable Emissions Measurement System (PEMS) equipment. The SEMS equipment is simple system, and it is less expensive than the PEMS equipment, as it comprises an On-Board Diagnostics (OBD) signal from the test vehicle and a NOx sensor. The SEMS equipment based on low-cost sensors has an advantage of building big data, but there are insufficient previous studies comparing of NOx emissions with certified the PEMS equipment. Therefore, this study is important in verifying the suitability of the SEMS equipment by comparing the NOx emissions measured by the various test modes and RDE using the two types of equipment. To analyze the correlation between the PEMS and SEMS equipment, the advanced diesel vehicle was equipped with the two types of equipment to simultaneously measure NOx emissions. After installing the equipment on the test vehicle, it was conducted under various test modes in the laboratory and the Real Driving Emission (RDE) test to verify the correlation of NOx emissions measured by the SEMS equipment. The correlation analysis for the NOx emissions measured by the PEMS and SEMS equipment under various test conditions and the RDE test indicated that the slope of the NOx emissions was approximately equal to 1, and the coefficient of determination was 0.9 or higher. Based on these test results, it was concluded that NOx emissions measured by the PEMS and SEMS equipment are highly similar. Full article

(This article belongs to the Special Issue Advances in Reduction Technologies of Gas Emissions (CO2, NOx, and SO2) in Combustion-Related Applications)

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12 pages, 7140 KiB

Open AccessArticle

Spraying and Mixing Characteristics of Urea in a Static Mixer Applied Marine SCR System

by Jaehwan Jang, Sangkyung Na, Heehwan Roh, Seongyool Ahn and Gyungmin Choi

Energies 2021, 14(18), 5788; https://doi.org/10.3390/en14185788 - 14 Sep 2021

Cited by 7 | Viewed by 2196

Abstract

The most effective de-NOx technology in marine diesel applications is the urea-based selective catalytic reduction (SCR) system. The urea-SCR system works by injecting a urea solution into exhaust gas and converting this to NH₃ and CO₂. The injection, mixing, and [...] Read more.

The most effective de-NOx technology in marine diesel applications is the urea-based selective catalytic reduction (SCR) system. The urea-SCR system works by injecting a urea solution into exhaust gas and converting this to NH₃ and CO₂. The injection, mixing, and NH₃ conversion reaction behavior of the urea-water solution all have a decisive effect on the performance of the system. To improve de-NOx efficiency, it is important to provide enough time and distance for NH₃ conversion and uniform distribution prior to the solution entering the catalyst. In this study, therefore, the characteristics of gas flow, NH₃ conversion, and its distribution are investigated with a static mixer by means of numerical methods, providing a special advantage to ship manufacturing companies through the optimization of the urea-SCR system. The results show that the inclusion of the mixer induces strong turbulence and promotes the NH₃ conversion reaction across a wider region compared to the case without the mixer. The mean temperature is 10 °C lower due to the activated endothermic urea-NH₃ conversion reaction and the NH₃ concentration is 80 PPM higher at 1D than those without the mixer. Moreover, the uniformity of NH₃ distribution improved by 25% with the mixer, meaning that the de-NOx reaction can take place across all aspects of the catalyst thus maximizing performance. In other words, ship manufacturing companies have degrees of freedom in designing post-processing solutions for emissions by minimizing the use of the reduction agent or the size of the SCR system. Full article

(This article belongs to the Special Issue Advances in Reduction Technologies of Gas Emissions (CO2, NOx, and SO2) in Combustion-Related Applications)

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13 pages, 4530 KiB

Open AccessArticle

Influence of DC Electric Field on the Propane-Air Diffusion Flames and NO_x Formation

by Sang-Min Kim, Kyeong-Soo Han and Seung-Wook Baek

Energies 2021, 14(18), 5745; https://doi.org/10.3390/en14185745 - 13 Sep 2021

Cited by 4 | Viewed by 1696

Abstract

The aim of this research is to investigate the effects of a direct current (DC) electric field on the combustion behavior of a co-flow propane diffusion flame. The flame length and NO_x emission were observed and measured. The electric field enhances the [...] Read more.

The aim of this research is to investigate the effects of a direct current (DC) electric field on the combustion behavior of a co-flow propane diffusion flame. The flame length and NO_x emission were observed and measured. The electric field enhances the combustion process of propane diffusion flame by causing the movement of ions and molecules in the flame, resulting in a change in the shape of the flame. The flame heights decrease with an increase in the applied voltage and polarity, a more dominant effect to be observed with a positive DC electric field. However, for the applied negative polarity, the inner-cone of the propane diffusion flame is shifted by the electric field. Drastic reduction in the NO_x emission is observed with an increase in the applied DC voltage and polarity. In the existing system, the reduction percentage of NOx is within the range of 55 to 78%. Full article

(This article belongs to the Special Issue Advances in Reduction Technologies of Gas Emissions (CO2, NOx, and SO2) in Combustion-Related Applications)

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12 pages, 2821 KiB

Open AccessArticle

Thermal Absorption Performance Evaluation of Water-Based Nanofluids (CNTs, Cu, and Al₂O₃) for Solar Thermal Harvesting

by Youngho Lee, Hyomin Jeong and Yonmo Sung

Energies 2021, 14(16), 4875; https://doi.org/10.3390/en14164875 - 10 Aug 2021

Cited by 6 | Viewed by 1792

Abstract

For solar thermal harvesting, an experimental study was performed on the thermal absorption performance of water-based carbon nanotubes (CNTs), Cu, and Al₂O₃ nanofluids using a halogen lamp-based thermal radiation system. The effect of nanoparticle concentrations (0.01 wt.%, 0.1 wt.%, and [...] Read more.

For solar thermal harvesting, an experimental study was performed on the thermal absorption performance of water-based carbon nanotubes (CNTs), Cu, and Al₂O₃ nanofluids using a halogen lamp-based thermal radiation system. The effect of nanoparticle concentrations (0.01 wt.%, 0.1 wt.%, and 1 wt.%) on the nanofluid dispersion, stability, and thermal absorption characteristics was investigated, and a comparative analysis was performed for each type of nanofluid. All types of nanofluids increased the absorbance and electrical conductivity with increasing nanoparticle concentration, which contributed to improving the thermal absorption performance of nanofluids. The results showed that the thermal absorption performance was high in the order of carbon-based nanofluids (CNTs), metal-based nanofluids (Cu), and oxide-based nanofluids (Al₂O₃). In CNTs nanofluids, the thermal absorption performance expressed the time reduction rate, which was 12.8%, 16.3%, and 16.4% at 0.01 wt.%, 0.1 wt.%, and 1 wt.% test cases, respectively. Therefore, the 0.1 wt.%-CNTs nanofluid is more economical and appropriate. However, in Al₂O₃ nanofluids, the time reduction rate of the 1 wt.% nanofluid was significantly higher than that of the 0.01 wt.% and 0.1 wt.% nanofluids. In Cu nanofluids, unlike CNTs and Al₂O₃ nanofluids, the time reduction rate constantly increased as the nanoparticle concentration increased. Full article

(This article belongs to the Special Issue Advances in Reduction Technologies of Gas Emissions (CO2, NOx, and SO2) in Combustion-Related Applications)

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16 pages, 5744 KiB

Open AccessFeature PaperArticle

Analysis of Driving Dynamics Considering Driving Resistances in On-Road Driving

by Jingeun Song and Junepyo Cha

Energies 2021, 14(12), 3408; https://doi.org/10.3390/en14123408 - 9 Jun 2021

Cited by 11 | Viewed by 2937

Abstract

Internal combustion engine emissions are a serious worldwide problem. To combat this, emission regulations have become stricter with the goal of reducing the proportion of transportation emissions in global air pollution. In addition, the European Commission passed the real driving emissions–light-duty vehicles (RDE-LDV) [...] Read more.

Internal combustion engine emissions are a serious worldwide problem. To combat this, emission regulations have become stricter with the goal of reducing the proportion of transportation emissions in global air pollution. In addition, the European Commission passed the real driving emissions–light-duty vehicles (RDE-LDV) regulation that evaluates vehicle emissions by driving on real roads. The RDE test is significantly dependent on driving conditions such as traffic or drivers. Thus, the RDE regulation has the means to evaluate driving dynamics such as the vehicle speed per acceleration (v·a_pos) and the relative positive acceleration (RPA) to determine whether the driving during these tests is normal or abnormal. However, this is not an appropriate way to assess the driving dynamics because the v⋅a_pos and the RPA do not represent engine load, which is directly related to exhaust emissions. Therefore, in the present study, new driving dynamic variables are proposed. These variables use engine acceleration calculated from wheel force instead of the acceleration calculated from the vehicle speed, so they are proportional to the engine load. In addition, a variable of driving dynamics during braking is calculated using the negative wheel force. This variable can be used to improve the accuracy of the emission assessment by analyzing the braking pattern. Full article

(This article belongs to the Special Issue Advances in Reduction Technologies of Gas Emissions (CO2, NOx, and SO2) in Combustion-Related Applications)

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15 pages, 4613 KiB

Open AccessArticle

Nitric Oxide Emission Reduction in Reheating Furnaces through Burner and Furnace Air-Staged Combustions

by Yonmo Sung, Seungtae Kim, Byunghwa Jang, Changyong Oh, Taeyun Jee, Soonil Park, Kwansic Park and Siyoul Chang

Energies 2021, 14(6), 1599; https://doi.org/10.3390/en14061599 - 13 Mar 2021

Cited by 2 | Viewed by 2417

Abstract

In this study, a series of experiments were conducted on a testing facility and a real-scale furnace, for analyzing the nitric oxide (NO) emission reduction. The effects of the temperature, oxygen concentration, and amount of secondary combustion air were investigated in a single-burner [...] Read more.

In this study, a series of experiments were conducted on a testing facility and a real-scale furnace, for analyzing the nitric oxide (NO) emission reduction. The effects of the temperature, oxygen concentration, and amount of secondary combustion air were investigated in a single-burner combustion system. Additionally, the NO-reduction rate before and after combustion modifications in both the burner and furnace air-staged combustion were evaluated for a real-scale reheating furnace. The air-to-fuel equivalence ratio (λ) of individual combustion zones for the furnace was optimized for NO reduction without any incomplete combustion. The results indicated that the NO emission for controlling the λ of a single-zone decreased linearly with a decrease in the λ values in the individual firing tests (top-heat, bottom-heat, and bottom-soak zones). Moreover, the multi-zone control of the λ values for individual combustion zones was optimized at 1.13 (top-preheat), 1.0 (bottom-preheat), 1.0 (top-heat), 0.97 (bottom-heat), 1.0 (top-soak), and 0.97 (bottom-soak). In this firing condition, the modifications reduced the NO emissions by approximately 23%, as indicated by a comparison of the data obtained before and after the modifications. Thus, the combined application of burner and furnace air-staged combustions facilitated NO-emission reduction. Full article

(This article belongs to the Special Issue Advances in Reduction Technologies of Gas Emissions (CO2, NOx, and SO2) in Combustion-Related Applications)

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13 pages, 3342 KiB

Open AccessArticle

Evaporator Optimization of Refrigerator Systems Using Quality Analysis

by Sangkyung Na, Sanghun Song, Seunghyuk Lee, Jehwan Lee, Hyun Kim, Sungwoo Lee, Gyungmin Choi and Seongyool Ahn

Energies 2021, 14(3), 555; https://doi.org/10.3390/en14030555 - 22 Jan 2021

Cited by 3 | Viewed by 2292

Abstract

In this study, evaporator optimization, via both experimental and simulation methods was conducted. To evaluate the evaporator performance, under the optimal system, the compressor operating time and the effects of oil on the refrigerator system were studied. If the temperature of the refrigerator [...] Read more.

In this study, evaporator optimization, via both experimental and simulation methods was conducted. To evaluate the evaporator performance, under the optimal system, the compressor operating time and the effects of oil on the refrigerator system were studied. If the temperature of the refrigerator chamber reaches the setting value, the compressor stops working and it leads to the temperature of the refrigerator chamber slowly increasing, due to the heat transfer to the ambient. When the refrigerator temperature is out of the setting range, the compressor works again, and the refrigerator repeats this process until the end of its life. These on/off period can be controlled through the compressor piston movement. To determine the optimal compressor operating conditions, experiments of monthly power consumption were conducted under various compressor working times and the lowest power consumption conditions was determined when the compressor worked continuously. Lubricating oil, the refrigerator system, using oil, also influenced the system performance. To evaluate the effect of oil, oil eliminated and oil systems were compared based on cooling capacity and power consumption. The cooling capacity of the oil eliminated system was 2.6% higher and the power consumption was 3.6% lower than that of the oil system. After determining the optimal operating conditions of the refrigerator system, visualization experiments and simulations were conducted to decide the optimal evaporator and the conventional evaporator size can be reduced by approximately 2.9%. Full article

(This article belongs to the Special Issue Advances in Reduction Technologies of Gas Emissions (CO2, NOx, and SO2) in Combustion-Related Applications)

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Review

Jump to: Research

29 pages, 18845 KiB

Open AccessReview

Recent Advances in Ammonia Combustion Technology in Thermal Power Generation System for Carbon Emission Reduction

by Hookyung Lee and Min-Jung Lee

Energies 2021, 14(18), 5604; https://doi.org/10.3390/en14185604 - 7 Sep 2021

Cited by 46 | Viewed by 11041

Abstract

With the formation of an international carbon-neutral framework, interest in reducing greenhouse gas emissions is increasing. Ammonia is a carbon-free fuel that can be directly combusted with the role of an effective hydrogen energy carrier, and its application range is expanding. In particular, [...] Read more.

With the formation of an international carbon-neutral framework, interest in reducing greenhouse gas emissions is increasing. Ammonia is a carbon-free fuel that can be directly combusted with the role of an effective hydrogen energy carrier, and its application range is expanding. In particular, as research results applied to power generation systems such as gas turbines and coal-fired power plants have been reported, the technology to use them is gradually being advanced. In the present study, starting with a fundamental combustion research case conducted to use ammonia as a fuel, the application research case for gas turbines and coal-fired power plants was analyzed. Finally, we report the results of the ammonia-air burning flame and pulverized coal-ammonia-air co-fired research conducted at the authors’ research institute. Full article

(This article belongs to the Special Issue Advances in Reduction Technologies of Gas Emissions (CO2, NOx, and SO2) in Combustion-Related Applications)

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